Latest revision as of 11:50, 9 December 2021

Text

Summarizes 870829 Meeting W/Nuclear Util Group on Station Blackout in Bethesda,Md Re Differing Subpopulations of Nuclear Power Plants Chosen for 8 H Group.List of Attendees Encl
	ML20195G349
Person / Time
Issue date:	08/07/1987
From:	Baranowsky P; Office of Nuclear Reactor Regulation
To:	Serkiz A; NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
Shared Package
ML20195F793	List: ML20195F789; ML20195G040; ML20195G349; ML20207D767; ML20207D778; ML20207D800; ML20207D810; ML20207D969;
References
	FOIA-87-652 NUDOCS 8708110540
	Download: ML20195G349 (4)
	v • d • e

~

t

'g UNITED STATES 8 e NUCLEAR REGULATORY COMMISSION E wAsmNoToN. D. c. 20555

\*...*/ AUS 0 7 g . .

MEMORANDUM FOR: 41.Sertin Reactor & Plant Safety Issues Branch, RES FROM: Pat Bararowsky, Section Chief BWR Section Events Assessment Branch, NRR

SUBJECT:

MEETING W:TH MEMBERS OF NUGSB0 ON AUGUST 79, 1587 This memorandum documents an informal meeting held in Room 414 of the Phillips Building on August 29, 1987 between members of the Nuclea Utility Group on Station Blackout (NUGSBO) and NRC staff. A list nf atten'ees is attached. The purpose of the meeting was to try to ascertain why BLQB0 is identifying a different subpopulation of nuclear plants to be i' the "8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months group" from that determined by NRC analyses.

After comparison of several site location and design factors, it was concluded that the differences could be attributed to three factors: (1) the use of a 0.8 availability factor by the NRC for severe weather terms, (2) assumed need for more thanone EDG per unit by NUGSB0; and (3) tornado hazard rate dis-crepancies between NUGSB0 and MRC. The current tornado hazard rates used by W.C staff are attached to this memorandum. The NRC staff indicated that they would double check the proper use of the 0.8 availability factor and, if appro-priate correct the draft MUREG and Regulatory Guide.

The NUGSB0 members also expressed interest in clarfying criteria for con-sidcrtion of common mode failure of "alternate" AC power sources. A copy of the NRC staffs multiple diesel generator failure data base was requested.

A coepilation of those failures is also attached.

a

$k at Baranowsky, Sectio Chief BWR Section Events Assessment Br ch, NRR

Attachment:

As stated l f

r cc: A. Rubin, NRC-RES l J. Flack, NRC-RES S. Mal m y, NUGSB0 PDR 1 \

/

\ /

l (aguashyy I g 1

HEETING ATTENDEES AUGUST 29, 1957 P. W. Baranowsky, NRC A. M. Rubin, NRC J. Flack , NRC S. Maleney, NVGSB0 B. Malinovich, NUGSB0 M. Childers, NVG380 0

rdC PLANT FS FW75 FW125 FTH FT U FGH 1 SAN ONOFRE O O.001 0.0001 0.( .

0.00.c153 .T. 0 2 HATCH O O.022 0.0009 O.000 O. 00<c290 . T . O y DIABLO CANYON O O.070 0.0001 0.000 0.0/40001 .T. O

'A VOGTLE 2 0.022 0.0006 c.000 O.0000360 .T, O

'S - RANCHO SECO O O.100 O.0005 O.000 O.0000006 .T. O 6 CARROL COUNTY O O.000 O.0002 0.000 O.0001030 T. O 7 CRYSTAL RIVER O O.100 C.0060 0.000 O.00<c130 .T.

~

4 8 WATERFORD 0 O.090 C.0068 O.000 O. 0000320 . T. O 9 PALO VERDE O O.125 O.0004 O.000 O.0000018 .T. O 1O MCGUIRE 6 O.030 C.0001 O.000 O. CCCc302 . T . O 11 FARLEY O O.050 0.0020 0.000 0, r/h0810 . T. O 12 PERRY O O.080 O.0001 O.000 O. (O<c660 . T . O 13 SOUTH TEXAE O O.120 C.0120 C.000 O. 0%3310 . T . O 14 ST. LUCIE O O.150 C.0170 C.000 O. CQCc! 30 . T . 7 15 CALVERT CLIFFS 9 0.062 0.0038 C.000 O. OX :477 .T. O le TURKEY POINT O O.100 C.0230 C.000 O.00G0120 .T. 9 17 COMANCHE PEAK 4 C.050 C.0001 C.000 O. OOC 1090 .T. O 18 TROOAN 7 C.140 C.0011 O.000 O.0000004 .T. O 19 OCONEE 6 O.120 C.0011 O.000 O.OOCc380 .T. O

. 20 HARTSVILLE 10 C.000 O.0001 C.000 O.0001115 .T. O 21 BRUNSWICK 2 C.120 O.0130 C.000 O.0000870 .T. 4 22 SURRY 8 O.100 O.0060 C.000 O.0000440 .T. O

~".- RIVER BEND 0 C.090 C.0068 C.000 O.0001540 .T. O 2 /. SUMMER 2 O.120 O.0011 C.000 O. 0001060 . T . O 25 OYSTER CREEK 17 C.063 O.0050 C.000 O.OCCOO38 . T. 2 26 YELLOW CREEM 5 O.020 C.0001 O.000 O.0001800 .T. O

~

27 NORTH ANNA 15 O.000 C.0034 C.000 O.0000367 .T. O i CATAWBA 6 O.120 O.0011 C.000 O.0001040 .T. O

, . J LIMERICK 22 C.027 O.0020 O.000 O.0000285 .T. O 30 SEQUOYAH 4 O.100 C.0007 C.000 O.0001499 .T. O 31 ROBINSON 1 C.090 C.0036 O.000 O.0001970 .T. O 32 SALEM 22 Q.045 O.0038 O.000 O.0000275 .T. 1 33 HOPE CREEK 22 O.045 O.0038 0.000 O.0000275 .T. O 34 PEACH BOTTOM 22 O.026 O.0026 O.000 O.0000601 .T. O 35 BELLEFONTE 4 O.029 0.0001 O.000 O. 0000530 . T . O 36 WATTS BAR 10 O.100 C.0001 O.000 O.OOCT422 .T. O 37 SHOREHAM 26 O.080 O.0100 0 000 O.0000:51 .T. 3 38 INDIAN POINT 29 C.080 O.0079 0.000 O. OCc0141 .T. 3 39 CALLAWAY 24 0.050 0.0001 0.000 0. 0001060 . T . O 40 HARRIS 8 O.130 O.0100 C.000 O.OC40220 .F. O 41 GRAND GULF 1 O.030 C.0040 C.000 O. OC43 900 . T. O 42 THREE MILE ISLAND 35 O.027 O.0020 O.000 O. 0000392 . T. O 43 HADDAM NECK 27 O.080 C.0100 0.000 O.0000890 .T. O 44 FERMI 32 O.050 O.0001 0.000 O.0000939 .T. O

.45 IION 40 O.010 C.0001 C.000 O. OCCO500 . T. O 46 BROWNS FERRY 4 0.029 0.0001 0.000 0. 0004150 . T . O 47 BYRON 35 O.010 C.0002 O.000 O. 0001180 .T. O 48 SUSQUEHANNA 44 0.028 O.0018 O.000 O. OCCO292 .T. O 49 BEAVER VALLEY 45 O.030 C.0001 C.000 O.0000692 .T. O 50 POINT BEACH 42 C.100 C.0036 0.000 O.0000350 .T. O W .

-s ,, .' C .

.i

. .s t -

s E

h [ ,

(

51 KEWAJNEE 42 0.100 0.0036 0.00 0.0000360 .T. O 52 ARr.AASAS NUCLEAR ONE 6 0.067 O.0002 O.000 0.0004000 .T. O

-( t prp-2 53 C.030 C.0001 0.000 O.0000002 .7. O 3'JJ ' DAVIS-BESSE 30 O.110 0.0004 0.000 O.0000830 .T. O

~ 55 CLINTON 24 C.100 C.0002 O.000 0.0003050 .T. O 56 FORT ST. VRAIN 59 0.020 0.0001 0.000 0.0000130 .T. O 5'1 QUAD CITIES 40 0.150 0.0002 0.000 0.0000890 .T. O 58 DRESDEN 40 0.080 0.0001 0.000 0.0001810 .T. O 59 MONTICELLO 46 0.080 0.0000 0.000 0.0001218 .T. O 60 PRAIDWOOD 40 O.080 O.0010 O.000 O.0002050 .T. O 61 LA cc !F _40 M R:E ISLAND 46 O. O8L10002 0.6,80 O.000 O.0002210_.T. O 0.00iv O.1 00 T.J.OOO 1717. . T . O 67 COOL 48 0.100 0.0006 0.000 0.0001450 .T. O e, 4 MIELAND 45 0.000 O. CCO 2 0.000 0.0002720 .F. O 65 SE ABRCO) . . --

- ~ 65 O.045 O.0038 C.000 O.0000291 .T. O 6m PALISADES 48 O.100 0.0006 0.000 O.0001845 .T. O 67 WOLc CREEL: 20 C.230 C.000: O.000 C.0003815 .T. O GS MAINE YANKEE 74 O.034 O.0028 O.000 O.0000010 .T. 1 69 ARtOLD 33 0.250 0.0008 0.000 0.0002570 .T. O 70 FORT CALHOUN 29 0.500 O. CC 14 O.000 O.0001410 .T. O

-' 1 VERMONT YANKEE 79 C.040 C. Cc34 O.000 O.0000071 .T. O 72 YANKEE ROWE 79 C.063 C.0056 C.000 O.0000600 .T. O 77 GINNA 89 O.060 O. Cco l O.000 O.0000054 .T. O 4 FIT 2PATRICI: 89 O.060 C.0001 O.000 O.0000057 .T. 0 75 NINE MILE POINT 89 C.060 C.0001 C.000 O.COC,0058 .T. O

?o COO:ER 30 0.500 0.CC14 0.000 O.OOO2400..T. O

~7 7 BIG ROCK POINT 97 0.006 0.0001 0.000 0.0000183 .T. O

} PILGRIM 42 0.000 O.0068 0.080 C.0000050 .T. 1 f MILLSTONE 27 O.000 O.0120 C.186 O.OOOO46b .T. 2 r

-5

, . .-t :

, s , ~ . .9 .L

v ,.... - -

-- 3

wast 87)/

2 k d3 6 83-67 f f ASSESSMENT OF COPING DURATION REQCIREMENTS REVISION 2.0 OCTOBER 14,1986 l

NUCLEAR UTILITY GROUP ON STATION BLACKOUT l

SUITE 700 l

1200 SEVENTT.ENTH STREET, N.W.

WASHINGTON, D.C. 20036 E 71$3 e^ O A5 YSN M /M ,

f '

ASSESSMEST OF COPING DURATION REQUIREMENTS REVISION :..'

OCTODER A 't&6 I

L REVISION SUNIN!ARY l

l I

Revision Description 0.0 ORIGIN AL ISSUE FOR COMMENT BY NUGSBO MEMBERS 1.0 Modified Utle, added the fouowing new uccons:

Introduction. Definidons. Correcuve Measures.

References, and Appendix; and provided clanticacons ta response to changing guidance from b7C Staff, and

adustry comments.- General distnbucon 10 Issued revised precedures inccrporating alternate AC concept wis restncuens on use of standby power wxtree.- - General distnbution i

l l

ASSESSMENT OF COPING DURATION REQUIREMESTS REVISION 2.0 OCTODER Id.1986 CONTENTS INTRODUCDON 4 DEFINITIONS 13

. PROCEDURE STEP ONE* DETERMINE OFFSTTE POWER DESIGN CARGORY 15 STEP TWO: ClassFY THE EMERCD4CY AC POWER CONRCLhTION 29 STEP THREE. DeinMINE CL1UtDir EDG REUABu1TY 33 STEP FOUR: DETERMINE COPNG DLET10N REQtRREMENr 35 l SUMMA 8Y 36 l

CORRECTIVE MEASURES 37 REFERENCES 39 APPENDIX 41 l

l. .

l t

l l

l l 3

< 'f ASSESSMENT OF COPING DURATICS REQUIREMENTS RE*GSION 2.0 OCTO B ER 14.1986 INTRODUCTION PREAMBLE Late in 1985, the Nuclear Utility Mz: age:nent and Resources Committee (NUMARC) esublished a working group cu station blackout to a:' dress the issues raised by the Staff. De Nuclear Utdity Group on Station Blackout (NUGSBO) has provided the major portion of NUMARC's tech::ical support including preparation of comments on he rulemaking record and the analysis of factors centributing to station blackout risk. On the basis of:: tis analysis, NUMARC determined that many of the concerns related to station blackout could be allevia:ed through industry initiatives to reduce the irdindual sites' contribution to the overall risk. NUMARC also believes that most of tne anticipated benefits from the proposed rule would be derived from improvement at a limited number of plants.

In the light of these conside:atices, on June 10, 1986, the NUMARC Exce:tive Group overwhelmingly endor,ed four inc'.ustn in=iatives to address the more important contribu: ors to station blackout. nese initiatives are sun anar.:ed below:

(1) RISK REDUCTION Each utility will review its site (s) against the cr.teria specified in NUREG-1109 (Rubin (19861), a:d if the site (s) fai! into the category of an eight41our sue after utilmng all power sources available, the trility will take actions to reduce the site (s) contributun to the overall risk of station blackout. Non hardware changes will be made within one year. Hardware changes will be made in a reasonable time thereafter.

(2) PROCEDURES Each utility will implement procedures at each cf its site (s) for.

a. coping with a station blackout,

b. restoration of AC power following a station blackout event, and

c. preparing the plant for severe weather conditions, such as hurricanes and tornado 4s. ec 4

r.

l ASSESS 51E.N'T OF COPING DUR ATION REQUIRES!ENTS REVISION 2.0 l

OCTODER 14.1986 reduce the likelihocd and consequences of a loss of offsite power and to reduce the overall risk of a station blackout event.

(3) COLD FAST STARTS Each utility will, if applicable, reduce or eliminate cold fast starts of emergency diesel generators for testing through charges to technical specifications or other appropriate means.

. (4) AC POWER AVAILABILITY Each utility will monitor emergency AC power unavailability utilizi:g data utilities provide to INPO on a regular basis.

His procedure is designed to assist utilities in responding to the first initiative conceming station blackout risk reduction.

OBJECTIVE This procedare provides guidance for determining the minimum station blackout coping duration required and is based on our current understanding of NRC Suff guidance presented in the draft station blackout regulatory guide (NRC [1986], see also Rubin [1986], Table 3). De origmal methodology was developed by the NRC and provides two coping duratices which r,lllicensees must meet if the proposed sta: ion blackout rule is enacted: 4-ho us, and S hours. This methodology has been modined by NUGSBO as necessary to bring the guidance more in line with industry terms and definitions, and to clarify Staff reqturements for coping criteria.

S

i e ! l ASSESSN1EST OF COPING Dt.',tATION REQUIRE 51ESTS REVISION 2.0 OCTODER 14.1986 METHOD THERE ARE FOUR STEPS IN THIS PROCEDURE:

1 DETERMINE THE OFFSITE POWER SYSTEM DESIGN CATEGORY Two categones are possible: labeled P1 or P2.

2 CLASSIFY THE EMERGENCY AC POWER CONFIGI.1ATION Three groups are possible: labeled A, B, and C.

3 DETERMINE CURRENT EMERGENCY DIESEL GENERATOR RELIABILITY This reliabili.? is based on the last 100 valid demands.

4 DETERMINE COPING DURATION REQUIREMENT Two serpoints are ofspecialinterest: 0.025 and 0.05 failures pe- valid demand These serpoin:t constitute commitments for EDG reliability whuh must be mamtamed. 74 coping duration will beformd using the logic ir. figures 1-t combined wim the results of thefirst two steps.

l l

l DISCUSSION A logic diagram containing the s:eps for determining the minimum coping regturenent is presented in Figure 1. As a brief review of the diagram indicates, the offsite AC power system design characteristics are important to determining whether a plant will have a 4 or 8 hourcoping requirement.

According to the draft regulatory guide, all plants with offsite AC design charscrristics of class P1 require 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of coping. Sites in the P2 category may also be limited to 4-hours. depending on the presence of other plant features and utility commitments to maintain EDG reliability above certain levels.

l 6

, ?

ASSESSMENT OF COPING DURATION REQt IREMENTS REVISION 2.0 OCTODER 14,1986 Th structure of Figure 1 is intended to separate pla::s :nto a small number of groups according to G the site's features, and (2) emergency diesel generator or standby AC power source (EDG cenSguration and reliability. Site feattues are disnnguished on the basis of susceptibility to losing offsite power due to "plant-centered" initiators (e.g., a lightning strike in the switchyard) and "weather related" initiators (e.g., a hurricane or torndc. Sites susceptible to losing offsite power due to such initiators are generally classified as P2 s:tes. P2 sites may incur a 4 or 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping requirement depending on EDG configuration and re'iability. In contrast, P1 sites lack such sensinvity and incur a 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months coping requirement.

To use Figure 1, begin at the Start box and preceed abag the line to the first decision diamond, entitled "AC DESIGN P1/P2". This diamond tests whether the offsite AC design characteristics meet the cr::enon for P1 or P2. If the site is P1, then 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of coping are required regardless of EDG configuration or committed EDG reliability. Otherwise, the P2 line points to the second decision diamcmd, which tests whether the AC power configuranon meets the criterion for EAC Group "A".If the EDG configuration qualifies for EAC Group "A". then 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of coping are required; otherwise, the "no" response leads to the next decision diamoni. This process thrcugh the decision diamonds ends when the shaded bar for a 4-hour or an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months required coping duration is reached.

The Staffs logic for determining the offsite AC design characteristic class (i.e., P1 or P2) is summarized in Figure 2. A decision flow diagram, s:milar to Figure 1, is used in classifying sites as either P1 cr P2. The features distinguishing P1 and P2 sites are (1) independence of the offsite power sources, (2) the pasence of alternative power sources. (3) the frequency of extremely severe weather at the site, and (4) the frequency of severe weather at the site combined with the presence of severe mather mitigation features or the ability to restore offsste AC power within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months .

As was previously noted, in addition to site classification, a P2 site's minimum required coping durmion may also be affected by EDG configuration and reliability. The EDG configuration is based on (1) the total number of standby power sources normary available to hot shutdown equipment, and (2) the minimum number of such sources needed to operate a single train of hot shutdown equipment.

Nose this charactenzation may differ from the number of standby power sources available or needed to mitigate design basis accidents.

If equipment other than Class IE sources are relied on to operate hot shutdown equipment, these nons: lass IE sources must not suffer undue risk of failure due to common cause initiators or 7

ASSESSMENT OF COPIM DURATION REQUIREMENTS REVISION 2.0 OCTOBER 14,1986 single. point vulnerabilities m order to be credited for station blackout purpous Funher, the reljabdity of this equipment must be =gularly tested and maintained in a manner simur to that of Class 1E power sources. However, while umilar to Class 1E sources, this reliability progra::: for non Class 1E power sources credited for statioe blackout purposes need not become pan of the techrxal specifications or the operating license.

Figure I summanzes the 4 and 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping criteria without providing a dr.aded discussion of EDG configuration and reliabiliy. Two EDG failure rate serpoints are available fer unlity commitment and appear in Figures 3 and 4 It needs to be emphasized that the EDG (ailure rate setpoint used to determine the coping duration requirement becomes an implicit commitment which must not be euceded. This perspective reflects our current understanding of Staff requirements.

This procedure is structured to allow a utility to quickly determine the potential new requirements of the station blackout rule for its facility. Funher, it also identifies various means for reducing the coping requirement to 4-hours. Figure 5 provides a checklist for use in completing ths ;rocedure.

Note that assessing the actzal station blackout coping capability of a plant's design is beyond the scope of this document. The second NUMARC initiative addresses procedures for coping with a station blackout event.

Questions or comments cescerning this procedure should be directed to the Nu:! ear Utility Group on Station Blackout at 617-42' A 55C or 202457 9333.

8

I l

l

. t l

ASSESSMENT OF COPING DURATION REQCIREMENTS REVISION D OCTOBER IJ. lu STATION BLACKOUT COPING REQUIREMENT LOGIC r 3 START '

( J l'

P2 '

k P1 'i AC DESIGN l'

YES U i AC POWER 3 CONFIG. A R :

i i

NO

1r

/ YES EDG Yl!S

! >\

AO POWEH FAILURE I' N

CONRG.B '

RATE

< 0.025

/ .

NO NO 9r 1r I

l FIGURE 1 l

9 i

l . - -

< /

ASSESSMENT OF COPING DURATION REQUIREMENTS REVISION 2.0 OCTODER 14,1986 OFFSITE AC DESIGN CHARACTERISTICS r m START L J 1'

NO POWER y

<8ACKUP SOUR P

YES EXTR NO WEATHER 5 l < 1/3 YES P

YES SEVERE

< WEATHER

< 1/100 i No I v YII E i

l t ST AC g 2 E\ 5 HOURS I

l FIGURE 2 10

'l ASSESSMENT OF COPING DURATION REQCIREMENTS REVIS:O N :.0 OCTOBER 14.1986 DETERMINATION OF MAXIMUM EDG FAILURE RATE FOR AC DESIGN CLASS P1 h

4 HOURS 0.025- 4 HOURS 4 HOURS EDG FAILURE RATE O.05 0.10 &

A B C AC POWER CONFIGURATION FIGURE 3 1

I DETERMINATION OF MAXIMUM EDG FAILURE RATE l FOR AC DESIGN CLASS P2 6

4 HOURS 8 HOURS O.025- 4 HOURS ,

EDO FAILURE 3 HOURS RATE O.05 lCT '

l O.1 O '

A B C AC POWER CONFIGURATION FIGURE 4 11

e ASSESSMENT OF COPING DURATION REQUIREMESTS REVISION 2.0 OCTODER 14.1986 COPING DURATION ANALYSIS CHECKLIST 1 CLASSIFY OFFSITE AC POWER SYSTEM DESIGN CATEGORY 1.1 OFFSITE POWER SYSTEM INDEPENDENCE AND REDUNDANCY YES/NO 1.2 FREQUENCY OF EXTREMELY SEVERE WEATHER <1/350 SITE YEARS YES/NO 1.3 A. FREQUENCY OF SEVERE WEA1HER<!/100 SITE. YEARS. OR. YES/NO B. PROCEDURES TO RESTORE OFFSTTE PO%IR<2 HOURS YES/NO IF 'YES" TO QUESTIONS 1.1.1.2, AND EITHER 1.3 A OR 1.3 B.

THE SITE IS P1, OTHERWISE IT IS P2 2 CLASSIFY EMERGENCY AC POWER CONFIGURATION i

2.1 NUMBER OF STANDBY POWER SUPPLIES NORMALLY AVAILABLE 2.2 NUMBER OF STANDBY POWER SUPPLIES REQUIRED FOR HOT SHUTDOWN 2.3 DETERMINE EAC OROUP 3 DETERMINE CURRENT EDG RELIABILITY l

l l 4 DETERMINE COPING DURATION REQUIREMENT FIGURE 5 12

. .. m .

ASSESSMENT OF COPING DURATION REQUIREMENTS REVISION 2.0 OCTOBER 14.1986 DEFINITIONS Terms specifically developed for his procedure or of special importance are defined below. Other terms are defined in various standa:is issued by the Institute of Electrical and Elec:r:ru:s Engineers (IEEE), NRC regulatory guides, or cognizant professional societies.

ALTERNATE SOURCE OF OFFSITE POWER - a power source in addition to the unit and preferred offsite power source. NUREG/CR 3992,page 2.

ELECTRICAL INDEPENDENCE - the state in which two or more incoming transmission lines are available to hot shutdown equipment, and there is no mechanism by which the single failure of a bus transfer scheme or isolation device, located onsite or in a switchyard, can preclude at least one incoming transmission line from being available to a hot shutdown bus. Based on NUREG/CR 3992,page 2;lEEE STD 7651982: andlEEE STD 3081980.

NORMAL SOURCE OF AC POWER - the power source for Class lE systems dur=g normal plant operation (e.g., the unit power supply). Bared on NUREG/CR 3992, Table 2.la. Categorf II.1.

PREFERRED POWER SUPPLY that power supply from the transmission systers to the Class IE distribution system which is preferred to furnish electric energy under accident or postaccident conditions. lEEE-STD 7651983;IEE2 STD 3081980; andNUREG/CR 3992,page 2-SEPARATE INCOMING TRANSMISSION LINE - an offsite transmission line tha: can supply i power to electric busses supplying hot shutdown equipment and that is independent from the preferred power supply. Based on NUREG/CR 3992, page 2.

STANDBY POWER SUPPLY - the Class IE power supply that is selected to furnish electric energy to hot shutdown equipment when the preferred power supply is not available. Based on IEEE STD 3081980.

13 l

a ASSE.55 MENT OF COPING DURATION REQUIREME.VT5 REVISION 2.0 OCTOBER 14,1986 UNIT POWER SOURCE - that power supply availa'ole to hot shutdown equipment that is directly conne::ed to the main generator through a unit transformer. NUREG/CR.3992, page 2.

i l

I t

I i

l l

l L

-t 14

ASSESSMEST OF COPING DGATION REQUIREMESTS REVISION .0 OCTOBER 14.1986 PROCEDURE STEP ONE: DETERMINE OFFSITE POWER DESIGN CATEGORY Thi objective of thisfirst s:ep is to distinguish between sites having particular susceptibilities to losing ofsite power due to plant centered or weather related events. Two ofsite power design categories areprovided:

P1 -

Sites characterized by redundant and independent power sources which are cons:dered less susceptible to loss e a result ofplant< entered and weather 4nuiated events: and.

P2 -

Sius whose ofsite power sources are less redundant or independent. or which are more susceptible to extended offsite power losses due to weather vunated events or morefrequent losses due to plant centered events.

These categories are provided by t'2 Stagin the draft station blackout regulatory guide and are designed to be mutually exclusive. Further discussion concerning independence of ofsite sources is providedin the Appendix.

l 15

GSESSMEYr OF COPING DURATION REQt'IREMESTS REVISION :.0 OCTOBER 14.1984 1.1 CLASSIFY OFFSITE AC POWER SYSTEM DESIGN BVO APPROACHES ARE AVAILABLE TO COMPLETE STEP 1.1:

METHOD " A" REFLECTS THE CURRENT DRAFT REGULATORY GUIDE CRITER'A.

METHOD"B" PROVIDES AN ALTERNATIVE APPROACH.

~

l METHOD A. DRAFT REGULATORY GUIDE APPROACH DIE OFFSITE POWER SYSTEM IS E2 IF:

(1) A "NLQ" ANSWER CAN BE ASSIGNED TO QUESTlON "A" BELOW, AER l

l (2)

' A "EQ" CAN BE ASSIGNED TO EITHER QUESTIONS ~B(1)" .QR ~B(2)"

BELOW.

A. Are all offsite power sources connected to the unit's hot shutdova buses through (1) two or more switchyards that are not interconnected, or (2) separate incoming transmission lines (i.e., separare from the switchyard) with at least one of the AC sources electrically independent of the others?

I l

B(1) Are all offsite power scurces connected to the unit through one switchyard, or through two or more switchyards that are electrica'ly connected, and if the normal AC power source is lost, has an automatic transfer capabilit/ to the preferred power supply?

l l

l B(2) If the preferred power supply of B(1) also fails, is there one or more l automatic or manual transfers to another source of offsite power?

! 16 l

l

ASSESSMEYT OF COPING DURATION REQUIREMENTS REVISION 2.0 OCTODER 14.1986 IF A "1ES" IS PROVIDED FOR QUESTION "A", OR QUESTION "B(1)" AE.Q QUESTION ~B(2)", THE OFFSITE POWER SYSTEM NIAY BE "Pl" AND YOU SHOULD PROCEED TO STEP 1.2 (page 18)

OTHERWISE. THE SITE IS P2. PROCEED TO STEP 2 (pge 29) l l

, METHOD 3. ALTERNATIVE APPROACH THE OFFSITE POWER IS CLASSIFIED AS P1 IF ALL OF THE FOLLOWING CONDITIONS ARE TRUE:

(1) At least 2 sources of offsite pcwerare normally avadable to the Class IE or hot shutdows buses of each unit at a site; ANll (2) Physical independence is provided between the offsite mer sources for each unit; AND, l

, (3) At least one source of offsite power is available to the Cass IE or hot shutdown buses withm a few seconds following a unit trip; AER l

'(4) Ammainingsource of offsite power is available to the Cass 1E or hot shutdown buses within approximately one hour.

IF A "1ES" IS PROVIDED FOR ITEMS (1) THROUGH (4), THE OFFSITE POWER SYSTEM MAY BE"Pl" AND YOU SHOULD PROCEED TO S'mP 1.2 (page 18)

OTHERWISE. THE SITE IS P2 PROCEED TO STEP 2 (pap 29) 17

ASSESSME.VT OF COPING Dt! RATION REQUIREMENTS REVISIOs :,3 OCTOBER :4 1986 1.2 DETERMINE FREQUENCY OF EXTREMELY SEVERE WEATHER The estimatedfrequency ofloss of ofsite power due to extremely severe weather is dete mned by the annual e.xpectation of storms at the site with wind velocities greater than or equal to 125 mph.

USE METHOD "A" OR "B" BELOW TO DETERMINE THE FREQUENCY OF EXTREY.ELY SEVERE WEATHER AT THE SITE:

A. Site specific data provi!.es the most accurare source for calculating the annual frequency of storms with wind velocities greater than or equal to 125 mph, and should be used in calculating the frequency of extremely severe weather.

B. If site data is not readily available to perform this calculation, the annual frequency of extremely severe storms may derived from data recorded at local weather stations. A'rernatively, a frequency estimate for extremely severe weather may be based on data obtained from the National Oceanic and Atmospheric Admimstration (NOAA). Site specific NOAA data is summarued in Table 1.

IF THE CALCULATED FREQUENCY IS LESS THAN 0.003 PER SITE YEAR (COMPARABLE TO APPROXIMATELY I EVENT PER 350 SITE YEARS), THE SITE MAY BE Pl. PRCGED l TO STEP 1.3 (page 22).

l l

IF THE CALCULATED FREQUENCY IS GREATER THAN OR EOUAL TO 0.003 PER SITE YEAR, THE SITE IS P2. PROCEED TO STEP 2 (page 29).

1 18 l

l l

ASSESSMENT OF COPING DURATION REQUIREMENTS REVISION 2.0 OCTODER 14,1986 EXTREMELY SEVERE WEATHER DATA SITE STORMS 125 MPH +

ARKANS AS NUCLEAR ONE 0.0002 ARNOLD 0.0008 BEAVER VALLEY 0.0001 BELLEFONTE 0.0001 BIG ROCK POINT 0.0001 BRAIDWOOD 0.0010 BROWNS FERRY 0.0001 BRUNSWICK 0.0130 BYRON 0.0002 CALLAWAY 0.0001 CALVERT CLIFFS 0.0038 CARROL COUNTY 0.0002 CATAWBA 0.0011 CLINTON 0.0002 COMANCHE PEAK 0.0001 COOK 0.0006 COOPER 0.0014 CRYSTAL RIVER 0.0060 DAVIS 8 ESSE 0.0004 DIABLO CANYON 0.0001 DRESDEN 0.0001 FARLEY 0.0020 FERMI 0.0001 FTTZPAT1UCK 0.0001 FOR T CALHOt>N 0.0014 FORT ST. YRAIN o.0001 GINNA 0.0001 GRAND CULF 0.0040 HADDAM NECK 0.0100 HARRIS 0.0100 HARTSVILLE 0.0001 HATCH 0.0009 HOPE CREEK 0.0038 INDIAN POINT 0.0079 KEWAIJNEE 0.0036 l

TABLE 1 19

ASSESSMENT OF COPING DINATION REQCIREMENTS RI'GSION 2.0 OC3B ER 14,1986 EXTREMELY SEVERE WEATHER DATA (CONTLNLID)

SITS STOR5tS 125 MPH +

LASALLE *W2 LLMERICK 0.00'O MAINE YANKEE 0.0028 MCGUIRE 0.0001 MIDLAND 0.0001 MILLSTONE 0.0120 MONTICELL O 0.0003 NLNE MILE POINT 0.0001 NORTH ANNA 6.0034 OCONEE 4.0011 OYSTER CREEK t.00S0 FALISADES 4.0006 PALO VERDE 4.0004 PEACH BOTTOM t.0026 PERRY 0.0001 PILGilIM 0.0068 POINT DEACH 9.0036 PRADtIE ISLAND 4.0020 QUAD CTTIES 4.0002 RANCHO SECO t.0005 RIVER BEND 4.G068 ROBINSON t.3036 SALEM t.0038 S AN ONOFRE 4.0001 SEADR00K t.0038 SEQUOYAH 4.0007 SHOREHAM 8.0100 SOUill TEXAS 6.0120 ST LUCE 4.0170 SUMMER t.0011 SURRY 8.0060 SUSQUEHANNA t.0018 THREE MILE ISLAND t.0020 TROJAN t.0011 TURKEY POINT 4.0230 TABLE 1 s

20

ASSESSMENT OF COPING DURATION REQUIREMESTS REVISION 2.0 OCTODER 14.1986 EXTREMELY SEVERE WEATHER DATA (COVTINUEDJ SITE STORMS its MPH +

\T.RMONT YANKEE 0.0034 VOGTLE 0.0006 WATERFORD 0.0068 WAT13 B AR 0.0001 WNP.2 0.0001

_ WOLF CREEK 0.0003 YANKEE ROWE 0.0056 YELLOW CREEK 0.0001 ZION o.0001 TABLE 1 21

.-- .~ .-_. _

ASSESSMENT OF COPING D*.'AATION REQUIREMENTS R.EVISION :.0 OCTOBER 14.1986 1.3 DETERMINE SITE SUSCEPTIBIL?.T" TO SEVERE WEATHER Fourfactors are ated to cal-4=e thefrequency ofloss of offsite power due tc sewre wearl er: i (1) Annual expecta: ion of snowfallfor Ihe site. in inches (hj];

. (2) Annual expecta: ion of tornadoes of severityf2 or greater c tr.e site, in events Per squie nu [hg];

(3) Annual expectation of storms for the site with wind velocines between 7S and 124 riph [h3 ]; and, (4) Annual expectazion of tropical storms and hurricanesfor the site in which salt spray is likely to directly affect the switchyard [h ].

These factors are combined in the following relationship to yiefd the estinuedfrequency of

\

loss of ofsite. power due so severe weather:

l

[

(7.8f')) (0.249)

f = (12 x 10*#) hy + or hg + (129 x 10*2) h 3 + er h4 (43M) (0.783i)

a -

applies to sites with multiple righis of way l b -

applies to sites with a single righe ofway c -

applies to coastalsites 1

d -

applies to hiilLnone and Pilgnm 1

22 l

l g

GSESSMENT OF COPING DUR ATION REQUIRE.NU.NTS REVISION 2.0 OCTODER 14,1986

.tes which are determined to be suscepnble to sr.e e weather may remedy this situation in tuc

~c'.s:

1:>

through design or procedures minimi:,e :v kss ofsite power due to a hurricane while operating atpower, thereby reducing the c=cGedfrequency of severe weather events; or.

C have the capability andprocedures to res: ore ofsite (nonemergency) AC powerfrom the preferredpowe? supply to the site within : scus,

~

53th issues will b: addresed in NUGSBO guida ce concerning the second NUMARC initiative regarding stanon blackout.

Note: Sites considering relying on power restoratim procedures to achieve M status should refer to the, Appeadurfor additional discussion.

4 23

ASSESS %1E.vT OF COPING Dl3tATION REQUIRD1EVTS REVISION 2.0 OCTOGER IJ.1986 DETERMINE 'GiE FREQUENCY OF SEVERE WEATHER AS FOLLOWS:

A.

Calculate the total amount of snowfall in inches whi:h falls on the site in any year. Site specific NOAA da:a for snowfall is provided in Table 28 Label the data used as ht.

B. Calculate the. expected frequency of "f2+" tornadoes per square mile for the site using plant specific data. Sire specific NSSFC data is also provided in Table 2. Label the data used as h2-C. Determine the frequency of storms with winds between 7S and 124 mph at the site. Site specific NOAA data is also provided in Table 2.

Label the data used as h3.

D. Calculate the expected frequency of hurricanes and tropical storms for the site. Site specific NOA A data is also provided it. R.ble 2. -

Label the data used as h4.

E. Calculate the frequency of severe weather, f, in events per year.

None (a): Daa promed ta Table 2 u palurunary, perucatar1y fw canan sie snowfan and tomado fnquene)

==maan TaNe 2 4 he rmand etwa das daarpenoes me nacent IFf IS LE9S THAN 0.01 EVENTS PER YEAR (1 EVENT PER 100 STTE YEARS). AND THE SITE ALSO SATISFIES STEPS 1.1 AND 1.2, THEN THE SITE IS Pl. PROCEED TO STEP 2 (page 29).

' IF f IS GREATER THAN O.01 EVENTS PER YEAR (1 EVENT PER 100 SITE-YEARS).

THEN PROCEED TO STEP 1.3.F (page 25).

l 24

l ASSESSMENT OF COPING DL' RATION REQUIREMESTS REVISION :.0 OCTODER 14.1986 l

l 1

F. Sites having severe weather occur more frequently than I per l'.C s:te years may achieve P1 status if they have de capabililty to res re offsite ]

(nonemergency) AC power within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months foEcwing a l loss of-offsite pcaver event due to severe weather. This capeility must l consider the effects of the weather event (i.e., snowfall, tornad:. or storm)

{

on the availah'.i:y of offsite power and the ability to restore a stane electrical connection to a hot shutdown bus.

Sites deemed susceptble to hurricanes may delete the contribution of th: h.: term if the capability exists to prepare the site in advance.

{

F IF STEP 1.3.f IS SATISFIED, AND STEPS 1.1 AND 1.2 ARE ALSO SATISFIED, CLASSIFY THE SITE AS Pl. OTHERWISE, THE SH IS P2.

PROCEED TO STEP 2 (page 29).

NOTE: GUIDANCE DEFINING hfETHODS FOR PREPARING THE PLANT FOR SEVERE WEATHER OR RESTORING POWER SHOULD IT BE LOST WILL BE PROVIDED IN NUMARC GUIDANCE CONCERNING THE SECOND NUhfARC INITIATIVE (see items 2.b and 2.c of the June 17, 1986 NUMARC letter to Chairman N. J. Palladino from Mr. J. H. Miller) 25

ASSE.SSN1ENT OF COPING DURATION REQUIRE 51ENTS REVISION 2.0 OCTORER 14.1986 SEVERE WEATHER DATAb SITI SNORTALL TORNADO STORMS HURRICANES

@l) @2) @3) @4)

ARKANSAS NUCLEAR ONE 6 0.0004H 4.667 0.000 ARNOt.D 33 0.000486 1250 0.000 BEAVER V ALLEY 45 L000172 L839 0.000 SELLETOSTE 4 4.0003M t.029 0.000 BIG ROCK POINT 97 L900272 LOO 6 0.000 BRAIDWOOD 4t 4.004475 Late 4.000 SROWN5 FTRRY 4 4.000415 Lt29 0.000 3RLHSWICK 2 0.000222 L124 4.000 BYRON 35 0.000475 L410 0.000 CALLAWAY 24 0.000388 L650 0.000 CALVERT CLDTS 9 0.00C263 Leet 4.200 CARROL COUNTY

4.000475 Leos 0.000 CATAWBA 6 0.000293 Lile 8.000 CLINTON 24 4.006475 L100 0.000 COMAM'HE PEAK 4 4.606447 L054 0.000 COOK 48 Leto272 Lite 0.000 COOPER 34 4.000456 L540 0.000 CRYSTAL RIVER 4 L600013 L100 4.000 DAYlS.BESSE 38 0.004348 L110 4.000 D[AB LO CA.%70N 0 4.000022 Le70 0.000 DRESDIN de 4.000101 Late 4.000 FARLEY 0 4.tes394 Lose 4.000 FERMI 32 4.000272 Lose 0,000 FITZPAT11CK 09 a.800472 L864 0.000 FORT CALHOUN 29 4.000141 L500 4.000 FORT ST. YRAIN 39 6.000138 L420 4.000 CINNA 89 Lee 6472 Lt64 4.004 GRAND CULF 1 8.444458 L434 Lete NADDAM NECK 27 6.400292 Lese 4.004 HARRIS 8 4.000222 4.130 0.000 TABLE 2 e 1

l l

26

ASSESSMENT OF COPISG DURATION REQUIREMENTS REVISION 2.0 OCTOBER 14.1986 SEVERE WEATHER DATAb (CONTLNUED)

SITE SNOWFALL TORNADO STORMS HURRICANES

&)I (ha) (h3) (h4)

HARTSVILLE 14 0.000267 0.000 0.000 HATCH e 4.000360 a022 0.000 HOPE CREEK 22 0.000201 0.045 0.000 INDIAN POINT 29 4.000072 4.040 0.000

, KEWAUNEE 42 0.000327 4.100 0.000 LASALLE 40 0.000475 toto 0.000 LIMERICK 22 4.000172 4,027 0.000 MAINE YANKEE 74 0.006475 6834 0.000 MCGUtRE 6 4.000222 L634 0.000 MIDLAND 45 1908272 Lett 4.000 MILISTONE 27 0.000292 4.000 0.180 MONTICELLO 46 0.000199 toto 0.000 NINE MILE POINT 99 4000072 4.460 0.000 NORTH ANNA 15 0.000142 1 000 0.000 OCONEE 6 0.000293 4.124 0.000 OYSTER CREEX' 17 4.006201 1 963 0.000 PALISADES 44 4.000272 a.100 4.000 PALO VERDE 9 0.000031 (125 0.000 PEACH BOTTOM 22 4.000172 L026 0.000 PERAY

4.000340 Lett 4.000 PILCRIM 42 4.000465 ttot 4.000 POINT BEACH 42 4.006327 alm 4.000 PRAIRIE ISLAND de 4.000199 atte 4.000 QUAD CTTTES e t000475 also 6.000 RANCHOSECO 4 4.00$022 4,164 4.000 RIVER BEND e 4.000442 4.994 6.000 ROSINSON 1 0.048293 & 094 4.000

$ALEM 22 0.00020I L045 0.000 SAN ONOFRE e ketet22 L601 0.000 SEABROOK 65 4.400234 6445 4.000 l

TABLE 2 l

27 l

l l

l

ASSESSMENT OF COPING DURATION REQUIREN!ESTS R.EVISION 2.?

OCTOBER 14.1H4 SEVERE WEATHER DATAb EITE SNOWFALL TORNADO STOLMS NURRICANES (ht ) %. (h2) (hv SEQUOYAH 4 Lese 267 kl00 0.000 SHOREHAM 26 Laese72 L000 0.140 SOLTH TEXAS e LeeN47 0.120 0.000 ST LUCIE e Leese13 0.004 0.310

. SL'MMER 2 Lasa293 L120 0.000

$UREY e Letel42 tite 4.000 SUSQUEHANNA 44 Late 172 4 420 L000 THREE MILE ISLAND 33 4400172 1 927 s.004 TROJAN 7 L800000 &les e.000 TURKEY FOINT e Leese12 Leet 4.27e VER.'dOST YANK EE 79 Laesee9 todo 0.000 YOGTLE 2 aane w E022 0.000 WATERFORD e Lee 6402 1 090 0.000 WAT'I3 BAR le Late 247 L100 0.000 W N P.2 $3 Leete17 &$34 0.004 WOlJ CREEK 24 LaeteS2 L234 0.000 YANKEE ROWE 79 tAete67 L663 0.000 YELLOW CREEK 3 a -ea tale e.000 110N de a amante ke10 0.000 NOTE (b): THIS TABLE IS PROYlDED FOR THE CONVENIENCE OF ANALYSTS USING THIS PROCEDURL DATA PROVIDED IN T1(13 TABLE WAS OBTAINED FROM THE NUCLEAR RECULATORY COMMISSION STAF7 USING CLIMATOLOGICAL SOURCES CITED IN THE REFER ENCES TO THIS PROCEDURL sour stTE DATA MAY RF IN F R R O R.

ASTERISKED DATA ARE KNOWN TO BE IN ERROR. NUCSBO RECOMMENDS THAT i

UTILITIES VERIFY THE ACCURACY OF THE DATA PROVIDED IN THIS TABLE AND l IDENTIFY DISCREPANCIES. IN ALL CASES, UTILITIES SHOULD RELY ON PRIMARY SOURCES FOR CALCULATING THE POTESTIAL F02 SEVERE WEATHER AT THEIR l SITES.

TABLE 2 28

ASSESSNIENT OF COPING DURATION REQUIRE 5 TESTS REVISION 2.0 OCTODER 14.1986 STEP TWO: CLASSIFY THE EMERGENCY AC POWER CONFIGURATION Three emergency AC (EAC) power configuration groups are provided:

A .

Sites characterized by highly redundant and independent EAC sources to hot shutdown equipment; B -

Sites having normally redundant and independent EAC sources to hot shutdown epupment; and, C -

Sites having less redundant and independent EAC sources to hot shutdown epupment.

Sites are placed in one of the groups listed depending on the number of standby power supplies available and the number required to operate AC powered decay heat removal equipment necessary to achieve and maimain hot shutdown in a station blackout. Sites having a Group A configuration require a smaller number of standby power supplies out of the total number of EDGs normally available. Group C configurations, on the other hand, require a larger number of the total EAC power supplies avadable to the site to operate hot shutdown decay heat removal equipment. Overall.

the greater the level of EAC redundancy, the less restrictive are the station blackout coping durations .

and maxsmum EDGfadure rates before longer coping durations are required, or corrective actions become .ucessary.

I 29

ASSESSMENT OF COPING DL* RATION REQ 1;IREMENTS REVI!!ON :.0 ocrocta t4.19s6 2.1 DETERMINE THE NUMBER OF EAC POWER SUPPLIES NOR>lALLY I AVAILABLE 1

l A. SINGLE UNIT OR ML1TI UNIT SITES WITH DEDICATED POWIR SUPPLIES Count the total number of standby power supplies available te the unit's het shutdowm equipment.

B. MULBUNIT SITES %TTH SHARED POWER SUPPLIES If any EAC standby power supplies are shared among units at a multi-umt site, count the total number of shared and supplies which may be available to hot shutdown equipmem at each unit.

l l

l 30

ASSESSNtENT OF COPING DURATION REQUIRES 1ENTS REVISION 2.0 OCTODER 14,1986 2.2 DETER 5 TINE THE NUhtBER OF EAC POWER SUPPLIES REQUIRED The number of EAC standby power supplies requiredfor station blackout is based on the AC loads needed at each unit to remove decay heat (includ.ng the heat generated by AC powered decay heat removal systems) in order to achieve and maintmn hot shutdown with offsite power unavailable.

The number of EDGs required to operate hot shutdown equipment may be less than that required for LOCA loads.

The number of required EAC power sources may be determined by accountingfor the individual hot shutdown loads, or inferredfrom the site's design basisfor operating Class 1E AC equspment without offsite ACpower.

y&

See the Appen6sfor additional discussion concerning standby power supplies and alternate AC power.

31

ASSESS 51ENT OF COPING DURATION REQUIRES 1ENTS 1rGS10N 2.0 0 TCBER 14.1986 2.3 SELECT THE EAC POWER CONFIGURATION GROUP FOR THE SITE l

l l

USE THE TABLE PROVIDED BELOW TO SELECT THE EAC GROUP I EAC GROUP SUPPLIES REQUIRED SLTPLIES AVAILAELE FOR HOT SHUTDOWN A 1 3 A 1 4 A 2 5 B 1 2' B 2 4

. C 1 P C 2 3 C 3 4 C 3 5 WHERE:

Note (c) -

FOR EAC POWER SUPPLIES NOT SH ARED WITH OTWER UNITS AT A SITE Note (d) -

FOR EAC POWER SUPPLIES IN WHICH EACH RAStBY POWER SUPPLY 15 CAPABLE OF PROVIDING AC POWER TO HOT SHUTDOWN EQUIPMENT AT MORE THAN ONE L%TT AT A SITE CONCURRENTLY 32

ASSISSMENT OF COPING DURATION REQUIREMENTS REVISION 2.0 OCTOBER 14. t986 STEP THREE: DETERMINE CURRENT EDG RELIABILITY The EDG failure rate per demand is used in conjune: ion with the site's offsite power desip.

charseteristics (i.e., P1 or P2), and the EAC configuration (A, B, or C) to determine the unit's mi: m=n station blackout duration. This failure rate is calculated from the total number of EDG fail.res experienced among all available standby power supplies in the last 100 valid demands for eset mxhine.

DETERMINE THE CURRENT EDG RELIABILITY BY:

(1) REVIEWING THE LAST 100 VALID EDG DEMANDS 8 RECORDED FOR EACH EDG AT *IEE SITE CONSIDERED IN SELECTING AN EAC GROUP.

(2) IDENTIFY 1NG THE TOTAL NUMBER OF FAILURES

FOR EACH EDG.

(3) CALCULATING THE MOST RECENT EDG RELIABILITY AS A MOVING

, AVERAGE (USING NSAC 108 METHODOLOGY CONTAINED IN SECTION 2 OF THAT DOCUMENT) BY DIVIDING THE TOTAL NUMBER OF EDG FAILURESe FOR EACH EDG BY THE LAST 100 VALID EDG DEMANDS.

THE QUOTIENT IS THE CURRENT FAILURE RATE FOR THAT EDG. -

(4) THE POOREST EDG RELIABILITY OF ALL EDGS ONSITE IS THE SITE'S EDG RELIABILITY.

NOTE (e): NOTE THAT THIS REVISION OF THE PROCEDURE REFLECTS A RECENT CHANGE IN STAFF INTERPRETATION. THE NEW INTERPRETATION TRACKS EDG FAILURE RATES ON AN

, INDIVIDUA L MA CHINE B A SIS. THE POOREST PERFORMING EDG IS USED TO ESTABLISH THE SITE'S OVERALL EDG RELI ABILITY. THE METHODOLOGY FQUND IN 33

ASSESSMENT OF COPING Dt.llATION REQU1REMENTS REVISION 2.0 OCTODER 14.1986 NSAC 108 SECTION 2 SHOULD BE USED IN DETERMINING EDG RELIABILITY.

I

}

f d

T

(

h i

I

l ASSESSMENT OF COPING DURATION REQUIRD1ESTS REVISION :.0 oCTODER 14.194 STEP FOUR:

DETERMINE COPING DURATION REQUIREMENT USE THE TABLE PROVIDED BELOW TO DETERMINE THE COPING DURAT ON REQUIREMENT IN HOURS.

OFFSITE POWER EAC GROUP EDG FAILURE COPING GROUP (A, B, OR C) RATE DURATIOS (Pt oR P2) (now STEP 2) (PER DEMAND) REQUIREMENT (FROM STEP 1) (FROM STT,P 3) (Hot;RS)

P1 A 50.050 4 P1 B $0.050 4 P1 C s0.025 4 P2 A 50.050 4 P2 B i

50.025 4 P2 B 50.050 8 P2 C s0.025 8 l

l l

35 i

l

ASSESSMENT OF COPING DUR ATION REQUIREMENTS REVISION 2.0 OCTODER 14.1986

SUMMARY

This procedwe yields the two coping durations accepted by the Staf. c: discussed in the draft station blackout regulatory gM: 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months , and 8. hours. Ifyou are in a 4 how ca:egory, you are committed to not exceed the nw.r.mwn EDGfailure rate serpointfor your respecnw c:.:egory. Ifyou are in the 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months category you should undertake corrective measures to achien a minimum 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months statas consistent with the bT.iMARC initiatives. The following section, provaes several examples of ways to achieve a 4 hou. status. it also discusses an alternate AC power zurce as a means to provide extendedcoping capability.

36

ASSESSN1EST OF COPING DUR ATION RL2CIRE51ESTS REVISION 1.0 ocrontR 14.1986 CORRECTIVE MEASURES In order to support the NUMARC initiat,es for resolving the station blackout issue, those ;' ants (or units) determined to have an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping duration requirement must implement corrective c:easures either to reduce the coping duration reqc:rement to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months or to provide an alternate sour:e (s) in c: der to achieve extended coping capabilzy. The discussion below identifies some sugges:ed areas for utilities to consider and should be adaped to the plant specific considerations which may apply.

EAC Configuration P2 sites with EAC Group B and C configurations having the 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping duration requ:rement should examine the AC power requirements for achieving hot shutdown conditions. Since these loads may be less than required for a design basis accident (e.g., a large. break loss of coolaN accident), units with more than two standby power supplies may be able to achieve hot shutdown on fewer EDGs. An analysis of load requmments, their distribution, and necessary control schemes would also be needed to determine the feashtlity of this approach. It is possible that such analysis of some EAC Group B and C sites would support their reclassification as Group A sites with a commensurate .tduction in the required copmg duration to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

Severe Weather Procedures P2 sites with EAC Group B and C configu:stions having the 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping duration requirement ma reduce the coping duration requirement n 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months if the P2 classification was based on severe weather occumng more frequently than once every 100 years. A reduction in coping requirements from 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months can be achieved by p@g plant design or operating features which would minimize the possibility of losing offsite power due to severe weather (e.g., salt spray).

Alternatively, utilities can overcome severe weather by providing the capability and proceden:s for restoring offsite power within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . The implementation of such capability would reclass:fy the site as a P1 site, imposg a 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months coping mquirement. It is important to note that the guide!=es for 37

ASSESSMEST OF COPING Dt/ RATION REQUIREMENTS ftE VISION 2.0 OCTOBER 14,1986 such capabili:y and procedures do not yet exist. Consequently, plan:s relying on such capabilities and procedures to achieve Pl status should consider the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months requirement to be tentative until the guidelines are .ssued.

EDG Reliability l

P2 sites with EAC Group B configuration having the 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping duration requirement may commit to a program to improve EDG reliability (i.e., reduce the failure rate) to 0.975 (0.025 failures

~

per demand) dereby reducing the coping duration requirement to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . His program would likely include =casures to assure the successful improvement in EDG reliability.

Alternate AC Power Sources Backup AC power sources independent of the offsite power system and the onsite emergency AC power system may be used to respond to a station blackout event by providing additional sources of power to hoc stutdown equipment. De availability of these AC power supplies in a station blackout would depend on three factors:

(1) The absence of single. point vulnerabilities in the system design and operation; C) No undue risk of common cause failure; and.

O) A program to provide reasonable assurance of the backup power source's availability in a station b1xkout event.

These alternate AC sources may not require the same capacity as the Class IE EDGs provided they can operate at least one train of hot shutdow equipment for each unit at a site.

Examples of ahernae AC power sources include "blackstart" gas turtunes or diesel generators located onsite or nearby to the extent that they can be made available to power the hot shutdon equipment within 30 minues of a station blackout.

38

ASSESSMENT OF COPING DURATION REQUIREMENTS RI.','510N 2.0 OCO BER 14.1986 l

l REFERENCES '

B ARANOWSKY, P.W. \1985), Evalwion ofStation Blackout Accidents at Nuclear ?ner Plants.

NUREG 1032 Office of Nuclear Regulatory Research, Office of Nuclear Reactor Eq.'ation, U.S.

Nuclear Regulatory Commission, Washington, DC (1985).

B ATTLE, R. \1985), Collection and Em1tuation of Complete and Partiallasses of O'.Sae Power at Nuclear Power Plants, NUREG/CR-3992, ORN!JTM 9384, Oak Ridge Natiotal Laboratory.

Oak Ridge, TN (1985).

CHANGERY, M. (1982), Historical Extreme Windsfor the United States Great Lakes and Adjacent Regios, NUREG/CR 2890, National Climatic Center, National Oceanic a:d Atmospheric Administration, Asheville, NC (1982).

CHANGERY, M. \1982a), Historical Extreme Windsfor the UnitedSt.ates Atlarac and Gulf of Mexico Ceartlines, NUREG/CR 2639, National Climatic Center, National Oceanic ard Atmospheric Administration Asheville, NC (1982).

IEEE STD-3081980, IEEE Standard Criteria for Class IE Power Systemsfor Nuclear Power Generating Stationr, Institute of Electncal and Electronics Engineers, New York, NY !!980).

lEEE-STD-765 1983, lEEE Standardfor Preferred Power Supplyfor Nuclear Pour Generating Stations, Institute of Electrical and Electronics Engineers, New York, NY (1983).

JARVINEN, B. R., NEUMANN, C. J., AND DAVIS, M. A. S. [1984), A Tropicalcyclone Data Tape for the North Atlantic Basin 18861983: Contents, Limitations, and Uses NOAA Technical Memoranden NWS NHC 22, National Hurricane Center, Miami, FL (Matt:h 1984)

NOA A [1980), Climatological Data Nationa/ Summary, National Climatic Center, Naional Oceanic and Atmospheric Administration, Asheville, NC (1980).

r 39

ASSESSMENT OF COPING DURATION REQUIREMENTS REYlSION :.0 OCTODER 14,1984 NOAA (1981), Comparative Climatic Datafor the United States, National Climatic Center, National Oceans and Atm: spheric Administration, Asheville, NC (1981).

NRC (1986), Draft Regulatory Guide, Station Blackout. Task S1501-4,51 Fed Reg 11494, (March 1986).

RUBIN, A. (1986), Regulatory Analysis for the Resolution of Unresolved Safety issue A-t.t.

Station Blackout, NUREG 1109, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC (1986).

SCHAEFER, J. T., KELLY, D. J. L., and ABBEY, R. F. [1985), A Minimum Assumption Tornado Probability Model, NOAA Technocal Memorandum NWS NSSFC 8, National Severe Stonns Forecast Center, Kansas City, MO (May 1985).

WYCKOFF, H. (1986), The Reliability of Emergency Diesel Generators os U.S. Nuclear Power Planu. NSAC 108, Nw: lear Safety Analysis Center, Palo Alto, CA (September 1986).

40

ASSESSMENT OF COPING DOTATION REQUIREMENTS REVISION 2.0 OCTOBER 14.1966 APPENDIX ELECTRICAL INDEPENDENCE in this analysis, electrical independence of incoming transmission lines is relreant only within site boundaries up to the -aput t<~t.nals of the Class 1E buses . De independence af power sources in the regional transmission and ismbution system is not addressed in this procedue.

. Note that compliance with the current form of General Design Criterion 17, A;pendix A to 10 CFR Pan 50, generally satisfies the requirements of Question 1.1, provided the man generator can be isolated. Another important consideration is that power source availability be measured at the interface with the Class 1E bsees.

Figure A 1 contains a diagra:n for a single unit plant's offsite power system. The normal power source to station auxiliaries for this example is the Main Generator which is dactly connected to a single switchyard through a generator output breaker. The Main Generator a:so directly supplies Class IE and nonsafety loads through two station transformers. Two transmusion lines enter the switchyard which is arranged in a "breaker and a half" scheme. Power is stepped down through normal and reserve transformers to supply Class 1E and nonsafety loads. T.sese loads have an automatic transfer capability between the offsite preferred source and the normal (unit or main generator) power source. In addition to switchyard related power sources, nis example is also

' assurred to have a separate incoening transmission line that is electrically independent of the main switchyard. Further, Class 1E and nonsafety loads are also assumed to have automatic transfer capability ber us the prefened offsite power source and the separate incomirg transmission line.

This offsite power configuratan satisfies Question A and both pans of Question 3 in Step 1.1.

In the second example provided in Figure A 2, the main generator output bremiter is replaced by a disconnect link. This is a more common arrangement. Further, this example asumes no separate incoming transmission line is provided to the site. Therefore, on unit trip, power is automatically transferred to the reserve station service transformer. However, no other power source is available should offsite power through this transformer be lost. This is because, based on discussion with NRC Staff, the disconnect links cannot be removed to isolate the Main Generatorin sufficient time to restore power through the no .nal station service transformer in a station blackout scenario. This i

t i

ASSESSN1EST OF COPING DL,'R ATION REQtlTREStENTS REVISION 2.0 OCTODER 14.1966 configuration qualifies as a P2 site. The site could be upgraded to P1 either by replacing the Mair.

Generator disconnect links with an output breaker or load break switch, or by bringing in a separate tscoming transmission to the Class IE bus in a manner which bypasses the switchyard (see Figure A 3). De independence of the switchyard is necessary to ensure that the new power source is not sweptible to a "plant-centered" loss of offsite evem m the yard.

Mdnple unit sites should perform a similar analysis for offsite power to each unit. Transfer of power between adjacent units should consider the loss of Class IE EDGs dedicated to a single um:

and those commonly shared.

42 I

ASSESSMENT OF COP:N3 Dtl RATION REQUIREMENTS REVISION 2.0 OCTODER 14.1986 SAMPLE ANALYSIS OFFSITE POWER CONFIGURATION TRANSMISSION LINES TRANSMISSION LINE SWITCHYARD -

NORMALSTATION RESERVESTATION SERYlCE TRANSFORMER SERYlCE TRANSFORMER

( ) ( )

< , r , r- ,

TRANSFOLMER TRANSTORMER T:MNSFOR.MER

( ) t J L J L AD SW CE, ,

v v v

N0$00 rey" PoNR E T roEI3rt.Y TO HOT SHUTDOWN BUS MAINGENERATOR FIGURE A 1 43

l l

, ae o ASSESSMENT OF COPING DURATION REQt.'.RDtENTS REVISION O OCTOBER 14.;W SAMPLE OFFSITE POWER CONFIGURATION l

l l

l 1

TRANSMISSIOS LINES SWITCHYARD NORMAL STATION RESERVE STATION SERVICE TRANSFORMER SERVICE TRANSFORMER

( ) ( )

r , r ,

11A.N5FOt90t TRANSFORMER L J Q J DISCONST47 V V totMAL ALTTRNATE Powt3 stlyyLY POWER SUPPLY TO HOT SH1ADOWN BUS MAIN GENERATOR FIGURE A.2 l

44 l

4,

.a =

ASSESSMENT OF COPING DURATION REQUIREMENTS REVISION 2.0 OCTOBER 14.1986 SAMPLE ANALYSIS OFFSITE POWER CONFIGURATION 5

TRANSMISSION LINES TRANSMISSION LINE SWITCHYARD NORMAL STATION RESERVE STATION SERVICE TRANSFORMER SERYICE TRANSFOLMER

. ( ) ( )

< , r , r ,

TRANSFORMER TRAMEMER TRANSFORMER L J L J L >

4 DISC 09(ECT y 'l v NORMAL ALTERNATE BACKLT POWER SL7 PLY POWEA SLTPLY POWER SL7 PLY Y

TO HOT SR,7DOWN BUS MAIN GENERATOR FIGURE A 3 s

45

', 3 N'J8 E o 9?2(

M t-is.c7 Ta kW 2.

ASSURING THE ADEQUACY OF STATION BLACKOUT RESPONSE PROCEDURES Guidelines and Technical Bases REVISION 0.0 AUGUST 10,1987 NUCLEAR UTILITY GROUP ON STATION BLACKOUT SUITE 700 1200 SEVENTEENTII STREET, N.W.

WASlilNGTON, D.C. 20036

i.E

l. <

, ....T' ,

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES RD'1510N 0.0 Aarm 10,19e REVISION

SUMMARY

Ruision Description 0.0 ISSUED BY NUCSBO STEERING COMMITT:.E FOR COMMENT J

9 e

i s

+

2 4

1

..m_.- - - - - - . - - -

.O e NUGSDO STAT 10N BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 l

CONTENTS l

1

1. INTRODUCTION 4 i 1.1 DOCUMENT STRUCTURE 4 1.2 ACTIONPLAN 4 l

2. BACKGROUND 6 2.1 NL'\fARCINITIAT1VES 6 2.2 OBJECTIVE 7 2.3 GENERAL CRITERIA 8

3. BASELINE ASSUMPTIONS 9

3.1 thTnALPLANTCONDITIONS 9 3.2 INTnATING EVENT 10 3.3 STAT 10NBLACKOUTTRANSIENT 14 3.4 RCPSEALLEAKAGE 15 3.3 OPERATOR ACTION 15 3.6 EFFECTS OF LOSS OF VENTILATION 16 3.7 SYSTEM CROSS TIE CAPABILITY 17 3.8 INSTRUMENTAT10N 18 3.5.

4. OPERATTNG PROCEDURE GUIDELINES 19

4.1 INTRODUCTION

19 4.2 STAT 10N BLACKOUT RESPONSE GUIDELIN'ES 19 4.3 AC POWER RESTORAT10N 21 4.4 SEVERE WEATHER GUIDELINES 22 APPENDIX 24 A. DEFINITIONS 24 B. ALTERNATE AC POWER CRITERIA 26 C. STATION BLACKOUT RESPONSE GUIDELINE SUPPORT 1NG INFORMATION 29 D. AC TOWER RESTORAT10N OUIDELINE SUPPORTING INFORMA110N 35 E.

SEVERE WEATHER GUIDELINE SUPPORTING IN7ORMATION 37 F. SAMPE AAC COh710URAT10NS 41 G. REFERENCES 49 3

.t .

NUGSDO STATION BLACKOL T RESPONSE GUIDELINES REVISION 0.0 August 10.191*

1. INTRODUCTION 1.1 Document Structure The purpose of this document is :o provide guidance to plant operators for pre;m responding to a station blackout event. This doc ..t

' contains 4 main sections z.d appendices.

Section 1 provides an introduction to the os rii d .-

This introduction in:ludes an outline of the actions utilities should take in implem ung a N / ;ar Utility Manage. ent and Res Committee (hM1 ARC) station blackout initiauve fet << + raring response procedu Initiative 2).

Section 2 summarizes the h%iARC station blackout initiatives and provides tie ob document.

Section 3 contains baseline assumptions for a station blackout event. These ass bases enderlie the guidance provided in this document.

Section 4 provides guidance to be used in preparing station blackout respons: proc guidance complements information and direction provided in vendor specifi: p an guidelines. Th: guidance also addresses procedures for severe weather, particulan AC power resteration.

The appendices contain the definitions used in this document, supporting in'ormation fo guidelines, sample Altemate AC conSgurations, and references.

1.2 Action Plan To implement Initiative 2, plant operators are expected to take the fo!)owing a:tions 4

9 =

NUGSDO STATION BLACKOUT RESPONSE GLlDELINES REVISION 0.0 August 10,1987

{

l (1) Review the guidelines and develop a strategy for responding to a station blackout; I 1

(2) Review Plant Operating Procedures and station procedures against the sppropriate guideline;

, (3) Implement any necessary design modificatione .. accordance with the plant's beensing basis; and,

~

(4) Revise procedures appropriately to inct porate topics addressed in the guidelines.

9

,.q .

NUGSBO ST ATION BLACKOLT RESPONSE GUIDELINES REVISION 0.0 Au;;ust 10,191*

2. BACKGROUND 2.1 NUMARC Initiatives Late in 1985, NUMARC es:ablished a working group on station blackout u a ddress the issues raised by the NRC Staff. NUMARC membership includes all electric utilities operating nuclear power plants. The Nuclear Utility Group on Station Blackout (NUGSBO) has previded the major portion NUMARC's technical support in '.his area, including preparing commens on the rulemaking reco and analyzing the factors contributing to station blackout risk. On tie basis of this analysis.

NUMARC determined tha: many of the concerns related to station bla:koct could be alleviated through industry initiatives to reduce the individual sites' contribution to tie overall risk. NUMARC also believes that most of the anticipated benefits from the proposed rs would be derived from improvements at a limited number of plants.

In light of these considerations, on June 10,1986, the NUMARC Executise Group overwhelmingly endorsed four industry ini:iatives to address the more important contrib2 tors to station blackout.

These initiatives are contained in comments filed with NRC concerning the proposed station blackout rule. The initiatives are sum:narized below:

(1) Initiative 1 RISK REDUCTION Each utility will review its site (s) against the criteria specified in NUREG 1109 (Rubin

[1986)), and if the site (s) fall into the category of an eight hour site ah:r u:ilizing all power sources available, the u:ility will take actions to reduce the site (s) cont:bu:fon to the overall risk of station blackout. Non hardware changes will be made within one year. Hardware changes will be made in a rea snable time thereafter.

(2) Initiative 2 ... PROCEDURES Each utility willimplement procedures at each ofits site (s) for:

6

'S NL GSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 1.0 August 10,19F (a) coping with a station b:ackout; (b) restoration of AC power following a station blackout event; and, (c) preparing the plant for severe weather conditions (e.g., hurricanes and tomadoes) to reduce the likelihood and consequences of a loss of offsite power and to reduce the overall risk of a station blackout event.

. (3) Initiative 3 - COLD FAS1 STARTS Each utility will, if applicable, reduce or eliminate cold fast-starts of emergency diese generators for testing through changes to technical specifications or other appropriate mean (4) Initiati'ce 4 AC POWER AVAU ABILITY Each utility will monitor emergency AC p:wer unavailabihty, utilizing data provided t:

INPO on a regular basis.

2.2 Objective ne objective of this document is to provide a methodology for assuring that plant specific re procedures address statien blackout cor.cerns. When implemented, plant operators will htve completed NUMARC Initiative 2, Procedures Addressing Station Blackout.

Current procedures direct the operators' response to a variety of events, including station bla This document supplements operating procedures by providing guidance on enhancing the a cope with station blackout.

In addition to procedural guidance, these guidelines also provide criteria for Alternate AC (AAD 7

't

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 power sources. AAC power sources may include special purpose diese's. gas turbine generators, ga boilers, hydroelectric facilities or other independent electrical power supplies. These sources m located onsite or at of.er units in close proximity to the site, including adjacent units' Class IE p supplies.

Station procedures may utilize availhele AAC power sources to suppc . shutdown operations in a station blackout. Thes: guidelines are discussed funher in Section 4 Acceptance criteria fo: AAC power sources are provided in Appendix B.

2.3 General Criteria Procedures relied upon in a station t'.ackout must ensure that the peak c!idding temperature will not exceed 2200 0F in the course of the station blackout event or followir.; restoration of onsite AC power.

8

i

't -

NUGSDO STATION BLACKOLTT RESPONSE GUIDELINES REVISION 0.0 Augmt is'.1957 1

3. BASELINE ASSUMPTIONS The Section 4 guidelines for assessing plant procedures with respect to station b of baseline assumptions concerning the course and nature of the e"ent. These as derived from a variety of sources in the technical literature, including NRC Staff infermatio ,

submitted in support of the proposed station blackout ru.e. This section contains a l baseline assumptions, a brief description of their bases, and appropriate references to so '

De assumptions cover the following areas:

Section 3.1 ---

plant conditions at the time of the station blackout, Section 3.2 --- the initiating event, Section 3.3 --- station blackout transient, Section 3.4 --- reactor coclant pump sealleaiage, Section 3.5 --- operator action Section 3.6 - effects of the loss of ventilation Section 3.7 --- system cross tie npability Section 3.8 --- instrumentation 3.1 Initial Plant Conditions 3.1.1 Assumptions (1) De station blackout event occurs while the reactor is operating at 100% rated the has been at this power level for at least 100 days.

(2) Immediately prior to the postulated station blackout event, the reactor and support I within normal operating ranges for pressure, temperature and water luel. All plant either nermally operating or available from the standby state, i

9 l l

i

t NUGSDO STATION BLACKOt.T RESPONSE GUIDELINES REVISION 0.0 August 10,198*

3.1.2 Basis

())

The potenn::f:r core damagefrom a station blackout is boundes by events initia substantial de:cy heat generation capability. (NUGSBO position)

(2)

Transiens vuta:edfrom normal operating conditions are conside ed to be of gre position) 3.2 Initiating Event 3.2.1 Assumptions (1) 'D.e initiating event is assumed to be a loss of offsite power at a plant sit (a) a switchyard related event due to random faults,(b) a g-id disturbance, or (

that affects de offsite power system either throughout the g id or at the plant.

LOOPS caused by fire, flood, or seismic activity are nce expected to occur w frequency to require explicit criteria, and are excluded from :onsideration.

(2) The LOOPis assumed to affect all units at a plant site. However, the u (Class IE) power sources shall be limited as follows:

(a) Siagle Unit Sites:

Two standby (Class IE) AC power sources are issumed to be unavailable w the LOOP occurs. For a unit having more that two onsite AC power source (eitner Class lE or Non Class IE), these additenal sources are assumed to b available if thev meet the A AC criteria orovided M Anoendix B.

(b)

Multi Unit Site with Non Shared Standby (Class 1E) AC Power Source:

For a muld unit site that does not share standby (Class IE) AC power sou two standby (Class 1E) AC power sourcesW p toassumega e

unavail y

affected unit}Any additional sources f a,s, sum,<ed y AAC criteria orovided in Anoendix B(The no 6e occurrence of a single active failure of a sandby (Class lE) A scurre in addition to the LOOP affecting the site. 2Ea "

L-10

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 Aagust 10,198*

_T_ n.s c M 3 2 I(h (c1 #

/

s Multi-Unit Sites W Shared Standbv Class lE Power Sources:

\ 'Fors multi

, unit sites that share standby (Class IE) ACywer 6=es betw units, two uandby (Class 1E) AC power sources.are assumed to be unavailable N / '

at the affected unh-The non blacked out unit shall assume the o:ct: en single active failu e o ass IE) AC power source in V.dnion to the LOOP affecting_t}

.- cute. The singlifailure shall be a shared stan6y (Class IE) power supply. Any additional sources are as,s'umed to be availabh if they meet i

j y .thE AAC criteria tmvided in Anoendix D.

~

N~

(3) No design basis accidents or other events are assumed to occur immediately prer station blackout.

3.2.2 Basis (1)

LOOPS that are of concern to station blackout involve those scenarios that are within the NRC analysis ofLOOP experience separates these events into three categories: plant-centered, r severe weather. Plant centered events insolve hardwarefailures, design depciencies, hu nan e- oes in and switching, and localised weather.inducedfaults. such as due to lightning and ice. These p.snt-reportedly occw as afrequency of 0.O!6 ewnts per site year with a median duration of 03 host. Grid dist events have been shown to be of muck lesser concern for most plants. Events in this categon frequency of 0.020 events per site. yea . with a median duration of 0.7 hour8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months . Severe weather esen:s e.xperience with 0.0)) events and a. medu.n duration of2.6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months . (Section 3, including Table ll. NUREG It ispossiblefor a station blackout to resultfrom circumstances that are outside the plant's desy b this potentialis remote. Seismic. pre, andfooding events include accident scenariosfor w requirements specify protective meantes. For example, the potentialfor apre. induced sanon blackou extremely remote due to the efectiveness of current pre protection programs, and 10 CFR 50 separation requirements imposed on shutdown systems. NRC analysis concludes thatpre induced sxad is not a generic concern, cidng a station blackoutfrequency ofless than 1110 6 per reactor-yestfew most plants.

particularlyforplants in conformance Mth Appendiz R separadon requirements. Consequenz.> sna events that may occur at a pardcular she imotvingpre initiators are not likely to occur, and need not be a in this generic gwdance.

I1

i 3.2.1 c Multi-unit sites that share standby (Clar.s IE) AC power sources between units may consider the Class IE AC power sour:es to be AAC power sources provided:

(a) There are at least four Class IE AC power sources.

(b) The Class IE AC power sources meet the AAc criteria provided in Appendix B.

(c) The Class IE AC power sources must be sized to meet the required shutdown loads at both units.

l I

l

\

ww w-' -

--msg -

--3--,7 + y * , -,,y --y-y 9---w--.---,.,y-g. - w --ew -, - -y

NUGSDO STATION BLACKOLT RESPONSE GUIDELINES REVISION 0.0 August 10,193*

The seismic andfooding iss-e: :re similar to thefire risk concern regarding the p::eualfor causing blackout. The Class IE poner s~..=:em is currently designed to withstand seismic even::. in ad induced LOOP event has not been observed at a nuclear power plant to date. ? SimiWi .pooding pro addressedin the plant's licens tt :esis. As a result, the potentialfor seismically induce: :' ooding induce blackout is on the same order a: &e. induced events, and may be ignoted.

For these reasons. seismic.po:a -g. andpre induced station blackout events are not a:.:reased in thes (Appendix J, NUREGICR.322h (2)

The major contnbutor to over::1:::ation blackout risk is the likelihood oflosing ofsite m er and the dur power unavailability. A LOOP ray occur as a result of a switchyard problem either a;=ecting a single ur.:t.

possibly multiple units at a .u:e. Alternatively, the cause of the LOOP may be a gria or area. wide disturbance associated with severe wea:her :en.ditions, although these events are a much smallerfra:a.:n of the tot events (in fact, weather rela:ed events represent on the order of 10% of all LOGPs experienced to date).

Consequently. to be conservati>e the LOOP is assumed to afect all units at a site.

The next most important conmbuaor to station blackout risk for a given plant is low EDG availability. EDG availability varies among opera:1.tg sites, based on the number of EDGs onsite, the retz. ability to startfro standby state and overall availah i.y of the machine, and the potentialfor dependentfailses.

Industry EDG reliability to sta-f om a standby state is typically in the range of 0.98-: % It is very unlikely have average EDG reliabilityf:* .a' machines at a site below 0.95 over a sustainedre ::a Consequently. EDG reliability is a small contributor to station blackout riskfor most plants.

EDGfailures may also occur due te dependent causes. Thisfactor may resultfrom desige or operating depc that mansfest themselves in a concurrentfailure. Examples of suchfailures include: (a) the enstence of a com dependency or single. point vulnerability in support or cuxiliary systems usedfor start. convol, or cooling. or (b) vulnerability to common causefailwe.

The potensialfor these dependencies affecting all EDGsfor multiple unit sites is conrJered remote since most reactors have staggered operating cw:les. Staggered operating cycles also make it less likey that major maint activities are scheduled as the so.~.e time. Similarly, redundant units are often desig<ed and constructed on 12

s '

l I

Nt.CSDO STATION BLACKOUT RESPONSE GL1DELINES REVISION C.: 1 August 10,198* j i

v.iependent schedules. with initial commercialoperation c.::e separated by up to severalyears in time.

Ge .erally high EDG reliability and low dependentfailee rates provide a basisfor screening EDG cor/1gura:

having a remote potentialfor totalfailure. NUGSBO*: a .alysis indicates that the potentialfor simultane: ..

fung 2 EDGs with each machine at industry average rehability (i.e., approximately 2% averagefailure rc:t : .

de~.andfor each machine) and nominal susceptibility a cependentfailure (i.e.,2%) is approximately 7.8 2 l:'

The likelihood of 3 EDGsfailing is even loser. at abos.: t 2 x 10'for machines with 0.98 reliability.

These results suggest that the potentialfor more than 2 EDGs failing is very low for most of indu:.~.

Cc .sequently, failure of only 2 machines is initially cor.:1dered in these guidelines, permitting the availabihr. :

rer-aining machines onsite under certain circurratances.

The availability during station blackout of any remaining EDGs onsite may be assumed if two conditions cre rre (1) the machine satisfies the Alternate AC power source crueria provided in Appendix B; and (2) the machir.e:

svadability is maintained in accordance with Alternate AC power source criteria. The)1rst condition is directec :

minimizing the pot <ntialfor dependentfailurt events ad.ersely affecting the Alternate ACpower source in sta:.:-

bla:kout scenarios ofconcern. The second condition pic ,1desfor power source availability. lfone or both ente .:

are no't metfor the additional EDGs onsite, these machir.es would be assumed to be unavailable in1 a stat:

blackout.

The stated objective of the proposed station bla:kout rule a to reduce the station blackout core damagefrequency .:

approximately 10 3per yearfor the average site. As pronied in the proposedrule, these benefits would be o by e.nending the current nominal 2. hour coping capabilin to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . Comparable safety benefits may be obtave:

by implementing an AACpower source. For example. as:wmng a LOOPfrequency of 0.1 per year and a 113 ED.?

configuration with a 2-hour coping capability the station blackout core damagefrequency is well below the JC*!

per year threshold sought by the Staf. (Section 4, NUREG 1032; also NUGSBO position)

(3) The likelihood of a design basis accident or other event coincident with a station blackout is considered to be remene and is not adhessed in this document. (NUGSBO posinon) 13

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 3.3 Station Blackout Transient 3.3.1 Assumptions (1) Following the loss of all offsite power, the reactor automatically ps with sufficient shutdov,r.

margin to maintait subcriticality for the duration of the event.

(2) The main steam sy 5:e= valves operate properly.

- (3) Safety / relief Valves (S/RVs) or Power Operated Relief Valves (PORVs) ope Normal valve resea:ing is also assumed.

(4) No failure, other than these presented in Section 3.2.1, are assumed to occur in the transient. The pote::ial for mechanistic failures resulting from the '.oss of ventilation in blackout event is addressed separately as a station blackout topic.

(5) AC poweris assurred :o be available to required shutdown equipm=: within 4-hours fro 3.3.2 theBasis offsite or blacked-out unit's Class IE sources or within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months f ac

( (3) These assumptions on: ine some of the more important features of the st::cn blackout tr considerations are a acrma! LOOP transient, proper unit trip withfull reactiv.y a .sertion and addition, the likelihoodsfPORV or SIRV misoperation in a station blackout is :n :v order ofI 2, NUREGICR 1988: Section 2 and 6. NUREGICR-2182; and NUREC 1032) (4) Imposing additionalfaGres on the station blackout response capability has dadmshing mostpower plants. Th.:is because the dominant accident contributors to a a=on blackou involve ofsite power sytem reliability, the reliability and level of redundarcy of the emerg system. and the nation bmschout coping capability. in that order. Since the coping :apability is a so stazion blackout risk than AC power system reliability, additionalfailures in shis sys importance. The resporue capability also depends on Class 1E systems that are kigkl and maintenance standa ds used. Consequently, the potentialfor randomfailure in the the safety efects of res; case capability loss are significant only sf they are c:enenced e blackout transient (i e.. y.m:'ily in theprst 30 minutes). This potential has been sd: esse ' 14

NUGSD0 STATION BLACKOUT RESPONFE GUIDELINC REVISION 0.0 August 1",,1 5" which estimates the probability of decay he:: re' oval systemfailure early in a station blackout . ?nge ese from 0.001for High Pressure Core Spray tii?CS)RCIC combinations to 0.04for a single ste train auxiliaryfeedsater system (AFW). T1 se results underscore the relative unimportanc . .

ennmechanisticfailures in the station blackos: sce*nario. (Appendi.x C, particularly Table ::soC.2. N NUGSB0 position)

           .      15)

The vast majority of LGOP events are of 1.ce: duration. NRC Staff analysis reports the med restoration timefor all!OOP events to be a::ut 1/2 hour, with offsite power restoredin approximate:. ? for 90% of all events. Consegently, assumir.i a 4 hour restoration time addresses the bulk ofp blackous events. For AAC systems.1 hour is sensidered a reasonable period of time to source and restore power to a shutdown bus NUMARC Initiative 1 places allplants in the 4 requires an AAC capability. tOfsite power resx:ra=on times are sakenfrom Supplementary I Station Blackout Rule. Sl FR SS, at 9830) Q f c kwf Alaw Seclh, 3Y !n M f K .0SS L ' ~ N 3.4 Reactor Coolant Pump Seal Leakage i 3.4. ssumptions I j Reactor coo act. pump (RCP) seal leakage :cncem applies only to Westinghouse pum pumps, RCP seal Teakage N is assumed not to exceed 25 gpm per pum fe'r the duration2:fon of the s: blackout event. Plants may assume RCP leikage rates less than 5 gpm if it can be appropriate analysis or testin /

        \                                                                                                                                       i
          \     3.4.2      Basis l

NRC analyses supporting the proposed station l ek:ut rulemaking recognise that concerns over RCP seal leakage can be separatedfrom the ssation blackout ev n!' Further. he RCP se ge concern appears to befocused Wesug %use pumps. The topic is currently the abject ofits own resolution program .. NRC Generic issue 23), neanng pnal l resolution with a material dification correcting the problem. These cons ations consribute to the NRC's assumption of ~20,gynrper pump in NUREG 1032 :: be a reasonable "upper bound l' ' ~ of RCP s j sation blackout. Appendh G,NUREGICR 3226; al:a WCAP 10541) i f 15

I 3.4 Reactor Coolant Inventory Loss f 3.4.1 Assumptions Sources of expected reactor coolant inventory loss include l i normal system leakage, losses from letdown and losses due to l

      . reactor coolant pump seal leakage. Expected rates of reactor     l coolant inventory loss under station blackout conditions do not result in core uncovery in the four-hour time period. Makeup systems in addition to those currently available under blackout conditions are therefore not required.

3.4.2 Basis Normal system leakage is limited by technical specifications to a low rate. These rates do not increase under station blackout conditions. Emergency operating procedures developed in accordance with NSSS vendor Emergency Procedure Guidelines direct operators to isolate letdown. Reactor coolant pump (RCP) seal leakage concern applies principallly to Westinghouse pumps. For these pumps, RCP and leakage is assumed not to exceed 25 gpm per pump for the duration of the station blackout event. RCP seal leakage is currently the subject of its own resolution program (i.e., NRC Generic Issue 23) nearing final resolution with 25 gpm per pump as a reasonable leakage rate.

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 3.5 Operator Action 3.5.1 Assumptions Operator action is assumed to follow the direction provided in the Plant Operating Procedures for the underlying symptoms or identified event scenario associated with a station blackoul

    . 3.5.2    Basis NRC analyses supporting the proposed station blackout rulemaking assume that a reasonable set ofoperator actions will occur. The governing document for defining operator actions are the plant's procedures. (Appendix H, NUREGICR 3226) 3.6       Effects of Loss of Ventilation

3. 6.1 Assumptions Under station blackout conditions, ventilation systems are not available. However, sufficient natural circulation is assumed to be available, or can be either established or augmented in plant areas by operator action to minimize the potential for equipment failure by overheating.

3.6.2 Basis The potentialfor mechanisticfailures of systems and components due to loss of ventilation is dependent on the time requiredfor temperatures to rise in closed compartments and cabinets. Temperature buildup in a compartment is a slow process due to the normally large thermallag associated with natural convection and the loss of AC supplied heat sources. This large thermal tag allows sufficient timefor operator action to identify areas .equiring supplemental cooling and take appropriate action to terminate the thermal buildup. Consequently, these guidelines direct that operat actions in a station blackout include providing supplemental cooling where necessary,. and do not assume any mechanisdefailures to occur as a result ofloss of ventilation. NUGSB0 has performed an analysis of temperature buildup that supports these assumptions. Using a lumpedparameter model of the compartment air temperature, and conservative assumptions concerning heat loads and heat transfer coefficients. the average air temperature in a compartment was estimated as afunction of time. The heat sources considered are electrical and mechanical equipment present in the compartment, and hot steam pipes that dissipate heat 16

NUGSDO STATION BLACKOUT RESPONSE GtJIDELINES REVISION 0.0 August 10,1987 throug h natural convection and thermal radiation. The concrete walls were considered . opening doors was modeled by using empirical heat transfer correlations that describe the conve through openings between rooms. For typicalRCIC and control room configurations and heat loads, the temperature rise after afou was estimated. The results of the model show that if compartment doors remain closed during the blac temperature risefor afewplants may be large enough to affect the operability ofequipment in the . model accountsfor opening doors at the beginning of the staion blackout, temperature rise in the

is significantly reduced. This reduction in temperature rise is .'arge enough to demonstrat measures are a sufficient response to the loss of ventilation concern.

Occasionally, supplemental cooling measures may conflict with other safety or administrative consid example, procedural requirements may existfor keeping fire or flooding doors closed. Despite these considerations, opening doors would be an acceptable technique in a station blackout in order to increase n circulationfor instrumentation necessaryfor shutdown. Other techniques, such as using permanently m battery-operatedfans inside cabinets, could also be considered as an option in lieu ofprovidi measures procedurally. (Section 3 and Appendix 1. NUREGlCR.3226: also NUGSBO position } 3.7 System Cross tie Capability 3.7.1 Assumptions Under station blackout conditionsAd it MdM is assumep' in that,gultiunit sites with fluid or DC cross tie capability will be able to achievea safe shutdown in the affected unit by utilizing the unaffected unit's cross tied systems. 3,7.2 Basis NRC analysis supporting other rulemakings (i.e.,10 CFR $0 Appendit R) allow multiunit sites to rely on cross. capability offluid systems to bring the afected unit to sqfe shutdown conditions. For station blackout considerations, the systems of the unaffected unit must be electrical.) independent of the blacked out unit in order to credit their availability to bring the afected unit to safe shutdonn. l 17

i

       .e 1

NUCSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 . August 10,1987 3.8 Instrumentation 3.8.1 Assumptions Emergency Procedure Guidelines provide guidance on instnamentation to be used during station blackout conditions. Appropriate actions will be taken by operations personnel to assess plant status in the event of erratic performance or failure of shutdown instrumentation. 3.8.2 Basis NSSS emergency procedure guidelines identify instrumentation requirements to safely shutdown. Operator train includes the use of backup instrumentation andidentsfying erratic performance. (NUGSBO position) G 18

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987

4. OPERATING PROCEDURE GUIDELINES 4.1 Introduction Existing plant procedures are based on NSSS generated procedure guidelines and provide the operator with substantial direction for responding to a station blackout event. Plant procedure also address power restoration and severe weather concerns. Additional actions that may n addressed in existing procedures, but are important considerations during a station blackout, ar addressed below. Operators should revise their plant procedures to include these considerations.

As provided by the second NUMARC initiative, plant operating staffs should review and revise as apprcpriate their operating procedures using the technical bases and associated guidelines pr this document. 4.2 Station Blackout Response Guidelines (NUMARC Initiative 2.a) This section provides guidance for operator actions to be taken in a station blackout event. A C contains additional information and bases for the guidelines provided in this section. These guidelines assume a single path to achieving shutdown conditions in a station blackout. The path consists of repeated attempts at restoring AC power to a shutdown bus while performi operations designed to stabilize the plant using available equipment. Guideline (1) reflects a AC power restoration which may be made from either the preferred or a standby (Class IE) p source. If an AAC power source is available, it may also be used to restore power through (Id) address items to be considered in stabilizing the plant until AC p L'k \(L) (1) Plant procedures should identify site specific actions necessary to restcre offsite or standby (Class IE) AC power sources. If one is available, an AAC power source should be started as soon as possible. Plants relying on AAC power sources should start and commence loading 19 . l

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10.1987 shutdown equipment within the first hour of a station blackout. (2) Plant procedures should specify actions necessary to assure that shutdown equip (including support systems) required in a station blackout can operate without AC powe (3) Plant procedures should recognize the importance of AFW/HPCI/RCIC during the early of the event, and direct the operators to invest appropriate attention to assuring its continued reliable operation throughout the transient. (4) Plant procedures should identify the larger sources of potential reactor inventory loss, a specify actions to be taken to prevent or limit significant loss. (5) Plant procedures should ensure that a flowpath is promptly established for makeup flow the CST to the steam generator / nuclear boiler and identify backup water sources to the CST in order of intended use. Additionally, plant procedures should specify clear criteria for performing system line up for the next available source of water. (6) Plant procedures should identify individual loads that may be stripped from the plant DC bu (both Class IE and non Class IE) for the purpose of conserving DC power. (7) Plant procedures should specify actions to be taken to permit pneumatic valve operation AC power is unavailable. These actions may include: (a) providing additional bottled air or nitrogen at the valves; (b) specifying manual valve operation to maintain shutdown (e.g., manual valve seating to reduce system losses) (8) Plant procedures should specify whether portable lighting is necessan for access and egr plant areas containing shutdown or AAC equipment that may require manua! operation. (9) Plant procedures should consider the effects of AC power loss on area access, as well as the need to gain enny to other locked areas where remote equipment operation is necessary. 20

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 (10) Plant procedures should consider loss of ventilation effects on specific energized equip required for shutdown (e.g., those containing intemal electrical power supplies or other local heat sources that may be energized or present in a station blackout). These procedures shou address: (a) specific room temperatures or cabinet temperatures or symptoms (e.g., alarms or indication of loss of cooling) readily identifiable by the operator, and the action that should be taken when those temperatures are reached, and (b) methods for providing ventilation ar.d/or supplemental cooling.

                                    ,,,;y   a doce< v b;h is K        . *'" ms   7c" (11)     Plant proceduresjhnM i operator access wwermswbaarm when specifying manual operation.

(n) .% )es if af+pm*J liuI 'tc a h ccpe fA bfu k o , t dueaNm y d .s/= Non sieaid 6e a dd'+<ned )n a e, aln w,, ce prepm, 4.3 AC Power Restoration (NUMARC Initiative 2.b) This section provides guidance for operations and load dispatcher personnel concerning the p course of action for restoring AC power in a station blackout. Appendix D contains additional information and bases for the guidelines provided in thic t;c;jc,n, 9 J,;4).*s! few U' P'I'" (1) Load dispatchers should givegN = ;y to restoring power to nuclear units. Procedures and training should consider several potential methods of transmitting power from blackstart capable units to the nuclear plant. (2) Should incoming transmission lines to a nuclear power plant be damaged, high priority should be assigned to repair and restoration activities to at least one line capable of feeding shutdown equipment. (3) Repair crews engaging in power restoration activities for nuclear units should be given high priority for manpower, equipment, and materials. (4) Portable AC generators should be designated as backup sources if available and directed to nuclear power plant sites. 21

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 (5) Once preferred and/or standby (Class 1E) AC power becomes available, station procedures should specify the sequence of circuit breaker operations required to restore AC power to shutdown equipment. Any additional actions such as pulling or replacing fuses should also be identified. 4.4 Severe Weather Guidelines (NUMARC Initiative 2.c) ~ This section provides guidance for operators to determine the proper course of action due to the onset of severe weather, particularly hunicar.es. Appendix E contains additional information and bases for the guidelines provided in this section. The ability to track hurricanes and take appropriate actions to put the plant into a shutdowm condition can greatly reduce the consequences of a station blackout. With sufficient warning, actions may also be taken to enhance the reliability of AC power sources. ACTIONS FOR HURRICANE (1) The plant procedures should identify site-specific actions necessary to prepare for the onset of hurricane. These actions should include: (a) inspecting the site for potential missiles and red.!cing this potential (b) reviewing the adequacy of site staff to support operations and repair (c) expediting the restoration of important plant systems and components to service (d) warming and lubricating standby (Class IE) AC power sources (e) determining the status of Alternate AC sources (if available) and take necessary actions to ensure their availability (f) increasing CST inventory 22

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 (g) placing battery chargers in service (if applicable, i.e., not on float charge) (h) testing EDGs (2) Utility procedures should identify additional plant staff to be recalled in order to support the present staff and the means to contact them once a hurricane notice has been issued by the National Weather Service. (3) Plant procedures should specify actions necessary to ensure equipment required for a possible station blackout is available. (4) Plant procedures should address the following items prior to a hurricane arrival at a site: (a) the site-specific indicator to initiate shutdown in order to obtain a nominal 2 hour period prior to an anticipated LOOP due to high wind speed (b) operator review of station blackout procedures (c) operator review of procedures to line up and operate the switchyard spraydown system (if installed) ACTIONS FOR TORNADO Plant procedures should identify site specific actions necessary to prepare for the onset of a tornado.

            'Diese actions should include:

(a) inspecting the site for potential missiles and reducing this potential, and (b) expediting the restoration ofimportant plant systems and components to service 23

NUGSDO STATION BLACKOUT RESPONSE GL1DELINES REVISION 0.0 August 10,1987 APPENDfX A. DEFINITIONS Terms defined below were specifically developed for these guidelines and are of special _ its use. hyvl k AbTERNATE AC POWER - one or more sources of AC power tha independent of the unit's preferred and blacked-outunitdass IE power lies i N; ' j (2) provides sufficient protection against ~ pendent failures in the preferred and i blacked out unbass 1E'4C power system from propagating to t of adversel (

                            ,( 3) is su ntlyacie/y        affecti(the albtelource; sized to stait and supply shu                                            (

I

                                                                                             ;and,                          .

(4) ts not unduly susceptible to the occurrence of severe wea 14he site. l Bas n NUREGICR 3992,page 2. l PREFERRED POWER SUPPLY that power supply from the transmission system to the Class distribution system which is preferred to furnish electric energy under accident or postacci. conditions. lEEE STD 7651983;lEEE STD 3081980; andNUREGICR 3992, page 2. SEVERE WEATHER - the occurrence of annual average snowfall, tomado of F2 severity o hurricane with salt spray potential, and windspeeds in excess of 75 mph. NUREG-1032. STANDBY POWER SUPPLY the Class IE power supply that is selected to fumish electric en to shutdown equipment whe, the preferred power supply is not available. Based on IEEE-STD 3081980. Zir.rer / 8 STAlluN15tAGKOUL4utloss of all preferred (offsite) power en a-plannmnlirthe unav

                                  ~
                                                                  ~

24

Insert A "Alternate ac source" means an alternating current (ac) power source that is available to and located at or nearby a nuclear power plar: and meets the following requirements: (i) is not'normally directly connected to the preferred or onsite emergency ac power systems for the unit affected by a station blackout , (ii) has minimum potential for common mode failure with offsite power or the onsite emergency ac power sources, (iii) is available in a timely manner after the onset of station blackout, (iv) has sufficient capacity and reliability for operation of systems required for the time requiced to bring and maintain the plant in a safe shutdown condition.

Insert B "Station blackout" means the complete loss of alternating Current (AC) electric power to the essential and nonessential switchgear buses in a nuclear power plant (i.e., loss of offsite electric power system concurrent with turbine trip and unavailability of the onsite emergency AC power system). Station blackout does not include the loss of available AC power to buses fed by station batteries through inverters or by alternate AC sources as defined in this section, nor does it assume a concurrent single failure or a design basis accident.

 - .-                 , -.     .    - , . , - . . , . , , _ _ . . . . , - - . - . . , , . - , . . _ .   .. ,..~ -, - -

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987

of at least two stan3Fy -(Class-lE)-ACpwegpJlies of imnirat the site. Based on no p _' lon otackout, Federal Register Vol. 51, No. 55M2.

           , SUCCESSFUL                             - the result of         test in which the AAC system is shown to be capable of stani       eo. pung a load within one                                   event.

NUG non.

       . u                                                                                           ,          J

     .                                                                                                              i NUGSBO STATION BLACKOUT RESPONSE GUIDELINES                                              REVISION 0.0  i August 10,1987 APPENDIX B. ALTERNATE AC POWER CRITERIA This appendix describes the criteria that must be met by a power supply in order to be classified as an Alternate AC power source. De criteria focus on ensuring that station blackout equipment is not unduly susceptible to dependent failure by establishing independence of the AAC system from the emergency and non Class IE AC power systems.

The AAC power source criteria and exceptions are as follow'.,: B.1 The AAC system and its components need not be designed to meet Class IE or safety system requirements. B.2 Unicss othenvise provided in this criteria, the AAC system need not be protected against the effects of: (1) failure or misoperation of mechanical equipment or (2) seismic events. Included among these effects are: (i) fire, (ii) pipe whip, (iii) jet impingement, (iv) water spray, (v) flooding from a pipe break, (vi) radiation, pressurization, elevated temperature or humidity caesed by high or medium energy pipe break, and (vii) missiles resulting from the failure of rotating equipment or high energy systems.

                              &);y 4,wmina, hm &~' n% Wnd p* **"D B.3 Components and subsystemsgall be protected against the effects of weather that may initiate the loss of offsite power event. Protection may be provided by enclosing AAC components within structures that conform with the Uniform Building Code, and burying exposed electrical cable run between buildings.

B.4 Failure of AAC components shall not adversely affect Class IE AC power systems. B.5 Physical separation of AAC components from safety related components or equipment shall conform with the separation criteria applicable for the uni;'s licensing basis. 26 i

NUGSBO STATION BLACKOtJT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 B.6 Electrical

J se H isolation NC of AAC scene a power shall be provided through an appropriate isolation device.

s n o, n e c ie s fc ,1<ss it as s la r,m p ,s W,.4 a.7 -c dn de f c rs.es .4 a f a ti uc c u s vv: , A C ietr /E .a <ad 1 in s e di eJ (l c/4aaif p / BT--The'-AAC-p=ar syttemMall

                                                                                                                        . tu , in '

al be ecuinned -ith as vws ErC powerWun;c tnat is electr 6.'l Q Yi ~u&nt ifrom the blacked out unit's Class IE power system. ^# ' B.8 The AAC power system shall be capable of operating during and after a station blackout without any suppon systems powered from the preferred power supply, or the blacked-out unit's Class 1E power soun es affected by the event. B.9 The AAC power system shall be sized to carry the required shutdown loads for at least 4 hours, and be capable of maintaining voltage and frequency within limits that will not d _the performance of any shutdown system or componen1[At a multiunit site, an adjaeemd

                             ' Class IE power source may be used as wwu iLm far-th= bMeA-on_t unit                    n if it is

( capabl_e of noweWutred lonAs at hnth unite jhe AAC system shall not be capable of automatic loading of shutdown equ blacked out unit unless already licensed with such capability. I i B.11 Unless otherwise govemed by technical specifications, each AAC power source shall be initially and periodically tested in accordance with vendor recommendations to demonstrate th capability of the unit to perform its intended function. B.12 Unless otherwise governed by technical specifications, the AAC power source shall be staned l and brought to operating conditions that are consistent with its function as an A AC source at intervals not longer than three months, following manufacturer's recommendations. Once every 18 months, a timed start (within the time period specified ur der blackout conditions) and load to rated caprity test shall be performed. t l B.13 Unless otherwise governed by technical specifications, surveillance and maintenance Procedures for the AAC system shall be implemented in accordance with manufacturer's I recommendations. l r % 7ke nac po w s w -a s L..td mf mv~ Hy s%/ cwurid m i- -@ }, + 4, cas * \ s a , .. p..a .- ve-,

94 blu/ cod 27 Zn a dd,4bi

                                  # hd             +>y Nunoi                         _

l l

 .     ,                                                                        1 B.7 There shall be minimal potential for common mode failure of    ,

{ the AAc power source which I , preferred or onsite emergency AC l power source. The following system features provide assurance that the minimal potential for common mode failure has been adequately addressed: (a) The AAC power system shall be equipped with its own DC power source that is electrically independent from the blacked-out unit's Class IE power system. (b) The AAC power system shall be equipped with its own air start system as applicable that the onsite emergency AC power source.is independent of (c) The AAC power system shall be provided with its own fuel oil supply as applicable that is separate from the fuel oil system, supply for the onsite emergency AC power i.e., a sepa. rate day tank supplied from a common storage tank is sufficient provided the fuel oil is adequately sampled and tested prior to transfer to the day tank. (d) If the AAC power source is an identical machine as the

                 -  onsite emergency AC power source, failures of the emergency AC power some shall be evaluated for applicability and corrective action for its AAC power source.

(e) No single point vulnerability shall exist whereby a wecther-re'.ated event or single active failure could disable any portion of the onsite emergency AC power sources or the preferred power sources, and simulttneously find the AAC power source (s).

NUGSDO STATION BL ACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 B.14 Unless otherwise cham overned by technical specifications, the AAC system shall be designed and f

          @%ing p$im ;..$be bt$1Mh t its rdlabi'h eshutdown equipmer.t within one hour of a station blackout event.

B.15 The Non Class IE AAC system should attempt to meet target reliability and availabilit depending on norma) system state. In this context, reliability and availability goals apply

       .        overall AAC system rather than individual machines, where a system may comprise more tha or,e AAC power source.

(a) Systems not norma 1]y operated (Standby systems) --- Availability AAC systems normally rnaintained in a standby state should attempt to be %pa<tional" at least 95% of the time the reactoris operating. Reliability System reliability should be established by analysis of an appropriate sample size taken from periodic testing. This reliability should (1) attempt to meet or exceed 95% successful starts (See definition for a successful start); and (2) be maintained abrve 90% calculated successful starts based on NSAC 108 methodology (or equivalent)[ Data censoring is acceptable if it ca - 1 (ifioMHerMaduretar_c ei, either ositives, the false p underlying ow (causes have-beiin corrD,'or e a stausucal anomaly. N re y (b) Systems normally operated (Online systems) -- Availability AAC systems normall; online should attempt to be available to its associated unit at least 95% of the time the reactor is operating. Reliability No reliability targets or standards are established for online systems. 28

NUGSBO STNTION BLACKOtJT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 APPENDIX C. STATION BLACKOUT RESPONSE GUIDELINE SUPPORTING INFORMATION This appendix nrovides the bases and related supplemental information for the guidelines of Se: tion 4.2. (1) Plantprocedures shouldidennfy site specific actions r:ecessary to restore ofsite sources. lf one is available. an AAC power source should be started as soon as possibl power sources should .tcrt and commence loading shutdown equipment within thefirst hour of a blackout. These actions include: (a) Early commitment ofavailable staf to restore ACpower -- this should occur within the first few minutes of a station blackout (b) Isolating the shutdown bus to be loaded onto the AAC system from the preferredpower supply and black:dout unit's Class 1Epower sources - this can be achieved by circuit breaker operation, and pulling fuses at the switchgear dis 011ng circuit breaker control power or by msnual interlocks. (c) Starting and/orpreparing the AAC source lor loading. (d) Transferring the designated shutdown bus to the AA C system. (2) Plant procedures should specify actions necessary to assure that shutdown equipmen systems) requiredin a station blachut can operate without ACpower. 29 1

NUGSBO STATION BLACKOLTT RESPONSE GUIDELINES REVISION 0.0

                                                   ,     7 n ;t  m,
                                                                        ,wy,,,p) + Ui              Augun 10,1987
                                                .C Cooling functions provided by such systems as auxiliary building cooling water, service water, or component cooling water may be required in order for shutdown systems to oerform their
                                                                                     ,,,, p          ,,e4 -

safety function. For example,;,a steam driven auxiliary feedwater pump c:y ::'y on com cooling or service water to cool the bearing lubricating oil rather than relying hmmy ph m, these f=:tiem m; be &c provided by 2: d!:: ! d?; n fL: pump E . efess conncctcJ iv & opywynetc Nbiating cil cc010:s e h::t :Wmgm - Systems potentially supplemented in this manner may include component / auxiliary cooling water, service water, and auxiliary / reactor building cooling water systems. (3) Plant per Jures should recognize the importance ofAFWlHPCitRCIC during the early stages of the eve direct .. operators to invest appropriate attention to assuring its continued, reliable operation througho trarcient. The risk of core damage due to station blackout can be significantly reduced by assuring th availability of AFW/HPCI/RCIC, particularly in the first 30 minutes to I hour of the event. A substantial ponion of the decay and sensible reactor heat can be removed during this period. AFW/HPCURCIC availability can be assured by providing a reliable supply of condensate, monitoring turbine conditions (particularly lubricating oil flow and temperature), and maintaining nuclear boiler / steam generator water levels. (4) Plant procedures should idennfy the larger sources ofpotential reactor inventory loss. and specify actions taken to prevent or limit sigraficant loss. Actions should be linked to clear rymptoms of inventory loss (e.g., specific temperature readings provided by sensors in relief valve tail pipes), associated manual or DC motor driven isolation valves, and their location. Procedures should establish the priority for manual valve isolation based on estimated inventory loss rates early in the event. If manual valves are used for leak isolation, they should be accessible, sufficiently well lit for operation, and equipped with a handwheel, chain, or reachrod. If valves are locked in position, keys or cutters should be available in the control room. Procedures should idantify the location of valves, keys, and 30

NUGSDO STATION BLACKOlIT RESPONSE GL1DELINES REVISION 0.0 August 10,1987 Cutters. ($) Plant procedures should ensure that aflowpath is promptly establishedfor makeupflowfrom the CST to th steam generatorinuclear boiler and identify backup water sources to the CST in order cfintended use. Additionally, plant procedures should specsfy clear criteriafor performing system line upfor the next availabic source ofwa:er. All stored water sources may be assumed to be available in a station blackout at their nominal capacities, including water stored in nonsafety tanks. In general, all condensate storage tanks should be used first. The main condenser may be assumed to be available if a pump can be operated and is capable of making up (1) to the AFW/HPCI/RCIC pump suction with sufficient head and flow, or (2) directly to a CST (safety or nonsafety). After the CSTs are exhausted. demineralized or borated water tanks may be used, as appropriate. Heated torus water should be used only if sufficient NPSH can be established. Finally, when all other reliable water sources have been u .ed, brackish water may be pumped as makeup flow using a diesel driven fire pump. Procedures clearly should specify the conditions when the operator is required to resort to increasingly impure water sources. (6) Plant procedures identify individual loads that may be strippedfrom the plant DC buses (bon Class IE and non Class 1E)for the purpose of conserving DCpower. DC power is needed in a station blackout for such loads as shutdown system instrumentation, EDG field flashing, circuit breaker operations, and motor-driven valve operators. Emergency lighting may also be powered by safety related batteries. However, for many plants, this ! lighting may have been supplemented by Appendix R and security lights, thereby allowing the emergency lighting load to be eliminated. Station bh;kout procedures should attempt to l conserve DC power during the event by st"pping nonessential loads as soon as practical, preferably within the first 30 minutes when DC loads tend to be large. Early load stripping can significantly extend the availability of the blacked out unit's Class IE batteries. For plants wi'h i tuming gear loaded on the batteries, stripping this load early in the transient can also 3' i

I NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 1 August 10,1987 j i signincantly extend battery availability. In certain circumstances, AFW/HPC1/R may be extended by throttling flow to a constant rate, rather than by stroking valves open shut cycles. (7) Plant procedures should specify actions to be talen to permit pneumatic valve operations unmailable. The:e actions may include:

                                @         providing additionalbattled air or nitrogen at the valves; (b) specshing manual vala operation to maintain shutdown (e.g.. manual valve stati to reduce system losses)

Compressed air is used to operate (cycle) some valves used for decay heat removal a reactor auxiliary systems (e.g., identifying letdown valves or reactor water cleanup sys valves closed). When stored air is exhausted, manual valve operation may also be (8) Plant procedures sbuld specsfy whether portable lighting is necessaryfor access and egre containing shutdown o. MC equipment that may require manual operation. Areas requiring continuous occupancy for instrumentation monitoring or equipment o may require portable lighting as necessary to perform essential functions. Lighting prov meet the requirements of Section III.3,10 CFR 50 Appendix R, for achieving safe shutdown generally adequate ifit is independent of the preferred and emergency AC power system (9) Plant procedures should consider the effects ofACpow er loss on area access. us well as other locked areas where remote equipment operation is necessary. At some plants, the security system may be adversely affected by the loss of the pref Class 1E power supplies in a station blackout. In such cases, manual actions speci station blackout response procedures may require additional actions to obtain access. 32 _ ~

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 (l0) Plant procedures should consider loss cf ventilation efects on spec @c energized equipmen (e.g., those containing internal electricalpower supplies or other local heat sources that may be en present in a stadon blackout). These procedures should address: (a) specific room temperatures or cabinet temperatures or symptoms (e.g.. alarms or indication oflos of cooling) readily idennfiable by the operator, and the action that should be taken when those tenperances are reached.and (b) meshodsfor providing ventilation and/or supplemental cooling. Station blackout procedures should identify specific actions to be taken to ensure that equipment failure does not occur as a result of a loss of forced ventilation. Actions should be tied to either the actual loss of AC power or upon reaching certain temperatures in the pla Plant areas requiring additional cooling are likely to be locations containing shutdown instrumentation and power supplies, turbine-driven decay heat removal equipment, and in the vicinity of the inverters. These areas may include AFW rooms, HPCI/RCIC rooms, the control i room, and logic cabinets. Coo.ing may be accomplished by opening doors to rooms and electronic and relay cabinets, and/or providing supplemental cooling. Air temperatures may be monitored in a station blackout through the use oflocally mounted thermome'ers inside cabinets ano in plant aress where cooling may be needed. Alternative procedures may direct the operator to take action to provide for alternate cooling in the event nntmal cooling is lost. Upon loss of these systems, or indication of temperatures outside the maximum norn.al range of values, the procedures should direct supplemental cooling be - provided to the affected cabinet or area, and/or designate altemate means for monitoring system functions. For the limited cooling requirements of a cabinet containing power supplies for instrumentation, simply opening the back doors is likely to be effective. Should terrrperatures continue to rise, additional cooling may be provided by bringing supplemental blowers into the vicinity. For larger cooling loads, such as HPC1/ECIC arid AFW rooms, portable engine-driven blowers may be considered during the transient n augment the natural cir:ulation provided by opening doors. The necessary rate of air supply to these rooms may be :stimated 33

NUGSDO STATION BLACKOUT RESPONSE GUIDELTNES REVISION 0.0 AuCust 10,1987 on the basis of rapidly turning over the room's air volume. b' Y Ylon" pesceda s doJ/ ao s's /e,. 4. b: /.44 /, cmce ., pr o p a l. , ., aes e w k., of uify;y m J cy < A . m O L.) No n - C4 er /f s p ,p m / n lokal upos 4 c p fe, u< n,u;,./ a'wa r', 'm .s he.!/ be </fa n */ in , ,,, ,, ;n & n a n e g 4',,, blocAc.1 p ny m . v f (' i 34 I-

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 APPENDIX D. AC POWER RESTORATION GUIDELINE SUPPORTING INFORMATION This section provides the bases and related supplemental information for the AC power resto procedure guidelines of Section 4.3 Grid Disturbance and Weather Induced Area Blackout Supporting Information 4Q My Lui posN (1) Lead dispatchers should give .% priority to restoring power to nuclear units. Procedures and t consider severalpotential methods of transmitting powerfrom blackstart capable units to the nucle During a complete loss of AC power other power stations may be affected by the ini event. Grid load dispatchers should give high priority to locating altemate transmission sources in order to restore power to the affected nuclear unit. (2) Should inconung transmission lines to a nuclear power plant be damaged. high priority should be repair and restoratwn activities to at least one line capable offeeding shutdown equipment. Multiple incoming transmission lines to a plant switchyard exist at most nuclear utilities. However,it is not necessary to restore all lines in order to feed the necessary shutdown equipment. Transmission line repair should be prioritized in such a way as to ensure that the most efficient manner of AC power restoration is achieved. (3) Repair crews engaging in power restoration actintiesfor nuclear units should be given high priorityfor manpower. equipment, ud materials. e 35

NUGSDO STATION BLACKOUT RESPONSE GtJIDELINES REVISION 0.0 August 10.1987 During severe weather conditions repair activities will be competing for repair resource manpower. Procedures should be implemented to ensure that repair crews are assign priority basis to tasks related to power restoration to nuclear units. Manpower, eq and materials should also be allocated to these crews on a priority basis. (4)

Portable AC generators should be designated as backup sources if available and directe sites.

The use of portable generators as backup sources of AC power, whether located onsite o locally contracted, should be considered whenever possible. Procedures should b instruct plant operations personnel concerning: (a) backup generator location and contact penonnel (b) means of transporting portable generators from outside the plant (e.g., tractor trailer) (c) location of equipment necessary to connect the backup generator to the plant's electrical system. ($) Once preferrcd antor standby (ClasslE) A C power become available. station procedures sequence of circuit breaker operations to restore AC power to shutdown equipment. Any adStior.alactio as pulling or repla:ingfuses should also be identified. Numerous circuit breaker trips will likely occur in the event of a loss of AC power. Plant procedures should address breaker operation sequencing to facilitate AC power restoration a well as identify any additional operator actions such as pulling or installing fuses. 36

., a NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 APPENDIX E. SEVERE WEATHER GUIDELINE SUPPORTING INFORMATION This section provides the bases and related supplementalintormation for the operating pr

      . guidelines of Section 4.4.

. Actions For Hurricane {1) Ptant procedwes should idennfy site specs /c actions necessary to preparefor the onset of hurricar.e. The following actions should be initiated once a hurricane warning has been issued by the National Weather Service: (a) inspecting the sitefor potential missiles and reducing this potential (b) re\iewing the adequacy of site staf to support operations and re;>,ir (c) expediting the restoration ofimportant plant systemt and components to senice (& warming andlubricating standby (Class IE) ACpower sowces ' (e) determining the status ofAlternate AC sowces (sf available) and take racessary actwns to enswe their availability (f) increasing CSTinventory (g) placing banery chargers in service (if applicable. i.e..not onpoat charge) (h) testing EDGs (2) Utilityprocedwes should idennfy additionalplant staf to be recalled in order to support the present sigf and th means to contact them once a hurricane notice has been issued by Ihe National Weather Service. The normal plant operations staff may not be adequate to deal with the added activities necessary to mitigate the effects of a hurricane. Utility procedures should be responsive to the 37

NUGSDO STATION BLACKOUT RESPONSE GtJIDELINES REVISION 0.0 August 10.1987 need to recall additional personnel. (3) Plantprocedures should specify action necessary to ensure equipment requiredfor a possible st awalab/c. With the onset of a severe weather conditions the potential for a LOOP increases. It is therefore, necessary to verify the availability and operability of equipment riecessary responding to a station blackout. Any equipment testing in progress should be comple soon as practical and no unnecessary testing (i.e., testing not associated with surveillance requirements) staned until the severe weather warning has been lifted. Equipment important to station blackout response should include but not be limited to: (a) Emergency diesel generators - EDGs should be kept in a warm standby condition with circulating water and lubricating oil if possible. Pre lubricating should also be accomplished if such means are provided. (b) Station batteries Station batteries should be checked to verify they are charged (e.g., by checking bus voltage). (c) Decay Heat Removal Systems The status of systems fed from DC or emergency AC power should be determined and appropriate actions should be taken to ensure the availability of such systems. i (4) Plansprocedures should address thefollonkg items prior to a hurn' cane's arrival at a site. (4a) The site specific indicator to initiate shutdown in order to obtain a nominal 2 twur periodprio anticipated LOOP due to high shdspeed 38 i ._.

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 The possibility of sustaining core damage from a station blackout can be greatly red the plant nas been placed in a hot standby status at least two hours before th LOOP. During this two hour time frame, decay heat is removed by means of the feedwater pump supplying water to either the steam generator (PWR) or directly reactor (BWR) and then condensing the steam that has been subsequently generated

       ,             through the main condenser.

For hurricanes, ample time usually exists in which to shut down the reactor prior t experiencing storm effects. In order to achieve hot standby 2 hours before the an LOOP, the operators should begin shutting down the reactor based on a site spe indicator that will provide the necessary 2 hour window for decay heat removal. (4b) Operator review ofstation blackoutprocedures During a station blackout it may be necessary to perform plant shutdown independ power. All personnel involved in the operation of the plant should review the appropr procedures dealing with an AC independent shutdown. Specific duties, such as manual valv and breaker operations, should be assigned to eliminate confusion or duplication of task (4c) Operator review ofprocedwes to line up and operate the switchyard spraydown system (sfinstal Some utilities have installed spraydown systems to reduce salt spray accumulation on switchyard equipment during severe weather. The alignment and operation of these should be reviewed by the appropriate plant personnel. Actions For Tomado {1) Plant procedures should identsfy site specific actions necessary to preparefor the onset of a t actiort shouldinclude: 39

u NUGSDO STATION BLA CKOLT RESPONSE GL1DELINES REVISION 0.0 August 10,1987 (c) inspecting the sitefor potential missiles and reducing that potential and (b) expediting the restoration ofimportantplant systems and components to serstce The waming associated with impending tomadoes may not be of sufficient duration extensive actions.- However, the above mentioned activities should be undertaken as a minimum as well as any sdditional actions that may be deemed prudent by plant p e 4 40

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 APPENDIX F. SAMPLE AAC CONFIGURATIONS AAC Configuration JA: Non Class JE Power Source e S%TTCHYAR D ltLLE b g fi?, : mar E, g NA NA y %% %$ ges o - TUR BBE CENERATOR t] t] A,o ges LI E3 We .5 MW .S c Ah m.xv.us"= 9 9c""" ( _ o - g < ,@ @, og e.- c, wu - , - , w u -- JoWACSUS 9 9 40e VAC SU, e* 41

NUGSDO STATION BLACKOUT RESPONSE GL1DELINES RET 1SION 0.0 August 10,1987 AAC Configuration .*B: DG Class 1E or Non Class 1E

     ,                                            SWITCHYARD t

auKX 22 Kv aggy 2 LEX ptsCoNwtCT o uv u xv DsvlCE 2211 u uv m u xv NA NW gg NW MAIN n om Gesmro. {} ses ,, ,. ses hN4 ' hNa O 4.tsxyses Cl - A

                                                         "$5 "
                                                                  ,     9 DG CtAss E                                                     4.16 KV ses 11LX1                                          L1LK1 NON M E              **

EDG I EDG 2 yy 480 VAC S US detvACSLS 42

NUGSDO STATION BLACKOUT RESPONSE GL1DELINES REVISION 0.0 August 10,1987 AAC Configuration 2A: Swing Diesel SWITCHYARD 12 KV g gu, Decowtc7 m u O, g y g;y, OtvlCT g g, gy g ,

               ., xv B U5 0l

[] = Tt'R tbT. C EN ERATOR [] [] Uxv sts r""I f""1 L3 LJ L L ' O A CumE 8 O L14 D' BUS um Y Y ' ua wy .c. wo, my "" 44 VAC SUS 9 9 se VAC S US EDG 3 AAC stmv I

l 43

                ' NUGSDO STATION BLACKOLTT RESPONSE GUIDELINES                                                                 REVISION 0.0 August 10,1987 AAC Configuration 28: Shared diesels WIT I         2                    %

m WU 2 SWITCHYARD k SWITCHYARD l l l DL$CO% % f CT tot VV % see arv DEVICE g IIEY DLSCONNICT DD1CE g 22 EY

                        " " '         ""           u nv u.n              -

MA "* atu % u sv a unv % g g g g d'"' A$ gg unv hn e ra a n uav its k"" g Q0 w e re li b on ses u rv 30s c h g

                                                                          %     u nv 30s
                                                                                             -C                l}- -

U 4le KV

                                                                         \
                                                                         \

MA E AR 414 KV CLASS E I' II CLA333 ggg gy gtg 416 xV ats % M M esv

                                   @Y EDG3              $W                                 MY                      3MM m,                    %     e.v                     u, ee v4C 3Us                        g                       dev4CSUS w

O

NUGSDO STATION BLACKOUT RESPONSE GL1DELINES RE;1SION O.0 August 10,1987 AAC Configuration JA: Nearby Power Source Connected to Non. Class JE Bus Am To E ED ra M TRE LN T1%C tvtwT im TEE VIC1MrrY OF Tut MUCLE AR SWITCIIYARD FOSST11 H YDRO Jdl.xl 32 KV o act U KV

                                               ~+ ~+
                                                                                                                          ~+ m (l"",                                                   -

TL1BINE OmEAATOR O ..Kv R US

4. KV BUS

                                                                         ~#                  axx 4.34KV                      d' 4 leuxx                     KY W SSIE                                                                                   C@ lE A

I g ' als KV BUS 4 le KY SUS iu rv C Y Y um vn Ex ,unas v~ 484 Y AC B US ete V AC D l l 1 i 45 1

I

i a
NUGSDO STATION DLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 AAC Configuration 3D: Nearby Power Source Connected to a Class JE Bus TRANSM1$$10N LbE3 FROM THE A AC LSTT ARK EVENT TO LSTT BE b 781L PROTECTED VICBTTY OF THE SLCL AR FROM THE BT.T1ATING SWITCHYARD FOSSIU

           ,          I HYDRO     I                             -

mixx 22 Ky

                               $YSTEM VOLTAGE                                        I I

3 4 3 ),y 11Xx DESCOVNECT ,21XX L. KV (, g y DE%1CE (9 gy g, gy

                                     ., xv B U$

o ->~ 7t*Ra tSI G ENTRATOR a o ., xv ges AA WFA .% WM .%

                             .le xV
                           -{                       m 4.16 KV SUS g         gA                          gI         34 KV B L'1 CLASSE                                                          S3 E L11Er                                            M 4eo v sao v YW                               YY 464 YAC BUS 480 VAC BUS l

l l ( ! 46 l [ I I

1

     . NUGSilO STATION DLACKOUT RESPONSE GUIDELINES                                                      REVISION 0,0 August 10,1987 AAC Configuration 4A: Onsite IC Turbine Connected to a Non Class JE But l

cAsLLs nO4 TNI IC R? tbt TO THE Lt K V BL.3 ARA to St FloftCTt D FRoM TM8 bfTIARNG 5% EW l ngh.g W SWITCIfYARD V f U MiXX Eo cs h g gxy Discontc7 m u mv o uv oss1c u xv u xv t,1 " *' g o ,,, a g ,,,,, a a u,x,

                            . xv 20% <W                         $@ <W c=" o       9                                    '"'"

m 6 y u. x,,e.3, w-62 g43 480 Y AC SUS 9 9

est v4C BL3 l

47

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 AAC Configuration 4B: Onsite IC Turbine Connec:ed to a Class JE Bus h LU 04 TH I R 8BE TO THE us EV lts 4 tt 70 82 PRCrrierID I IC mg3g

                                     &                 SWITCHYARD
                  %./                $

i U EV axx ' o sv u ry

                                                                         --cr otner m            ,

uxv uxv o iv 3US [] e [] [] oxv Tt13TNICENDATOR ges

                       $YSTIM v0LTAGE h 6%                                                     ]

tl61Y 4

                                          ==                                           Cuss a
                                        $^                       ti4 EY 3L1 B

LtLLE Ll1%X mu . . . . wu -- 400 YAC 305 9 9 400 YAC BL1 48

,e

NUGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 August 10,1987 APPENDIX G. REFERENCES B ARANOWSKY, P.W. l1985), Evaluation of Station Blackout Accidents at Nuclear Power Pla NUREG 1032, Office of Nuclear Regulatory Researth, Office of Nuclear Reactor Regula U.S. Nuclear Regulatory Commission, Washington, DC (1985).

B ATTLE, R. l1985), Collection and Evaluation of Complete and Partial Exsses of Of Site Power Nuclear Power Plants, NUREG/CR 3992, ORN1.JTM 9384, Oak Ridge National Labora Oak Ridge, TN (1985). HASKIN, F. E. (1981) Analysis of a Hypothetical Core hieltdown Accident Initiated by Exss Offsite Power for the Zion 1 PWR, NUREG/CR 1988, Sandia National Laboratories, Albuquerque, NM (1981). HODGE, S. A. et al. I1981), Station Blackout at Browns Ferry Unit Onc Accident Sequence Analysis, NUREG/CR 2181, ORNIJNUREG/IM 455, Oak Ridge National Laboratory, Oak Ridge, TN (1981). LEEE-STD-485 1983 (1983) Recommended Practice for Si:ing Large Lead Storage Batteriesfo Generating Stations and Substations, The Institute of Electrical and Electronic Engineers, New York, NY (1983). KOLACZKOWSKI, A.M., AND PAYNE, A.C. (1983) Station Blackaut Accident Analyses (Part of' NRC Task Action Plan A 44), NUREG/CR 3226, Office of Nuclear Regulatory Research, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC (1983). NRC (1986), Draft Regulatory Guide, Station Blackout, Task SI $01-4,51 Fed. Rec. I1494 (March 1986). 49 l l l

      ****^     NUGSDO STATION BLACKOUT RESPONSE GUIDELINES                               REVISION 0.0 August 10,1987 RUBIN, A. \1986), Regulatory Analysis for the Resolution of Unresolved Safety issue A 44, Station Blackout, NUREG-1109, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC (1986).

WOO (1986), Reactor Coolant Pump Performance Following a Loss of AC Power, WCAP-10541, Revision 2, Westinghouse Owners Group,(December 10,1986). i L l l l I e 50 1

   .                                                     /'UM60                By5; Ron g 3.e-r   .,

l l fro o os CA J. ,u O A ' '*.O

                                                                                    '.             I l

ASSESSING THE ABILITY TO COPE WITH

        .          A STATION BLACKOUT EVENT Procedures and Technical Bases Revision 2.0 August 10,1987 NUCLEAR UTILITY GROLP ON STATION BLACKOLT SUTTE 700 1200 SEVENTEENTH STREET, N.W.

WASHINGTON DC 20036 _, . , _ , , . _ , , , w-,-e- - , - - p -

i ! l l ASSESSING THE ABILTTY TO COPE MTTH ACGLST 10.193* 1

     ,1      A STATION BLACKOLT EVEST                                            l l

I 1 CONTENTS ' d'

1. INTRODUCTION 5 l 1.1 OBJECi1VE $ ,

1.2 DOCDENT STRUCTURE $ 1.3 ACTION PLAN $ / 1.4 NLNARC WITIATIVES 6

2. OVERVIEW i8 1.1 PROCEDUREOVERVEW 8 [

2.2 COPING MET 1tODS 8 2.3 COPING DURATION 9

3. BASELINE ASSUMPTIONS 13 3.1 INTHAL PLANT CONDITIONS 13 3.2 lhTRATNG EVENT I4 3.3 STAT 10N BLACKOUT TRANSENT 18 3.4 REACTOR COOLA57 PUMP SEAL LE.OCAGE 1 3.5 OPERATOR ACTION 2 3.6 EHECTS OF LOSS OF VESTILAT10N )

3.7 SYS1Bt CROSS. TIE CAPABILITY l 3.8 INSTRLMENTAT10N 2 1

4. CONDENSATE INVENTORY FOR DECAY HEAT REMOVAL 23 4.1 DISCUSSION 23 42 PROCEDURE 23

5. CLASS IE BATTERY CAPACITY 27 S.1 DISCUS $10N 27 52 PROCEDURE 24 3

_. n ,. . . . ., . . . - . . . . . . . . . - . - .. ,= . . . . .

                                                %  t :
                         .. ASSES $ LNG THE ABILITY TO COPE M1TH
                                                                                                                                                                            . AU C1.57 1: 1987 g          ,           A STATION BLACKOLT EVENT t

REVISION SUS 151ARY P i REVISION NOf BER DESCRIPTION , 0.0 ORIGINAL REN15:ON > i 1.0 Added DC Mwer tysa= com/.es: ::s 2.0 SigtScant tevisioes to estet decL=ent i 4 i

i I

. i f

i n i 2 e

   - - - , , -        4y +-      ww--- -v , . ,  .,,,-.,-,.,w,-       - - - , , ,,m,   a  , . , ,   -- , , . - , - , .    -,m,nn,,,---            -,,w-,,,--n,,-,nw,,n--,---_,.r,c,,                   . - - - ,

              . .   .- ._.           -. _ _ - .  -. _. .  - . . , - ~ .   . - . .   . . .    ..           -
                      -A$$E$5BC THE ABILTTY TO COPE WITH AUGUST 10.1989 A ST ATION BLACKOLT EVENT P
                                                                                                          /

6. CO\lPRESSED AIR

 ,.                                                                                                   '3 i                                   61 DISCUSSION                                             30 6    PROCEDURE                                            30
                                                                                                  ./

APPESDIX 33 [ A DEFINITIONS 3 B- ALTERNATE AC POWER CRITERIA 35 C REFERENCES 33

I d b i

l k l 4 i

ASSESSING THE ABILITY TO COPE %1TH AUGUST 10.1987 A STATION BLACKOLT EVENT

1. INTRODUCTION 1.1 Objectise The objective of this doeurr.en: is to provide a first order methodology for L.a'> zing the plant's basic coping features needed to r.2=tain stable conditions for four hours (up t: one hour for units with Altemate AC).

1.2 Document Structure nis document contains six main sections and several appendices. Section 1 provides an introduction to the overall document, an outline of tie actions utilities should take in implementing a first order assessment of a unit's ability to cope with a station blackout event, and the NUMARC station blackout initiatives. Section 2 discusses the copir.g assessment procedure. This consists of an cnerview, an introduction to the two coping methods ((l) without AC powered equipment (AC In& pendent), and (2) with AC powcred equipment (Altemate AC)), and required coping times. Section 3 contains the baselir.e assumptions for this procedure. Each assump:en is accompanied basis discussion. Sections 4,5, and 6 provide the coping procedures for analyzing th::: coping prameters: condensate, DC power, and compressed air / manual valve operation. De Appendices contdn the definitions and references used in this document 1 1.3 Action Plan 5 l-

AsiLsSING THE ABllJTY TO COPE %TTH gt.G LsT 10,1987

 ,  ,      A STATION BLACKOt.T EVENT To implement the first ordt coping assessment procedure, each utility is expected to take u.e ffowing actions:

(1) Follow the assessment procedures in Sections 4,5, and 6, completing all forms for each unit; (2) If it is determined that the unit does not have sufficient coping capability, identify additional analysis that will be performed, and/or modifications 9cessag to provide the unit with sufficient assessed capabilities: I 1.4 NUMARC Initiatives Late in 1985, the Nuclear Utility Managenient and Resources Committee (NUMARC) established a working group on station blackout to address USI A 44. NUMARC membership includes C. e?ectrical utilities operating nuclear power plants. The Nuclear Utility Group on Station Blaci: : (NUGSBO) has provided the major portion of NUMARC's technical support in this area, inclui. the preparation of comments on the rulemaking record. NUMARC determined that many of :. e cencems related to stnion blackout could be alleviated through industry initiatives to reduce . e irdividual sites

contribution to the overall risk. NUMARC also believes that most of the antici benefits from the proposed rule would be derived from improvements at a limited number of p 1: light of these considerations, on June 10,1986, the NUMARC Executive Group overwhelmi '

erdorsed four industry initiatives to address the more important contributors to station blackoc-hse initiatives are contained in comments filed on the proposed station blackout rule. The initiar,es 1 are summariact! below: l l (1) Initiative 1 --- RISK REDUL ?!ON l 6 l C

ASSES $DG THE ABILTTT TO COPE WITH AUGUST 10,1987 A STATION BLACKoL7 EVENT O 9 Each utility wil: re'iew its site (s) against the criteria specified m NUREG 1109 (Rubin (1986]), and if the site (s) fall into the category of an eight hour site after utilizing all sources a"ailab:e. the utility will take actions to reduce the site (s) contribution to the overall risk of staCon blackout. Non hardware changes will be made within one year. Hardware changes will be rr.ade in a reasonable time thereafter. (2) initiative 2 - PROCEDURES Each utility v :D irnplement procedure; at each of its site (s) for: (a, coping with a station blackout; (b) testoration of AC power foUow.ng a station blackout event; ard, (c) preparing the plant for severe weather conditions (e.g., hurricanes and torr.adoes) to reduce the likelihood and consequences of a loss of offsite power and to reduce the overall risk of a station blackout event. (3) Initiative 3 - COLD FAST STARTS Each utility will,if applicable, reduce or eliminate cold fast starts of emergency diesel generators for testing through changes to technical specifications or other appiopriate means. (4) Initiative 4 - AC POWER A VAILABILITY Each utility will monitor emergency AC power unavailability, utilizing data provided to INPO on a segular basis. I 7

ASSESSING Tile Adit.ITY To COPE WITH AUGLST 10.1M-A STATION BLACKOLT EVENT 1 l l

2. OVER VIEW 2.1 Procedure Overview This section provides an overview of the first order assessment procedure and the Ceping Assessment Review Form. Dere are three secuons to the procedure, addressing the followe.; ::pi:s:

(1) Water inventory for decay heat removal, (2) Class IE battery capacity, a .d (3) Compressed air capacity / manual valve operation. The procedure is structured to utilize information from readily available licensing documents (e.g., FSAR, licensing submittals), existing calculations, purchase specifications, and drawings. For most units, no additional computation or analyns is anticipated. De Coping Assessment Review Form

         ' Figure 21)is provided to record the results of this assessment.

2.2 Coping Methods For purposes of this analysi>, coping methods are separated into two different approaches The first is referrec' to as the "AC Independent" approach. In this approach, plants rely on availab'.e process steam, DC power, and compressed air to operate equipment necessary to achieve shu:dow conditions until offsite or emergency AC power is restored. A second approach is called tne "Alternate AC" r.pproach. His method is named for its use of equipment that is capable of being electrically isolud from the preferred off site and emergency on site AC power sources. Station blackout coping using the Alternate AC power approach would entail a short period of time in an AC Independent ttt/c (i.e., up to 1 hour) while the operators initiate power from the backup source. n nce power is avr.ilable, the plant would transition from the AC-dependent state and provide decay

           ...a removal until offsite or emergency AC-pow er becomes available. De AC power sources used in the Altemate AC power approach would be subject to electrical isolation requirements ir. order to
                                                                                                               )

8 i

i ASSESSi>G THE ABILTTY TO COPE M1TH AUG UST 10.19s7 A STATION BLACKOL.T EVEST l i l assure their avn' ability in the event of a station blackout. Appendix A p ovides a definition of Alternate AC power sou- e A separate NUGSBO docu:ne: :. titled Assur;ng :he Adequacy ofStation Blackout Response Pr:,:cdures provides criteria for Altema:e AC.

   ,      2.3      Coping Duration The coping du at:en establishec for plants depends en the me=od used. Alternate AC power plants may use this r ethodology to demonstrate the ability to mait: sin safe shutdown forapto 1 hour g(c=c;g2;r.; :: 'h: thegtmed-to ;tm and cone Ndir.g Oc A!:cr=:c AC sour;;;.

t AC Independe:t plants mt.st meet the requirements of this medodology for at lea. 4-hours. . L ; ,,c Ai wn.4 AC f-ow er source ;s availchie wW.o l O rnin d es a f O r. onse . 4 s-e ico blac ked , b.s ne copa$ an=Ly s,s ;s re q ui. e d. Y 9

l ASSESSING THE ABILITY TO COPE %TTH ALGLST 10,1987 A STATION BLACXOLT EVENT COPING ASSESSMENT REVIEW FORM l l l UNIT NAME , l NOTE: PLEASE COMPLETE A SEPARATE FORM FOR EACH UNIT AT A SITE. (1) Check the Coping Approach Followed: Alternate AC AC Independent is this a current or committed approach? If Alternate AC is used, list she time interval used in this procedue for the inistation of Alternate AC. (2) Using Section 4 of this procedure, is SUFFICIENT CONDENSATE INVENTORY AVAILABLE for four hours of shutdown operations (up to one Aour for Afternate AC approach)? YES (3) Using Section 5 of this procedure, is SUFFICIENT CLASS 1E DC POWER AVAILABLE for four hours of shutdown operations (up to ont Aour for Alternate AC approach)? YES O

l l l Figure 21 10 t [

l ASSESSING THE ABILTTY TO COPE %TTH AUGUST 10,1987

    ,  ,        A STATION BLACKOL7 EVENT                                                                                                              l (4)     Using Section 6 of this procedure, is SUFFICIENT AIR /.\f ANU A L VALVE OPERATION CAPABILITY AVAILABLE for four ho. rs of operatlons (up to one hour for Alternate AC approach)?

YES O

         \(5)          For escry NO recorded in Steps (2) through (4), list the actions that will be taken to N

low the plant to be assessed as having a ese or four hour coping capability, es appco riate. N N N T (6) Proside other plant specific considerations that cay have been used la the analysis.

                               - --                              __=         =-           _ - - -

1 l l FIGURE 21 j (Confloued) 11

I ASSESSTNG THE ABILTTY TO COPE MTTH A STATION BLACKOLT EVENT AtCUST 10,1989 Prepared by: Telephone Number: Utility / Department: Date: F1GURE 21 ' (Continued) 1 12

i a C NEGSDO STATION BLACKOUT RESPONSE GUIDELINES REVISIO* ' August 10.1M* I

3. BASELINE ASSUMPTIONS The Section 4 guidelines for assessing plant procedures with respect to st Of baseline assumptions concerning the course and nature of the event. D de .ved from a variety of sources in the technical literature, including NRC Staff infor= '

submitted in support of the proposed station blackout rule. This section contain baseline assumptions, a brief description of their bases, and appropriate references The assumptions cover the following areas: Section 3.1 -- plant conditions at the time of the sntion blackout, Section 3.2 -- the initiating event, Section 3.3 --- station blackout transient, Section 3.4 --- reactor coolant pump sealleakage, Section 3.5 --- operator action Section 3.6 -- effects of the loss of ventilation Section 3.7 -- system cross. tie capabiliry Section 3.8 --- instrumentation 3.1 Initial Plant Conditions 3.1.1 Assumptions G) ne station blackout event occurs while the reactor is operating at 100% rate has been at this power level for at least 100 days. (2) Immediately prior to the postulated station blackout event, the reactor and s withis normal operating ranges for pressure, temperature and water level. All p either normally operating or available from the standby state. r 9 1

NUCSDO STATION BLA CKOLT RESPONSE GL'lDELINES REVISION 0.0 August 10. If 87 2.!.2 Basis fl) The potennalfor c:re d.1magefrom a station blackout ss bounded by tw :s instiatedfrom 100% pow substannat decay hea: generanon capability. (NUGSBO postuon) (2) Transients ininate:fr:m normal operating conditions are corndered to u of greatest probability. tNU pos: tion) 3.2 Initiating Event 3.2.1 Assumptions (1) ne initiating event is assumed to be a loss of offsite power at a plant site (LOOP) resulting (a) a switchyard related event due to random faults, (b) a grid 6:sturbance, or (c) a weather eve that affects the offsite power syste.m either throughout the grid cc at the plant. LOOPS caused by fire, flood, or seismic activity are not expected to occur with sufficie frequency to req 2 ire explicit criteria, and are excluded from cons;deration. (2) The LOOP is assumed to affect all units at a plant site. However, the unavailability of the stand (Class IE) power sources shall be limited as follows: (a) Sire'e Unit Sites: Two standby (Class IE) AC power sources are assu=ed to be unavailable when the LOOP occurs. For a unit having more than two onsite AC power sources (either Class IE or Non Class IE), these additiona' sources are assumed to be avaEable if they meet the AAC criteria erovided in Arendix B. (b) Muhi Unit Site with Non Shared Standbv (Clast ID AC Power Source: For a multi unit site that does not share standby (Chss 1E) AC power sources, twostandby (Class IE) AC power a ected unitgAny additional sources gasgs tpyngailgley,@c . assumed 16 he available ifThey rneet the AAC eriteria erovided in Anpen Bt De non blacked-out unit shall assume' b occurrence of a single active failure of a stan:!by (Class IE) AC power sour:e in addition to the LOOP affecting the site. Tm L_. J 10

NUGSDO STATION BLACKOLT RESPONSE GL'IDElJNES REV1510N 0.0 l August 10.1987

                       .T. n s e ,,f      3, 2.1 (c)                                                                            _

l 1Q N Multi t' nit Sites with SFed Standby class IE Power Sources:

Torgiti. unit sites th ' share standby (Class lE) ACywer s/ be: ween ources units, two standby (Class lE) AC power sources are assumed to be unavai'able N / at the affected unit.-Qe non blacked f art unit shall assume the occurrer.:e single active failure of a 5 (Class 1E) AC power source in additice to the

                                                              /                                                                     :

LOOP affectin esite. The singl failure shall be a shared standby (Class IE) N power supply. Any additional sources are assumed to be available if the. -eet i (e'AAC criteria crovided in Anoendix B. I L l x (3) No design basis accidents or other events are assumed to occur immediately prior to ce d station blackout. l 3.2.2 Basis (1) LOOPS that are of conce n to station blackout involve those scenarios that are within the plant's dengn , NRC analysis ofLOOP e.sperience separazes these evenu into three categories: plans. centered, grid d severe weather. ! lam.cenered events involve hardwarefailves, design defciencies, human errors in mavutnar.: and switching, and localized weather inducedfaulu, such as due to lig htning and ice. These plans. centered reportedly occw at afrequency of 0.056 evenu per site. year, mich a median duration of 03 hour. Grid &cban: events have be<n shown te be of much lesser concernfor most planu. Events in this category repor:eq have : frequency of 0.020 events per site. year, with a median duration of 0.7 hour. Severt weather events have a lesse-e.xpenence wah 0 01i events and a median dwasson of 2.6 hours. iSection 3. including Table 3.1. NUFEG 103: It is posssblefor a station blackout to resultfrom circumstaues that are outside the plant's design bas::. Howev shis potentialis remour. Seismic.fre, andfloodin evenu imlude accident scenariosfor which current licensin: requiremems specify protective measures. For emnple, the potentialfor a pre induced station blackout s: emently remote due so the eftenveness of curren pre protection programs, and 10 CFR $0 Appendiz F separation regnirements imposed on shutdown systems. NRC analysis concludes chasfue. induced staaan blac is not a generic concern, clang a station blackoutfrequency ofless than !x]&per reactor.yearfor sese planu. panicularlyfor plants in conformante with Appendix R separanon requiremenu. Consequently, staden blackou: events that may occur as a particular site inwNagfte initiators are not likely to occur, and need not be addresse: in this generic gundance. l 11

3.2.1 e Mu".t:-unit sites that share standby Class IE) AC power sources etween units may consider the Class IE AC power source-to be AAC power sources provided: (a Chere are at least four Class IE AC power sources. (b The Class IE AC power sources meet the AAc criteria provided in Appendix B. (c The Class IE AC power sources must be sized to meet t h' required shutdown loads at both units.

I NUGSDO STATION BLACKOLT RESPONSE Gll1DELINES REVISION 0.0 ) Angust 10,1987 l l The seamac andfooding issues are su ular to thepre risk concern regarding the pote blackout. The Class lE power systen u curremly designed to withstand seismic events. In v-mn. a seisrmec { induced LOOP event has not been observed at a nuclear power plant to date. Similarly. addressedin the plam's licensing bas:s. As a resuh, the potentialfor seismically induced orf. blackout u on the same order aspre-x:a:ed evens. and may be ignored. For these reasons. seamsc.pooding, snapre induedstatson blackout events are not addre (Appenda J.NUREG1CR 3226) l (2) The major contnbutor to overall sta::on blackout risk is the likelihood oflosing ofsite powe' a d the power unavailability. A LOOP may occur as a result of a switchyardproblem either afec:ing a si possibly muhiple units at a site. Alternatively, the cause of the LOOP may be a grid or area-side dist associated with severe weather condaans ahhough these events are a much smallerfraction of t evenn (in fact, weather related events represent on the order of 10% of all LOOPS experzenced t Consequently. to b conservative. the LOOP is assumed to afect all uniu at a site. The next most important contributor to station blackous risk for a given plant is low EDG availability varies among operating sues. based on the number of EDGs onsite, the reliakl standby state and o verall availability of the machine, and the potentialfor dependentfailures. Industry EDG relu1bility to startfrom a standby state is typically in the range of 0.98-0.99 f have average EDG reliabilityfor al na:hines at a sue below 0.95 over a sustainedperiod Co reliability is a small contributor to stance blackout riskfor most planu. EDGfailures may also oces.r due to dependent causes. Thisfactor may resuhfrom design or shot manifest shemselves in a concurrentfailure. Examples ofsuchfailures include: (a) the ex dependency or single. point vulnerabilig in support or auxiliary systems usedfor start. control. vulnerabilisy to common causefailure. The potentialfor these dependencies qfecting all EDGsfor muhiple unit sites is considered remote reacon have staggered operating cycles. Ss.sggered operanng cycles also make it less likely th actisties are scheduled at the same time. Similarly. redundant units are often designed sad const 12

l l . . l l NUGSD0 STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.C l August 10.1987 inde;e .ent sehedules. with initial corrvnercial operatwn date separated by up to severalyears an ttme. Gened:y high EDG reliability and low dependentfailure raus provide a basisfor screening hamg a remote potentialfor totalfailure. NUGSBO's analysis indicates that the potentialfor stmult faile.g : EDGs with each machine at industry average reliability (i.e.. approximately 2?o averag dew.ifor each machine) and nominal suscepnbility to dependentfailure (i.e. 2?o)is approximately The lachhood of 3 EDGsfailing is even lower, as about 4.1 z 10'for machines with 0.98 reliability.l 1 These results suggest that the potentialfor more than 2 EDGs failing is very low for m ' Conuquently. failure ofonly 2 machines is initially ccarideredin these guidelines, permitting the av remg machines ortite under certain circumstances. The availability during stadon blackout of any remaining EDGs onsite may be asswned if two conditions ar (1) the machine sansfies the Alternate AC power source criuria provided in Appendiz B; and (2) the machir.. avm!Mry is mainsamedin accordance with Alternate ACpower source criteria. Thefirst condition is directec mininnsing the potentialfor dependentfailure events adversely q7ecdng the Alternate AC power source in blacLun scenarios of concern. The second condition providesfor power source anzitability. lf one or bot are not metfor the additional EDGs onsite. these machines would be assumed to be unavai 6lacAcut The suued objecnive of the propoced stanon blackout rule is to reduce the station blackout core damag appear.mately 100 per yearfor the averoge site. As prowied in the proposed rule. these benefits would be obta.r. by emn&ng Ihe current nominal 2. hour coping capability to 4 hours. Comparable safety benefits may by iwp;enendng an AACpower source. For example. assuming a LOOPfrequency of 0.1 per year and a l confipranon with a 2 hour coping capability, the stadon blackous core damagefs equency is well below per year threshold sought by the Staf. (Section 4. NUREG 1032: also NUGSB0 position) (3) The latiskood of a design basis accident or other event coincident with a station blackous is considered to t remose and is not addressed in this document. (NUGSB0 posidan) 13

NUGSDO STATION BLACKOt.T RESPONSE GlilDELINES R EVISION 0.0 August :0.1987 3.3 Station Blackout Transient 3.3.1 Assumptions (1) Following the loss of a" offsite power, the reactor automatically trips wi:5 s margin to maintain sube .: ality for the duration of the eventA dyM y /s/

/%

(2) "Ite main steam system vakes operate properly. gl f5N 0 gu Y %

                                                                  .d                                            -

(3) Safety / relief Valves (SRVs) or Power Operated Relief Valves (POR Normal valve rescating is also assumed. (4) No failure, other than those presented in Section 3.2.1, are assumed to occu transient. The potential for mechanistic failures resulting from the loss of ventila blackout event is addressed separately as a station blackout topic.

                                                                                                      $M 7 (5) AC poweris assumed to be available to required shutdown equipment wd.is 4-h 3.3.2 theBasis offsite or blacked out unit's Class 1E sources or within 1 ho (1). (3)

These auumptions outline some of the more imporsant features of the station b ac considerassons are a normal LOOP transient, proper unit trip withfull reacavity insertw addition. she likelihood of PORV or S!RV misoperation in a station blackous u on th 2.NUREGICR l988; 5ection : and 6. NUREGICR.2182; and NUREG 1032) (4) Imposing Stinnalfailures ce the station blackout response capability has dimin most power plants. This is be:au,se the dominant accident contributors to a statio involve ofsise power system reliabilisy. the reliability and level of redundancy of system. and the station blackow coping capability. in that order. Since the coping capak so sanon bladost ria than AC power system reliability. additionalfailures la this sy importance. De response capabiusy also depends on Class JE systems thas a and maintenance standards used. Consequently. the potendalfor randomfailure the saferf efecu of response capability loss are signipcant only if they a blackout trarnent (i.e.. pnmariy in thefest 30 minutes). This potential has been add 14

NLGSBO STATION BLACKOLT RESPONSE GUIDELINES REVISIOS : August 10.191* which estsmates the probabshly of decay heat remosa. systemfailure early in a statson a- bla frcen 0 001for High Pressure Core Spray (HPCS)tRCIC combsnations to 0.01for a single train auxiliary feedwater system (AFW). These results underscore the relative n u. unim nonmechanisticfailures in the station blackout scenano rAppendis C, particularly Table a bT.lGSBC position)

     .      (5)

The vast majority of LOOP events are of short dwation. NRC Staff analysis reports the restoratwn timefor all LOOP events to be about 1/2 hour. with offsite power restoredin a for 90% of all evenss. Consequently, assuming a 4 how restoration time addresses the blackout events. For AAC systems.1 hour is considered a reasonable period of tim source and restore power to a shutdown bus. NUMARC Initiative i places allplants i requires an MC capability. (Ofsite power restoradon ames are takenfrom Suppleme

                 $sation Blackow Rule 31 FR 33, at 9830) y y            f-p p,, f           Alew        Sec.h           3. +      Ynd           y Loss '        ^

3.4 % Reactor Coolant Pump Seal Leakage 3.4. ssumptions Rea: tor coo gpump (RCP) seal leakage concern applies only to Westinouse pumps. For thes: pumps, RCP sealbkage N is assumed not to exceed 25 gpm per pump.for the bladout event. Plants may ume RCP leakage rates less thawf5 gpm ifit can be suppone:f 5 appopriate analysis or testing. i

     \
      \    3.42       Basis NRC snalyses supponing the proposed station ekow ruiemding N recognise that concerns over RCP sealleakage c:r be uperasedpom the ssanion blackour s
                                                      . Further, the RCP seafbekate concern appears to befocused We pumps. The topic is carrently the ject ofits own resolution program     . HRC Ger.oric luue 23), nearing M reso8maon uish a mesenal fication correcting the problem. These connanzadons contribute to the NRC's assunynon of-20 pump in NUREG 1032 to be a ressonable

upper bound ' ~ of RCP stalleakage in a station blackout.

pendiz G.NUREGICR 3226 also WCAP 10$41)

15

3.4 Reactor CO0lant Inventory Loss 3.4.1 Assumptiens Sources Of expected reactor coolant invent:ry loss include normal system leakage, losses from letdown a:d losses due to reacter coolant pump seal leakage. Expected rates of reactor coolant inventery loss under station blackou: conditions do not result in core uncovery in the four-hour time period. Makeup systems in addition to those currently available under blackout conditions are therefore not required. 3.4.2 Basis Normal syster. leakage is limited by technical specificatior to a low rate. These rates do not increase :nder station blackout conditions. Emergency operating precedures developed : accordance with NSSS vendor Emergency Proced:re Guidelines diret operators to isolate letdown. Reactor coolatt pump (RCP) seal l leakage concern applies principal 11y to West:nghouse pumps, ro: i these pumps, RCP and leakage is assumed not to exceed 25 gpm pet pump for the duration of the station blackout event. RCP seal leakage is currently the subject of its own resolution program (i.e., NRC Generic Issue 23) nearing final resolution with 25 gp per pump as a reasonable leakage rate. l l

             , , , - - - - , - - , ,, , - , - , , - ,             ,-  -  -    ~~      - , ,,

NUGSDO STATION BLACKOUT RESPONSE GtllDELINES R E \ E O N 0.0 A ugur: 11 193* 3.5 Operator Action 3.5.1 Assumptions Operator action is assumed to follow the dire:::on provided in the Plant Operating Proced. :s fer - underlying symptoms or identified event scenario associated with a station blackout.

         .        3.5.2        Basis NRC analyses suppornng the proposed station bla:kea.s rulemaking assume that a reasonable set of ope w wsli occur. The governsng document for defirang operator actions are the plant's procedures. (Ascenda i NUREGICR 3226) 3.6        Effects of Loss of Ventilation 3.6.1 Assumplions Under station blackout conditions, ventilacon systems are not available. However, sufficiet nana circulation is assumed to be available, or can be either established or augmented in plan areas t operntor action to minimize the potential for equipment faijun: by overheating.

3.4.2 Basis The potentialfor mechanisticfailures of systems and components due to loss of ventilation is dependens :n the !?. requiredfor temperatwes to rise sn closed comparonen:s and cabineu. Temperatwe buildup in a compartme process due to the acimally large thermallag associosed with natual convection and the loss of AC supiled h sowces. This large thermal lag allows suficient cme for operator action to identsfy areas requiring saqcleme cooling and take appropriase action to termnnate the Aermalbuildup. Consequently. these guidelines direct the op actions in a station blackout include providing supplemental cooling where necessary, and do not scume a mechanisicfailwes so occur as a result ofloss of = tanan. NUGS30 hasperformed an analysis of temperature kaldup that supports these assumptions. Using a lumedpa model of the comparonent air temperatue. and conservative assumptions concerning heat loads and hene tra ufe coeficienu. the average air temperature in a compartment was estimated as afunction of time. The hen socce. \ l consdered are electncal and ruchanical equipmens present in the comparonent, and hot steam pipes that daw l 16 l l

1 I 1 NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 l August 10.19s? { 3.8 Instrumentation 3.8.1 Assumptions Emergency Procedure Guidelines provide guidance on instrumentation to be used during stati: blackout conditions. Appropriate actions will be taken by opera:ic ts personnel to assess plant sta: in the event of errar: performance or failure of shutdown instrumentation. 32.2 Basis NSSS emergency procedure guidelines identsfy instrumentation requirements to safely shutdown. Operator includes the use of whp instrumentadon and identifying erratic performance. (NUGSBO position) l8

NUGSBO STATION BLACKOUT RESPONSE GUIDELINES REVISION 0.0 Aupu 10.1987 through natural comecnon and thermal radia::: n The concrete walls were consxdered to be a heat:...l opemng doors was modeled by using emptrscal heat transfer correlanons that descrsbe the co through operungs between rooms. For typucalRCIC and control room t con)i waas ns and heat lods. the temperature rise after afou was esumated. The results of the model show that if compartment doors remain closed dursng. th. teb temperature risefor afewplans may be large enough to affect the operability of equipment in . model accountsfor opening doors at the beginnng of the station blackcut. temperature rise in is sigmficantly reduced. This reduction in temperature rise is large enough to demonstrate measures are a ssqficient response to the loss of wntilation concern. Occasionally, supplernental cooling measures my conpict with other safety or administrative co example, procedural requirements may exist for keeping fire or flooding doors closed. Despi considerations. :pening doors would be an acceptable technique in a station blackout in order to uscreas circulationfor instrumentation necessaryfor skandown. Other techniques, such as using perman banery.operatedfans inside cabinets. could also be considered as an option in lieu ofprov measwes procedurally. l5ection 5 and Appends 1. NUREGICR 3226: also NUGSB0 position) 3.7 System Cross tie Capability 3.7.1 Assumptions Under station blackout conditions a it isrul dassumje f h "fRi n that rnultiunit sites with fluid or cross. tic capability will be able to achieve n safe shutdown in the affected unit by utilizin unaffected unit's cross tied systems. 3.12 Basis NRC analysis supporting other rulemaWgs (i.e 10 CFR 30 Appendu R) allow multiunit sites to re capability offluid systens to bring the afected unit to safe shutdown condidens. For station blackout cons \ the systems of the unafecsed unit must be electrically independent of the blacked.out unit in order :o credit t auxilability to bring the afected unit to safe shutdown. 17

ASSESSING THE ABILITY TO COPE WITH

 ,         A STATION BLACKOL.T EVEST                                                           ALGUST 10.1987

4. CONDENSATE INVENTORY FOR DECAY HEAT REMOVAL MMw wOdM The condensa e inventory for the decay heat removal basic c: ping feature is asse analysis. lf th:s quantity is less than the Technical Specificaticn minimum available in the cond

    -    storage tank (CST), then the plant's current configuration has bee assess d to eet th feature. If no:, other sources of water that can be aligned 2n er statih. 3 r              ackout conditions are identified and :onsidered. hie results of this assessment aremdea on hgureRN f]$-

4.2 Procedure f%.Ja? Complete all steps, unless otherwise directed by the procedure. Step 1: Ptaat Rating Record in A the urut's licensed reactor output in A= rnegawarts thermal (Wt) from the unit's opraung license. Srep 2: NominalCoping Time Use either (a) or (b), below, depending on the selected appr.ach: (a) if the AC Independer.< method was checked on Figure : 1, B= shen recerd ~4' (for four hours) as B. (b) If the Alternate AC method was checiabn Figure 21. AND (i) the Altemate ACpowersou/rce is sized to inchda normt! condensate syste operadon with at least one emidensate and one f water pump running. OR s 23

                       -.           - _ - ..                 ..                           ~     . . .          -

ASSESSING THE ABILTTY TO COPE M7TH ALC*.5T 10,19M A STATION DLACKOLT EVENT (ii) manual align: e .: of systems can be made within one hout to allow te :endensor hotwell to teused as a source of wate- te maintain decay bat cooling with the Afternate AC power sou/rce sized to accor%date pumps,

valves, insat: ens, etc. required for the alignment,

                                               ./
   ,                   then record "1" (for one nos:) as B,
         ,/
                  /    othemise record *4Worb LodfsTas B Step 3:       Required Condensate mergency operating procakres do.not require a pnmary system                C=

cooldown to minimize reaaor coolant pump seal leakage or to maintain 6= reactor subcriticalitygyecrd the number of gallons of water required for decay heat removal m, una (.) m (b), below: (a) IfB=1: C=A 0 A11MWt) b i

f. (b) If B = 4: C = A* 21.88 AUMWt) @ g( )fb J

s if emergency cperating prnm'ures do. require a pnmary sypicm cooldown to minimize reacer coolant pump seal leakage or to maintain reactor subcriticaliry, then}, u -.a t,y the amount of water required to achieve the cooldown rate for the duradon equal to B. Step 4: TecnolealSpecincatico for CST Level D= Obtain the minimum permissible usable gallons of water in the CST as found in the unit's Techrdcal Specifications. Record this value as D. 24 l

l ASSESSIM THE ABILtTY TO COPE WITH AUGUST 10, t987 A STAT;ON DLACKOLT EVENT l l Step 8: Test for Adequacy CST Quantities Alone i Compare the value of C with the value of D. l (a) If C is less than D, go to Step 9 (b) Otherwise, continue to Step 6. i Step 6: Additional Water Sources In this step, additional water sources are identified as backup condensate makeup sources for de::s hn: rernoval. The following sources of water may sene e this role. Adjacent unit water sources Fire water tanks Cooling water pond River or lake water Hotwell Note: Plant procedures need to reflect actions and mater sources assumed to be n.ied upon in responding to a station blackout event. The following criteria must be met prior to assuming the availability of any backup water sources: g g p u p,,4.re.;po w sei,.a (a) A physical connection is provided independers o( theglacked out unit's Class IE AC power sources and capable of providing a sour.e of water to the CST. (b) Plant procedures must exist to accomplish th:s makeup to the CST. (c) The source must be be able to be connected a'e the CST is emptied. A 3 i /

        /      Note: Water relied os from adjacent units at a semitiunit site must be capable of beic:

I transferred to the blacked out unit without affecting or diminishing decay beat removal activities at the soa blacked out unit. Reccrd below the usable volurne of each additional source of water satisfying Criteria (aHe), above. Source 1: Amt. Water (gal.)

                         ~ Q) A4ier- 3 hou r , on $bC tonrec. f% b e, (4 Sed 40 fedvidC p.,,, 4. pu m ps a 4 y'"<> ;4 % c .gu.meo ;g p ,e,,g hem A e. A A C. 6o u r . < .

ASSESSING Tile ADil.ITY TO CGPE MlTH A ST ATION DLACKOLT EVENT Al'G US T 10,1987 Source i Arnt. Water (g al.) Source :: _. Arnt. Water (gal.) Source 4 Amt. Water (gal.) Toul the amount c( 4 a:er from Sources 1 to 4 and record this E= arnount after E. Step 7: Condensate Available Sum the values of D and E. Record the result as F. F= (i.e. F-D+E) Step 5: Test for Adequacy - With Backup Sources Compare the value of F to the value of C (a) If C is less than F go to Step 9. (b) If C is greater than F, p :: D:; :^ ich ^ 4 o WP 6 saJ i M h (.ddik e..eI W a447 58 0 f1:41* Step 9: Record the result Yes in response to Question 2 on Figure 2 1. procede so Section 5. Sicp 10: Record the result No in res proceae io Sectioe. /ponse to.Quescon 2 on Figure 2-1. 26

l ASSESSING THE ABILrrY TO COPE %TTH AlGt.ST 10,1987 ! A STATION BLACKOLT EVF.NT

   .     .                                                                                                                     I

5. ASSESSING THE CLASS 1E BATTERY CAPACITY 5.1 Discussion W/'

vy The total DC power requirements for a 4 hour station blackout (1 hour for AAC plams) depend on ,

             -                                                                                                                 l the required loads, their duration of operation, and the capacity of the batteries to hold a charge. De batteries' capacity varies with the rate of discharge, which also varies with the loads. Consequently,
       ^

the amount of energy recoverable from the batteries depends to a large measure on the rate of discharge associated with the stadon blackout response loads. De battery's ability to dischagre stored I energy is defined in a series of banery curves provided by the manufacturer. Capacity curves are generally provided for discharge periods ranging from 5 minutes to upwards of 16 hours. ; The station blackout loads can be estimated from design basis accident loads since ticy are generally a subset of these loads. They may be classified as being one of three categories: (1) continuous,(2) discontinuous, and (3) momentary loads. Continuous loads are required for the duration of the station ! blackout event. Inverters and ann:nciators required for instrumentation and control are common l examples of continuous loads. Discontinuous loads are required for short durations throughout the event. Examples of these loads include motor-operated valves and loads necessary to support circuit breaker operations. Momentary loads are of a temporary nature and are required only once or for a limited number of cycles. EDO field flashing is an example of a momentary load, l l Knowing the magnitude and timing of loads,it is possible to use the battery capaci:y curves provided for each plant to determine whether sufficient capacity is available for a 4 hour station blackout ( l hour for AAC plants). 1 The DC power requirements for a required station blackout may be estimated using the methodology the plant is licensed to. The methodology generally accepted by most analysts for this purpose is IEEE Recommended Prac or Shing Large Lead Storage Baneriesfor Generating Stations and \ Substations (IEEE- -485 . This methodology calculates battery load requirements for various sections of time.De tude of DC loads for each such section of time is referred to as the section h . l 27

ASSESSDG THE ABILTTY TO COPE MTTH AUGUST 10,1987 A STATION BLACKOLT EVE.Yf size. Vicio.:s section sizes are calculated in order to constr.:ct a tattery duty cycle. He batte y sized tc address the maximum section calculated for the entue duty cyc! . This prrxedure offers two analytical methods that can be used to ensure sufficient capaci:y exi each site. An EEE-STD-485 or other design basis battery analysis updated as necessary to refle: curren: bads, should be used. The two alternatives are outlined below. (a) Use an existing battery capacity cas.ulation or perform one that verifies sufficient coping capacity under station blackout conditions. (b) Use an existing battery capacity calculation or perform one tthat verifies sufficier.t coping capacity by stripping loads in order to extend the battery life in a station blackout m f 5.2 Procedure w q 67-4 3 5.2.1 Battery Capacity Calculation - No Load Stripping Step 1: Test for Battery Adequacy Review an existing banery capacity calcula: ion for a stacon blackout event or perform one for either ts or (b) below: (a) AC. Independent: 4 hours (b) Alternate AC: sp to 1.bour. (use value recorded in Step 2, Section4) Step 2: Test for Adequacy Without L,oad Stripping Me W wee 6 Compare results of Step I to the bageg=acity carves. If sufficient capacity exists, record Ye response to Question 3 in Figure 21 and exit this ucoon. Otherwise, go no Section 5.2.2. l 1 28 l

ASSESSTNG THE AB!!JTY TO COPE HTTH AUGUST 10,1987 A STATION BLACKOLT EVENT l 1 5.2.2 Battery Capacity Calculation ... With Load Stripping l l Step 1: List DC Loads to be Stripped List loads on the Class IE batteries that are not required to cope with a station blackout and can be stripped commencing 30 minutes after the initiation of the station blackou: emt: NOTE: Loads listed above must be based on actions reflected in plant procedures and which can be acconsplished mader station blackout conditions. Step 2: Adjust Duty Cycle Curves Delete the loads listed in Step 1 from the Section 5.2.1 duty cycle cwves in the battery capacity calculation. Recalculane the maximum section size md follow the steps used in the calculation to assess , Class IE battery capacity. t i ! Step 3: Test for Adequacy With Load Stripping Compare results of Sep 2 to the battery manufacruter's capacity curves. If sufficient battery capacity etists with load shedd2ng, record Yes to Question 3 in Figure 21. Otherwise, eseesdhr- ba.+4 eq c.a{ u.i { y rn ad h e fMe4 J s d iu e%ar. b i l me.+ w. re game ) si n i te s A k e d ce pin 3 Jue=4ie a. A c'9+abic. to8a.A s 4 ar f.W4 dia 3 ba41u) d*pasi h incluje, 4he 4ddi 4to/l 04 hAiicrit.s o r We, A Edi +10 A cr4 c., haditt3 c.hargin $ fer We esis+iq 44+4eeres prov;J.J we source ,g* j5 - j power der %g dar.j;nj g 342n) I6 IAdeptoda44-04 4te. Peteer = > power son,.e. sa % %;c.) yo a.nws claw P(ver Siplom . Ihrd q %+ %e, t ega;,eJ 'adJ;4)oa l capw.i is acAieveJ and te,,,) 6.5 +o nes4 ion 2 ;4 Figure 2-I. 29 l _ _ _ . - _- ..

AssE5sBG THE ADILTn'TO COPE WITH AUGUST 10.1987 A STATION DLACKoLT EVENT

6. COMPRESSED AIR 6.1 Discussion gM W

With the initiation of a stadon blackout, instmment air systems lose their air compressors, and h;:- to depressurize. As the air headers bleed down, air-operated valves operation also degrade ulte: 2 resulting in their unavailability. With prolonged loss of instniment air systems, it is possible :.n decay heat removal and reactor coolant inventory may be adversely affected. Tne amount of air needed for decay heat removal depends on the expected number of valve cy es. the failure mode for air operated valves on the reactor coolant system boundary, and the abilin to manually cycle or close air operated valves. Atmospheric dump valves on PWRs generally require 2:r fcr prolonged operation. In contrast, most other valves, such as feedwater regulator valves, gene-Q fail in the "as-is" position. Similarly, reactor coolant pressure boundary valves generally fail as is or closed, in order to limit reactor coolant inventory loss. Valves failing in such a manner do c; ncemally require repositioning in a station blackout For these reasons, loss ofinstrument air in a station blackout are minimized, provided a strateg; :s oc: lined for operator intervention to overcome the event. This procedure step provides the requn .e information for developing that strategy. l 6.2 Procedure Step 1: Identify Air Operated Valves Necessary for Decay Heat Removal List below nD air operated valves that are reqdW to be cycled during a station blxkout. l l l 30 I

l ASSESSISG THE ADILTTY TO COPE WITH AUGUST 10,1989

A STATION BLACKOUT EVENT )

1

Step 2: Backup Air Supplies Review each valve listed and identify the valves that are not supplied with air within design pressure and moisture lirr;ts from at least one of the following sources for at least 4 hours f.up4en,1. hour for AAC plants) . #r * - e. C o a P 8M' f i h C A ike A 4C 3* /pl7, chsewis e 4

keu rt)

A q % ; ( l.j @ i M N MI (a) Backup air compretsors that are - supplied froe the adjacent unit,or F powered from Alternate AC poner sources, or

                                                                           - powered by DC power (b) Backup local sources of compressed air or nitrogen located at the valses.

Step 3: Criteria for Manual Operation For all valves not supplied by backup sources, determine whethec uwy meet all of the following entens for manual operation-d Procedsres specify manual operation for valves in a station blackout (b) Accessible la a station blackout (c) Identifiable in a station blackout (d) Necessary tools, reachrods, or chains are normally present (e) Appropriate ladication and means for communication are provided (f) Sufficient manpower is available onsbitt to accomplish specified tasks Step 4: Test for Adequacy ... Manual Valve Operation i l 31 l

ASSESSTNG THE ABILITY TO COPE WITH Al'Gt;ST 20,1W

          ,                                                                                  A STATION BLACKOLT EVENT If all air operated vdhes required f r decay heat ternoval have backup sources or m:> :s :nu:I!>

operated in a station blackout, record Yes to Question 1 in Figure 1 1. Ot' ervase, record No. Nue: Plant procedures need to reflec* the manual acti s and backup air supplici assumed to be relled upon in responding to a station blacsout event. 1 t 3 e 4 , 32 i

    . k r.

7. Loss-cf-Ventilation The egalpment necessary to operate is a station blackout

 'i vill be assessed to determine if the effe:ts of a station blackout :nduced loss of ventilation are ;nacceptable. This assessmen. will:                                            ,,M
                                                                      ;                g

1. !dentify the primary plan room, the HPCI/RCIC room areas of concern as the APW r

nd the Ocntrol room. n

2. _

Perform analysis aforrepresentative each primary2area. dimentional room heat-up' s_

3. :ndividual plant parameters will be compared to the

nput parameters of the ref erenced analysis to determine

          -                      :f the referenced analysis adequately reflects plant primary area characteristics,

4. Identify equipment in primary area rooms necessary to respond to a station blackout.

5. Identify the design temperature of this equipment.

6. If the design temperature of the equipment is greater taan the resulting temperature of the ane. lysis of the referenced plant Area, this situation is considered acceptable.

                 #3                                 emperature of the equipment d.oes not 7.(((significantif f the-5FEig rg                                      xceed the resulting temperature of the a:alysis of the referenced plant area this situation is g

c:nsidered acceptable based upon an analysis of che i l

                                  .storical data of thermal stresses on plants equipment. y l                          8. If the design temperature of the equipment is less than the resulting temperature of the analysis of the referenced plant area, this situa: ion is unacceptable to correct the situation the following actions can be
                                                                                /     p provida additional sufficient cooling.

perform a specific demonstration of the adequacy of the subject equipment. conduct additional analyses which address the matter in further detail and reach e satis-factory result. 1/ [ Analysis will be supplied f or referencing. ] t l

asses 5TNG Tile ABILTTY TO COPE WITil AL'GLsT 10.1989 A STATlo"' BLACKo'.T EVENT

 , 'w ,

APPENDIX A. DEFINITIONS Terms defined below were specifica4 developed for these guidelines and are of spe:ia' mportan:e to its use. 9 .* S N

             ~
                                                                                                                         .=

ALTERNATE AC POWER one or more sources of AC power that meet the following criteria; (1) independent of the unit's preferred and blacked out unit'sT Cla3s er 1E ow/ supplies; ' (2) provides sufficient protection against dependent f$iu'res in the preferred and

blacked out unit's Class IE AC powef system frem propagating to the point of adversely affecting theallemate source; (3) is sufficiently sized to stan and supply shutdown loads; and, (4) ipotin'dby suscegible to the occurrence of severe weather at the site. Based omVlfREGICR 3992. nac'd - g_ ~ PREFERRED POWER SUPPLY - that power supply from the transmission system to the Ciass IE distribution system which is prefem:d to furnish electric energy under accident or postaccident conditions. lEEE STD 7651983;IEEE STD 3081980; andNUREGICR 3992, pay :. SEVERE WEAmER the occurren:e of annual average snowf.*1, tomado of F2 sese..y or grea'er. hurricane with salt spray p<stential, ard windspeeds in excess of 75 mph. NUREG 1032. l j TANDBY POWER SUPPLY - the Class 1E power st:pply that is selected to furnish e.tectric energy l to shutdown equipment when Ce preferred power supply is not available. Based on l IEEE S2D 3081980. ATION BLACKOUT- the loss of aD she unavailab ty of at least two standby C ' power supplies of I unit at the site. Based on notice of proposed r station blackout, Federal Register Vol. 51, No. 55, page 9832. 33 l \ . .

l l insert A "Alternate ac source" means an alternating current (ac) power source that is available to and located at or nearby a nuclear power plant and meets the folleving requirements: (i) is

     , not normally directly connected to the preferred or onsite emergency ac power systems for the unit affected by a station blackout   , (ii) has minimum potential for common mode failure with offsite power or the onsite emergency ac power sources, (iii) is available in a timely manner after the onset of station blackout, (iv) has sufficient capacity and reliability for operation of systems required for the time required to bring and maintain the plant in a safe shutdown condition.

l l l t l l t , r I

Jnsert B "Station blackout" means the complete loss of alternating current (AC) electric power to the essential and nonessential switchgear buses in a nuclear power plant (i.e., loss of offsite electric power system concurrent with turbine trip and unavailability of the onsite emergency AC power systen). Station

               . blackout does not include the loss of available AC power to buses fed by station batteries through inverters or by alternate AC
      -             sources as defined in this section, nor does it -nssume a concurrent single failure or a design basis accident.

l l f i l l l l i e .. . . _ . _ . _ _ _ , , _ - _ _ _ . . . - _ . _ , ,, , _ , _ _ , c _ , - . , - - _ _ _ ._ ,-_

ASSEilDG THE ABILTTY TO COPE WITH At;GI;ST 10,1987 A STATION BLACKOLT EVENT SUCCESSFUL AAC SYSTEM START - the result of a periodic test in which the AAC syste:r .s show. to be capable of stardng and accepting a load within one hour of a station blackout eve . NUGSSO definition. e I I l i

               *~ -'       - - - - -                          _ _. -.-,_ ,__,.___,,____,_ _ ___ _ ___ _ _ _ .         _ _.         ,

NUGSBO STATION BLA CKOLT RESPONSE GUIDELINES REVISION 0.0 August 10.198* APPENDIX B. ALTERNATE AC POWER CRITERIA This appendix describes the criteda that must be met by a power sup;iy in order to be classified a.s a Alternate AC power source. The criteria focus on ensuring that sta:oc blackout equipment is nc unduly susceptible to dependent failure by establishing independence of the AAC system from th emergency and non Class IE AC power systems. ne AAC power source enteria and exceptions are as follows: B.1 ne AAC system and its components need not be designed to nee: Class 1E or safety sys requirements. B.2 Unless othenvise provided in this criteria, the AAC system need not be protected against effects of: (1) failure or misoperation of mechanical equipment or (2) seismic events. Includec j among these effects are: (i) fire, (ii) pipe whip, (iii) jet impi:gement, (iv) water spray, (v; flooding from a pipe break, (vi) radiation, pressuriution, eleuted temperature or humidity caused by high or medium energy pipe break, and (vii) missiles resulting from the failure of rotating equipment or high energy systems.

                            & )is, 4 sesmimin h *" S'*" "* & WA )** *                                       ***'

B.3 Components and subs'ystempall be protected against the effe::s of weather that may initiate l the loss of ofisite power event. Protection may be provided by enclosing AAC componen within stmetures that conform with the Uniform Buuding Code, and burying exposed electr cable run between boDdings. B.4 FaBare of AAC components shall not adversely affect Class IE AC power systems. B.S Physicahepuntion of AAC components from safety related ccmponents or equipment shau 1 conform with the separation criteria applicable for the unit's licersing basis. 26 l l l

I NUGSB0 STATION BLACKOtJT RESPONSE GUIDELINES REVISION 0.0 Aagust 14,19:7 i B.6 Electrical

                                           ;?f   t w <14Cisolation             of,o AAC     s             .s power     nee ns shall                    ;      .be p&,rovided Class   it 006*Wthrough          an appropriate s e c re f                                                                                                                us e sa r, e,       s sa l/ s po de'sd a,y
                                                           -e    c     t r es wo o                    c esa rs n i                                       serou (I cinu er e,sLe c la er if e.s                          <=a, rr #     -Cfa ry 4 G.
     ., ,, c . v.,
     '                            B.7 'Ibe AACpowersystem shill be1 quipped with itrewn D*C power _.so) usee,tfiat~                                                                                                         ,

l p., .C / indepen[ent from the black'ed out unit'sc IE po l B.8 The AAC power system shall be capable of operating during and after a statico blacko ) without any support systems powered from the preferred power supply, or the blacked c unit's Class IE power sources affected by the event. B.9 The AAC power system shall be sized to carry the ;tquired shutdown loads for at least hours, and be capable of maintaining voltage and frequency within limits that will not degrac l _the performance of any shutdown system or componenMt a multiunit site, an ade' =i Class IE power source may be used as an

e_ pvou w=n k.- i: 9"w out of nnwM InaAc at hath unite h AAC system shall not be capable of automatic loading of shutdown equipment blacked out unit unless already licensed with such capability.

B.11 Unless otherwise govemed by technical specifications, each AAC power source shall ! initially and periodically ter.d in a:cordance with vendor recommendations to demonstrate ti . capability of the unit to perform its intended function. B.12 Unless otherwise govemed by techmcal specifications, the AAC power source sha'l be startt and brought to operating conditioas that are consistent with its function u an AAC source intervals not longer than three months, following manufacturer's recommend =hs. On every 18 mocths., a timed stan (within the time period specified under blackcut ccahrinns) ar -

                   !                        load to rated capaQy test shall be perfanned.

B.13 Unless otherwise governed by technical specifications, surveillance and maintenanc { psocedarts for the AAC system shall be implemented in accordance with mamafacturer

                                                                                                                                                                                                 """**Nh si:    po w sov u                                  s L..I/ m+                                               mr~ /f         k */1$

sg y,,,jas/ o ,- o do n c ="q < ~sy M /* * *10"' Y 6 7 A blu k oA 27 1n a d&4cos, ( ,,;i .lf JJ

B.7 There shall be minimal potential for co con mode f ailure of the AAc power source which I preferred or casite emergency AC power source. The following system features provide assurance that the minimal potential for common mode failure has been adequately addressed: (a) The AAC power system shall be equipped with its own DC power source that is electrically independent from the tlacked-out unit's Class IE power system. (b) The AAC power system shall be equipped with its own air start system as applicable that is independent of the onsite emergency AC power source. (c) One AAC power system shall be provided with its own fuel oil supply as applicable that is separate from the fuel oil supply for the onsite emergency AC power system, i.e., a separate day tank supplied from a common storage tank is sufficient provided the fuel oil is adequately sampled and tested prior to transfer to the day tank. (d) If the AAC power source is an identical machine as the onsite emergency AC power source, failures of the emergency AC power some shall be evaluated for applicability source. and corrective action for its AAC power (e) No single point vulnerability shall exist whereby a weather-related event or single active failure could ( disable any portion of the onsite emergency AC power sources or the preferred power sources, and simultaneously find the AAC power source (s) . l i l l l L

NtJGSDO STATION BLACKOtfr RESPONSE GUIDELINES REVISION 0.0 Aogust 10,198* B.14 Unless otherwise govemed by technical specifications, the AAC system sha" be desi operating procedures shall be wr.tten to support its availability to shutdown egipment with one hour of a station blackout event. B.15 The Non Class IE AAC system should attempt to meet target reliability and availabilit depending on normal system sta:e. In this context, reliability and availability goals apply t

            .      overall AAC system rather than mdividual machines, where a system may co= prise more thr one AAC power source.

(a) Systems not normally operated (Standby systems) -- Availability AAC systems normally maintained in a stancy state should attempt to be "operational" at least 95% of the time the reactoris operating. Reliability System reliability should be established by analysis of an appropriate sample size taken from periodi: testing. This reliability should (1) attempt to meet or exceed 95% successful starts (See definition for a su:cessful start); and (2) be maintained above 90% ca'culated successful starts based on NSAC-108 methodology (or equivalent)[ Data censoring is acceptable if: e risb% 1.; :c:t 'a""q eitherfalst underlying causej.have-5een correc -* can

g a statistical anomaly. (b) Systems normally operated (Online systems)- Availability AAC systems normally online should attempt to be available to its associated unit at least 95% of te time the reactoris operating. Reliability No reliability targets or stan&ds are established for online systems. s 28

 .      .       ~-

4 ASSES $fNG THE. ABILITY TO COPE WITH At;G t'ST 10.1987 A STATION BLACKOt.T EVE.NT . t . APPENDIX C, REFERENCES B ARANOWSNY, P.W. ll985), Evaluation ofStation Blaci.:u Accidents at Nuclear Power Pla ::s. NUREG-1032, Office of Nuclear Regulatory Researd. Office of Nuclear Reactor Reguladr U.S. Nuclear Regulatory Commission, Washington, DC (1985). B ATTLE, R. \ 19851, Collection and Evaluation of Complete and Partial L.osses of Off Site Power at Nuclear Power Plants, NUREG/CR 3992, ORNL/T.49384, Oak Ridge National Laboratory, Oak Ridge, TN (1985). HASKIN, F. E. (19811 Analysis of a Hypothetical Core Meltdown Accident initiated by Loss of Offsite Powerfor the Zion 1 PWR, NUREG/CR 2988, Sandia National Laboratories. Albuquerque, NM (1981). MODGE, S. A. et al. l1981), Station Blackout at Browns Ferry Unit One . Accident Sequence Analysis, NUREG/CR 2181, ORNUNUREG/TM-455, Oak Ridge National Laboratory, Oak Ridge, TN (1981). 1EEE STD-4851983 [1983) Recommended Practicefor Sidng Large Lead Storage Batteriesfor Generating Stations and Substations, The Institute of Ecc:rical and Electrordc Engineers, New York, NY (1983). KOLACZKOWSKI, A.M., AND PAYNE, A.C. (1983] Statica Blackout Accident Analyses (Part of NRC Task Action Plan A-44), NUREG/CR-3226, Office of Nuclear Regulatory Research, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC (1983). NRC [1986), Drafr Regulatory Guide, Station Blackout, Task S1501-4,51 Fed. Rec.11494, (March 1986). 38

ASSESSING THE ABILTTY TO COPE %TTH A STATION BLACKOL7 EVENT Al O L ST 10,1987

e a NUGSBO ll987), Assuring the Adequacy ofStation Blackout Response Procedu e:

Guidelines aru TechnicalBases, Nuclear U2::y Group on Station Blackout, Washington, X (19 RUBIN, A. fl986), Regulatory Analysis for the Resolution of Unresolved L:fe:y iss Station Blackout, NUREG 1109, Office of Nuclear Reactor Regulat: . U.S. Nucle Regulatory Cornmission, Washington, DC (1986). WOG (1986), Reactor Coolant Pwnp Perfortnance Following a Loss of AC Pose Revision 2, Westinghouse Ownen Group, (December 10,1986). 39

   / seca m utrrutur a E                                                          P   CONN 8cTicVT 061414rro w     y ;=.=.r~a :' ~.N as ,,
                             == mm swnorame==.

JOHN P. oP(KA

            ?NN!$5!EN!$w August 31, 1987 Mr. Themis P. Speis, Deputy Director for Generic and Regulatory Issues Office of Nuclear Regulatory Research U.S. NUCLsAR REGULATORY COMMI88!0N washington, D.C.            20553 RE:      NUMARC-4700, "Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," August 31, 1987.

Dear Mr. Speis Enclosed with this letter are 10 copies of NUMARC-8700, "Quidelinea and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water asactors," dated

 . ..            August 31, 1987. This document, formally NUG850-8700,
         .       provides guidance and methodologies that utilities use to implement the Nuclear Management and Resources Council (NUMARC) station blackout initiatives.            As stated below, the NUMARC Board h&s not yet reviewed or approved Initiative 5 or revised Initiative 1 refers. iced in NUMARC-8100. In addition, the NUMARC soard has not had the opportunity to review NUMAEC-8700.

The first four NUMARC station blackout initiatives were endorsed by the NUMARC executives, as described to the Commission by letter dated June 23, 1987. These initiatives address the more important contributors to station blackout and are structured to reduce overall station blackout risk, ensure procedures are adaquate to prepare for and respond to

a station blackout event, and maintain or laprove energency l AC power availability.

Additionally, the NUMARC 5tstion Blackout Working Group has recommended a proposed fif th 850 initiative to assess plant's coping capability. The working Group has also recommended I that NUMARC station blackout Initiative 1 be revieed to include use of the staff's revised coping duration category l matrix. These recommendations have been reviewed by { 1

        . . _. . .JW         ^NJ f             9y>

g//b

the NUMARC Technical Subcommittee and are expected to be endorsed by the NUMARC soard in October, 1987. The en:losed document includes use of the revised astrix and a coping assessment methodology. Consistent with past practice, we expect this transmittal will be placed in the public document room. Very truly yours, I n F. eka, Chairman NUMARC 850 Norking Group JF0 gbs Enclosure cci Aleck serkis Senior Task Manager Reactor and Plant Safety Issues Stanch J. F. Colvin Executive Vice President NUhARC

I 1 i . l l l l l l 'I l e}}

ML20195G349: Difference between revisions

Latest revision as of 11:50, 9 December 2021

Contents

Text

SUBJECT:

Attachment:

SUMMARY

SUMMARY

4.1 INTRODUCTION

Navigation menu

ML20195G349: Difference between revisions

Latest revision as of 11:50, 9 December 2021

Text

SUBJECT:

Attachment:

SUMMARY

SUMMARY

4.1 INTRODUCTION

Navigation menu

Search