Regulatory guides are issued to describe and make available to the public such information as methods acceptable to the NRC staff for implementing specific partsof the NRC’s regulations, techniques used by the staff in evaluating specific problems or postulated accidents, and data needed by the NRC staff in its review ofapplications for permits and licenses. Regulatory guides are not substitutes for regulations, and compliance with them is not required. Methods and solutions differentfrom those set out in the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or license by guide was issued after consideration of comments received from the public. Comments and suggestions for improvements in these guides are encouraged at alltimes, and guides will be revised, as appropriate, to accommodate comments and to reflect new information or experience. Written comments may be submitted to theRules and Directives Branch, ADM, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.
Regulatory guides are issued in ten broad divisions: 1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials Facilities; 4, Environmental and Siting;5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health; 9, Antitrust and Financial Review; and 10, General.
Single copies of regulatory guides (which may be reproduced) may be obtained free of charge by writing the Distribution Services Section, U.S. Nuclear RegulatoryCommission, Washington, DC 20555-0001, or by fax to (301)415-2289, or by email to DISTRIBUTION@. Electronic copies of this guide and other recentlyissued guides are available at NRC’s home page at <> through the Electronic Reading Room, Accession Number ML032740277.
conditions (i.e., remain functional under all postulated service conditions) and that design controlmeasures such as testing are to be used to check the adequacy of design. Section 50.55a(h) of 10 CFRPart 50 states that protection systems must meet the requirements of the Institute of Electrical andElectronics Engineers (IEEE) standard (Std) 603-1991, “Criteria for Safety Systems for Nuclear PowerGenerating Stations,”1 or IEEE Std 279-1971, “Criteria for Protection Systems for Nuclear PowerGenerating Stations,”1 contingent on the date of construction permit issuance. The design basis criteriaidentified in those standards, or by similar provisions in the licensing basis for such facilities, include therange of transient and steady state environmental conditions during normal, abnormal, and accidentcircumstances throughout which the equipment must perform. Criterion III, “Design Control,” CriterionXI, “Test Control,” and Criterion XVII, “Quality Assurance Records,” of Appendix B, “QualityAssurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants,” to 10 CFR Part 50establish practices to confirm that a design fulfills its technical requirements. Furthermore, 10 CFR 50.49and 50.55a address validation measures such as testing that can be used to check the adequacy ofdesign. Related requirements are contained in General Design Criteria 1, 2, 4, 13, 21, 22, and 23 ofAppendix A, “General Design Criteria for Nuclear Power Plants,” to 10 CFR Part 50. Additionally,Subpart B, “Standard Design Certifications,” of 10 CFR Part 52, “Early Site Permits; Standard DesignCertifications; and Combined Licenses for Nuclear Power Plants,” addresses verification requirementsfor advanced reactor designs. Specifically, 10 CFR 52.47(a)(vi) requires that an application for designcertification must state the tests, inspections, analyses, and acceptance criteria that are necessary andsufficient to provide reasonable assurance that a plant will operate within the design certification.
Methods for addressing electromagnetic compatibility (EMC) constitute Tier 2* information under the 10CFR Part 52 requirements.2Electromagnetic interference (EMI), radio-frequency interference (RFI), and power surges havebeen identified as environmental conditions that can affect the performance of safety-related electricalequipment. Confirmatory research findings to support this observation can be found in NUREG/CR-5700, “Aging Assessment of Reactor Instrumentation and Protection System Components”3 (July 1992);NUREG/CR-5904, “Functional Issues and Environmental Qualification of Digital Protection Systems ofAdvanced Light-Water Nuclear Reactors”3 (April 1994); NUREG/CR-6406, “Environmental Testing ofan Experimental Digital Safety Channel”3 (September 1996); and NUREG/CR-6579, “Digital I&CSystems in Nuclear Power Plants: Risk-Screening of Environmental Stressors and a Comparison ofHardware Unavailability With an Existing Analog System”3 (January 1998). Therefore, controllingelectrical noise and the susceptibility of I&C systems to EMI/RFI and power surges is an important stepin meeting the aforementioned requirements.
12 IEEE publications may be purchased from the IEEE Service Center, 445 Hoes Lane, Piscataway, NJ 08855-1331. An applicant who references an advanced reactor certification is not allowed to depart from the Tier 2* commitments withoutNRC approval. Thus, changes cannot be made under a process such as that in 10 CFR 50.59. Copies are available at current rates from the U.S. Government Printing Office, P.O. Box 37082, Washington, DC 20402-9328(telephone (202)512-1800); or from the National Technical Information Service by writing NTIS at 5285 Port Royal Road,Springfield, VA 22161; (telephone (703)487-4650;. Copies are available for inspection orcopying for a fee from the NRC Public Document Room at 11555 Rockville Pike, Rockville, MD; the PDR’s mailing address isUSNRC PDR, Washington, DC 20555; telephone (301)415-4737 or (800)397-4209; fax (301)415-3548; email isPDR@.31.180-2
This regulatory guide endorses design, installation, and testing practices acceptable to the NRCstaff for addressing the effects of EMI/RFI and power surges on safety-related I&C systems in a nuclearpower plant environment. The design and installation practices described in IEEE Std 1050-1996,“IEEE Guide for Instrumentation and Control Equipment Grounding in Generating Stations,”1 areendorsed for limiting EMI/RFI subject to the conditions stated in the Regulatory Position. EMC testingpractices from military and commercial standards are endorsed to address electromagnetic emissions,EMI/RFI susceptibility, and power surge withstand capability (SWC). Selected EMI/RFI test methodsfrom MIL-STD-461E, “Requirements for the Control of Electromagnetic Interference Characteristics ofSubsystems and Equipment,”4 and the IEC 61000 Series are endorsed to evaluate conducted andradiated EMI/RFI phenomena for safety-related I&C systems. The IEC standards include IEC 61000-3, “Electromagnetic Compatibility (EMC) - Part 3: Limits,”5 IEC 61000-4, “ElectromagneticCompatibility (EMC) - Part 4: Testing and Measurement Techniques,”5 and IEC 61000-6,Electromagnetic Compatibility (EMC) - Part 6: Generic Standards.”5 This regulatory guide providesacceptable suites of EMI/RFI emissions and susceptibility methods from the most recent versions of themilitary standard and international commercial standards. These suites of test methods can be applied asalternative sets (guidance is provided in the Regulatory Position). This regulatory guide also endorseselectromagnetic operating envelopes corresponding to the MIL-STD-461E test methods. Theseoperating envelopes were tailored from the MIL-STD-461E test limits to represent the characteristicelectromagnetic environment in key locations at nuclear power plants. Comparable operating envelopesfor the IEC 61000 test methods are also endorsed. The operating envelopes are presented within theRegulatory Position, along with descriptions of the endorsed MIL-STD-461E and IEC 61000 testmethods.
The SWC practices described in IEEE Std C62.41-1991 (reaffirmed in 1995), “IEEERecommended Practice on Surge Voltages in Low-Voltage AC Power Circuits,”1 and IEEE StdC62.45-1992 (reaffirmed in 1997), “IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC Power Circuits,”1 are acceptable to the NRC staff regarding the effect of power surges onsafety-related I&C systems in nuclear power plants. A specific set of surge test waveforms are endorsedfrom IEEE Std C62.41-19911 as acceptable SWC test criteria. The associated test methods in IEEEStd C62.45-19921 are endorsed to describe the approach to be employed when assessing SWC.
General withstand levels are endorsed for use with the SWC test criteria and are presented within theRegulatory Position, along with the description of the endorsed surge waveforms. Alternative SWCpractices from IEC 61000-45 are acceptable to the NRC staff and are also presented within theRegulatory practices endorsed in this regulatory guide apply to both safety-related I&C systems andnon-safety-related I&C systems whose failures can affect safety functions. The rationale for the selectionof the practices depicted in this guide is that they provide a well established, systematic approach forensuring EMC and the capability to withstand power surges in I&C equipment within the environment in Military Standards are available from the Department of Defense, Standardization Documents Order Desk, Building 4D, 700Robbins Avenue, Philadelphia, PA 19111-5094.4 IEC publications may be purchased from the International Electrotechnical Commission, 3 rue de Varembé, Geneva,Switzerland. Telefax: +41 22 919 0300.51.180-3
which it operates. The technical basis for selecting these particular practices is given in NUREG/CR-5941, “Technical Basis for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related I&C Systems”3 (April 1994), NUREG/CR-6431, “Recommended Electromagnetic OperatingEnvelopes for Safety-Related I&C Systems in Nuclear Power Plants”3 (April 1999), NUREG/CR-5609, “Electromagnetic Compatibility Testing for Conducted Susceptibility Along Interconnecting SignalLines”3 (May 2003), and NUREG/CR-6782, “Comparison of U.S. Military and InternationalElectromagnetic Compatibility Guidance”3 (May 2003).In general, information provided by regulatory guides is reflected in the Standard Review Plan(NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear PowerPlants”).3 NRC’s Office of Nuclear Reactor Regulation uses the Standard Review Plan to reviewapplications to construct and operate nuclear power plants. This regulatory guide conforms to therevised Chapter 7, “Instrumentation and Controls,” of the Standard Review information collections contained in this regulatory guide are covered by the requirements of10 CFR Part 50, which were approved by the Office of Management and Budget (OMB), approvalnumber 3150-0011. The NRC may not conduct or sponsor, and a person is not required to respond to,a request for information or an information collection requirement unless the requesting document displaysa currently valid OMB control number.B. DISCUSSIONExisting I&C equipment in nuclear power plants is currently being replaced with computer-baseddigital I&C systems or advanced analog systems. However, these technologies may exhibit greatervulnerability to the nuclear power plant EMI/RFI environment than existing I&C systems. This regulatoryguide provides an acceptable method for qualifying digital and advanced analog systems for the projectedelectromagnetic environment in nuclear power typical environment in a nuclear power plant includes many sources of electrical noise, forexample, hand-held two-way radios, arc welders, switching of large inductive loads, high fault currents,and high-energy fast transients associated with switching at the generator or transmission voltage levels.
The increasing use of advanced analog- and microprocessor-based I&C systems in reactor protectionand other safety-related plant systems has introduced concerns with respect to the creation of additionalnoise sources and the susceptibility of this equipment to the electrical noise already present in the nuclearpower plant l technology is constantly evolving, and manufacturers of digital systems are incorporatingincreasingly higher clock frequencies and lower logic level voltages into their designs. However, theseperformance advancements may have an adverse impact on the operation of digital systems with respectto EMI/RFI and power surges because of the increased likelihood of extraneous noise beingmisinterpreted as legitimate logic signals. With recent advances in analog electronics, many of thefunctions presently being performed by several analog circuit boards could be combined into a single1.180-4
analog circuit board operating at reduced voltage levels, thereby making analog circuitry moresusceptible to EMI/RFI and power surges as well. Hence, opera-tional and functional issues related tosafety in the nuclear power plant environment must address the possibility of upsets and malfunctions inI&C systems caused by EMI/RFI and power NRC staff accepted the Electric Power Research Institute (EPRI) topical reportTR-102323, "Guidelines for Electromagnetic Interference Testing in Nuclear Power Plants," in a SafetyEvaluation Report (SER) by letter dated April 17, 1996, as one method of addressing issues of EMC forsafety-related digital I&C systems in nuclear power plants. The original Regulatory Guide 1.180(January 2000) and this revision complement the position set forth in the SER. The guidance in thesedocuments constitutes acceptable methods for addressing EMC considerations for qualifyingsafety-related I&C systems for the expected electromagnetic environment in nuclear power plants. Thisguide provides additional acceptable methods and includes guidance on testing to address signal linesusceptibility and very high frequency (> 1 Ghz) EMI/RFI practices, SWC practices, and operating envelopes endorsed in this guide are onlyelements of the total package that is needed to ensure EMC within nuclear power plants. In addition toassessing the electromagnetic environment, plants should apply sound engineering practices for non-safety-related upgrades and I&C maintenance as part of an overall EMC program. While non-safety-related systems are not part of the regulatory guidance being developed, control of EMI/RFI from thesesystems is necessary to ensure that safety-related I&C systems can continue to perform properly in thenuclear power plant environment. When feasible, the emissions from non-safety-related systems shouldbe held to the same levels as safety-related with the original Regulatory Guide 1.180, this revision endorses IEEE Std 1050-1996 withone exception as stated in Regulatory Position 2. The exception was cited in NUREG/CR-5941. IEEEStd 1050-1996 provides guidance on the engineering practices needed to control upsets andmalfunctions in safety-related I&C systems when exposed to EMI/RFI and power surges. IEEE Std1050-1996 was developed to provide guidance on the design and installation of grounding systems forI&C equipment specific to power generating stations. Further purposes of the standard are to achieveboth a suitable level of protection for personnel and equipment and suitable electrical noise immunity forsignal ground references in power generating Std 1050-1996 addresses grounding and noise-minimization techniques for I&C systems ina generating station environment. This standard recommends practices for the treatment of both analogand digital systems that address the grounding and shielding of electronic circuits on the basis ofminimizing emissions and their susceptibility to EMI/RFI and power surges. The standard iscomprehensive in that it covers both the theoretical and practical aspects of grounding andelectromagnetic verification measures for EMI/RFI testing (emissions and susceptibility) are beyond thescope of IEEE Std 1050-1996. To determine the adequacy of safety-related I&C system designs, theNRC staff has endorsed the applicable EMI/RFI test methods in MIL-STD-461E and the IEC 610001.180-5
Series (i.e., the most recently issued military and international commercial guidance), along with customoperating envelopes developed to represent the characteristic electromagnetic environment for nuclearpower plants. The test methods and operating envelopes are cited in Regulatory Positions 3, 4, and 6 ofthis guide. MIL-STD-461E is included in this revision because it replaced MIL-STD-461D and MIL-STD-462D. The associated changes are discussed in NUREG/CR-6782. The original RegulatoryGuide 1.180 cited EMI/RFI test guidance from MIL-STD-461C, 461D, -462, and -462D. MIL-STD-461E was developed as a measure to ensure the electromagnetic compatibility of equipment. Theapplication of the MIL-STD-461E test methods is tailored for the intended function of the equipment andthe characteristic environment (i.e., which tests are applied and what levels are used depend on thefunction to be performed and the location of operation). Previous versions of the standard have beenused successfully by the U.S. Department of Defense for many years and are commonly referenced incommercial applications. The IEC 61000 series of tests include IEC 61000-3, IEC 61000-4, and tory Position 3 describes the conducted EMI/RFI emissions tests and operating envelopesacceptable to the NRC staff. In turn, Regulatory Position 4 describes the acceptable EMI/RFIsusceptibility tests and operating envelopes. The rationale for the selection of the particular EMI/RFItests and operating envelopes is discussed in NUREG/CR-6782. These discussions include how theEMI/RFI tests were selected, how the IEC 61000 tests should be applied, the exemptions that can beapplied with the use of some tests, and the adjustments made to the operating envelopes recommendedin addition, Regulatory Position 4 also describes the conducted EMI/RFI susceptibility tests andoperating envelopes that are acceptable to the NRC staff for addressing the susceptibility of signal linesto interference. The rationale for the selection of the test methods and operating envelopes is discussedin detail in NUREG/CR-5609. Regulatory Position 6 describes the guidance that is acceptable to theNRC staff for validating the performance of safety-related I&C systems above 1 GHz, and its rationale iscited in NUREG/ verification measures for power surge withstand testing are also beyond the scope ofIEEE Std 1050-1996. Accordingly, the NRC in the original regulatory guide endorsed the test criteriarecommended in IEEE Std C62.41-1991 and the associated test methods recommended in IEEE StdC62.45-1992. This revision would update that guidance to also include the IEC 61000-4 tests relevantto power surge withstand testing. The entire complement of SWC test criteria, test methods, andoperating envelopes endorsed by the NRC are described in Regulatory Position 5. Comparisons of theIEEE and IEC power surge withstand tests, along with rationale for adjusting test levels, are discussed inNUREG/l operating envelopes that form the basis for establishing EMI/RFI and power surgetesting levels are cited in this regulatory guide. The technical basis for the electromagnetic operatingenvelopes is presented in NUREG/CR-6431, NUREG/CR-5609, and NUREG/CR-6782. Theoperating envelopes are applicable for locations within a nuclear power plant where safety-related I&Csystems either are or are likely to be installed. These locations include control rooms, remote shutdown1.180-6
panels, cable spreading rooms, equipment rooms, relay rooms, auxiliary instrument rooms, and otherareas (e.g., the turbine deck) where safety-related I&C system installations are planned. The operatingenvelopes are also applicable for both analog and digital system modifications to the electromagnetic operating envelopes (e.g., lower site-specificenvelopes) should be based on technical evidence comparable to that presented in NUREG/CR-6431,NUREG/CR-5609, and NUREG/CR-6782. Relaxation in the operating envelopes should be based onactual measurement data collected in accordance with IEEE Std 473-1985 (reaffirmed in 1997), “IEEERecommended Practice for an Electromagnetic Site Survey (10 kHz to 10 GHz).”C. REGULATORY LEstablishing and continuing an EMC program for safety-related I&C systems in nuclear powerplants contributes to the assurance that safety-related structures, systems, and components are designedto accommodate the effects of and to be compatible with the environmental conditions associated withnuclear power plant service conditions. Application of consensus standard practices regarding thedesign, testing, and installation of safety-related I&C system modifications or new installations constitutesan important element of such a program. This guidance recommends design and installation practices tolimit the impact of electromagnetic effects, testing practices to assess the emissions and susceptibility ofequipment, and testing practices to evaluate the power SWC of the equipment. Operating envelopescharacteristic of the electromagnetic environment in nuclear power plants are cited in this guidance as thebasis for establishing acceptable testing levels. Table 1 lists the specific regulatory positions on EMC thatare set forth below. This guidance is applicable to all new safety-related systems or modifications toexisting safety-related systems that include analog, digital, or hybrid (i.e., combined analog and digital)electronics equipment. The endorsed test methods for evaluating the electromagnetic emissions,EMI/RFI susceptibility, and power surge withstand capability of safety-related equipment are intendedfor application in test facilities or laboratories before electromagnetic conditions at the point of installation for safety-related I&C systems shouldbe assessed to identify any unique EMI/RFI sources that may generate local interference. The EMI/RFIsources could include both portable and fixed equipment (e.g., portable transceivers, arc welders, powersupplies, and generators). Steps should be taken during installation to ensure that systems are notexposed to EMI/RFI levels from the identified sources that are greater than 8 dB below the specifiedoperating ensure that the operating envelopes are being used properly, equipment should be tested inthe same physical configuration as that specified for its actual installation in the nuclear power plant. Inaddition, the equipment should be in its normal mode of operation (i.e., performing its intended function)during the testing. Following the tests, the physical configuration of the safety-related I&C system shouldbe maintained and all changes in the configuration controlled. The design specifications that should be1.180-7
maintained and controlled include wire and cable separations, shielding techniques, shielded enclosureintegrity, apertures, gasketing, grounding techniques, EMI/RFI filters, circuit board layouts, and otherdesign parameters that may impact the EMC qualification testing results.
Exclusion zones should be established through administrative controls to prohibit the activation ofportable EMI/RFI emitters (e.g., welders and transceivers) in areas where safety-related I&C systemshave been installed. An exclusion zone is defined as the minimum distance permitted between the pointof installation and where portable EMI/RFI emitters are allowed to be activated. The size of theexclusion zones should be site-specific and depend on the effective radiated power and antenna gain ofthe portable EMI/RFI emitters used within a particular nuclear
Table 1 Specific Regulatory Positions for EMC GuidanceRegulatoryPosition2EMC IssueAddressedEMI/RFI limitingpracticesStandards EndorsedIEEE Std 1050-1996Comments/ConditionsFull standard endorsed with oneexception taken.3, 4, 6EMI/RFI emissionsand susceptibility(radiated, conductedpower line andconducted signalline) testingMIL-STD-461ESelected MIL-STD-461E testmethods and operating ed IEC 61000 test methods andoperating envelopes of alternative test suites frommost recent versions of MIL-STD andIEC l electromagnetic operatingenvelopes for key nuclear power plantlocations are included in Regulatory
Positions 3, 4, and 61000-3IEC 61000-4IEC 61000-61.180-8
5SWC testingIEEE Std C62.41-1991IEEE Std C62.45-1992IEC 61000-4Selected IEEE Std C62.41-1991surge test waveforms endorsed withassociated IEEE Std C62.45-1992test ed IEC 61000-4 surge testwaveforms and test l withstand levels for nuclearpower plants are included inRegulatory Position plant. The size of exclusion zones should also depend on the allowable electric field emissionlevels designated for the area in the vicinity of the installed safety-related I&C system. To establish thesize of an exclusion zone, an 8 dB difference between the susceptibility operating envelope and theallowed emissions level should be maintained. For the radiated electric field operating envelope of 10V/m (140 dBµV/m), the size of the exclusion zones should be set such that the radiated electric fieldsemanating from the portable EMI/RFI emitters are limited to 4 V/m (132 dBµV/m) in the vicinity ofsafety-related I&C systems. The minimum distance of an exclusion zone (d) in meters should becalculated by the following equation derived from the free space propagation model:30PGttd=(meters)Ewhere:Pt = the effective radiated power of the EMI/RFI emitter (in Watts);Gt = the gain of the EMI/RFI emitter (dimensionless); and,E = the allowable radiated electric field strength of the EMI/RFI emitter (in
Volts/meter) at the point of that unintentional transmitters (welders, motors, etc.) will typically have a gain that is less than orequal to 1 (the gain of an isotropic emitter), and the gain for intentional transmitters (two-way radios, cellphones, etc.) will typically be greater than 1. Typical values for the gain of intentional transmitters mightvary from 1.5 for a short dipole antenna to 3 for a monopole antenna, and to 6 for a horn Std 1050-1996IEEE Std 1050-1996, “IEEE Guide for Instrumentation and Control Equipment Grounding inGenerating Stations,”1 describes design and installation practices that are acceptable to the NRC staffregarding EMI/RFI- and power surge-related effects on safety-related I&C systems employed in nuclearpower plants with the following exception.
1.180-9
Section 4.3.7.4, “Radiative Coupling,” of the standard maintains that the “field strength” ofpropagating electromagnetic waves is inversely proportional to the square of the distance from the sourceof radiation. This statement needs to be re-evaluated because radiative coupling is a far-field effect. Adistance, r, greater than the wavelength divided by 2p (r > ?/2p) from the source of radiation isconsidered to be far field, which is the region where the wave impedance is equal to the characteristicimpedance of the medium. Both the electric and magnetic “field strengths” fall off as 1/r in the far , in inverse proportion to distance (not as its square). This concept is not to be confused with thepropagation of electromagnetic waves in the near field (r < ?/2p) where the wave impedance isdetermined by the characteristics of the source and the distance from the source. In the near field, if thesource impedance is high (>377O), the electric and magnetic “field strengths” attenuate at rates of 1/r3and 1/r2, respectively. If the source impedance is low (<377O), the rates of attenuation are reversed:
the electric “field strength” will fall off at a rate of 1/r2 and the magnetic “field strength” at a rate of 1/r3.
The user should understand that radiative coupling is a far-field effect and the “field strength” falls off as1/r, not as 1/ Std 1050-1996 references other standards that contain complementary and supplementaryinformation. In particular, IEEE Std 518-1982 (reaffirmed in 1996), “IEEE Guide for the Installation ofElectrical Equipment To Minimize Noise Inputs to Controllers from External Sources,” and IEEE Std665-1995 (reaffirmed in 2001), “IEEE Guide for Generating Station Grounding,” are referencedfrequently. The portions of IEEE Std 518-1982 and IEEE Std 665-1995 referenced in IEEE Std 1050-1996 are endorsed by this guide and are to be used in a manner consistent with the practices in IEEE /RFI EMISSIONS TESTINGMIL-STD-461E, “Requirements for the Control of Electromagnetic Interference Characteristicsof Subsystems and Equipment,” contains test practices that can be applied to characterize EMI/RFIemissions. IEC 61000-6, “Electromagnetic Compatibility (EMC) – Part 6: Generic Standards,” alsospecifies test practices that can be applied to characterize EMI/RFI emissions for industrial environments.
The specific test methods acceptable to the NRC staff in regard to emissions testing for safety-relatedI&C systems in nuclear power plants are presented in Tables 2 and 3. Table 2 lists the EMI/RFIemissions test methods in MIL-STD-461E while Table 3 lists the corresponding criteria in IEC 61000-6-4, “Electromagnetic Compatibility (EMC) – Part 6: Generic Standards – Section 4: Emission standard forindustrial environments.” These test methods cover conducted (along power leads) and radiatedinterference emitted from equipment under test.1.180-10
Table 2 MIL-STD-461E Test Methods for EMI/RFI EmissionsMethodCE101CE102RE101DescriptionConducted emissions, low-frequency, 30 Hz to 10 kHzConducted emissions, high-frequency, 10 kHz to 2 MHzRadiated emissions, magnetic field, 30 Hz to 100 kHzRE102Radiated emissions, electric field, 2 MHz to 1 GHzC = conducted, R = radiated, and E = 3 IEC 61000-6-4 Test Methods for EMI/RFI EmissionsMethodNoneCISPR 11NoneDescriptionConducted emissions, low-frequency, 30 Hz to 10 kHzConducted emissions, high-frequency, 150 kHz to 30 MHzRadiated emissions, magnetic field, 30 Hz to 100 kHzCISPR 11Radiated emissions, electric field, 30 MHz to 1 GHzMIL-STD-461E provides the latest revision of domestic guidance for emissions test methods(including improvements based on experience and the most recent technical information), thus itrepresents current practice. IEC 61000-6-4 provides the most recent international guidance foremissions test practices and incorporates by reference the test methods of CISPR 11, “Limits andMethods of Measurement of Electromagnetic Disturbance Characteristics of Industrial, Scientific andMedical (ISM) Radio-Frequency Equipment.” It is intended that either set of test methods be applied inits entirety, without selective application of individual methods (i.e., no mixing and matching of testmethods) for emissions testing. Because of the absence of IEC 61000 test methods to address low-frequency conducted emissions testing, low-frequency (magnetic field) radiated emissions testing, andhigh-frequency conducted emissions testing in the frequency range from 10 kHz to 150 kHz, the IECemissions testing option is only acceptable under conditions that correspond to the special exemptionconditions for the MIL-STD emissions testing option related to power quality control and proximity toequipment sensitive to magnetic MIL-STD-461E test methods listed in Table 2 have associated operating envelopes thatserve to establish test levels. General operating envelopes that are acceptable to the NRC staff are givenbelow in the discussion of the listed MIL-STD-461E test methods. Likewise, operating envelopes for theIEC 61000-6-45 test methods have been identified that are comparable to the corresponding MIL-STDcounterparts and are given below in the IEC discussion. These operating envelopes are acceptable forlocations where safety-related I&C systems either are or are likely to be installed and include controlrooms, remote shutdown panels, cable spreading rooms, equipment rooms, auxiliary instrument rooms,1.180-11
relay rooms, and other areas (e.g., the turbine deck) where safety-related I&C system installations areplanned. The operating envelopes are acceptable for analog, digital, and hybrid system installations.
The detailed technical basis for the electromagnetic operating envelopes is presented inNUREG/CR-6431, NUREG/CR-5609, and NUREG/CR-6782. The technical basis for the operatingenvelopes begins with the MIL-STD envelopes corresponding to the electromagnetic environment formilitary ground facilities, which were judged to be comparable to that of nuclear power plants based ongeneral layout and equipment type considerations. Plant emissions data were used to confirm theadequacy of the operating envelopes. From the MIL-STD starting point, adjustments to the equipmentemissions envelopes were based on consideration of the primary intent of the MIL-STD envelopes (e.g.,whether the envelopes were based on protecting sensitive receivers on military platforms) and maintainingsome margin with the susceptibility envelopes. When changes to the operating envelopes from the MIL-STD origin were motivated by technical considerations, consistency among the envelopes for comparabletest methods was promoted and commercial emissions envelopes for industrial environments werefactored into adjustments of the operating envelopes. As a result of these considerations, the operatingenvelopes presented in this regulatory guide are equivalent or less restrictive than the MIL-STDenvelopes that served as their initial c envelopes for industrial environments were identified in IEC 61000-6-4 for bothconducted and radiated emissions. These envelopes were compared with the plant-data-based operatingenvelopes and selected based on their compatibility with the nuclear power plant environment. As aresult, the IEC 61000-6-4 envelopes are equivalent or as restrictive as the plant-data-based MIL-STD- 461E test methods that demonstrate EMI/RFI emissions compliance arediscussed below. These methods are acceptable to the NRC staff for accomplishing EMI/RFI emissionstesting for safety-related I&C systems intended for installation in nuclear power plants. Whereapplicable, conditions permitting exemption of specific tests are described.3.1CE101—Conducted Emissions, Low FrequencyThe CE101 test measures the low-frequency conducted emissions on power leads of equipmentand subsystems in the frequency 30 Hz to 10 kHz. Equipment could be exempt from this test if thefollowing two conditions exist. First, the power quality requirements of the equipment are consistent withthe existing power supply; and second, the equipment will not impose additional harmonic distortions onthe existing power distribution system that exceed 5% total harmonic distortion (THD) or other powerquality criteria established with a valid technical basis. When the test is to be performed, it is applicableto ac and dc power leads, including grounds and neutrals, that obtain power from other sources not partof the equipment under test. Conducted emissions on power leads should not exceed the applicable rootmean square (rms) values shown in Figure 3.1. Alternative envelopes are given for ac-operatedequipment based on power consumption (less than or equal to 1 kVA and greater than 1kVA). For ac-operated equipment with a fundamental current (i.e., load current at the power line frequency) greaterthan 1 ampere, the envelopes in Figure 3.1 may be relaxed as follows:1.180-12
dB relaxation = 20 log (fundamental current)Figure 3.1 Low-Frequency Emissions Envelopes3.2 CE102—Conducted Emissions, High FrequencyThe CE102 test measures the high-frequency conducted emissions on power leads of equipmentand subsystems in the frequency range 10 kHz to 2 MHz. The test is applicable to ac and dc powerleads, including grounds and neutrals, that obtain power from other sources that are not part of theequipment under test. Conducted emissions on power leads should not exceed the applicable rms valuesshown in Figure 3.2. The values are specified according to the voltage of the power source feeding theequipment under test. Equipment could be exempted from application of this test in the frequency range10 kHz to 450 kHz if the nuclear power plant has power quality control (see the conditions for exemptionof the CE101 test). In addition, the following exemptions are permissible at higher frequencies. FCCClass A certification is acceptable in lieu of CE102 testing in the frequency range from 450 kHz to 21.180-13
MHz. CISPR 11 Class A certification is acceptable in lieu of CE102 testing in the frequency range from150 kHz to 2 MHz. Otherwise, the CE102 test should be performed over the full frequency range from10 kHz to 2 3.2 High-Frequency Conducted Emissions Envelopes3.3RE101—Radiated Emissions, Magnetic FieldThe RE101 test measures radiated magnetic field emissions in the frequency range 30 Hz to100 kHz. Equipment not intended to be installed in areas with other equipment sensitive to magneticfields could be exempt from this test. The test is applicable for emissions from equipment and subsystemenclosures, as well as all interconnecting leads. The test does not apply at transmitter fundamentalfrequencies or to radiation from antennas. Magnetic field emissions should not be radiated in excess ofthe levels shown in Figure 3.3. Magnetic field emissions are measured at the specified distances of 7 cmand compared against the corresponding envelope.1.180-14
Figure 3.3 Magnetic-Field Radiated Emissions Envelope3.4RE102—Radiated Emissions, Electric FieldThe RE102 test addresses measurement of radiated electric field emissions in the frequency rangeof interest, 2 MHz to 1 GHz. This test is also applicable at frequencies above 1 GHz and the criteria forthose applications are given in Position 6. It is applicable for emissions from equipment and subsystemenclosures, as well as all interconnecting leads. The test does not apply at transmitter fundamentalfrequencies or to radiation from ic field emissions should not be radiated in excess of the rms values shown in Figure 3.4.
At frequencies above 30 MHz, the test method should be performed for both horizontally and verticallypolarized fields.1.180-15
Figure 3.4 Electric-Field Radiated Emissions Envelopes3.5IEC Emissions TestsThe IEC 61000-6-4 test practices that demonstrate EMI/RFI emissions compliance incorporatethe test methods of CISPR 11 by reference. Under the following conditions, these methods areacceptable to the NRC staff for accomplishing EMI/RFI emissions testing for safety-related I&C systemsintended for installation in nuclear power plants. For the IEC emissions testing option to be acceptable,two conditions must be met. First, power quality controls must be in place, which eliminates the need toperform the CE101 test. Second, separation from equipment that is sensitive to magnetic fields must bemaintained, hence it is unnecessary to perform the RE101 specifications for the IEC 61000-6-4 test call for employing the CISPR 11 measurementtechniques. These techniques are similar to those used in the MIL-STD-461E CE102 and RE102 tests,with some differences. For example, CISPR 11 requires a quasi-peak or average test signal detector,while CE102 requires a peak detector. Also, CISPR 11 requires that radiated electric fieldmeasurements be made at 30 meters and 10 meters in an open area site, while RE102 requires that thetesting be performed in a shielded enclosure and that measurements be made at a distance of 1 meter.
Despite the differences, the tests are expected to yield similar results. Values for the IEC 61000-6-4envelope comparable to CE102 are given in Table 4. Since the CISPR 11 Class A operating envelopes1.180-16
are the same as the IEC 61000-6-4 operating envelopes, the CISPR 11 Class A certification forconducted emissions satisfies IEC 61000-6-4 in the frequency range from 150 kHz to 2 MHz. In turn,the CISPR 11 Class A certification for radiated emissions satisfies IEC 61000-6-4 in the frequency rangefrom 2 MHz to 1 GHz. Values for the IEC 61000-6-4 envelope comparable to RE102 are given inTable 4 IEC 61000-6-4 Conducted Emissions Envelopes(CISPR 11 Class A)Frequency Range150 kHz to 500 kHz500 kHz to 5 MHz5 MHz to 30 MHzTest Level (dBµV)79 quasi-peak, 66 average73 quasi-peak, 60 average73 quasi-peak, 60 averageTable 5 IEC 61000-6-4 Radiated Emissions Envelopes(CISPR 11 Class A)Frequency Range30 MHz to 230 MHz230 MHz to 1 GHzTest Level (dBµV/m)30 quasi-peak, measured at 30 m37 quasi-peak, measured at 30 m3.6EMI/RFI Emissions Test SummaryThe CE101, CE102, RE101, and RE102 tests represent the baseline emissions testing program.
Alternative programs are allowed if the conditions for two exemptions for low frequency emissions testingare met. A CE101 exemption is allowed if power quality control is employed and a RE101 exemption isallowed for equipment not intended to be installed in the proximity of magnetic field emitters.
Alternatively, either emissions testing based on IEC 61000-6-4 or that satisfying FCC Part 15 Class Arequirements is acceptable under the identified conditions. Figure 3.5 shows all of the acceptable testingprograms and notes that the alternative programs are acceptable only when the conditions for exemptionare satisfied. Thus, when the identified conditions for exempting low frequency emissions testing are met,any of the three alternative emissions testing programs may be selected. However, regardless of theemissions testing program selected, it is intended that each be applied in its entirety, without selectiveapplication of individual methods (i.e., no mixing and matching of test methods) for emissions testing.1.180-17
EMI/RFI EmissionsMIL-STDMIL-STDIECFCCConductedCE101CE102RE101RE102exemptions(450 kHz -2 MHz)CE102or61000-6-4(CISPR 11Class A)orFCC Part 15Class ARadiatedwithRE102BaselineAlternate #1Alternate #2Alternate #3Figure 3.5 Acceptable Alternatives for Emissions Testing4. EMI/RFI SUSCEPTIBILITY TESTINGMIL-STD-461E contains test methods that can be applied to address EMI/RFI susceptibility fora selection of environments. IEC 61000-4, “Electromagnetic Compatibility (EMC) – Part 4: Testing andMeasurement Techniques,” also specifies test methods that can be applied to characterize equipmentsusceptibility to conducted and radiated EMI/RFI. The specific test methods acceptable to the NRCstaff in regard to susceptibility testing for safety-related I&C systems in nuclear power plants arepresented in Tables 6 and 7. Table 6 lists the EMI/RFI test methods in MIL-STD-461E while Table 7lists the corresponding methods in IEC 61000-4. It is intended that either set of test methods be appliedin its entirety, without selective application of individual methods (i.e., no mixing and matching of testmethods) for susceptibility testing. These methods cover susceptibility to conducted and radiatedinterference resulting from exposure to electric and magnetic fields and noise coupling through power andsignal leads.1.180-18
Table 6 MIL-STD-461E EMI/RFI Susceptibility Test MethodsMethodCS101CS114CS115CS116RS101RS103DescriptionConducted susceptibility, low frequency, 30 Hz to 150 kHzConducted susceptibility, high frequency, 10 kHz to 30 MHzConducted susceptibility, bulk cable injection, impulse excitationConducted susceptibility, damped sinusoidal transients,10 kHz to 100 MHzRadiated susceptibility, magnetic field, 30 Hz to 100 kHzRadiated susceptibility, electric field, 30 MHz to 1 GHzC = conducted, R = radiated, and S = 7 IEC 61000-4 EMI/RFI Susceptibility Test MethodsMethod61000-4-461000-4-561000-4-661000-4-1261000-4-1361000-4-1661000-4-861000-4-961000-4-1061000-4-3DescriptionConducted susceptibility, electrically fast transients/burstsConducted susceptibility, surgesConducted susceptibility, disturbances induced by radio-frequencyfieldsConducted susceptibility, 100 kHz ring waveConducted susceptibility, low frequency, 16 Hz to 2.4 kHzConducted susceptibility, low frequency, 15 Hz to 150 kHzRadiated susceptibility, magnetic field, 50 Hz and 60 HzRadiated susceptibility, magnetic field, 50/60 Hz to 50 kHzRadiated susceptibility, magnetic field, 100 kHz and 1 MHzRadiated susceptibility, electric field, 26 MHz to 1 GHzThe MIL-STD-461E test methods listed in Table 6 have associated operating envelopes thatserve to establish test levels. General operating envelopes that are acceptable to the NRC staff are givenbelow in the discussion of the MIL-STD 461E test methods. Likewise, operating envelopes for the IEC61000 test methods have been identified that are comparable to the corresponding MIL-STD1.180-19
counterparts and are given below in the discussion of the MIL-STD 461E test methods. These operatingenvelopes are acceptable for locations where safety-related I&C systems either are or are likely to beinstalled and include control rooms, remote shutdown panels, cable spreading rooms, equipment rooms,auxiliary instrument rooms, relay rooms, and other areas (e.g., the turbine deck) where safety-relatedI&C system installations are planned. The operating envelopes are acceptable for analog, digital, andhybrid system installations.
The detailed technical basis for the electromagnetic operating envelopes is presented inNUREG/CR-6431, NUREG/CR-5609, and NUREG/CR-6782. The technical basis for the operatingenvelopes begins with the MIL-STD envelopes corresponding to the electromagnetic environment formilitary ground facilities, which were judged to be comparable to that of nuclear power plants based ongeneral layout and equipment type considerations. Plant emissions data were used to confirm theadequacy of the operating envelopes. From the MIL-STD starting point, susceptibility envelopes wereadjusted to account for the plant emissions data reported in NUREG/CR-6436, “Survey of AmbientElectromagnetic and Radio-Frequency Interference Levels in Nuclear Power Plants” (November 1996)and EPRI TR-102323. When changes to the operating envelopes from the MIL-STD origin weremotivated by technical considerations, consistency among the envelopes for comparable test criteria waspromoted. As a result of these considerations, the operating envelopes presented in this regulatory guideare equivalent or less restrictive than the MIL-STD envelopes that served as their initial MIL-STD-461E and IEC test methods that demonstrate EMI/RFI susceptibility complianceare discussed below. These methods are acceptable to the NRC staff for accomplishing EMI/RFIsusceptibility testing for safety-related I&C systems intended for installation in nuclear power plants.
Where applicable, conditions permitting exemption of specific test methods are described.4.1EMI/RFI Conducted Susceptibility Testing—Power LeadsThe MIL-STD-461E test methods that are acceptable to the NRC staff to address conductedEMI/RFI susceptibility along power leads are listed in Table 8. The comparable IEC 61000-4 testmethods that are acceptable to characterize equipment susceptibility to conducted EMI/RFI along powerleads are listed in Table 9. These test methods cover susceptibility to conducted interference resultingfrom noise coupling through the power leads of safety-related I&C systems in nuclear power plants.
Discussions of the test methods and operating envelopes follow below.
Table 8 MIL-STD-461E EMI/RFI Conducted Susceptibility Test Methods—PowerLeadsMethodCS101CS114DescriptionConducted susceptibility, low-frequency, 30 Hz to 150 kHzConducted susceptibility, high-frequency, 10 kHz to 30 MHz1.180-20
C = conducted and S = 9 IEC 61000-4 EMI/RFI Conducted Susceptibility Test Methods—Power LeadsMethod61000-4-661000-4-1361000-4-16DescriptionConducted susceptibility, disturbances induced by radio-frequencyfieldsConducted susceptibility, low-frequency, 16 Hz to 2.4 kHzConducted susceptibility, low-frequency, 15 Hz to 150 kHz 4.1.1CS101—Conducted Susceptibility, Low FrequencyThe CS101 test ensures that equipment and subsystems are not susceptible to EMI/RFI presenton power leads in the frequency range 30 Hz to 150 kHz. The test is applicable to ac and dc inputpower leads, not including grounds and neutrals. If the equipment under test is dc operated, this test isapplicable over the frequency range 30 Hz to 150 kHz. If the equipment under test is ac operated, thistest is applicable starting from the second harmonic of the power line frequency and extending to 150kHz. The equipment under test should not exhibit any malfunction or degradation of performancebeyond specified operational tolerances when subjected to a test signal with the rms voltage levelsspecified in Figure 4.1. Alternative envelopes are given for equipment with nominal source voltages at orbelow 28 V and those operating above 28 V. Acceptable performance should be defined in the test planby the end user or testing organization according to the applicable equipment, subsystem, or systemspecifications.1.180-21
Figure 4.1 Low-Frequency Conducted Susceptibility Operating Envelopes4.1.2CS114—Conducted Susceptibility, High FrequencyThe CS114 test simulates currents that will be developed on leads as a result of EMI/RFIgenerated by antenna transmissions. The test covers the frequency range 10 kHz to 30 MHz and isapplicable to all interconnecting leads, including the power leads of the equipment under test. Althoughthe CS114 test can be applied to assess signal line susceptibility, the test levels given in this section applyonly to power and control lines.
The equipment under test should not exhibit any malfunction or degradation of performancebeyond specified operational tolerances when subjected to a test signal with the rms levels shown inFigure 4.2. Acceptable performance should be defined in the test plan by the end user or testingorganization according to the applicable equipment, subsystem, or system specifications.
1.180-22
12070600.010.10.211Figure 4.2 High-Frequency Conducted Susceptibility Operating Envelopes for Power Leads4.1.3IEC Conducted Susceptibility Tests—Power LeadsThe IEC counterparts to the CS101 and CS114 tests are IEC 61000-4-13, IEC 61000-4-16,and IEC 61000-4-6. The Class 2 devices in IEC 61000-4-13 are similar to the industrial-gradedevices used in nuclear power plants and the Class 2 operating envelope is shown in Table 10. For theIEC 61000-4-16 test, the Level 3 (typical industrial) environment is representative of the nuclear powerplant environment. The Level 3 operating envelopes for the IEC 61000-4-16 test are shown in Table 11.
The Level 3 test level for IEC 61000-4-6 is 140 dBFV and is most similar to the CS114 operatingenvelope recommended for a typical industrial environment. These are the levels acceptable to NRCstaff.1.180-23
Table 10 IEC 61000-4-13 Operating Envelope for 115-V System(Class 2)Harmonic no. (n)2345678993133353739Class 2 (% of supply voltage) 2 (voltagelevel)3.59.21.79.2—7.5—2.9—5.8—5.2—3.52.3—2.32.3—1.71.7—1.71.7—Table 11 Operating Envelopes for IEC 61000-4-16 Conducted SusceptibilityTests(Level 3)Disturbancedc and power line frequency,continuous disturbancedc and power line frequency,short-duration disturbanceConducted disturbance, 15 Hz to150 kHzSelected levelLevel 3—typical industrialenvironmentLevel 3—typical industrialenvironmentLevel 3—typical industrialenvironmentTest level10 Vrms100 Vrms 10–1 Vrms (15–150 Hz)1 Vrms (150–1.5 kHz)1–10 Vrms (1.5–15 kHz)10 Vrms (15–150 kHz)1.180-24
4.2EMI/RFI Conducted Susceptibility Testing—Signal Leads
MIL-STD-461E contains test methods that can be applied to address conducted EMI/RFIsusceptibility for interconnecting signal leads. In addition, IEC 61000-4 specifies test methods that can beapplied to characterize equipment susceptibility to conducted EMI/RFI along interconnecting signal leads.
The specific test methods acceptable to the NRC staff in regard to conducted susceptibility testing for signalleads of safety-related I&C systems in nuclear power plants are presented in Tables 12 and 13. Table 12lists the EMI/RFI test methods for signal leads in MIL-STD-461E, while Table 13 lists the correspondingmethods in specific sections of IEC 61000-4. These test methods cover susceptibility to conductedinterference resulting from noise coupling through interconnecting signal leads.
Table 12 MIL-STD-461E Conducted Susceptibility Test Methods—Signal LeadsMethodCS114CS115CS116DescriptionConducted susceptibility, high-frequency, 10 kHz to 30 MHzConducted susceptibility, bulk cable injection, impulse excitationConducted susceptibility, damped sinusoidal transients, 10 kHz to 100 MHzC = conducted and S = 13 IEC 61000-4 Conducted Susceptibility Test Methods—Signal LeadsMethod61000-4-461000-4-561000-4-661000-4-1261000-4-16DescriptionElectrical fast transient/burst immunity testSurge immunity testImmunity to conducted disturbances, induced by radio-frequency fieldsOscillatory waves immunity testTest for immunity to conducted, common mode disturbances in thefrequency range 0 Hz to 150 kHzThe MIL-STD-461E test methods listed in Table 12 have associated operating envelopes that serveto establish test levels for signal leads. General operating envelopes that are acceptable to the NRC staffare shown in Table 14. Likewise, signal lead operating envelopes for the IEC 61000-4 test criteria listed inTable 13 have been identified in Table 15 and are comparable to their corresponding MIL-STDcounterparts. Note that the withstand level is based on the location of a cable, along with its level ofexposure. Most locations in the interior of a facility, which are typical for signal leads, correspond to aCategory B classification, as described in IEEE Std C62.41-1991 and discussed in Regulatory Position 5.
1.180-25
Most signal leads are expected to be subject to surge environments that correspond to Low Exposure levels(see IEEE Std C62.41-1991 and Regulatory Position 5). However, for I&C systems that are implementedin plant areas that are characterized by surge environments corresponding to Medium Exposure levels (seeIEEE Std C62.41-1991 and Regulatory Position 5), the operating envelopes for signal leads that are given inTable 14 should be doubled. For the IEC tests, the operating envelopes in Table 16 should be used for I&Csystems that are implemented in plant areas that are characterized by surge environments corresponding toMedium Exposure 14 MIL-STD-461E Conducted Susceptibility Operating Envelopes—SignalLeadsMethodCS114CS115CS116Description91 dBFA2 A
5 ATable 15 IEC 6100-4 Conducted Susceptibility Operating Envelopes
for Low Exposure—Signal LeadsMethod61000-4-461000-4-561000-4-661000-4-1261000-4-16Level 3: 1 kV test voltageLevel 2: 1 kV open circuit test voltage and 0.5 kA short circuitcurrent Level 2:130 dBµV test voltage,Ring wave: Level 2 - 1 kV test voltage
Level 2: 3/10 of the values in Table 11Description1.180-26
Table 16 IEC 6100-4 Conducted Susceptibility Operating Envelopes
for Medium Exposure—Signal LeadsMethod61000-4-461000-4-561000-4-661000-4-1261000-4-16Level 4: 2 kV test voltageLevel 3: 2 kV open circuit test voltage and 1 kA short circuitcurrentLevel 3:140 dBµV test voltage,Ring wave: Level 3 - 2 kV test voltage
Level 3: see Table 11Description4.3EMI/RFI Radiated Susceptibility TestingThe MIL-STD-461E test methods that are acceptable to the NRC staff for addressing the radiatedEMI/RFI susceptibility of safety-related I&C systems in nuclear power plants are listed in Table 17. Thecomparable IEC 61000-4 test methods deemed acceptable to characterize equipment susceptibility toradiated EMI/RFI are listed in Table 18. These test methods cover susceptibility to radiated interferenceresulting from electromagnetic emissions in nuclear power plants. Discussions of the test methods andoperating envelopes follow below.
Table 17 MIL-STD-461E EMI/RFI Radiated Susceptibility Test MethodsMethodRS101RS103DescriptionRadiated susceptibility, magnetic field, 30 Hz to 100 kHzRadiated susceptibility, electric field, 30 MHz to 1 GHzR = radiated and S = 18 IEC 61000-4 EMI/RFI Radiated Susceptibility Test MethodsMethod61000-4-861000-4-961000-4-1061000-4-3DescriptionRadiated susceptibility, magnetic field, 50 Hz and 60 HzRadiated susceptibility, magnetic field, 50/60 Hz to 50 kHzRadiated susceptibility, magnetic field, 100 kHz and 1 MHzRadiated susceptibility, electric field, 26 MHz to 1 GHz1.180-27
4.3.1RS101—Radiated Susceptibility, Magnetic FieldsThe RS101 test ensures that equipment and subsystems are not susceptible to radiated magneticfields in the frequency range 30 Hz to 100 kHz. Equipment that is not intended to be installed in areaswith strong sources of magnetic fields (e.g., CRTs, motors, cable bundles carrying high currents) and thatfollows the limiting practices endorsed in this regulatory guide could be exempt from this test. The test isapplicable to equipment and subsystem enclosures and all interconnecting leads. The test is notapplicable for electromagnetic coupling via equipment under test should not exhibit any malfunction or degradation of performancebeyond specified operational tolerances when subjected to the rms magnetic field levels shown inFigure 4.3. Acceptable performance should be defined in the test plan by the end user or testingorganization according to the applicable equipment, subsystem, or system 4.3 Low-Frequency Radiated Susceptibility Envelopes4.3.2RS103—Radiated Susceptibility, Electric FieldsThe RS103 test ensures that equipment and subsystems are not susceptible to radiated electricfields in the frequency range 30 MHz to 1 GHz. This test is also applicable at frequencies above 1 GHzand the criteria for those applications are given in Position 6. The test is applicable to equipment andsubsystem enclosures and all interconnecting leads. The test is not applicable at the tuned frequency ofantenna-connected receivers unless otherwise equipment under test should not exhibit any malfunction or degradation of performance1.180-28
beyond specified operational tolerances when subjected to the radiated electric fields. The impressedelectric field level should be 10 V/m (rms), measured in accordance with the techniques specified in theRS103 test method. The test method should be performed for both horizontally and vertically polarizedfields. According to MIL-STD-461E, circularly polarized fields are not acceptable because radiatedelectric fields are typically linearly polarized. Acceptable performance should be defined in the test planby the end user or testing organization according to the applicable equipment, subsystem, or systemspecifications.4.3.3IEC Radiated Susceptibility TestsThe IEC counterparts for the RS101 test are IEC 61000-4-8, IEC 61000-4-9, and IEC 61000-4-10. Operating envelopes for the typical industrial environment (Class 4) are shown in Table 19. TheIEC counterpart for the RS103 test is IEC 61000-4-3 and its frequency range is 26 MHz to 1 GHz. TheLevel 3 in IEC 61000-4-3 is most similar to the nuclear power plant environment and requires a test levelof 10 V/m. This level is equal to the RS103 operating envelope of 10 V/m. These levels are acceptableto NRC staff for the IEC radiated susceptibility 19 IEC 61000-4-8, -4-9, and -4-10 Operating EnvelopesMethodIEC 61000-4-8Selected ClassContinuous pulses: Class 4 – typicalindustrial environmentShort duration pulses: Class 4 – typicalindustrial environmentIEC 61000-4-9Test Level30 A/m (152 dBpT)300 A/m (172 dBpT)300 A/m (172 dBpT)30 A/m (152 dBpT)Class 4 – typical industrial environmentClass 4 – typical industrial environmentIEC 61000-4-104.4EMI/RFI Susceptibility Test SummaryThe CS101 and CS114 tests for power leads, the CS114, CS115, and CS116 tests for signalleads, and the RS101 and RS103 tests represent the baseline susceptibility testing program. Analternative susceptibility testing program based on IEC 61000 is acceptable for establishing susceptibilitycharacteristics of safety-related I&C systems. Figure 4.4 shows the two acceptable susceptibility testingprograms. While there is no restriction on the selection of either susceptibility testing program, it isintended that each be applied in its entirety, without selective application of individual methods (i.e., nomixing and matching of test methods) for susceptibility testing.1.180-29
EMI/RFI SusceptibilityBaselineMIL-STDPowerCS101CS114AlternateIECPower61000-4-6SignalSignal61000-4-661000-4-1661000-4-4ConductedCS11461000-4-13CS115CS11661000-4-1661000-4-561000-4-12RadiatedRS101(*)61000-4-8(*)61000-4-9(*)61000-4-10(*)61000-4-3RS103(*) Exemption based on proximity to magnetic field emittersFigure 4.4 Acceptable Alternatives for EMI/RFI Susceptibility WITHSTAND CAPABILITYThe SWC practices described in IEEE Std C62.41-1991 (reaffirmed in 1995), “IEEERecommended Practice on Surge Voltages in Low-Voltage AC Power Circuits,” and IEEE Std C62.45-1992 (reaffirmed in 1997), “IEEE Guide on Surge Testing for Equipment Connected to Low-VoltageAC Power Circuits,” are acceptable to the NRC staff regarding the effect of power surges on safety-related I&C systems in nuclear power plants. IEEE Std C62.41-1991 defines a set of surge testwaveforms that has manageable dimensions and represents a baseline surge environment. IEEE StdC62.45-1992 describes the associated test methods and equipment to be employed when performing thesurge tests. Typical environmental conditions for power surges in a nuclear power plant can berepresented by the waveforms given in Table 20 IEEE C62.41-1991 Power Surge WaveformsParameterWaveformRise timeDurationRing WaveOpen-circuitvoltage0.5 µs100 kHzringing
Combination WaveOpen-circuit Short-circuit voltage current 1.2 µs 8 µs 50 µs 20 µsEFTPulses in15-ms bursts 5 ns50 ns1.180-30
The IEC 61000-4 tests comparable to the IEEE C62.41-1991 tests are listed in Table 21. Thetest waveforms are the same and the test procedures are very similar. Hence, a direct interchange of thetest methods is acceptable to the NRC staff. Test levels for the IEC 61000-4 tests are specifiedaccording to the intended 21 Comparable SWC Test MethodsIEEE C62.41-1991Ring WaveCombination WaveEFTIEC Method61000-4-1261000-4-561000-4-4IEEE Std C62.41-1991 describes location categories and exposure levels that define applicableamplitudes for the surge waveforms that should provide an appropriate degree of SWC. Locationcategories depend on the proximity of equipment to the service entrance and the associated lineimpedance. Exposure levels relate to the rate of surge occurrence versus the voltage level (e.g., surgecrest) to which equipment is exposed. The withstand levels presented in this regulatory position arebased on Category B and Category C locations, along with Low Exposure and Medium Exposurelevels. Category B covers feeders and short branch circuits extending to interior locations from theservice entrance. Category C covers the exterior and service entrance. Low Exposure levelsencompass systems in areas known for little load or capacitor switching and low-power surge activity.
Medium Exposure levels encompass systems in areas subject to significant switching transients andmedium to high lightning activity. Table 22 lists the withstand levels that are acceptable for nuclearpower plant application. Interior locations where safety-related I&C systems either are or are likely tobe installed include control rooms, remote shutdown panels, cable spreading rooms, equipment rooms,auxiliary instrument rooms, relay rooms, and other areas (e.g., the turbine deck). Many of these areascan be classified as Category B locations with Low Exposure levels. However, locations where primarypower is provided through connection to external lines or there are sources of significant switchingtransients present (e.g., switchgear, large motors) should be treated as Category B locations withMedium Exposure levels. A determination of the exposure level classification that characterizes alocation is necessary to select the applicable withstand levels.
Table 22 Surge Withstand Levels for Power LinesCategory BLow Exposure2 kVCategory BMedium Exposure4 kVCategory CExteriorN/ASurge WaveformRing Wave1.180-31
Surge WaveformCombination WaveEFT
5.1Category BLow Exposure2 kV / 1 kA2 kVCategory BMedium Exposure4 kV / 2 kA4 kVCategory CExterior6 kV / 3 kAN/AIEEE C62.41 Ring Wave and IEC 61000-4-12The Ring Wave simulates oscillatory surges of relatively high frequency on the ac power leads ofequipment and subsystems and is represented by an open-circuit voltage waveform. The waveform,100-kHz sinusoid, has an initial rise time of 0.5 µs and continually decaying amplitude. A plot of thewaveform is shown in Figure 5.1. The rise time is defined as the time difference between the 10% and90% amplitude points on the leading edge of the waveform. The amplitude of the waveform decays witheach peak being 60% of the amplitude of the preceding peak of the opposite polarity. The peak voltage value of the Ring Wave is given in Table 22. For the IEC test, the withstandlevels correspond to Level 3 and Level 4 for the Low Exposure and Medium Exposure categories,respectively. During the performance of the test, the equipment under test should not exhibit anymalfunction or degradation of performance beyond specified operational tolerances when subjected tothe Ring Wave. Acceptable performance of the equipment under test should be defined in the test planby the end user or testing organization according to the applicable equipment, subsystem, or systemspecifications.5.2IEEE C62.41 Combination Wave and IEC 61000-4-5The Combination Wave involves two exponential waveforms, an open-circuit voltage and ashort-circuit current. It is intended to represent direct lightning discharges, fuse operation, or capacitorswitching on the ac power leads of equipment and subsystems. The open-circuit voltage waveform has a1.2-µs rise time and an exponential decay with a duration (to 50% of initial peak level) of 50 µs. Theshort-circuit current waveform has an 8-µs rise time and a duration of 20 µs. Plots of the waveforms areshown in Figures 5.2 and rise time is defined as the time difference between the 10% and 90% amplitude points on theleading edge of the waveform. The duration is defined as the time between virtual origin and the time atthe 50% amplitude point on the tail of the waveform. Virtual origin is the point where a straight linebetween the 30% and 90% points on the leading edge of the waveform intersects the V=0 line for theopen-circuit voltage and the i=0 line for the short-circuit current. The peak value of the open-circuit voltage of the Combination Wave and the peak value of theshort-circuit current are given in Table 22. For the IEC test, the withstand levels correspond to Level 3and Level 4 for the Low Exposure and Medium Exposure categories, respectively. The Category C1.180-32
withstand level corresponds to the special class, Level x , for the IEC test. During the performance ofthe test, the equipment under test should not exhibit any malfunction or degradation of performancebeyond specified operational tolerances when subjected to the Combination Wave. Acceptableperformance of the equipment under test should be defined in the test plan by the end user or testingorganization according to the applicable equipment, subsystem, or system 5.1 100-kHz Ring Wave1.180-33
Figure 5.2 Combination Wave, Open-Circuit VoltageFigure 5.3 Combination Wave, Short-Circuit Current1.180-34
5.3IEEE C62.41 Electrically Fast Transients and IEC 61000-4-4The EFT waveform consists of repetitive bursts, with each burst containing individualunidirectional pulses, and is intended to represent local load switching on the ac power leads ofequipment and subsystems. The individual EFT pulses have a 5-ns rise time and a duration (width at half-maximum) of 50 ns. Plots of the EFT pulse waveform and the pattern of the EFT bursts are shown inFigures 5.4 and 5.5. The number of pulses in a burst is determined by the pulse frequency. For peaksless than or equal to 2 kV, the pulse frequency will be 5 kHz±1 kHz. For peaks greater than 2 kV, thepulse frequency will be 2.5 kHz±0.5 rise time is defined as the time difference between the 10% and 90% amplitude points on theleading edge of the waveform. The duration is defined as the time between the 50% amplitude points onthe leading and trailing edges of each individual pulse. Individual pulses occur in bursts of 15 ms peak value of the individual EFT pulses is given in Table 22. For the IEC test, the withstandlevels correspond to Level 3 and Level 4 for the Low Exposure and Medium Exposure categories,respec-tively. During the performance of the test, the equipment under test should not exhibit anymalfunction or degradation of performance beyond specified operational tolerances when subjected tothe EFT 5.4 Waveform of the EFT Pulse1.180-35
Figure 5.5 Pattern of EFT BurstsAcceptable performance of the equipment under test should be defined in the test plan by the enduser or testing organization according to the applicable equipment, subsystem, or system ED EMI/RFI TESTING ABOVE 1 GHzMIL-STD-461E contains test methods and criteria that can be applied to address radiatedEMI/RFI emissions and susceptibility above 1 GHz for a selection of environments. IEC 61000-3 andIEC 61000-4 do not. The RE102 test is applicable above 1 GHz for up to 10 times the highestintentionally generated frequency within the equipment under test. The associated emissions operatingenvelope is shown in Figure 6.1. The specific test method acceptable to the NRC staff in regard toradiated susceptibility testing above 1 GHz is contained in the MIL-STD-461E presentation of RS103.
This method covers susceptibility above 1 GHz to radiated interference resulting from exposure to need for radiated susceptibility testing in the frequency range 1 GHz to 10 GHz has arisenbecause of the development of faster speed microprocessors and wireless communications, whichcontribute to interference concerns in the very high frequency band. Susceptibility testing in this rangecovers the unlicensed frequency bands where much of the communications activity is taking place (2.45GHz and 5.7 GHz). The new developments are not expected to be strong emitters because of FCCrestrictions, so the susceptibility test operating envelope will remain the same as at lower frequencies, 10V/m (rms).1.180-36
6.1 Electric-Field Radiated Emissions Envelope Above 1 GHzDOCUMENTATIONElectromagnetic compatibility documentation should provide evidence that safety-related I&Cequipment meets its specification requirements and is compatible with the projected electromagneticenvironment, that the user adheres to acceptable installation practices, and that administrative controlshave been established covering the allowable proximity of portable EMI/RFI sources. Data used todemonstrate the compatibility of the equipment with its projected environment should be pertinent to theapplication and be organized in a readily understandable and traceable manner that permits independentauditing of the conclusion content of electromagnetic compatibility documentation should contain the information listedbelow, as well as any additional information specified in the standards cited by this regulatory guide.
These items, as a minimum, could be included as part of a qualification or dedication file.1.180-37
1. 2. 3. 4. 5. 6. 7. fication of the equipmentSpecifications on the equipmentIdentification of safety functions to be demonstrated by test dataTest planTest results, including5.1 Objective of the test5.2 Detailed description of test item5.3 Description of test setup, instrumentation, and calibration data5.4 Test procedure5.5 Summary of test data, accuracy, and anomaliesThe installation practices employed and administrative controls established to alleviatepotential EMI/RFI and power surge exposureSummary and conclusionsApproval signature and date.D. IMPLEMENTATIONThe purpose of this section is to provide information to applicants and licensees regarding theNRC staff’s plans for using this regulatory guide. No backfitting is intended or approved in connectionwith the issuance of this guide.
Except when an applicant or licensee proposes or has previously established an acceptablealternative method for complying with the specified portions of the NRC’s regulations, the methodsdescribed in this guide will be used in the evaluation of submittals in connection with applications forconstruction permits, operating licenses, and combined licenses. This guide will also be used to evaluatesubmittals from operating reactor licensees who propose system modifications that are voluntarily initiatedby the licensee if there is a clear connection between the proposed modifications and this guidance.1.180-38
REFERENCESCISPR 11, “Industrial, Scientific, and Medical Radio-Frequency Equipment—ElectromagneticDisturbance Characteristics—Limits and Methods of Measurement,” International Special Committee onRadio Interference, 1997.1
IEC 61000-3-2, “Electromagnetic Compatibility (EMC) - Part 3-2: Limits–Limits for Harmonic CurrentEmissions,” International Electrotechnical Commission, 2001.1IEC 61000-3-4, “Electromagnetic Compatibility (EMC) - Part 3-4: Limits–Limitation of Emission ofHarmonic Currents in Low-voltage Power Supply Systems for Equipment with Rated Current Greaterthan 16 A,” International Electrotechnical Commission, 1998.1IEC 61000-4-1, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 1: Overview of Immunity Tests," International Electrotechnical Committee, 1992.1IEC 61000-4-2, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 2: Electrostatic Discharge Immunity Test," International Electrotechnical Committee, 1995.1IEC 61000-4-3, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 3: Radiated, Radio-Frequency, Electromagnetic Field Immunity Test," InternationalElectrotechnical Committee, 1995.1IEC 61000-4-4, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 4: Electrical Fast Transient/Burst Immunity Test," International Electrotechnical Committee,1995.1IEC 61000-4-5, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 5: Surge Immunity Test," International Electrotechnical Committee, 1995.1IEC 61000-4-6, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 6: Immunity to Conducted Disturbances, Induced by Radio-Frequency Fields," InternationalElectrotechnical Committee, 1996.1IEC 61000-4-7, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 7: General Guide on Harmonics and Interharmonics Measurements and Instrumentation, forPower Supply Systems and Equipment Connected Thereto," International Electrotechnical Committee,1991.1 International Electrotechnical Commission documents are available from the IEC at 3 rue de Varembe, PO Box 131, 1211Geneva 20, Switzerland.11.180-39
IEC 61000-4-8, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 8: Power Frequency Magnetic Field Immunity Test," International Electrotechnical Committee,1993.1IEC 61000-4-9, “Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques,Section 9: Pulse Magnetic Field Immunity Test," International Electrotechnical Committee, 1993.1IEC 61000-4-10, “Electromagnetic Compatibility (EMC) - Part 4: Testing and MeasurementTechniques, Section 10: Damped Oscillatory Magnetic Field Immunity Test," InternationalElectrotechnical Committee, 1993.1IEC 61000-4-11, “Electromagnetic Compatibility (EMC) - Part 4: Testing and MeasurementTechniques, Section 11: Voltage Dips, Short Interruptions, and Voltage Variations Immunity Test,"1International Electrotechnical Committee, 61000-4-12, “Electromagnetic Compatibility (EMC) - Part 4: Testing and MeasurementTechniques, Section 12: Oscillatory Waves Immunity Tests," International Electrotechnical Committee,1996.1IEC 61000-4-13, “Electromagnetic Compatibility (EMC) - Part 4: Testing and MeasurementTechniques, Section 13: Immunity to Harmonics and Interharmonics," International ElectrotechnicalCommittee, 1998.1IEC 61000-4-16, “Electromagnetic Compatibility (EMC) - Part 4: Testing and MeasurementTechniques, Section 16: Test for Immunity to Conducted, Common Mode Disturbances in the FrequencyRange 0 Hz to 150 kHz," International Electrotechnical Committee, 1998.1IEC 61000-6-4, "Electromagnetic Compatibility (EMC) - Part 6: Generic Standards, Section 4: EmissionStandard for Industrial Environments,” International Electrotechnical Committee, 1997.1IEEE Std 279-1971, “Criteria for Protection Systems for Nuclear Power Generating Stations,” Instituteof Electrical and Electronics Engineers, issued 1971.2
IEEE Std 473-1985, “IEEE Recommended Practice for an Electromagnetic Site Survey (10 kHz to 10GHz),” Institute of Electrical and Electronics Engineers, issued 1985, reaffirmed 1997.2
IEEE Std 518-1982, “IEEE Guide for the Installation of Electrical Equipment To Minimize Noise Inputsto Controllers from External Sources,” Institute of Electrical and Electronics Engineers, issued 1982,reaffirmed 1996.22 IEEE publications may be purchased from the IEEE Service Center, 445 Hoes Lane, Piscataway, NJ 08855.1.180-40
IEEE Std 603-1991, “Criteria for Safety Systems for Nuclear Power Generating Stations,” Institute ofElectrical and Electronics Engineers, issued 1991.2
IEEE Std 665-1995, “IEEE Guide for Generating Station Grounding,” Institute of Electrical andElectronics Engineers, issued 1995, reaffirmed 2001.2IEEE Std 1050-1996, “IEEE Guide for Instrumentation and Control Equipment Grounding in GeneratingStations,” Institute of Electrical and Electronics Engineers, issued 1996.2IEEE Std C62.41-1991, “IEEE Recommended Practice on Surge Voltages in Low-Voltage AC PowerCircuits,” Institute of Electrical and Electronics Engineers, issued 1991, reaffirmed 1995.2IEEE Std C62.45-1992, “IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage ACPower Circuits,” Institute of Electrical and Electronics Engineers, issued 1992, reaffirmed in 1997.2MIL-STD-461C, “Electromagnetic Emission and Susceptibility Requirements for the Control ofElectromagnetic Interference,” Department of Defense, August 4, 1986.3MIL-STD-461D, “Electromagnetic Emission and Susceptibility Requirement for the Control ofElectromagnetic Interference,” Department of Defense, January 11, 1993.3MIL-STD-461E, “Requirements for the Control of Electromagnetic Interference Characteristics ofSubsystems and Equipment,” U.S. Department of Defense, August 20, 1999.3MIL-STD-462, “Measurement of Electromagnetic Interference Characteristics,” Department of Defense,July 31, 1967.3MIL-STD-462D, “Measurement of Electromagnetic Interference Characteristics, Department ofDefense, Jan 11, 1993.3NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear PowerPlants,” Chapter 7, “Instrumentation and Controls,” USNRC, June 1997.4NUREG/CR-5609, “Electromagnetic Compatibility Testing for Conducted Susceptibility AlongInterconnecting Signal Lines,” USNRC, August 2003.4
Military Standards are available from the Department of Defense, Standardization Documents Order Desk, Building 4D, 700Robbins Avenue, Philadelphia, PA 19111-5094.3 Copies are available at current rates from the U.S. Government Printing Office, P.O. Box 37082, Washington, DC 20402-9328(telephone (202)512-1800); or from the National Technical Information Service by writing NTIS at 5285 Port Royal Road,Springfield, VA 22161; (; telephone (703)487-4650;. Copies are available for inspection orcopying for a fee from the NRC Public Document Room at 11555 Rockville Pike, Rockville, MD; the PDR’s mailing address isUSNRC PDR, Washington, DC 20555; telephone (301)415-4737 or (800)397-4209; fax (301)415-3548; email isPDR@.41.180-41
NUREG/CR-5700, “Aging Assessment of Reactor Instrumentation and Protection SystemComponents,” USNRC, July 1992.4
NUREG/CR-5904, “Functional Issues and Environmental Qualification of Digital Protection Systems ofAdvanced Light-Water Nuclear Reactors,” USNRC, April 1994.4
NUREG/CR-5941, “Technical Basis for Evaluating Electromagnetic and Radio-Frequency Interferencein Safety-Related I&C Systems” April 1994.4
NUREG/CR-6431, “Recommended Electromagnetic Operating Envelopes for Safety-Related I&CSystems in Nuclear Power Plants,” USNRC, April 1999.4
NUREG/CR-6436, “Survey of Ambient Electromagnetic and Radio-Frequency Interference Levels inNuclear Power Plants,” USNRC, November 1996.4NUREG/CR-6406, “Environmental Testing of an Experimental Digital Safety Channel,” USNRC,September 1996.4
NUREG/CR-6579, “Digital I&C Systems in Nuclear Power Plants: Risk-Screening of EnvironmentalStressors and a Comparison of Hardware Unavailability With an Existing Analog System,” USNRC,January 1998.4NUREG/CR-6782, “Comparison of U.S. Military and International Electromagnetic CompatibilityGuidance,” USNRC, August 2003.4
Safety Evaluation Report (SER), issued by USNRC by letter dated April 17, 1996, to Carl Yoder,EPRI, from Eric Lee, NRC, Subject: Review of EPRI Utility Working Group Topical ReportTR-102323, "Guidelines for Electromagnetic Interference Testing in Power Plants."5
TR-102323, “Guidelines for Electromagnetic Interference Testing in Power Plants,” Electric PowerResearch Institute (EPRI) topical report, September 1994.6 Copies are available for inspection or copying for a fee from the NRC Public Document Room at 11555 Rockville Pike (firstfloor), Rockville, MD; the PDR’s mailing address is USNRC PDR, Washington, DC 20555; telephone (301)415-4737 or 1-(800)397-4209; fax (301)415-3548; e-mail
REGULATORY MPart 50 of Title 10 of the Code of Federal Regulations (10 CFR 50), “Domestic Licensing ofProduction and Utilization Facilities,” delineates the NRC’s design and qualification regulations forcommercial nuclear power plants. Appendix A, “General Design Criteria for Nuclear Power Plants,” to10 CFR Part 50 “establishes minimum requirements for the principal design criteria for water-coolednuclear power plants,” and 10 CFR 50.55a(h) requires that reactor protection systems also satisfy thecriteria of the Institute of Electrical and Electronics Engineers (IEEE) standard (Std) 603-1991, “Criteriafor Safety Systems for Nuclear Power Generating Stations,”1 or IEEE Std 279-1971, ?Criteria forProtection Systems for Nuclear Power Generating Stations,”1 contingent on the date of constructionpermit issuance. In particular, General Design Criterion (GDC) 4 in Appendix A to 10 CFR Part 50requires that structures, systems, and components be designed “to accommodate the effects of and to becompatible with the environmental conditions associated with normal operation, maintenance, testing, andpostulated accidents, including loss-of-coolant accidents.” Furthermore, 10 CFR 50.49 and50.55a(a)(1) address verification measures such as testing that can be used to confirm the adequacy ofdesign.
While these regulations address environmental compatibility for electrical equipment that isimportant to safety, they do not explicitly identify approaches to establishing electromagnetic compatibility(EMC). As a result, Regulatory Guide 1.180, “Guidelines for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related Instrumentation and Control Systems,”2 was developed toidentify practices acceptable to the NRC staff that can be employed to establish EMC for safety-relatedinstrumentation and control (I&C) systems in nuclear power plants. In addition, Electric Power ResearchInstitute (EPRI) topical report TR-102323, “Guidelines for Electromagnetic Interference Testing inPower Plants,”3 was accepted in a Safety Evaluation Report (SER) by letter dated April 17, 1996,4 withsome exceptions and clarifications. The guidance offered in the regulatory guide and the SER constituteconsistent approaches to addressing issues of EMC for safety-related digital I&C systems in nuclearpower plants, with each serving as equally valid, acceptable methods. However, experience in thenuclear industry has indicated some concern that the available guidance incorporates some conservatismthat could be reduced through development of an enhanced technical basis. In addition, certain EMC12 IEEE publications may be purchased from the IEEE Service Center, 445 Hoes Lane, Piscataway, NJ 08855. Requests for single copies of draft or active regulatory guides (which may be reproduced) or for placement on an automaticdistribution list for single copies of future draft guides in specific divisions should be made in writing to the U.S. NuclearRegulatory Commission, Washington, DC 20555, Attention: Reproduction and Distribution Services Section, or by fax to(301)415-2289; email
considerations (i.e., radiated emissions and susceptibility in the frequency band from 1 to 10 gigahertz andconducted susceptibility along signal lines) have been identified by the NRC staff and the EPRI EMIWorking Group as open issues that should be addressed. Finally, a revised complete series of EMCstandards by the International Electrotechnical Commission (IEC), which has been issued recently,warrants consideration for use by the U.S. nuclear power industry. The need to develop and maintainspecific practices for the nuclear power industry to address the effects of EMI/RFI and power surges onsafety-related I&C systems is stated in SECY-91-273, “Review of Vendors’ Test Programs To Supportthe Design Certification of Passive Light Water Reactors.”4
ATIVE APPROACHESThe existing guidance is based on military and industrial methods for ensuring the compatibility ofI&C equipment with the electromagnetic conditions to which they are subjected in nuclear power plants.
This guidance relies on consensus standards in the EMC community to ensure widespread familiarity andreasonable levels of agreement. Recently, the U.S. Department of Defense (DoD) issued a revision ofthe EMC testing standards, replacing military standard (MIL-STD) 461D and 462D with MIL-STD461E.5 In addition, the IEC has revised the complete series of standards (IEC 61000)6 that offer apotential alternative to the military EMC standards. The approach taken was to evaluate the recentstandards to establish conditions under which they can be applied as equivalent suites of test methods thatare relevant to the nuclear power plant electromagnetic environment. The revised standards contain testmethods that are applicable for assessing conducted susceptibility along signal lines so that issue wasaddressed. The issue of high-frequency radiated EMC was also addressed with the identification of testmethods that are applicable for assessing radiated emissions and susceptibility above 1 GHz. Thealternative approach considered was to take no action and retain the existing guidance for EMC atnuclear power plants. Thus, the two approaches considered are: no action, the existing guidance through development of an enhanced technical first alternative, taking no action, requires no additional cost for the NRC staff or applicantsover current conditions since no change to the process would occur. The existing guidance in theregulatory guide and SER provides clear, systematic approaches that are acceptable for ensuringelectromagnetic compatibility. However, the guidance endorses dated versions of EMC standards thathave been superseded by recent revisions. While there is currently substantial experience among testinglaboratories with the test methods from the previous versions of the standards, it is anticipated that suchcapabilities will diminish in a few years as most industries adopt the methods of the current versions.
Thus, taking no action places the responsibility for justifying the use of the most recent domestic andinternational standards on the applicants at some future time. Continuing with the existing guidanceunchanged does not address the issues of high-frequency radiated EMC and conducted susceptibility Military Standards are available from the Department of Defense, Standardization Documents Order Desk, Building 4D, 700Robbins Avenue, Philadelphia, PA 19111-5094.5 International Electrotechnical Commission documents are available from the IEC at 3 rue de Varembe, PO Box 131, 1211Geneva 20, Switzerland.61.180-44
along signal lines. As a result, the process of establishing EMC for safety-related I&C modifications ofnew installations may involve significant effort on the part of the applicant to anticipate the type and levelof evidence that is acceptable to the NRC staff to demonstrate compatibility of equipment in response tothese phenomena. In addition, the NRC staff review may involve considerable effort in evaluatingsubmitted approaches for addressing the open issues and reviewing the use of the revised standards on acase-by-case basis.
The second alternative, updating the existing guidance by developing an enhanced technical basis,was considered. Consensus standards on methods for establishing EMC are available and representcurrent good practice as agreed upon by responsible professionals in the U.S. military and industrial(domestic and international) EMC community. These standards are maintained by their respectivestandards bodies and each revision permits refinement of the consensus positions and improvement of thestandards through the resolution of open issues. Endorsing the current version of EMC standards allowsthe staff and applicants to obtain the benefit of the work of responsible EMC professional standardscommittee volunteers. In addition to the availability of a revised EMC standard from the U.S. DoD, therecent completion of a series of international EMC standards by IEC offers the opportunity to introducegreater flexibility in the choice of acceptable methods. Also, the issues related to high-frequency radiatedEMC and conducted susceptibility along signal lines can be addressed through identification of acceptabletest methods in the recent EMC standards. Adopting this approach requires NRC staff effort to reviewthe revised or new standards to select for endorsement those criteria and methods that address EMCissues of concern for safety-related I&C systems in nuclear power plants. In addition, NRC staff effortfor this approach includes a review of existing evidence characterizing the electromagnetic conditions atnuclear power plants and the rationale for electromagnetic operating envelopes to determine whether anyconservatism can be identified and justifiably reduced (i.e., by relaxing the operating envelopes aswarranted). The level of effort for each application is reduced for both NRC staff and applicant over thatinvolved with Alternative 1 because systematic review and endorsement of current standards by NRCstaff and up-front resolution of open EMC issues is a more effective use of resources than an ad hoc,case-by-case method of handling the transition to recent standards that more fully address the range ofEMC issues. The result of this approach is an up-to-date, more complete guide on acceptable EMCpractices with the flexibility to select among suites of test methods from domestic and internationalstandards. Of course, the applicant retains the flexibility to establish an equivalent technical basis fordifferent criteria and operating envelopes by performing its own detailed assessment of theelectromagnetic conditions at the point of installation and evaluating any emerging practices.1.180-45
AND IMPACTSValues and impacts for each of the two identified approaches are analyzed below. In thisanalysis, the probability of an alternative approach having a positive effect on EMC and the probability ofthat effect on the achievement of overall safety goals are not known quantitatively. However, based on aqualitative assessment of experience in the military and commercial industries, as well as the nuclearindustry, EMI/RFI and power surges clearly hold the potential for inducing an undesirable safetyconsequence. Therefore, a positive correlation between EMC and the achievement of safety goals isinferred from the negative effects of EMI/RFI and power surge susceptibility. Thus, EMC is a necessarybut not wholly sufficient factor by itself in achieving safety goals.
In the summary below, an impact is a cost in schedule, budget, or staffing or an undesiredproperty or attribute that would accrue from taking the proposed approach. Both values and impactsmay be functions of time.3.1Alternative 1—Take No ActionThis alternative has the attraction that its initial cost is low since there are no “start-up” activities.
However, the burden of establishing the technical basis for the suitability of revised or new EMCstandards would rest with the applicants. In addition, it would remain for the applicant to determine whatpractices, test criteria, and test methods are necessary to resolve the issues of high-frequency radiatedEMC and conducted susceptibility along signal lines. NRC staff would have to act on a case-by-casebasis for applications or requests to review safety questions involving the open issues or employingunreviewed versions of EMC standards. The absence of a clearly established technical basis regardinguse of these revised standards or the resolution of these open issues could have adverse effects on thelevel of staff effort required to conduct reviews or to ensure consistency among reviews of the EMC foreach I&C system modification. Thus, NRC staff review could take longer and require greater effort.
From the applicant’s perspective, the marketplace will ultimately drive the industry to use the revised ornew standards as the testing resources that support the older standards diminish. As a result, the absenceof guidance regarding the revised standards and the open issues could lead to higher costs for theapplicants because of potential unknowns associated with demonstrating compliance with regulationsusing unreviewed methods. Thus, although the initial cost would apparently be low, taking no actioncould result in greater total costs, both to the NRC staff and the applicant, during the safety –Impact–No value beyond the status quoSchedule, budget, and staffing cost, to the staff and applicant, associated with remainingregulatory uncertainty regarding technical basis for use of revised or new standards andresolution of open issues on a case-by-case basis1.180-46
3.2Alternative 2—Update Existing GuidanceIf the NRC staff endorses revised or new consensus EMC standards on the basis of a systematicreview, the staff and applicants obtain the benefit of the effort of expert professional organizations toestablish methods and practices to achieve and assess EMC. In addition, the update of the existingguidance provides the opportunity to address open issues and reduce conservatism as warranted. Thecost of this approach involves NRC staff effort in reviewing the revised or new EMC standards,identifying practices to address the open issues, and reevaluating the technical basis for plant operatingenvelopes. Given the participation of NRC staff members on standards committees that are consideredto address issues important to safety, this cost can be kept to a minimum. The value in this alternative isthe common understanding between the NRC staff and applicants of approaches that have currentacceptance as good practice in the expert technical community. The benefit of this approach would be amore comprehensive understanding of current EMC practices by the NRC staff and reduction of theburden on the applicants. From the applicant’s perspective, a clear determination of acceptableresolutions to open EMC issues, the flexibility of using methods from current domestic and internationalEMC standards, and the potential reduction in conservatism would reduce the regulatory ––––Impact––nance and evolution of the current definition of good practices by the EMCcommunity in military and commercial industriesProbable improvement in the likelihood of achieving safety goals as a consequence ofresolution of open EMC issuesGreater flexibility added in establishing EMC through the endorsement of equivalentsuites of test methods from both domestic and international standardsReduction of conservatism in existing guidance as warranted by the enhancedtechnical basisStaff cost of evaluating revised or new EMC practices for endorsementReduction of burden for applicantsCONCLUSIONSThere is clear evidence that the electromagnetic conditions can adversely affect the performanceof safety-related I&C equipment. The Code of Federal Regulations requires that systems, structures,and components important to safety be compatible with and accommodate the effects of environmentalconditions associated with nuclear power plant service conditions. EMC is an element of addressing thatrequirement. Addressing open EMC issues and adopting improved or revised consensus practices,where the safety case is maintained, can enhance the assurance of safety while potentially reducingregulatory burden. Two approaches to maintaining existing EMC guidance were examined.
Taking no action may result in accumulating regulatory expense as applicants propose ad hocsolutions to open EMC issues or adopt unreviewed methods from revised or new standards as the basisfor providing evidence to the staff that safety-related equipment is compatible with the electromagneticconditions at the site and, thus, meet the requirements of NRC’s regulations.
1.180-47
General endorsement of military and commercial EMC standards addresses the stated problemwith good value and minimal impact. However, regulatory uncertainty regarding the applicability of eachtechnical element embodied in the standards and the means to adequately determine the electromagneticservice conditions could still lead to accumulating regulatory expense as applicants submit proposedmethods based on the general practices for staff review. Eventually, a de facto standard set of practiceswould emerge through an inefficient review process.
The second alternative, updating the existing guidance through development of an enhancedtechnical basis, provides good value with minimal impact. While this approach involves some additionalNRC staff effort, it maintains the long-term relevance of the existing guidance through adoption of currentversions of EMC standards, introduces greater flexibility in the generation of the safety case by offeringthe option of equivalent suites of test methods from domestic and international EMC standards, andreduces the potential burden on the applicants by addressing open EMC issues in a systematic mannerand reducing conservatism as warranted by the enhanced technical basis. Therefore, the secondalternative provides the highest value with reasonable impact on NRC staff and the greatest potential forreducing the regulatory burden for applicants. Note that neither of these approaches present newregulatory requirements; they define acceptable approaches for meeting existing ON RATIONALEBased on the highest value and reasonable impact for problem solution capability (especiallyregulatory burden), the second alternative, updating existing guidance by developing an enhancedtechnical basis, has been chosen. The highest value will be achieved by reviewing revised and newconsensus EMC standards (both domestic and international), assessing the applicability and equivalenceof each technical element embodied in the standards, reevaluating the electromagnetic environmentcharacteristic of nuclear power plants and the technical basis for the current operating envelopes,determining testing methods that can address the open EMC issues, and identifying equivalent suites oftest methods from the alternative standards and the conditions under which they may be applied. Thisapproach will contribute to satisfying the safety goal for nuclear power plants.
1.180-48
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