Regulatory Guide 1.32

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

ML13350A366
Person / Time
Issue date:	03/31/1976
From:	NRC/OSD
To:
References
RG-1.032, Rev. 1
Download: ML13350A366 (3)

Revision I

U.S. NUCLEAR REGULATORY COMMISSION March 1976 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 i08-_ ,)71 has made the standard consistent with the require ment ij- Criterion 17 General Design Criterion 17, "Electric Power Sys- for two circuits to the uffsite network, each designed to tems," of Appendix A, "General Design Criteria for be available in sufficient time following a loss of onsite Nuclear Power Plants," to 10 CFR Part 50. "Licensing alternating current power supplies and the other ofl'sltt, of Production and Utilization Facilities," requires that electric power circuit. However. two potential conflicts an onsite electric power system and an offsite electric with Criterion 17 remain unresolved: one in the area of power system be provided to permit functioning of availability of offsitc power (Item I) and the other in structures, systems, and components important to battery charger supply requirements (Item 2). In addi- safety. In addition, Criterion 17 contains requirements tion. an inconsistency. exists between IEEI Std concerning system capacity, capability, independence, 308-1974 and IIEEE.SId 450-1975 (Itiem 3).

redundancy, availability, testability, and reliability. Gen- eral Design Criterion 18, "Inspection and Testing of 1. IEEE Standard 308-1974. Section 5.2.3(4). first Electric Power Systems," of Appendix A to 10 CFR Part paragraph. requires that off'site power be available within

50, contains requirements concerning periodic in- an acceptable tine following a loss-of-coclarrt accident.

spection, testing, and testability of electric power .ii, contrast, Criterion 17 requires that offsite power be systems important to safety. This guide describes a available within a few seconds following a loss-of-coolant method acccptable to the NRC staff of complying with.. lccident.;

Thus a potential for misunderstanding exists Criteria 17 and 18 with respect to the design, operation'. wi.vith regard to t[le maximum permissible time for access and testing of safety-related electric power systems' In all ,tro the offsite network in the event of a loss-of-coolant types of nuclear power plants. accident, and further guidance is needed.

B. DISCUSSION

2. Section 5.3.4 of IEEE Std 308-1974 requires. in part. that each battery charger supply (a) furnish electric IEEE Sid 3 08-1 9 7 4 ' is a revision of IEEE Std energy for 'he steady-state operation of connected loads

308-1971 and was prepared byWorking Group 4.1 of the required duial normal and postaccident oplration while Nuclear Power Engineermig Cobilnittee (NPEC) of the its battery is to turned to or maintained in a full!y charged Institute of Electrical and .Ele6tr6udlcs Engineers (IEEE).

state and (b) have sufficient capacity to restore the IEEE Std 308-1974--was .approv'ed by NPEC at its meeting on MayfA.18.7':J973 itnd subsequently by the batter)y from the design mninimum charge to its f'ully IEEE Standards Bard on December 13, 1973. charged state while supplying normal and postaccident steady-state loads. In contrast, the equivalent position of Criterion 17 requires that the onsite electric power

'IEEE Std"3(8-"974, "-lrF Standard Criteria for Class I- supplies, including the batteries and the onsite electric Power Sysiemti'for Nuclear Power Generating Stations," may be obtained from '*itb Institute of Electrical and Electronics distribution system. have sufficient independence, re- Engineers. United Eingineering Center. 345 East 47th Street. dundancy. capacity. and testability to perform their New York, New York 10017. safety functions assuming a single failure. Criterion 17.

USNRC REGULATORY GUIDES Comments should be sent to the Sectetaty of the Comrnison U S Nuclea, Regulatory Ctoniison Washiglon DC 2M56 Attention Oocketing &tid Rfqulatoty Guides ,..e...ued to describe and niafke dvuilable to th, pulibtc nt-thods acceptlble to ftle NRC Stall of implemtenting iSpecific prl,. tit tieo Conim-issin s teguldtions. to detineale lechniques used by the staff in avalo Ihe guides ate issued in the following ten broad divisions hlunq specitic ptiiblents or poItulated accident,. orto provide guidance lu apph cants Reguldtoiv Guides at. not substitutes tot regulations. and comph.ance I Power React.is 6P'odutcts with them is nut tequtoedl MeIthods and solutions different fion, those %elout 22t%Research aid Test Reactots 7 Ttansporalaton the guides will be accept.iblr it they provide a basis tot the fitdings requisite to J Fuels and Matetiats facilities 8 Occupational Heallh the isslance tit ciinlinuttsce il d p-totit os license by the Comntmission m*nvtonmental and Siting 9 Antitrust Review Comntits asd ll s i -iilqestii ntitttieh e guides aie encouraged l III

oinigtist 5 MuterldJs and Plant Protection t0 Generta at alt ltii. inld qiljes will li i-d.

tev is iltptopriale to 4tccuntndalole con.

noe,,fs a,, sitIle.*ter new tttliltli ittnot esgtellrent rit However. cotmme*ts Ill Copies ot published guides may be obtained by written tequest indicating the thi. ,utitfe. if rii, f** wiitthi .httiiI

utw toilithtl otter its issuartce. w*ll he pat divisions desired to the U S Nucleat Regulatory Commission, Washingtoin 0 C

ticulltai useful ...etlittiiqltil the iln-d fill .ill eily oI vitool l 20556, Attention Ditector. OfiIce of Standards Development

therefore, does not restrict the battery charger supply process for electric power systems in nuclear power loads to normal and postaccident steady.state loads. A plants have been the subject of such regulatory guides as conflict may therefore exist for those plants in which Regulatory Guide 1.9 (Safety Guide 9), "Selection of other loads (e.g., loads required during hot or cold Diesel Generator Set Capacity for Standby Power shutdown, large startup loads during an accident, or Supplies," and Regulatory Guide 1.93, "Availability of other design basis events) are greater than the normal Electric Power Sources."

and postaccident steady-state loads. The criteria and requirements in IEEE Std 308-1974 are indicated by the verbs "shall" and "must", and

3. Table 2, "illustrative Periodic Tests," of IEEE Std recommendations are indicated by the verb "fhould".

308-1974 lists a test interval of 3 years for the battery The terms "may", "suggested", and "illustrative" indi- performance discharge test and refers to IEEE Std 450-1972, "Recommended Practice for Maintenance, cate optional practices.

Testing, and Replacement of Urge Stationary Type Power Plant and Substation Lead Storage Batteries," for

C. REGULATORY POSITION

details regarding performance of such tests. Subsequent to the publication of IEEE Std 308-1974, IEEE Std 1. For the portion of safety-related electric power

450-1972 was revised and published as IEEE Std system within its scope, the criteria, requirements, and

450.1975, "IEEE Recommended Practice for Mainten- recommendations in IEEE Std 308-1974 are generally ance, Testing, and Replacement of Large Lead Storage acceptable to the NRC staff and provide an adequate Batteries for Generating Stations and Substations." basis for complying with the Commission's General IEEE Std 450.1975 specifies a battery performance Design Criteria 17 and 18 of Appendix A to 10 CFR

discharge test within the first two years of service and Part 50 %k ith respect to the design, operation, and testing thereafter at intervals of 5 years until the battery shows of e!ectric power systems, subject to the following:

signs of degradation or until 85% of expected service life is reached, at which time annual tests are required. The a. Availability of Offsite Powe

r. Consistent with

3-year interval specified in IEEE Std 308-1974 conflicts the requirements of Criterion 17, the phrase "within an with these requirements. IEEE Std 450-1975 also acceptable time" in Section 5.2.3(4), first paragraph, of describes a battery service test, but no test frequency is IEEE Std 308.1974 should be construed to mean specified. IEEE Std 308-1974 does not specifically "within a few seconds". A preferred design would mention the battery service test. include two immediate access circuits from the trans- mission network. Detailed guidance for operating pro- It should be noted that the scope of IEEE Std cedures and restrictions acceptable to the staff, appli.

308-1974 is more limited than that of Criteria 17 and cable where two immediate access circuits are available,

18. For example. the scope of IEEE Std 308-1974 is contained in Regulatory Guide 1.93, "Availability of excludes the unit generator(s) and th"ir buses; step-up, Electric Power Sources." An acceptable design would auxiliary, and startup transformers; connections to the substitute a delayed access circuit for one of the station switchyard. switchyard; transmission lines; and immediate access circuits provided the availability of the the transmission network. Except for the unit genera- delayed access circuit conforms to Criterion 17.

tor(s), these are all included within the scope of Criteria

17 and 18. b. Battery Charger Supply. The capacity of the battery charger supply should be based on the largest combined demands of the various steady-state and In the foreword to IEEE Std 308-1974 it is noted transient loads and the charging capacity to restore the that certain areas of this standard neee more extensive battery from the design minimum charge state to the treatment. These include shared systems in multi-unit fully charged state, irrespective of the status of the plant stations, independence between redundant standby during which these demands occur.

sourcem, connection of non-Class I E equipment to Class I E systems, and the definition of design basis events. c. Battery Performance Discharge Tests. The test Some of these topics have been the subject of other interval for the battery performance discharge test regulatory guides, e.g., Regulatory Guide 1.6 (Safety should be as specified in IEEE Std 450-1975 instead of Guide 6), "Independence Between Redundant Standby the 3 years specified in Table 2 of IEEE Std 308-1974, (Onsite) Power Sources and Between Their Distribution "Illustrative Periodic Tests." The battery service test Systems," which is concerned with electrical independ- described In IEEE Std 450-1975 should be performed in ence. Regulatory Guide 1.75, "Physical Independence of addition to the battery performance discharge test. The Electric Systems," which is concerned with physical battery service test should be performed during refueling independence of Class IE systems and the connection of operations or at some other outage, with intervals non-Class I E equipment to Class IE systems; and between tests not to exceed 18 months. The note Regulatory Guide 1.81, "Shared Emergency and Shut. following Table 2 of IEEE Std 308-1974 should refer- down Electric Systems for Multi-Unit Nuclear Power ence IEEE Std 450-1975 rather than IEEE Std Plants." Other matters of importance to the regulatory 450-1972.

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d. Independence of Redundant Standby Sources. IE Power System Conditions," of IEEEStd 308.1974 is Electrical independence between redundant standby considered unacceptable and should be supplanted by (onsite) power sources should be in accordance with the recommendations of Regulatory Guide 1.93.

Regulatory Guide 1.6. Physical independence should be in accordance with Regulatory Guide 1.75.

e. Connection of Non-Class IE Equipments to Class IE Systems. The guidance presented in Regulatory

D. IMPLEMENTATION

Guide 1.75 should be followed.

The purpose of this section is to provide information f. Selection of Diesel Generator Set Capacity for to applicants reg-irding the NRC staff's plans for using Standby Power Supplies. The guidance presented in this regulatory guide.

Regulatory Guide 1.9 should be followed.

Except in those cases in which the applicant proposes

2. The following optional practices are considered to an acceptable alternative method for complying with be unacceptable as given below: specified portions of the Commission's regulations. ( I )

the methods described in portions of this guide that a. Shared Electric Systems for Multi-Unit Nuclear reference other regulatory guides are being and will Power Plants. The provisions of Section 8.2 of IEEE Sid continue to be used in the evaluation of submittals for

308.1974, which permit sharing of standby power construction permit applications and (2) the methods supplies among units of a multi.unit station, are un- described in other portions of this guide will be used in acceptable except as specified in Regulatory Guide 1.81. the evaluation of submittals for construction permit The provisions of Section 8.3.1 of IEEE Std 308-1974 applications docketed after November 1. 1976, unless that permit sharing of battery supplies among units at a this guide is revised as a result of suggestions from the multi.unit plant are considered unacceptable and should public or additional staff review.

be supplanted by tne recommendations of Regulatory Guide 1.81. If an applicant wishes to use this regulatory guide in developing submittals for applications docketcd on or b. Availability of Electric Power Sources. Table 3, before November 1, 1976, the pertinent portions of the

"Suggested Operating Alternatives with Degraded Class application will be evaluated on the basis of this guide.

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