ML24306A049

Regulatory Guide (RG) 1.238, Revision 0, Criteria for the Protection of Class 1E Power Systems and Equipment for Nuclear Power Plants

ML24306A049
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Issue date:	01/14/2025
From:	Sheila Ray NRC/NRR/DEX/EEEB
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DG-1354 RG-1.238, Rev 0
Download: ML24306A049 (12)

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U.S. NUCLEAR REGULATORY COMMISSION REGULATORY GUIDE RG-1.238, REVISION 0 Issue Date: January 2025 Technical Lead: Sheila Ray Written suggestions regarding this guide may be submitted through the NRCs public website in the NRC Library at https://www.nrc.gov/reading-rm/doc-collections/reg-guides/index.html., under Document Collections, in Regulatory Guides, at https://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.html, and will be considered in future updates and enhancements to the Regulatory Guide series. During the development process of new guides suggestions should be submitted within the comment period for immediate consideration. Suggestions received outside of the comment period will be considered if practical to do so or may be considered for future updates.

Electronic copies of this RG, previous versions of RGs, and other recently issued guides are also available through the NRCs public website in the NRC Library at https://www.nrc.gov/reading-rm/doc-collections/reg-guides/index.html under Document Collections, in Regulatory Guides.

This RG is also available through the NRCs Agencywide Documents Access and Management System (ADAMS) at https://www.nrc.gov/reading-rm/adams.html, under ADAMS Accession Number (No.) ML24306A049. The regulatory analysis may be found in ADAMS under Accession No. ML24158A042. The associated draft guide DG-1354 may be found in ADAMS under Accession No. ML24158A041, and the staff responses to the public comments on DG-1354 may be found under ADAMS Accession No. ML24306A053.

CRITERIA FOR THE PROTECTION OF CLASS 1E POWER SYSTEMS AND EQUIPMENT FOR NUCLEAR POWER PLANTS A. INTRODUCTION Purpose This regulatory guide (RG) describes an approach that is acceptable to the staff of the U.S. Nuclear Regulatory Commission (NRC) for use in complying with NRC regulations that address the protection of Class 1E power systems and equipment at nuclear power plants. Subject to the conditions described in Section C, this RG revision endorses Institute of Electrical and Electronics Engineers (IEEE)

Standard (Std.) 741-2022, IEEE Standard for Criteria for the Protection of Class 1E Power Systems and Equipment for Nuclear Power Generating Stations (Ref. 1).

Applicability This RG applies to applicants and licensees subject to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities (Ref. 2), or 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants (Ref. 3). Under 10 CFR Part 50, this RG applies to applicants for and holders of licenses, as defined in 10 CFR 50.2, Definitions. Under 10 CFR Part 52, this RG applies to applicants for and holders of combined licenses, standard design approvals and manufacturing licenses, and applicants for standard design certifications for nuclear power plants.

Applicable Regulations 10 CFR Part 50 contains the following applicable regulations:

o 10 CFR 50.36(c)(1)(ii)(A) states, in part, that limiting safety system settings for nuclear reactors are settings for automatic protective devices related to those variables having significant safety functions. Where a limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting must be so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded.

RG 1.238, Revision 0, Page 2 o 10 CFR 50.55a, Codes and standards, requires, in part, that structures, systems, and components (SSCs) be designed, fabricated, erected, constructed, tested, and inspected to quality standards commensurate with the importance of the safety function to be performed.

Furthermore, 10 CFR 50.55a(h) provides requirements for protection and safety systems and incorporates by reference IEEE Std. 279-1968, Proposed IEEE Criteria for Nuclear Power Plant Protection Systems (Ref. 4), IEEE Std. 279-1971, Criteria for Protection Systems for Nuclear Power Generating Stations (Ref. 5), and IEEE Std. 603-1991, Criteria for Safety Systems for Nuclear Power Generating Stations (including the correction sheet dated January 30, 1995) (Ref. 6). The applicability of each of these standards to a given nuclear power plant depends on the plants licensing date and other criteria.

Appendix A, General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50 establishes the minimum requirements for principal design criteria for water-cooled nuclear power plants,1 which include the following:

o General Design Criterion (GDC) 1, Quality standards and records, requires, in part, that SSCs important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed.

o GDC 17, Electric power systems, requires, in part, that an onsite electric power system and an offsite electric power system be provided to permit functioning of SSCs important to safety.

o GDC 18, Inspection and testing of electric power systems, requires, in part, that electric power systems important to safety be designed to permit appropriate periodic inspection and testing of important areas and features to assess the continuity of the systems and the condition of their components.

o GDC 20, Protection system functions, requires, in part, that the protection system be designed to automatically initiate the operation of appropriate systems, including the reactivity control systems, to ensure that specified acceptable fuel design limits are not exceeded as a result of anticipated operational occurrences.

As stated in the introduction to Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants, to 10 CFR Part 50, nuclear power plants include SSCs that prevent or mitigate the consequences of postulated accidents that could cause undue risk to the health and safety of the public. Appendix B to 10 CFR Part 50 establishes quality assurance requirements for the design, manufacture, construction, and operation of those SSCs:

o Criterion III, Design Control, requires, in part, design control measures for verifying the adequacy of the design.

o Criterion XI, Test Control, requires, in part, a test program to provide assurance that all testing required to demonstrate that SSCs will perform satisfactorily in service is performed in accordance with written procedures that incorporate the requirements and acceptance limits in applicable design documents.

1 The GDC in 10 CFR Part 50, Appendix A are considered to be generally applicable to other types of nuclear power units and are intended to provide guidance in establishing the principal design criteria for such other units.

RG 1.238, Revision 0, Page 3 o Criterion XVII, Quality Assurance Records, requires, in part, the maintenance of sufficient records as evidence of activities affecting quality.

10 CFR Part 52 governs the issuance of early site permits, standard design certifications, combined licenses, standard design approvals, and manufacturing licenses. It specifies, among other things, that contents of certain applications must satisfy the requirements of 10 CFR 50.36, Technical Specifications; 10 CFR 50.55a; and 10 CFR Part 50, Appendices A and B.

Related Guidance Branch Technical Position 8-6, Adequacy of Station Electric Distribution System Voltages, issued March 2007 (Ref. 7), provides guidance on the design of undervoltage protection systems for Class 1E equipment.

Bulletin (BL) 2012-01, Design Vulnerability in Electric Power System, dated July 27, 2012 (Ref. 8), discusses open phase conditions and protection schemes for electric power systems. BL-2012-01 was subsequently closed on March 6, 2023 (Ref. 9).

Information Notice (IN) 1995-05, Undervoltage Protection Relay Settings Out of Tolerance Due to Test Equipment Harmonics, dated January 20, 1995 (Ref. 10), discusses operating experience on test equipment harmonics that could result in undervoltage relay actuation settings that are out of tolerance.

IN 2012-03, Design Vulnerability in Electric Power System, dated March 1, 2012 (Ref. 11),

provides more information on open phase conditions and protection schemes for electric power systems.

NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (Ref. 12), provides guidance to the NRC staff on performing safety reviews under 10 CFR Part 50 and 10 CFR Part 52.

Regulatory Issue Summary (RIS) 2006-017, NRC Staff Position on the Requirements of 10 CFR 50.36, Technical Specifications, regarding Limiting Safety System Settings during Periodic Testing and Calibration of Instrument Channels, dated August 24, 2006 (Ref. 13), provides regulatory clarification on NRC staff positions about operability determinations for instrument channels based on a plants technical specifications. In particular, the RIS clarifies staff positions about the appropriate establishment of as-found and as-left acceptance tolerances.

RIS 2011-12, Adequacy of Station Electric Distribution System Voltages, dated December 29, 2011 (Ref. 14), provides information on degraded voltage relaying design calculations for the protection of electric power systems.

RG 1.6, Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems (Safety Guide 6) (Ref. 15), provides examples of acceptable independence between redundant standby power sources and redundant distribution systems, to comply with GDC 17.

RG 1.30, Quality Assurance Requirements for the Installation, Inspection, and Testing of Instrumentation and Electric Equipment (Safety Guide 30) (Ref. 16) provides quality assurance requirements for the installation, inspection, and testing of nuclear power plant instrumentation and electric equipment.

RG 1.238, Revision 0, Page 4 RG 1.32, Criteria for Power Systems for Nuclear Power Plants (Ref. 17), provides guidance for the safety-related portions of systems and equipment in the alternating-current power systems, direct-current power systems, and instrumentation and control power systems.

RG 1.63, Electric Penetration Assemblies in Containment Structures for Nuclear Power Plants (Ref. 18), provides guidance on electrical protection of penetration assemblies.

RG 1.75, Criteria for Independence of Electrical Safety Systems (Ref. 19), provides guidance for the physical independence of the circuits and electrical equipment that comprise or are associated with safety systems.

RG 1.105, Setpoints for Safety-Related Instrumentation (Ref. 20) provides guidance establishing setpoints for safety-related instrumentation to protect nuclear power plant safety and analytical limits, and on maintaining instrument channels implementing these setpoints to ensure they are functioning as required, consistent with the plants technical specifications.

RG 1.106, Thermal Overload Protection for Electric Motors on Motor-Operated Valves (Ref. 21), provides guidance on electrical protection of motors on motor-operated valves.

RG 1.118, Periodic Testing of Electric Power and Protection Systems (Ref. 22), provides guidance on the periodic testing of the electric power and protection systems.

RG 1.180, Guidelines for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related Instrumentation and Control Systems (Ref. 23), provides guidance on design, installation, and testing to address the effects of electromagnetic and radio-frequency interference, power surges, and electrostatic discharge on safety-related instrumentation and control systems.

Purpose of Regulatory Guides The NRC issues RGs to describe methods that are acceptable to the staff for implementing specific parts of the agencys regulations, to explain techniques that the staff uses in evaluating specific issues or postulated events, and to describe information that the staff needs in its review of applications for permits and licenses. Regulatory guides are not NRC regulations and compliance with them is not required. Methods and solutions that differ from those set forth in RGs are acceptable if the applicant provides sufficient basis and information for the NRC staff to verify that the alternative methods comply with the applicable NRC regulations.

Paperwork Reduction Act This RG provides voluntary guidance for implementing the mandatory information collections in 10 CFR Parts 50, 50.55a and 52 that are subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et. seq.). These information collections were approved by the Office of Management and Budget (OMB),

under control numbers 3150-0011, 3150-0264, and 3150-0151, respectively. Send comments regarding this information collection to the FOIA, Library, and Information Collections Branch (T6-A10M),

U.S.Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0011, 3150-0264, and 3150-0151) Office of Management and Budget, Washington, DC 20503.

RG 1.238, Revision 0, Page 5 Public Protection Notification The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless the document requesting or requiring the collection displays a currently valid OMB control number.

RG 1.238, Revision 0, Page 6 B. DISCUSSION Reason for Issuance The NRC is issuing a new guide on the protection of Class 1E power systems and equipment at nuclear power plants which incorporates the NRCs implementation of a risk-informed, performance-based approach to licensing. Subject to the conditions described in Section C, this RG endorses IEEE Std. 741-2022, which provides design criteria, design features, and testing provisions for the protection of safety-related or Class 1E power systems and equipment supplied from those systems at nuclear power plants. This new guide also takes into consideration operating experience and lessons learned.

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Background===

This RG describes a method acceptable to the NRC staff for complying with the regulations for the design, operation, and testing of electric power systems. IEEE Std. 741-2022 was prepared by IEEE Nuclear Power Engineering Committee Working Group 4.7 and was approved by the IEEE Standards Board on March 24, 2022. IEEE Std. 741-2022 provides: (1) criteria that establish protection requirements for Class 1E power systems and equipment, (2) the purpose of and the means for obtaining protection from electrical and mechanical damage, or from failures that can occur within a time period that is shorter than that required for operator action, and (3) testing and surveillance requirements.

The NRC has published several documents on undervoltage relay considerations and the protection of Class 1E power systems, including IN 1995-05, RIS 2011-12, BTP 8-6, IN 2012-03, and BL 2012-01 together with its closure.

The capacity, capability, and availability of an offsite power system may be affected by grid maintenance and grid conditions, especially during times of high grid load and high grid stress. The North American Electric Reliability Corporation standard NUC-001-4, Nuclear Plant Interface Coordination (Ref. 24), requires coordination between nuclear plant generator operators and transmission entities to ensure safe plant operation and shutdown. NUC-001-4 establishes a protocol for communication with the plants transmission system operator, combined with information on the transmission system operators capabilities, that can help nuclear power plant operators understand changes in the grid that could affect plant operations.

In relation to harmonics and harmonic distortion, IEEE Std. 519, IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems (Ref. 25), provides guidance on the design of power systems with nonlinear loads. IEEE Std. 1159, IEEE Recommended Practice for Monitoring Electric Power Quality (Ref. 26), and IEEE Std. 1531, IEEE Guide for the Application and Specification of Harmonic Filters (Ref. 27), provide additional information on monitoring power quality and on monitoring harmonic filters, respectively. The NRC staff reviewed IEEE Stds. 519, 1159, and 1531 and found that these documents contain information on power quality, harmonics, and harmonic filters. However, this revision of RG 1.238 does not endorse IEEE Std. 519, 1159, or 1531. The NRCs Research Information Letter 2023-09, An Assessment of the Harmonics Effects on Undervoltage Relays in Nuclear Power Plants, issued January 2024 (Ref. 28), contains information on how harmonic distortion affects electrical protection relay operation.

There are wide variations in Degraded Voltage Relay (DVR) time delay settings for nonaccident conditions (i.e., conditions other than loss-of-coolant accident conditions) at nuclear power plants depending on plant technical specifications or final safety analysis reports. Some power plants have a single set of DVR time delay settings (typically a few seconds), which apply in both accident and nonaccident conditions (i.e., there are no separate time delay settings for nonaccident conditions). Other

RG 1.238, Revision 0, Page 7 power plants have two sets of DVR time delay settings: one for accident conditions (for which the delay is short), and other for nonaccident conditions (for which the delay may be longer). The DVR time delay settings for nonaccident conditions may range from a few seconds to a much longer period, such as a few minutes, or may involve only an alarm. Based on operating experience of a dual-unit trip at Calvert Cliffs Nuclear Power Plant in 2015 (see the licensee event report (Ref. 29), and the NRCs special inspection report (Ref. 30)), if separate (longer) time delay settings do not exist for nonaccident conditions, then the short time delay settings used for accident conditions may lead to an unplanned or unexpected plant trip under nonaccident conditions during a significant switchyard voltage transient.

Consideration of International Standards The International Atomic Energy Agency (IAEA) works with member states and other partners to promote the safe, secure, and peaceful use of nuclear technologies. The IAEA develops Safety Requirements and Safety Guides for protecting people and the environment from harmful effects of ionizing radiation. This system of safety fundamentals, safety requirements, safety guides, and other relevant reports, reflects an international perspective on what constitutes a high level of safety. To inform its development of this RG, the NRC considered IAEA Safety Requirements and Safety Guides pursuant to the Commissions International Policy Statement (Ref. 31) and Management Directive and Handbook 6.6, Regulatory Guides (Ref. 32).

The following IAEA Guides were considered in the development of this RG:

Specific Safety Guide No. SSG-34, Design of Electrical Power Systems for Nuclear Power Plants, issued March 2016 (Ref. 33).

IAEA Nuclear Energy Series No. NG-T-3.8, Electric Grid Reliability and Interface with Nuclear Power Plants, issued 2012 (Ref. 34).

Documents Discussed in Staff Regulatory Guidance This RG endorses, in part, the use of one or more codes or standards developed by external organizations and other third-party guidance documents. These codes, standards, and third-party guidance documents may contain references to other codes, standards, or third-party guidance documents (secondary references). If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulation. If the secondary reference has been endorsed in a RG as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC staff for meeting that regulatory requirement as described in the specific RG. If the secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a RG, then the secondary reference is neither a legally binding requirement nor a generic NRC approved acceptable approach for meeting an NRC requirement. However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified, consistent with current regulatory practice, and consistent with applicable NRC requirements.

RG 1.238, Revision 0, Page 8 C. STAFF REGULATORY GUIDANCE The guidance in IEEE Std. 741-2022, including Annex A, Illustration of concepts associated with degraded voltage protection, provides an acceptable approach to the NRC staff for meeting the agencys regulatory requirements for the protection of Class 1E power systems and equipment, subject to the following conditions:

1.

This RG does not endorse Section 2, Normative References, of IEEE 741-2022. The following RGs contain additional information:

RG 1.32, which endorses IEEE Std. 308, with clarifications RG 1.63, which endorses IEEE Std. 317, with clarifications RG 1.30, which endorses IEEE Std. 336, with clarifications RG 1.118, which endorses IEEE Std. 338, with clarifications RG 1.75, which endorses IEEE Std. 384, with clarifications RG 1.180, which endorses IEEE Std. 1050

2.

Supplement Section 5.1.2c of IEEE Std. 741-2022 with the following:

RG 1.105 should be used for guidance on establishing setpoints for safety-related instrumentation to protect plant safety and analytical limits, and on maintaining instrument channels implementing these setpoints to ensure they are functioning as required. RIS 2006-017 provides information about the appropriate establishment of as-found and as-left acceptance tolerances.

3.

Annex B, Guidelines for selection of overload protection for valve actuator motor (VAM) circuits, is informative but endorsement of IEEE Std. 741-2022 does not include endorsement of Annex B. RG 1.106 provides additional information on electrical protection of motors on motor-operated valves.

4.

The following annexes are informative, but endorsement of IEEE Std. 741-2022 does not include endorsement of these annexes:

a. Annex C, Auxiliary system automatic bus transferprotection concerns, and

b. Annex D, Use of high-speed magnetic circuit breakers for special applications.

RG 1.238, Revision 0, Page 9 D. IMPLEMENTATION Licensees generally are not required to comply with the guidance in this regulatory guide. If the NRC proposes to use this regulatory guide in an action that would constitute backfitting, as that term is defined in 10 CFR 50.109, Backfitting, and as described in NRC Management Directive 8.4, Management of Backfitting, Forward Fitting, Issue Finality, and Information Requests (Ref. 35); affect the issue finality of an approval issued under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants; or constitute forward fitting, as that term is defined in Management Directive 8.4, then the NRC staff will apply the applicable policy in Management Directive 8.4 to justify the action.

If a licensee believes that the NRC is using this regulatory guide in a manner inconsistent with the discussion in this Implementation section, then the licensee may inform the NRC staff in accordance with Management Directive 8.4.

RG 1.238, Revision 0, Page 10 REFERENCES2 These references indicate the versions of the documents available at the time of issuance of this regulatory guide (RG). Licensees or applicants using this RG should check all referenced documents to verify that no change has occurred since the issuance of the RG.

1.

Institute of Electrical and Electronics Engineers (IEEE), Standard (Std.) 741-2022, IEEE Standard for Criteria for the Protection of Class 1E Power Systems and Equipment for Nuclear Power Generating Stations, Piscataway, New Jersey, 2022.3

2.

U.S. Code of Federal Regulations (CFR), Part 50, Domestic Licensing of Production and Utilization Facilities, Chapter I, Title 10, Energy.

3.

CFR, Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants, Chapter I, Title 10, Energy.

4.

IEEE, Std. 279-1968, Proposed IEEE Criteria for Nuclear Power Plant Protection Systems, Piscataway, New Jersey, 1968.

5.

IEEE, Std. 279-1971, Criteria for Protection Systems for Nuclear Power Generating Stations, Piscataway, New Jersey, 1971.

6.

IEEE, Std. 603-1991, Criteria for Safety Systems for Nuclear Power Generating Stations (including the correction sheet dated January 30, 1995), Piscataway, New Jersey, 1995.

7.

NRC, Branch Technical Position 8-6, Adequacy of Station Electric Distribution System Voltages, Revision 3, Washington, DC, March 2007 (ML070710478).

8.

U.S. Nuclear Regulatory Commission (NRC),Bulletin 2012-01, Design Vulnerability in Electric Power System, Washington, DC, July 27, 2012 (ML12074A115).

9.

NRC, NRC Bulletin 2012-01: Design Vulnerability in Electric Power System (closure of Bulletin 2012-01), Federal Register, Vol. 88, No. 43, pp. 13855-13859 (88 FR 13855),

Washington, DC, March 6, 2023.

10.

NRC, Information Notice 1995-05, Undervoltage Protection Relay Settings Out of Tolerance Due to Test Equipment Harmonics, Washington, DC, January 20, 1995 (ML031060397).

11.

NRC, Information Notice 2012-03, Design Vulnerability in Electric Power System, March 1, 2012 (ML120480170).

2 Publicly available NRC published documents are available electronically through the NRC Library on the NRCs public website at http://www.nrc.gov/reading-rm/doc-collections/ and through the NRCs Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html. For problems with ADAMS, contact the Public Document Room staff at 301-415-4737 or (800) 397-4209, or email pdr.resource@nrc.gov. The NRC Public Document Room (PDR), where you may also examine and order copies of publicly available documents, is open by appointment. To make an appointment to visit the PDR, please send an email to pdr.resource@nrc.gov or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. eastern time (ET), Monday through Friday, except Federal holidays.

3 Copies of IEEE documents may be purchased from the Institute of Electrical and Electronics Engineers Service Center, 445 Hoes Lane, P.O. Box 1331, Piscataway, New Jersey 08855, or through the IEEEs public website at http://www.ieee.org/publications_standards/index.html.

RG 1.238, Revision 0, Page 11

12.

NRC, NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition, Washington, DC.

13.

NRC, Regulatory Issue Summary 2006-017, NRC Staff Position on the Requirements of 10 CFR 50.36, Technical Specifications, regarding Limiting Safety System Settings during Periodic Testing and Calibration of Instrument Channels, Washington, DC, August 24, 2006 (ML051810077).

14.

NRC, Regulatory Issue Summary 2011-12, Adequacy of Station Electric Distribution System Voltages, Revision 1, Washington, DC, December 29, 2011 (ML113050583).

15.

NRC, Regulatory Guide (RG) 1.6, Independence Between Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems, Washington, DC.

16.

NRC, RG 1.30, Quality Assurance Requirements for the Installation, Inspection, and Testing of Instrumentation and Electric Equipment (Safety Guide 30), Washington, DC.

17.

NRC, RG 1.32, Criteria for Power Systems for Nuclear Power Plants, Washington, DC.

18.

NRC, RG 1.63, Electric Penetration Assemblies in Containment Structures for Nuclear Power Plants, Washington, DC.

19.

NRC, RG 1.75, Criteria for Independence of Electrical Safety Systems, Washington, DC.

20.

NRC, RG 1.105, Setpoints for Safety-Related Instrumentation, Washington, DC.

21.

NRC, RG 1.106, Thermal Overload Protection for Electric Motors on Motor-Operated Valves, Washington, DC.

22.

NRC, RG 1.118, Periodic Testing of Electric Power and Protection Systems, Washington, DC.

23.

NRC, RG 1.180, Guidelines for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related Instrumentation and Control Systems, Washington, DC.

24.

North American Electric Reliability Corporation, NUC-001-4, Nuclear Plant Interface Coordination, Washington, DC.4

25.

IEEE, Std. 519, IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems, Piscataway, New Jersey.

26.

IEEE, Std. 1159, IEEE Recommended Practice for Monitoring Electric Power Quality, Piscataway, New Jersey.

27.

IEEE, Std. 1531, IEEE Guide for the Application and Specification of Harmonic Filters, Piscataway, New Jersey.

4 Copies of North American Electric Reliability Corporation documents can be obtained at www.nerc.com, by contacting the Washington, DC, office located at 1401 H Street, NW, Suite 410, Washington, DC 20005, or by telephone at (202) 400-3000.

RG 1.238, Revision 0, Page 12

28.

NRC, Research Information Letter 2023-09, An Assessment of the Harmonics Effects on Undervoltage Relays in Nuclear Power Plants, January 2024 (ML23352A256).

29.

Calvert Cliffs Nuclear Power Plant, Licensee Event Report 2015-002, Calvert Cliffs Unit 1 and Unit 2 Automatic Reactor Trips Due to Transmission System Disturbance, June 5, 2015 (ML15160A321).

30.

NRC, Calvert Cliffs Nuclear Power Plants Units 1 and 2NRC Special Inspection Report 05000317/2015009 and 05000318/2015009, May 27, 2015 (ML15147A354).

31.

NRC, Nuclear Regulatory Commission International Policy Statement, Federal Register, Vol. 79, No. 132, pp. 39415-39418 (79 FR 39415), Washington, DC, July 10, 2014.

32.

NRC, Management Directive and Handbook 6.6, Regulatory Guides, Washington, DC.

33.

International Atomic Energy Agency (IAEA), Specific Safety Guide No. SSG-34, Design of Electrical Power Systems for Nuclear Power Plants, Vienna, Austria, March 2016.5

34.

IAEA, IAEA Nuclear Energy Series No. NG-T-3.8, Electric Grid Reliability and Interface with Nuclear Power Plants, Vienna, Austria, 2012.

35.

NRC, Management Directive 8.4, Management of Backfitting, Forward Fitting, Issue Finality, and Information Requests, Washington, DC.

5 Copies of International Atomic Energy Agency (IAEA) documents may be obtained through their website: www.iaea.org or by writing the International Atomic Energy Agency, P.O. Box 100, Wagramer Strasse 5, A-1400 Vienna, Austria.