Regulatory Guide 1.32

Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants

ML003739990
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Issue date:	02/28/1977
From:	Office of Nuclear Regulatory Research
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RG-1.032, Rev 2
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Revision 2 U.S. NUCLEAR REGULATORY COMMISSION February 1977 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.32 CRITERIA FOR SAFETY-RELATED ELECTRIC POWER SYSTEMS

FOR NUCLEAR POWER PLANTS

A. INTRODUCTION

This revision to IEEE Std 308-1971 has made the standard consistent with the requirement in Criterion General Design Criterion 17, "Electric Power 17 for two circuits to the offsite network, each Systems," of Appendix A, "General Design Criteria designed to be available in sufficient time following a for Nuclear Power Plants," to 10 CFR Part 50, loss of onsite alternating current power supplies and

"Licensing of Production and Utilization Facilities," the other offsite electric power circuit. However, two requires that an onsite electric power system and an potential conflicts with Criterion 17 remain un offsite electric power system be provided to permit resolved: one in the area of availability of offsite functioning of structures, systems, and components power (Item 1)and the other in battery charger supp important to safety. In addition, Criterion 17 con ly requirements (Item 2). In addition, an incon tains requirements concerning system capacity, in sistency exists between IEEE Std 308-1974 and IEEE

dependence, redundancy, availability, testability, and Std 450-1975 (Item 3).

reliability. General Design Criterion 18, "Inspection and Testing of Electric Power Systems," of Appendix 1. IEEE Standard 308-1974, Section 5.2.3(4), first A to 10 CFR Part 50, contains requirements concern paragraph, requires that offsite power be available ing periodic inspection, testing, and testability of within an acceptable time following a loss-of-coolant electric power systems important to safety. This guide accident. In contrast, Criterion 17 requires that off describes a method acceptable to the NRC staff of site power be available within a few seconds follow complying with Criteria 17 and 18 with respect to the ing a loss-of-coolant accident. Thus a potential for design, operation, and testing of safety-related misunderstanding exists with regard to the maximum electric power systems in all types of nuclear power permissible time for access to the offsite network in

• plants. The Advisory Committee on Reactor the event of a loss-of-coolant accident, and further Safeguards has been consulted concerning this guide guidance is needed.

and has concurred in the regulatory position.

2. Section 5.3.4 of IEEE Std 308-1974 requires, in

B. DISCUSSION

part, that each battery charger supply (a) furnish electric energy for the steady-state operation of con IEEE Std 308-1974' is a revision of IEEE Std 308 nected loads required during normal and postacci

1971 and was prepared by Working Group 4.1 of the dent operation while its battery is returned to or Nuclear Power Engineering Committee (NPEC) of maintained in a fully charged state and (b) have suf the Institute of Electrical and Electronics Engineers ficient capacity to restore the battery from the design (IEEE). IEEE Std 308-1974 was approved by NPEC minimum charge to its fully charged state while sup at its meeting on May 17-18, 1973, and subsequently plying normal and postaccident steady-state loads. In by the IEEE Standards Board on December 13, 1973. contrast, the equivalent position of Criterion 17 re quires that -the onsite electric power supplies, in

• Lines indicate substantive changes from previous issue. cluding the batteries and the onsite electric distribu IEEE Std 308-1974, "IEEE Standard Criteria for Class IE Power tion system, have sufficient independence, redun Systems for Nuclear Power Generating Stations," may be obtained dancy, capacity, and testability to perform their from the Institute of Electrical and Electronics Engineers, United Engineering Center, 345 East 47th Street, New York, New York safety functions assuming a single failur

e. Criterion

10017. 17, therefore, does not restrict the battery charger USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission, US. Nuclear Regu latory Commission, Washington, D.C. 20555. Attention: Docketing and Service Regulatory Guides are issued to describe and make available to the public methods Branch.

acceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff in evaluating specific problems The guides are issued in the following ten broad divisions:

or postulated accidents, or to provide guidance to applicants. Regulatory Guides are not substitutes for regulations, and compliance with them is not required. 1. Power Reactors 6. Products Methods and solutions different from those set out in the guides will be accept- 2. Research and Test Reactors

7. Transportation

3. Fuels and Materials Facilities 8. Occupational Health able if they provide a basis for the findings requisite to the issuance or continuance 4. Environmental andSiting 9. Antitrust Review of a permit or license by the Commission. 5. Materials and Plant Protection 10. General Comments and suggestions for improvements in these guides are encouraged at all Requests for single copies of issued guides (which may be reproduced) or for place times, and guides will be revised, as appropriate, to accommodate comments and ment on an automatic distribution list for single copies of future guides in specific to reflect new information or experience. This guide was revised as a result of divisions should be made in writing to the US. Nuclear Regulatory Commission, substantive comments received from the public and additional staff review. Washington, D.C. 20555, Attention: Director, Division of Document Control.

supply loads to normal and postaccident steady-state nuclear power plants have been the subject of such loads. A conflict may therefore exist for those plants regulatory guides as Regulatory Guide 1.9 (Safety in which other loads (e.g., loads required during hot Guide 9), "Selection of Diesel Generator Set or cold shutdown, large startup loads during an acci Capacity for Standby Power Supplies," and dent, or other design basis events) are greater than Regulatory Guide 1.93, "Availability of Electric the normal and postaccident steady-state loads. Power Sources."

3. Table 2, "Illustrative Periodic Tests," of IEEE The criteria and requirements in IEEE Std 308 Std 308-1974 lists a test interval of 3 years for the bat 1974 are indicated by the verbs "shall" and "must,"

tery performance discharge test and refers to IEEE and recommendations are indicated by the verb Std 450-1972, "Recommended Practice for "should." The terms "may," "suggested," and "il Maintenance, Testing, and Replacement of Large lustrative" indicate optional practices.

Stationary Type Power Plant and Substation Lead Storage Batteries," for details regarding performance

C. REGULATORY POSITION

of such tests. Subsequent to the publication of IEEE Std 308-1974, IEEE Std 450-1972 was revised and 1. For the portion of safety-related electric power published as IEEE Std 450-1975, "IEEE Recom systems within its scope, the criteria, requirements, mended Practice for Maintenance, Testing, and and recommendations in IEEE Std 308-1974 are Replacement of Large Lead Storage Batteries for generally acceptable to the NRC staff and provide an Generating Stations and Substations." IEEE Std 450 adequate basis for complying with the Commission's

1975 specifies a battery performance discharge test General Design Criteria 17 and 18 of Appendix A to within the first two years of service and thereafter at 10 CFR Part 50 with respect to the design, operation, intervals of 5 years until the battery shows signs of and testing of electric power systems, subject to the degradation or until 85% of expected service life is following:

reached, at which time annual tests are required. The

3-year interval specified in IEEE Std 308-1974 con a. Availability of Offsite Power. Consistent with flicts with these requirements. IEEE Std 450-1975 the requirements of Criterion 17, the phrase "within also describes a battery service test, but no test fre an acceptable time" in Section 5.2.3(4), first quency is specified. IEEE Std 308-1974 does not paragraph, of IEEE Std 308-1974 should be con specifically mention the battery service test. strued to mean "within a few seconds". A preferred design would include two immediate access circuits It should be noted that the scope of IEEE Std 308 from the transmission networ

k. Detailed guidance

1974 is more limited than that of Criteria 17 and 18. for operating procedures and restrictions acceptable For example, the scope of IEEE Std 308-1974 ex to the staff, applicable where two immediate access cludes the unit generator(s) and their buses; step-up, circuits are available, is contained in Regulatory auxiliary, and startup transfomers; connections to the Guide 1.93, "Availability of Electric Power Sources."

station switchyard; switchyard; transmission lines; An acceptable design would substitute a delayed ac and the transmission network. Except for the unit cess circuit for one of the immediate access circuits generator(s), these are all included within the scope of provided the availability of the delayed access circuit Criteria 17 and 18. conforms to Criterion 17.

In the forward to IEEE Std 308-1974 it is noted b. Battery Charger Supply. The provisions of that certain areas of this standard need more exten Section 5.3.4 of IEEE Std 308-1974 should be con sive treatment. These include shared systems in multi strued to mean that the capacity of the battery unit stations, independence between redundant charger supply should be based on the largest com standby sources, connection of non-Class 1E equip bined demands of the various steady-state loads and ment to Class IE systems, and the definition of design the charging capacity to restore the battery from the basis events. Some of these topics have been the sub design minimum charge state to the fully charged ject of other regulatory guides, e.g., Regulatory state, irrespective of the status of the plant during Guide 1.6 (Safety Guide 6), "Independence Between which these demands occur.

Redundant Standby (Onsite) Power Sources and Between Their Distribution Systems," which is con c. Battery Performance Discharge Tests. The test cerned with electrical independence; Regulatory interval for the battery performance discharge test Guide 1:75, "Physical Independence of Electric should be as specified in IEEE Std 450-1975 instead Systems," which is concerned with physical in of the 3 years specified in Table 2, "Illustrative dependence of Class lE systems and the connection Periodic Tests," of IEEE Std 308-1974. The battery of non-Class IE equipment to Class 1E systems; and service test described in IEEE Std 450-1975 should be Regulatory Guide 1.81, "Shared Emergency and performed in addition to the battery performance dis Shutdown Electric Systems for Multi-Unit Nuclear charge test. The battery service test should be per Power Plants." Other matters of importance to the formed during refueling operations or at some other regulatory process for electric power systems in outage, with intervals between tests not to exceed 18

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months. The note following Table 2 of IEEE Std 308 b. Availability of Electric Power Source

s. Table

1974 should reference IEEE Std 450-1975 rather than 3, "Suggested Operating Alternatives with Degraded IEEE Std 450-1972. Class IE Power System Conditions," of IEEE Std 308-1974 is considered unacceptable and should be d. Independence of Redundant Standby Sources. supplanted by the recommendations of Regulatory Electrical independence between redundant standby Guide 1.93.

- (onsite) power sources should be in accordance with Regulatory Guide 1.6. Physical independence should

D. IMPLEMENTATION

be in accordance with Regulatory Guide 1.75.

The purpose of this section is to provide informa tion to applicants regarding the NRC staff's plans for e. Connection of Non-Class IE Equipment to using this regulatory guide.

Class 1E Systems. The guidance presented in Regulatory Guide 1.75 should be followed. Except in those cases in which the applicant proposes an acceptable alternative method for com f. Selection of Diesel Generator Set Capacity for plying with specified portions of the Commission'*s Standby Power Supplies. The guidance presented in regulations, (1) the methods described in portions of Regulatory Guide 1.9 should be followed. this guide that reference other regulatory guides are being and will continue to be used in the evaluation

2. The following optional practices are considered of submittals for construction permit applications to be unacceptable as given below: and (2) the methods described in other portions of this guide will be used in the evaluation of submittals a. Shared Electric Systems for Multi-Unit for construction permit applications docketed after Nuclear Power Plants. The provisions of Section 8.2 April 15, 1977, unless this guide is revised as a result of IEEE Std 308-1974, which permit sharing of stand of suggestions from the public or additional staff by power supplies among units of a multi-unit sta review.

tion, are unacceptable except as specified in Regulatory Guide 1.81. The provisions of Section If an applicant wishes to use this regulatory guide

8.3.1 of IEEE Std 308-1974 that permit sharing of in developing submittals for applications docketed on battery supplies among units at a multi-unit plant are or before April 15, 1977, the pertinent portions of the considered unacceptable and should be supplanted application will be evaluated on the basis of this by the recommendations of Regulatory Guide 1.81. guide. 0

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