ML20024C156

Forwards Response to Environ Qualification Branch & Containment Sys Branch Requests for Info Re Containment Purge & Vent Valve Operability.Encl Draft FSAR Pages to Be Incorporated in Aug 1983 Rev.Seismic Rept by 830801

ML20024C156
Person / Time
Site:	Limerick
Issue date:	07/07/1983
From:	Bradley E PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Schwencer A Office of Nuclear Reactor Regulation
Shared Package
ML20024C157	List: ML20024C156 ML20024C158
References
NUDOCS 8307120330
Download: ML20024C156 (15)

Text

___ _ _ _ ---___-_-_-_--_----_- - - -- - .

. , e PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 EDW ARD G. B AUER, JR.

(215)841 4000 no esses a6 counsas EUGENE J. BR ADLEY assoceaTu sansnab counsa6 DONALU BLANKEN ,

RUDOLPH A. CHILLEMI E. C. KIR K H A LL T. H. M AMER CORNELL PAUL AUERSACH assistant Sgng4ak CoWNsEL EDW ARD J. CULLEN. JR.

THOM AS H. MILLER, J R.

IR ENE A. McKEN N A July 7, 1983 assesTANT CoWNsEL Mr. A. Schwencer, Chief Licensing Branch No. 2 Docket Nos. 50-352 50-353 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Limerick Generating Station, Units 162 NRC Environnmental Qualification Branch (EQB) and Containment Systems Branch (CSB) Requests for Information Regarding Containment Purge and Vent Valve Operability

References:

(1) Letter, A. Schwencer to E. G. Bauer, Jr.,

dated July 30, 1982 (2) Letter, A. Schwencer to E. G. Bauer, Jr.,

dated March II, 1983 (3) Meeting, NRC Containment Systems Branch and Philadelphia Electric Company, April 7, 1983

Enclosures:

(1) Draft FSAR Page Changes Addressing Purge and Vent Valve Operability (2) FSAR Reference 6.2-23, " Purge and Vent Valve Operability Qualification Analysis, Report No. 6-06-83, Prepared for Philadelphia Electric Company, Linerick Generating Station Unit 1", Clow Corporation, June, 1983 File: GOVT l-1 (NRC)

Dear Mr. Schwencer:

This letter transmits information on containment purge and vent valve operability assurance requested by EQB and CSB as further specified below: ,

A O 52 W

A PDR {'

.

• s 1

I Reference (1)

Attachments 4 and 5 to the Reference (1) letter requested specific information to demonstrate operability of containment purge and vent valves.

Reference (2)

The Reference (2) letter transmitted, among others, EQB's Draft Safety Evaluation Report, which reiterated the Reference (1) request for purge and vent valve operability assurance information. We understand this is an open review item with EQB.

Reference (3)

At the Reference (3) meeting, CSB open review item no. 17 was discussed. Re solution o f this item is contingent upon the acceptance of the purge and vent valve operability assurance program by EQB. We understand this is a confirmatory review item with CSB.

'nformation responsive to the Reference (1), (2) and (3) requests for information on purge and vent valves is contained in the enclosures to this letter, with the exception of the seismic report requested by Item 1.D of Attachment 4 to the Re ference (1) letter. This seismic report will be provided by August 1, 1983.

The information contained in the enclosure (1) draft FSAR pages will be incorporated into the FSAR, exactly as it appears in the enclosure, in the revision scheduled for August, 1983.

l Sincerely, Eu ne . adley HDH/gra/94&95 Enclosures Copy to: See Attached Service List

a. . e cc: Judge Lawrence.Brenner (w/o enclosure)

Judge Richard F. Cole (w/o enclosure)

Judge Peter A. Morris (w/o enclosure)

Troy B. Conner, Jr. , Esq. (w/o enclosure)

Ann P. Hodgdon (w/o enclosure)

Mr. Frank R. Romano (w/o enclosure)

Mr. Robert L. Anthony (w/o enclosure)

' Mr. Marvin I. Lewis (w/o enclosure)

Judith A. Dorsey, Esq. (w/o enclosure)

Charles W. Elliott, Esq. (w/o enclosure)

Jacqueline I. Ruttenberg (w/o enclosure)

Thomas Y. Au, Esq. -(w/o enclosure)

Mr. Thomas Gerusky (w/o enclosure)

Director, Pennsylvania Emergency Management Agency (w/o enclosure)

Mr. Steven P. Hershey (w/o enclosure)

Donald S. Bronstein, Esq. (w/o enclosure)

Mr. Joseph H. White, III (w/o enclosure).

David Wersan, Esq. (w/o enclosure)

Robert J. Sugarman, Esq. (w/o enclosure)

Martha W. Bush, Esq. (w/o enclosure)

Spence W. Perry, Esq. (w/o enclosure)

Atomic Safety and Licensing Appeal Board (w/o enclosure)

Atomic Safety and Licensing Board Panel (w/o enclosure)

Docket and Service Section (w/o enclosure)

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LGS FSAR Position (5), Clarification (6)

The setpoint for the drywell high pressure isolation signal is set at the minimum compatible with normal operation. Section 7.3.1.1.2.4.6 describes the selection of the dryvell high pressure setpoint.

and bs See%s 4.z.4.2 and 9.4.G~I Position (6), Clarification (7)

Containment purge valves comply with Branch Technical Position CSB 6-4 as discussed below. wo purge isolation valves have closure times greater tha X_ seconds: 2"-HV-105 and 2"-HV-111 have closure times of 30 seconds 76 An analysis of the radiological consequences of a LOCA that occurs during purging was performed to justify the line size and the valve closure time used in the purge system. Using the assumptions of BTP CSB 6-4, the resulting doses were a small fraction of the 10CFR100 limits.

For local leak rate tests, the leakage rate of the purge isolation valves, combined with the leakage rate for all other penetrations and valves subject to Type B and C tests will be less than 0.60 La, in accordance with Appendix J to 10CFR50.

Position (7)

The containment purge isolation valves isolate on receipt of any one of the following safety-related isolation signals:

a. high drywell pressure

b. reactor low water level

c. reactor enclosure high radiation

d. refueling floor high radiation In addition to the safety-related isolation signals listed above, the containment purge and vent isolation valves greater than 3 inches in diameter isolate on receipt of a nonsafety-related north stack effluent high radiation signal.

An analysis has been performed to demonstrate that the offsite doses that might result if a LOCA were to occur during purging operations would be less than both 10CFR100 and EPA Protection -

Action Guide limits. This analysis used the assumptions of NUREG 0800 Section 6.2.4 and Branch Technical Position CSB 6-4 and assumes a pre-existing spike that results in coolant activity levels in excess of Technical Specification limits. The analysis methodology was in accordance with the letter from T.J. Dente (BWR Owners Group) to D.G. Eisenhut (NRC) " Supplement to BWR Owners Group Evaluation of NUREG 0737 Item II.E.4.2(7)", dated June 14, 1982.

1.13-39 Rev. 2/, 0[/83

LGS FSAR

d. Environmental design Section 3.11 Debric transported to the suppression pool by the emergency core cooling water is prevented from entering the ECCS suction lines g by suction strainers. The suction strainers are described in Section 6.2.2. .

9 j f Ensurance of the operability of valves and valve operators in th'e

'f 4y containment atmosphere under normal plant operating conditions and postul ted accident conditions is discussed in Section 3.9.3.

h Provisions for detecting leakage from systems connected to the

} RCPB which are provided with manual isolation valves are

.., discussed in Section 5.2.5.

I " . The design provisions for testing the operability of the

{ Q isolation valves and the leakage rate of the containment 0 isolation barriers are discussed in Section 6.2.6.

Y A leakage control system is provided for the main steam isolation 24 valves, and is discussed in Section 6.7. A seismic Category I

• "( fill system provides a water seal for the feedwater lines,,as g

O S .6 e discussed in Section 6.2.3.2.3.

t I O Containment isolation valve closure times are selected to ensure

'G N b rapid isolation of the containment following postulated accidents. The isolation valves in lines that provide an open

& { j path from the containment to the environs have closure times that

& 4

• minimize the release of containment atmosphere to the environs to 4o e 5* radiological below 10CFR100 guideline values, mitigate the offsite consequences, and ensure that ECCS effectiveness is o 4u not degraded. These valve closure times are identified with a s I double asterisk in Table 6.2-17. The isolation valves for lines in which high-energy line breaks can occur have closure times

' that minimize the resultant pressure and temperr.ture transients y

L These valve closure j49o astimes well are as the radiological identified with consequences.

a single asterisk in Table 6.2-17.

,3 vu All of the isolation valve closure times listed in Table 6.2-17

"*I are the actual closure times that the isolation valves were kpurchasedwith, which in all cases are equal to or lower than the closure times necessary to meet the aforestated design requirements.K Those closure times which are required to be met 1 to satisfy isolation valve closure time design requirements are identified by a single or double asterisk in Table 6.2-17. ]

The essential / nonessential classification of containment l isolation valves, as listed in Table 6.2-17, was based on the

< following: those systems identified as essential are regarded as indispensable or are backup systems in the event of an accident; nonessential systems have been judged to not be required after an Rev. 2 0[/83 6.2-46

LGS FSAR

(

accident. The classification of essential and nonessential systems is given in Table 6.2-27.

Isolation valves are designed to be operable under environmental conditions such as maximum differential pressures, seismic occurrences, steam atmosphere, high temperature, and high humidity. The normal and accident environmental conditions are described in Section 3.11. Electrical redundancy is provided for power-operated valves. Power for the actuation of two isolation valves in series is supplied by redundant, independent power sources without crossties. In general, outboard isolation valves receive power from the Division II power supply, while inboard isolation valves receive power from the Division I power supply.

ECCS penetrations are exceptions. Refer to Section 7.3.1.1.2 for a detailed description of the power supplies for these valves.

Motor-operated isolation valves remain in their last position upon failure of electrical power to the motor operator. Air-operated containment isolation valves are spring-loaded to close upon loss of air or electrical power.

The design of the isolation valve system gives consideration to the possible adverse effects of sudden isolation valve closure when the plant systems are functioning under normal operation.

C: . y.,sg Reopening of the containment isolation valves requires deliberate operator action. Control systems for the automatic containment isolation valves are discussed in Section 7.3.1.1.2.

2.4.3 Desian Evaluation I

The main objective of the containment isolation system is to provide protection by preventing release to the environment of radioactive materials. This is accomplished by isolation of system lines penetrating the primary containment. Redundancy is provided so that the active failure of any single valve or O9C component does not prevent containment isolation.

k The arrangements of isolation valves are described in Table 6.2-17 and Figure 6.2-36. In general, isolation valves have redundancy in the mode of actuation as indicated in Table 1 6.2-17. A program of testing, described in Section 6.2.4.4, is maintained to ensure valve operability and leaktightness.

The design specifications require each isolation valve to.be operable under the most severe environmental conditions that it might experience. Protection from potential missiles is discussed in Section 3.5.

Provisions for administrative control of the proper position.of (is]g all nonpowered isolation valves, including valves in test, vent, drain, and sim~ilar types of branch lines that serve as 6.2-47 Rev. , /83

g. - - .- - . - , _ , . . , . , .=-; - - .- - - - . . . - . - .

i n r i: r t A. Page ! 13-39 The Limerick containment purge valver have been desigaed to function should a LOCA occur while the purge valves were open. The valve manu f ac ture r has completed an extensive program of tests and analyses to demonstrate operability of the valves in accordance with all published NRC guidelines and criteria.

The following is a brief summary of the factors addressed in the valve operability qualification report (Ref. 6.2-23):

valves are supplied in accordance with ASME B & PV Code,Section III, Class 2 requirements finite element' analyses have been utilized to determine valve component stress levels for limiting combinations of loads the impact o f dynamic loadings is addressed by analysis and static load testing all valves are located outside containment thus eliminating concern over the effects o f containment pressure on pneumatic operator performance air operators are equipped with springs to facilitate valve closure; accumulators or other pneumatic systems are not utilized for valve closure or sealing valve dynamic torque coefficients have been determined by reduced scale and full scale testing the effects of installation geometry and arrangement have been fully considered containment pressure has been conservatively assumed to be constant at its maximum pressure for all valve angles back pressure caused by flow through downstream piping has been conservatively neglected clastomeric materials are not utilized for valve seating surfaces valve operators and pilot solenoids have been qualified to IEEE 323-1974 and NUREG-0588 Category I requirements motor operator performance has been de[monstrated at minimum available voltage levels motor operators are equipped with handwheels which automatically disengage upon electric activation P-97 '

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LGS FSAR i

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Evaluation of NUREG-0737, Item II.E.4.2(7)," dated June 14, 1982.

s.2 25 :re. K<vege< and R.e. sesone. , " %ye. nmd Vent %Ive.

_ Opembittby Qualifccattou Am tysis , Tepd slo. 6-06-15,

• Prepared for 'Philadelpi,ca Elechere c.. Lim e<icK unch 1 ", Clow Corpombton Gene i9e3.

(June <abing )Sbdcou e DRAgy;c l

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LG5 F5AR TABLE 6.2-17 (Cont'd)

LENGlH Of PIPC FROM C0%14t hM(NT h*C GENERAL C0hT. TO FthtTRATION LlhE L1hE DESIGN ISF ESSEhTIAL VAL VE VALVE VALVE VMVf ifPE C OUT510E NtiMB(R 150tATfD FLUID $12f(in.) CRITERION SYSTEM SYSTEM NUMSER TYPI(1) 10CA110N AjRA%GEMfhT(2) TEST VALVES 1 208 Instrumen. Water 1 55 - - F045C IFC Outside (37) ho 2*-2*

tation.

RTV level I-208 Instrumen. Water 1 55 - - 102C XFC Outside (40) ho 13" tation.

LPCI WP t-21 Service air Gas 3 56 No ho 1140 GT Inside (8) Yes -

ho ho 1139 GT Outside O' I-22 Instrumen- Gas 1 56 - - 147C GB Outside (41) ho 8' tation - dry-well pressure 1-23 Recirc pump Water 4 56 to ho 106 GT Outside (13) Yes 0" cc,oling water ho ho 108 GT Outside 3'-11" supply No ho 1090 GT Outside 5' 2" I-24 Recirc pump Water 4 56 ho No 107 GT Outside (13) Yes 0*

cooling water No ho 111 GT Outside 3'-8*

return ho No 689 GT Outside 5'-0*

X 25 Orywell Gas 24 56 ho ho 135 BF Outside (5) Yes 16'-7*

purge Yes Yes 121 BF Outside 3'-11*

supply No ho 123 BF Outside 3'-4" Yes Yes 131 BF Outside 60'-7" Yes Yes 163 BF Outside 3'-B" ho ho 109 BF Outside 42' 2' X 26 Orywell Gas 24 56 ho No 115 BF Outside (27) Yes $3'-7*

purge Yes Yes 145 GT Outside 66*-9' enhaust . ho ho 111 GR Outside 6'-6" ko ho 114 BF Outside 49'-7' Yes Yes 161 BF Outside e 4'-5" ho ho 117 GB Outside 60*-3*

X-27A Instrument Gas 1 56 ho Yes 1128 CK Inside (48) Yes -

gas supply ho Yes 151A GB Outside 7' I-278 Instru'ien- Steam 1 55 - - F0245 XFC Outside (40) No 12' tation-hPCI 1-278 Instrumen. 5 team 1 55 - - F024D XFC Outside (40) ho 12" t ation-HPCI Flow T1001550-01V DRAFT -

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POWER 5 1 MARY SECONDARY h0RMAL 5HUTDOWN POST. FAILURE DIVERSE VALVE METHOD OF WALVE VALVE ACCIDENT VALVE 150LAT10h 150LATION CLD5URE Pue.E R hTM000F JTUAT10N(3) ACTUATION P051T10h p POSITION POSITION P0511104 SIGH AL(5) SIGNAL (l?) T IME (6) 50URCE(7) NEhAkK5 ,

tw - 0 0 0 . . . - .

l You - 0 0 0 . . - - .

i h

1 hual .

C C C . . . . -

i, C .  !

tanual C C - - -

actor Manual 0 0 0 A5 15 RM - 30 see C 3motr Manual Manual 0

0 9 C A5 15 RM ho Standard 5tanoard C (15) 3 mottr 0 C AS 15 RM No D tanual - C C C - .

mottr Manual 0 0 C A5 15 RM ho 5tanoard C (15) 3 Motir Manual 0 0 C A5 15 RM ho standard D 4anual . C C C . . .

mot;r Manual C 0 C AS IS B.H.R.W , Yes E" see B

cmp air Spring C C C C 8.H.R.W ; h4 5** sec A Lemp air Spring C 0 C C B.H.R.W Yes 5** sec A ) T l cap air Spring -

Manual C C C 0

C A5 15 B.H.R NA G% 5 see sec A

0 l 'j mottr C C B.H.R NA

-mottr Manual C C C AS 15 B.H.R.W Yes #

• sec b -)[ Ft _

motor c111 Manual

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C 0

A5 15 C

8.H.R,W l B.H.R i Yes e A4 sec h4 W 2 sec A

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motor Manual C C C A5 15 B.H.R

• Tes 30** sec 8 p' .

omp air Spring C 0 C C B.H.R.W ; Yes 5" sec 8 <

1 3 mottr Manual C C C A5 15 B.H.R  ! NA , C ad i

cmp cir

$ prine, C C C C B.H.R Yes @/"sec5 see A

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mott r . Manual 0 0 C A5 15 H NA 30 sec C i

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LG5 FSAk TABLE 6.217 (Cont'dD lihG CONTAlhMthi hRC GE hE RAL .

U NT PEhETRATION Llhi llht DE51Gh [5F [55thilAL VtL VE VALVE V AL VE nALVE TYPE C OLT50 ht#BER ISOLATED FLUID $17Ef te,1 CR11ERION SY51fA SYSTE M h3 PIE R 1YPf(l[ 10f AT10h ARRuGf TENT (2) 1[57 VgTI I 66A Instrunea. Water 1 55 - - F045D IFC Outside (37) No ld '

tation -

KPV level l I-66A Instrumen- Water 1 55 - - 102D XFC Outside (40) ho 1) tation - - - 103D XFC Outside 1(

LPf3 P 1-668 Instrunen- Water 1 55 - - F045A XFC Outside (37) ho la tation -

RPV level 1 668 Inst rumen- liater 1 55 - - 102A XFC Outside (40) ho 1Y tation -

LPCI P I-67A.B Instrumen. Water 1 55 - - F04) XF C Outside (37) ho 2{

tation - - - F043A XFC Outside is RPV level; - -

F0498 1FC Outside 1)

RPV pressure 1-116 5tandby Sodium 2 55 Yes Yes F007 CK Inside (10) Yes -

Ilquid penta- Yes Yes F0068 SCK Outside Oc control t,or at e solution 1-1178 Drywell Gas 1 56 ho ho 190-A.B GT Cutside (23) Yes radiation ho ho 190-C.O. GT Outside l@

sampilng supply and return 1-201A Suppression Gas 20 56 ho ho 109 Outside BF (7) Yes 42'-9) poal purge ho No 147 BF Outside 17'-5 supply ho ho 124 BF Outside 7 13'-53 Yes Yes 131 BF Outside 7'-9j Yes Yes 164 BF Gutside 8'-73 Yes Yes 121 BF Outside 69'-1) 1 202 Suppression Gas 18 56 Yet ho 112 BF Outside (15) Yes 18'-6 pool purge Yes Yes 185 GT Outside 24'-6)3 ennaust Yes Yes 162 BF Out side 3 ' -Ir.

No No 105 GS Out side 6'-1$

No ho 104 8F Out side 4'-0 ho ho 118 BF Outside 32'-lb)

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(Page 11 of 19) 0F OM PowtR (

10 PRIMARY SEC0!,DARY MIRMAL 5HUID0dN POST- FAILURE DIVENSE VALVE METHOD OF METHOD OF V4VE b AL VE ACCIDEhi VALVE ISOLATION ISOLATION CLO5URE PO=ER ACTUATION (3) ACTUATI0', P051 TION (4) POSITION POSITION POSITION $1G%AL($ ) $ 1GAAL (12) TIME (6) 50VRCE(7) Et>ARr5 l

Flow .

0 0 0 - - - - -

Flow

( Flow 0

0 0

0 0

0 Flow .

0 0 0 - . - - -

+

Flow -

0 0 0 . . . . .

Flow -

0 0 0 - - - - -

F ?me -

0 0 0 - - - -

Tto. -

0 0 0 - . . - -

Flow -

C C C. - - - - -

Flow AC Mutor 0 0 0 A5 15 bl hA $tandard b 3

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(-4 ' AC ceil

-2' AC c111 C C C C B.N Tes 2 sec C, 8 0 C C C C.M Yes 2 sec C, 8 .,

AC motor Manual C A5 !$ f,N,R,W AC mot:r C C Yes ** Sec 8 Manual C 0 0 AS IS F:,H R,W Yes  % d** sec Comp air 8 Spring C 0 C C E.H R W Yes 5** sec A Cump air Sprin C C C C 2,H R W hA 5" sec A AC motor Manua C C 0 AS 15 B,H,R M Camp air

% sec D  !

f $pring C C C C E,H R W NA 5" sec A I AC motir Manual C 'O O AS IS E.M.R,W AA  %

• see A AC cill -

0 0 0 C - B H,R hA 2 sec C AC mottr Manual 0 i AC mot:r Manual C C AS 15 E,H,N NA A sec C Comp air spring C C 0

C AS 15 2,H R. Yes h 30** sec 8 j j C C C 8,H,R,W Yes 5" sec h Comp air spring r C C C C B,H,R Yes 5** sec A en

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LGS FSAR

( protect structures a d safety-related equipment (e.g.,

fans, filters, and ductwork) located beyond the purge system isolation valves against loss of function from the environment create.d by escaping air and steam, in

• accordance with BTP CSB 6-4 Position B.5.b.

'i. Specify the maximum allowable leak rate of the purge isolation valves giving appropriate consideration to valve size, maximum allowaale leakage rate for the containment (as defined in Appendix J to 10 CFR Part 50), and the maximum allowable bypass leakage fraction, in acc rdance with BTP CSB 6-4 Position B.5.d.

RESPONSE

a.. Section 9.4.5.1.2 has been changed to provide the requested information-.

, b. Section 9.4.5.1.2 has been changed to provide the requested

'information.

IC c. The low volume purge lines are 1 inch and 2 inches in

-diameter. The high volurae purge lines are 18 inches and 24 inches in diameter.

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Analysis of the radiological consequences of a LOCA occurring while the primary containment is being purged has been performed as a means of justifying the line sizes of the high

-volume purge lines. Using the assumptions in BTP CSB 6-4, the 2-hour thyroid dose at the exclusion area boundary was found to be well below the 10CFR100 guideline values.

d.- Table 6.2-17 has been changed to indicate,that the containment isolation valves associated with the drywell'and, suppression chamber purge supply and exhaust lines, together with the H,/0, sample return lines, are . actuated by diverse

, parameters other than high radiation.

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.e. . Table 6.2-17hasbeenchangedtoindicateclosuretimesof.f X~. . seconds or-less for all isolation valves on the purge' lines,

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with the exception of valves HV-57-105 and HV-57-111. Valves HV-57'105 and HV-57-111 have closure times of 30 seconds.

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closure' time has been justified by an analysis of the

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I 480.42-3 -

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.- j radiological consequences of a LOCA that occurs during ( i purging, as discussed in item c of this response.

f. Debris screens will be provided on the 18, 20, and 24 inch purge line penetrations. ,

These screens will be designed to be seismic Category I and to be capable of withstanding LOCA differential pressures.

g. The analysis of radiological consequences of a LOCA during purging is discussed in item c above. This analysis included the assumption that air and steam contaminated with fission products are released from the primary containment during the maximum interval required for closure of the isolation valves on the containment purge lines.

h. The Limerick containment purge and vent valves will be opened for a limited period of time during power operation for inerting and deinerting of the primary containment atmosphere. The inert atmosphere (diluted with nitrogen to

<4% 0,) is purged from containment in anticipation of outages requiring containment access to allow inspections and limited repairs while the reactor is at some reduced power level. (

Inspections are also performed during power ascension prior

'to the inerting of containment. These inspections facilitate the early detection and location of coolant system leaks which could have an impact on unit reliability and safety if uncorrected. _

The containment atmosphere control system is described in Section 9.4.5 and illustrated in Figure 9.4-5. Purging and venting operations are normally performed through one 24-inch supply penetration and one 24-inch exhaust penetration. All gases purged from containment are processed through SGTS prior to release.

Because the purge and ven; s 4;) are opened during only a limited period of power opgratica (typically less.than 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br />'per year), it is unlikely that a LOCA will occur while the valves are open. If 1 LOCA were to occur during this time, the containment isolation valves would close rapidly (less than 6 seconds af te r receipt of isolation signal) and would terminate the release. Isolation will be complete long before any fuel damage or significant offsite exnostre could occur. The containment isolation valves used have been specially designed and oualified for this service as I described in SectionT9,4W. It is possible in such cases, .

l g oi lo.2. 4,7- I Rev. M g/83 480.42-4~ .

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l ENCLOSURE (2)

PSAR REFERENCE 6.2-23 i

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