ML20082S484

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Responds to NRC Request for Addl Info Re 910621 Application for Amend to License NPF-42.Ltr Also Proposes Addition of Surveillance Requirement 4.6.2.3.a.2 to Replace Surveillance Deleted from Original Application
ML20082S484
Person / Time
Site: Wolf Creek Wolf Creek Nuclear Operating Corporation icon.png
Issue date: 09/11/1991
From: Rhodes F
WOLF CREEK NUCLEAR OPERATING CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20082S486 List:
References
ET-91-0135, ET-91-135, NUDOCS 9109170161
Download: ML20082S484 (30)
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Text

{{#Wiki_filter:, W8LF CREEK ' NUCLEAR OPERATING CORPORATION forrest T Rhodes Veoo Preisderet Ingmes mg & Technicat Services September 11, 1991 ET 91-0135 U. S. Nuclear Regulatory Commission ATTN Document Control Desk Hail Station P1-137 Wahington, D. C. 20555

Reference:

Letter ET 91-0109 dated June 21, 1991 from F. T. Rhodes WCNOC, to the NRC Subject Docket No. 50 482: Proposed Revision To Technical Specification 4.6.2.3 - Containment Cooling System Gentlemen: The reference submitted a license arendment request to modify the Volf Creek Generating Station (VCGS) Technical Specifications. The proposed amendment concerned the technical specification surveillance testing requirements for the containment coolers. The proposed revisions included a reduction in the required cooling water flow rate and the deletion of required monthly flow rerification. The purpose of this letter is to provide additional information requested by the NRC staff and to submit a modification to the originally proposed amendment. Additional information was requested during telephone conversations between Messrs. H. K. Chernoff and S. G. Wideman of Wolf Creek Nuclear Operating Corporation (WCNOC) and Messrs. D. V. Pickett and A. J. D'Angelo, NRC. Attachment I provides the requested information. As a result of the conversations with the NRC staff, WCN00 proposes to modify the originally submitted amendment request. The modification adds a surveillance requirement 4.6.2.3.a.2 to replace the surveillance deleted in the original amendment request. The conclusions reached in the originally proposed amendment request remain unchanged.

However, a revised safety evaluation, significant hazards consideration determination, and environmental impact determination are included as Attachments 11. III, & IV respectively.

These evaluations / determinations have been revised to include a description of the modification to the original amendment request. Attachment V contains a revised markup of the affected Technical Specification pages.

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ADOrF m,0 yuk : P rma ibUUOU eo. Exn 411 < Buriingtort xs c6839 / Phone: (316) 364-8831 [ An Egiw opportisJty Employer M f HCNET 9

j ET 91 0135 Page 2 of 2 l j I t i In accordance with 10 CPR S0.91, a copy of this supporting information, with attachments, is being provided to the designated Kansas State Official. .l If you have any additional questions concerning this matter, please contact mc or Mr. H.-K. Chernoff of my staff. l l Very truly yours, j /* f l p-sA*. Forrest T. Rhodes Vice President Engineering & Technical Services 'FTR/jra Attachments: I - Additional Supporting Information II - Revised-Safety Evaluation III Revised Significant Hazards Consideration Determination IV - Revised Environmental Impact Determination V - Proposed Technical Specification Changes cc G. W. Allen (KDHE), w/a L. L. Gundrum (NRC), w/a A. T. Howell (NRC), w/a R. D.'Hartin (NRC), w/a W. D. Rockely (NRC), w/a l-l

I 4 STATE OF KANSAS ) ) SS COUNTY OF COFFKY ) Forrest T. Rhodes, of lawful age, being ff -t duly sworn upon oath says that he is Vice President Engineering er 'echnical Services of Wolf Creek Nuclear Operating Corporations that he hs. nd the foregoing document end knows the content thereof that he has exec <1 that same for and on behalf of said Corporation with full power and author. y to do son and that the facts therein stated are true and correct to the best of his knowledge, information and belief. .,= A' t. E h l ) '(M ( .. Y.O By + e l.i M " (' Forrest T. Rhodes \\ Vice President 1 '., pg g L Engineering & Technical Services 41r r* SUBSCRIBED and sworn to before me this // day of f/[q 1991. ihR _ V i/ TY ^ Notary Public l-Expiration Date 'I 28 / i

~ Attechm:nt I to ET 91 0135 P:gs 1 of 12 ATTACIMENT I ADDITIONAL SUPPORTING INFORMATION l I l I i f l I 1

~ ttachment 1 to ET 91-0135 j Page 2 of 12 } ADDITIONAL SUPPORTING INFORMATION Comparison of CONTEMPT LT/28 and COPATTA Analyses l During the development of the CONTEMPT-LT/28 analytical model used for Wolf I Creek Generating Station (WCGS) Containment Integrity analyses, comparisons to the original COPATTA model were performed. Figures 1 and 2 show a comparison of the ontainment pressure and temperature response to a postulated LOCA usit.: these two models. For this comparison a containment } cooler flow rate of 40 0 gpm per cooler group was used. The initial and l boundary conditions for the two models used in this comparison are the same, (e.g. the magnitude of passive heat sinks and the mass and energy release rate during the blowdown and reflood phases) with the following exceptions. 1) A.a outside air temperature of 120 F was assumed for CONTEMPT-LT/28 vs. the previously assumed value of P5"F. [

2) A Containment Spray flow rate of 1.458E6 lbm/hr was assumed vs. the previous value of 1.535E6 lbm/hr.

CONTEMPT-LT/28 utilites a fixed conservative value for containment spray efficiency vs. the j variable spray efficient used by COPATTA.

3) The modeling capability of the residual heat removal (RHR) heat exchanger performance was different between the two computer

} models. CONTEMPT-LT/28 used a fixed component cooling water (CCW) inlet temperature (130 F) to the RHR heat exchanger whereas in COPATTA, the CCV inlet temperature is calculated by the code. The figures show good agreement between the two analytical methods. The l CONTEMPT-LT/28 model used for the analyses submitted in support of the ~ proposed license amendment in therefore, consistent with that used for the COPATTA analyses containet in the existing Updated Safety Analysis Report (USAR). ) Effect of Reducing the Containment Cooler Heat Rasmoval capacity on the CONTH4PT-hT/28 Analyses, Figures 3 and 4 show the relative effect of reducing the containment fan i cooler heat removal capacity as a result of changing the cooling water flow i rate on the CONTEMPT-LT/28 analyses. As can be seen from the figures, the I reduction in the containment ecoler heat removal capacity has little effect on the calculated peak containment pressure or temperature. The peak containment temperature occurs at the time the fan cooler and containment 3 epray are activated. The peak containment pressure occurs at the end of the reflood phase, shortly after the activation of the containment cooler. The i heat removed by the containment coolers is not significant during the course l in which the containment pressure is surging to its peak. This is confirmed by. a. comparison of the containment atmosphere energy with the total heat removed by the containment fan coolers shown in Figure 8. The affects of l the reduction in containment cooler heat removal capacity becomes f significant only after several hundred seconds after the peaks in that the reduced containment cooler heat removal capacity results in a comewhat slower reduction of pressure and temperature, i

4 ttachment to ET 91-0135 Page 3 of 12 Figure 6 shows the fan cooler heat removal rate compared with the heat removal rate for the containment spray system. As can bee seen from Figure ll( 6, the containment spray heat removal rate is initially comparable to that P"5 of the fan coolers at 4000 gpm cooling water flow. The containment spray

  • -4 heat romoval rate becomes negative later during the accident after the suction of the containment spray pump is switched from the refueling water storage tcnk to the containment suu p.

At the time of switchover to the

sump, the sump liquid temperature is higher than that of the containment atmosphere.

Figure 7 shows the distribution of energy between the containment atmosphere ll(k and the containment sump following the postulated LOC 3. Figure 8 shows the heat removal provided by the Containment spray Dystem and the containment coolere for this postulated accident as compsred to the energy contained in the containnet atmosphere. As shown in the figure, the heat removed by the c.ontainment cooiere does not become a significant factor until after several handred seconds, well after occurrence of the peak containment temperature y and pressure, r Contalument Cooler llent Removal Capacity Aasumed in the CON 1EMPT-LT/28 Analyses The analyses supporting the license amendment reqm. t asumed a reduction in the heat removal capacity for the containment m vars of approximately 55 perc.nt. This was to account for the reductirm i required cooling water flow from 4000 gpm to 20:0 gpm per cooler group a ecolor units). This value was derived oy taking the original der r1 heat traneter rate for a _f single cooler unit at 2000 gpm and applyin' an additional 10 percent reduction for conservatism. Figure 5 shows the profile of the fan cooler heat removal rate following a postulated LOCA in the analyses supporting the license amendmoot request compared with the heat removal rate calculated in the existisg USAR ar.alyses. As noted in the original s'andment request, the assumption of resucing the fan cooler heat removal capacity to approximately 55 percent is conservatJve. Subsequent analy.as sui 711ed by the fan cooler t7 censer ative att e of this assumption. Thase vendor have confirmed b calcalations indicated that by reducir ohe coolin3 water to a sta enoler g cup from 4000 gym to 2000 upm. the heat removal cepatity cf a cooler group (two cooler units) is reduced only appreximately 35 percent. A compariaen .= of the fan cooler heat removal capacit, provided by the vendor vs. the tan cccisr heat removal capacity assumed it 'he analyses to cupport the license amendnent is shown in Figure 9. 1 f

.) t 3 . s 50 'e, e> ' 40 M,. ; CD y : ? y CONTEMP1 -LT/28

"E' '

Ag. ' s. COPA TA 40 t- - e. o- .a_ s m s. m ~

3 s

u.

  • mn9 1
t i

'O-u

30

~- u' aa e u ~' Q - l ,c t 20 - ~ - - - - - - - ~ - - - - -- c --- -- -- c a ~ c a o O / 10 l, + i I h 0 1.0E-01 1.0 E+ 0 0 1.0E+ 01 1.0 E+ 0 2 1.0E+ 0 3 1.0 E+ 04 1.0E+05 1.0 E+ 0 6 Time (seconds) l ' Comparison of Containment Pressure Response - Figure 1: to a Postulated LOCA: CONTEMPT-LT/28 vs. COPATTA -r l l l. . + +c a+i--+.m + ew %wwe w,w, e. - - - -. - ..,,-vw-- e. ww = -w ...-,--,2v~.,-i,y. -, -i - weew ,-w .**-w n i-e.e'.-.--s. -,,.,4. ~,..--.-+,wv.-, <+meww--. ---v.ew ,wE-.----a- --we.----wv-

t Q t. 1 7 >... cr r+ : 350 WC1 a m =r - A -- 33 - u. CONTEMPT-LT/28 2,8 - a r+ -, e ,L 8 COPATTA Y' ^ 'i 300 -- =- - - m. u w-r 3 [ e, a 7. D. !250 I t-o. u Y e .c c. 200 - ~ - - - - - - - - - - - - - - - ~ ~ - - - - - - - - - - E ~ s 4 ~ ce t E150 .c. s a ~~~a c O ~~. ' o 100 i 1.0 E- 01 1.0 E+ 0 0 1.0 E+ 0.1 1.0 E+ 0 2 1.0E+ 0 3 - 1.0 E+ 0 4 1.0 E+ 0 5 1.0 E+ 0 6 Time (seconds) Figure 2: Comparison of Containment Temperature Response to a Postulated LOCA: CONTEMPT-LT/28 vs. COPATTA t i ./,--.,,,,..-4-_g,.,w...., ~ + - +..,..... ,*...,,,,-.m,g._,s ..,mm_,-..m.-,- w.,.,r.,,, .-.--4 ..m._.-,..--.,.~....,+. ,,,-,s.

uw. Cb e 50 BC e, n=. s _ N., 2000 gpm 2,8 N *-* 4 40 000 gpm g 1 m O I "4 _c_ ' w T .D. o .a t f.AP e m ba 30 - ~ ~ - - a m i e 6 i O, t ec e 20 .c. m c O s o 10 f 0 1.0E-01 1.0 E+ 0 0 1.0 E+ 01 1.0 E+ 0 2 1.0 E+ 0 3 1.O E+ 0 4 1.0 E+ 0 5 1.0 E+ 0 6 Time (seconds) Figuce 3: Compariscn of Containment Pressure Response to a Postulated LOCA w/ Minimum SI . ~

t a { t + > 's I 8G'

  • T 300 2 0_0.0 gp.m _,

o, o "i~ 1 j c+ - 4000 gpm ~u. g S O O ,o v

  • 250 5
s s

w 1 <n.. m i i b 4 e a i E e s H E200 e t E .c ,m c /- 1. o O i 150 ~ i ~ ~. l 1.0 E- 01 1.0 E+ 0 0 1.0 E+ 01 1.0 E+ 0 2 .1.0 E+ 0 3 1.0 E+ 0 4 1.0 E+ 0 5 1.0 E+ 0 6 Time (seconds) Figure 4: Comparison of Containment Temperature Response to a Postulated LOCA w/ Minimum SI ---e, m.. c-.#.. .ee.. . ' - +.... ..,,.....-,..a n,%..., .v.4 ....-.-..e..- .v,, v.w.-. .~r..- w m,2- .-.mc~r, 4._mc.,,g.y--..e.,.....,... 1*.y.,,&

- + 2.5 0E+ 0 8 ..; y a c+ (D r+ OW 2 000 gpm l my- =- OO M3 ;i n <+ : - j 4 000 gpm; C1 K;g 2.0 0E+ 0 8 ~ ~- =, - --. 2 g _ -= = =.- i

s o

ed g g. O 8 s V I .g I .l 4d 8 .t r f s o m w. 1.5 0 E+ 0 8 = -m c> E e E i 8 4, s i 8 1.0 0 E+ 0 8 - I-e I ,F-u i s g o o o I c 5.0 0E+07 e i 1 u. t l t l 0.0OE+00 1.0 E+ 0 0 1.0 E+ 01.

1. 0 E+ 0 2 1.0 E+ 0 3 1.0 E* 04 1.0 E+ 0 5 -

1.0E+ 0 6 Time' (seconds). ' Figure-5:' Comparison of Fan Cooler Heat Removal Rate j Y -,e, r,r-w...-,,,-.-,,,--...-,,,.. -~.,e--.v ...-..,.,-....,,,,-..,m.-<..w ..m,,....,..---..ym,u...~..-.----..-- m,.,..=..,- . - ~ ~

2.5 0 E+ 0 8 ' o>. me or QO ~ l...... ~ ~ ~ ~....,, 2000 gpm .g. a. 2.0 0 E+ 0 8

t! 2 225 -,

,B e 4000 gpm p l + o y 1.50E+08 -f- -~ SPR{_ g e ~ - a, ra l v i <o 1.0 0 E+ 0 8 -l-i c m er~ oc i i I S 3 o 5.0 0E-0 7 -l i 'c E i N g N 5 0.0 0 E+ 0 0 e I i r -5.0 0 E+ 0 7 1 - 1.0 0E+ 0 8 1.0 E+ 0 0 1.0 E+ 01 1.0 E+ 0 2 1.0 E+ 0 3 1.0 E+ 0 4 1.0 E+ 0 5 1.0 E+ 0 6 Time (seconds) Figure 6: Comparison of Fan Cooler and Spray Heat Removal Rate i-3

8.0 0E+ 0 8., JR .o n O Or ~ ~ -. Attr.osphere 6S i j O oo me [ Sump - .g ~. p-6.0 0 E+ 0 8 Tetal- - - ~ ~ - m ~ w ~, o ~. w n .a. u ~ m ~ v > 4.0 0E+ 0 8 -./ m u. ~~. e l c uJ e- ) i 2.0 0 E+ 0 8 /

t i

1 f ~ t 0.0 0 E+ 0 0 - - - - - ~~~ '.- 1 j 1.0 E+ 0 0 1.0 E+ 01 1.0 E+ 0 2 1.0 E+ 0 3 1.0 E+ 04 1.0 E+ 0 5 1.0 E+ 0 6 i Time (seconds) Figure 7: Comparison of Containment Atmosphere and Sump Energy b t w--,-e.<-- g w w..,, a ,,y ..,,,.,r., s..,,. ,a-.o,.- iw- .,,-c.,, .,,..,,,,,.m ,c--,,,,--,,,.,-.ww.---,---w,,*-,,..,,e,,,.,,vy ..,,.,..w,.m. y.,. wm-7.w--...g - +,,,

( 3.5 0 E+ 0 8 @ f., . O a, o ~ -=a _a 9 :.. ! O o2- -% r+ + 3.0 0E+ 0 8 CW =~ d'. 1 ~ , c+ O . rri - ~ ; 2.5 0E+ 0 8 - =- 3 o - ~~ 'Q = 1 u, i i. 4 2.0 0E+ 0 8 =- a v S Atmosphere j

  • 1.5 0E+ 0 8 c

Spray / 9 1.0 0E+ 0 8 Coolers ~(20 0 0 ~gpm) ' ' -~~ [ .s k 5.0 0 E+ 0 7 .4 0.0 0E+ 0 0 ^. ~ ~ ~ --^ 1.0 3.0 10.0 30.0 100.0 .300.0 1000.0.3000.0 10000.0 i r Time (seconds) l Figure 8: Comparison of Containment Atmosphere Energy with Total Heat Removed by. Containment' Spray or Fan Coolers i A I 'a t . - _ - - -. -. _ _... _..,. _ - - - _ +. .............. _. _. _. _ -....... - -.. ~.....,. -. ...... _,,. ~. -.. _, _ _. _.. _. _,. -..,... -....,. _ . _ _. ~.,

2. 5 0 E+ 0 8 m>.

c-s r+ CO r+ CD or n ~a cD O3 2.0 O E+ 0 8 _~ ^ <+ L.- O 1 m-N w 3 e ~ m 1.5 0 E+ 0 8 9 v w ,e a, a K r. a O E, 1.0 0 E+ 0 8 E e a e I 5.0 dE+ 0 7 Actual Performan::e (4000 gpm> ActualPerformance (2600 gpm)l WCN3C Containme it P/T Analysis 0.0 0 E'+ 0 0 l 120.0 160.0 200.0 240.0 280.0 320.0 360.0 400.0 440.0 l Saturated Temperature (Deg F) Figure 9: Fan Cooler Heat Removal Rate I. r,v ..,m . ~, -.. , ~.. +.

s

  • Attachm nt II to ET 91-0135 Pcgs 1 of 10 P

t i f ATTACIMENT II REVISED SAFETY EVALUATION t E b i f f I l i l 1 m,

Attechm2nt II to ET 91-0135 'Page 2 of 10 SAFETY EVALUATION Introduction and Description of Proposed Change Major modifications to the Service Water System (S; ;-and Essential Service Water System (ESWS) were implemented in 1990 during the fourth Wolf Creek Generating Station (WCGS) refueling outage to address concerns relative to erosion and corrosion. The modifications increased and redistributed the flow supplied by the SWS and increased the backpressure in the system to reduce the potential for erosion. Following subsequent flow balancing, mecourements indicated the pressure drcp across the system had increased. This resulted in a reduction in the cargins between the available cooling water flow rate ar.d the design cooling requirements for various components. To provide sufficient flow rate margins to accommodate future flow balancing and assure adequate flow is available to all components, a reduction in the required cooling flow to the Containment Cooling System (CCS) is proposed in this amendment request. The proposed reduction in the required ESWS flow to the CCS is possible due to conservatisms inherent in the original safety analysis. Two changes are proposed to the existing Technical Specification 4.6.2.3. Technical Specification 4.6.2.3.b is revised to reduce the required cooling water flow rate to the CCS with the ESWS in its post-accident alignment from 4000 to 2000 gallons per minute (gpm) for each containment cooler group. This surveillance is conducted at least once per 18 months. As detailed

below, reanalysis using plant specific data and more contemporary computer codes demonstrates adequate CCS performance at the proposed reduced ESWS flow rate.

The second proposed change is to Technical Specification 4.6.2.3.a. This specification requires measutement of the cooling water flow rate to each cooler group at 31 day intervals with the ESWS in its normal alignment. As discussed belor, flow measurements in the normal operating mode do not provide a consistent or reliable indication of the ability cf the cooler units to perform their safety function. Potential flow degradation is more reliably detected by an ongoing heat exchanger performance monitoring program. Therefore, this surveillance requirement is replaced by a periodic verification of proper positioning of valves in the cooling water flow path. Conforming changes are included for various sections of the Technical Specification Bases. Sytten Description Tec'inical Specification 4.6.2.3, ' Containment Cooling System," contains surveillance requirements for the CCS. During normal operation the GCS works together with the containment Heating, Ventilation and Air Conditioning (HVAC) system to maint in suitable conditions for equipment located within the contcinment and maintain the containment conditions within the bounds of the initial conditions assumed in the safety analysis. Following a Loss of Coolant Accident (LOCA) or Main Steam Line Break (MSLB), the CCS operates together with the Containment Sprsy System to maintain the containment temperature and pressure within design limits. The CCS also serves to limit offsite radiation exposure by reducing the pressure differential between the containment and the external environment following a LOCA. J

Attachment II to ET-91-0135

  • Page 3 of 10 h

The CCS is made.up of two independent groups of two cooling units each. Each cooling unit consists of an air-to-water heat exchanger and a two speed fan. During notmal plant operation the ESWS, and subsequently the CCS, is supplied with cooling water from the non-safety related SWS via a cross connection. .Under post-accident conditions the ESWS is isolated from the i SWS and cooling water is supplied from the safety related ESWS pumps. The l ESWS provides_ heat removal for safety-related equipment during and following design basis accidents. Higher cooling water flow rates are protided to the CCS in this mode of operation. The CCS fans are operated at high speed with a nominal cooling water flow of approximately 1850 gpm per cooler group supplied by the _SWS. Under accident conditions the CCS fans are automatically switched to the low speed setting to prevent overload of the fan motors and the flow of cooling water is increased to approximately 4000 gpm por cooler group as the ESWS is aligned for post-accident service. The t safety' analysis currently contained in the Updated Safety Analysis Report (USAR) assumes an ESWS flow rate to each containment cooler g;Jup in the r post-cccident mode is at least 4000 gpm. j l Evaluation The containment pressure and temperature response following a postulated i LOCA and MSLB accidents was reanalyzed to evaluate the impact of the j proposed reduction in the minimum allowable CCS cooling water flow rate. l These analyses showed no change in the peak containment pressure following a LOCA and only a small increase in the peak containment pressure following an MSLB. The revised MSLB peak pressure remains well below the design pressure of the WCGS containment. The peak contrinment temperature following an MSLB also increased slightly but remained within an acceptr.ble range. The results of these analyses are detailed below along with a description of the analytical methods. The current USAR analyses for the containment pressure and temperature code.y The revised response was performed using the g0PATTA computer analyses utilized the CONTEMPT-LT/28 computer code. In addition, the mass and energy release to the containment was reanalyzed using -more plant specific data and a more contempcrary computer code. The ar.ss and energy release data used in the current analyses ic based on generi data and was developed using the MARVEL computer code.g Weetinghouse For the MSLB i plant event only the first 300 seconds of mass and energy release data was e developed using the MARVEL code. This data was extrapolated to the end of the MSLB transient. For the revised analypes, WCGS specific data was used BN-TOP-3, Revision 4 ' Performance and Sizing of Dry Pressure Containments." Bechtel Corporation, October 1977 l t A Computer Program for Predicting l

  1. NUREG/CR-0225,

' CONTEMPT-LT/28 Containment Pressure-Temperature Response to a Loss-of-Coolant-Accident," p Hargroves, D. W., et al., Idaho National Engineering Laboratory, March, 1979 WCAP-8312-P-A, Revf.sion 1 (Proprietary) aad WCAP-8312-A (Non-Proprietary), i " Westinghouse Mass and Energy Release Data for Containment Design,' Shepard, R. M., et al., August 1975 l r

Attachment II to ET 91-0135 'Pege 4 of 10 l l and the LOFTRAN computer code was used to develop the mass and energy release data. The new analyses included development of mass and energy release data for the complete duration of the MSIB event. The revised analyses were performed using the same assumptions and initial conditions as specified in the USAR with the following exceptions. An outside air temperature of 120 F was assumed for the new analyses vs. a previously assumed valce of 95 F. The assumed Containment Spray flow was reduced by five (5) percent to 1.458E6 lbs/hr. These differences are conservative (i.e., would tend to result in higher values of calculated containment pressure and temperature). The effect of reducing the cooling water flow to each cooler group from 4000 gpm to 2000 gpm was accounted for by reducing the assumed heat transfer rate of a containment cooler group by approximately 55Z. This value was derived by taking the design heat transfer rate for a single cooler unit at 2000 gpm and applying an additional 10% reduction. This is ccaservative since the 2000 gpm required flow would be split between the cwo cooler units of each cooler group, resulting in a higher total heat transfer rate than for a single cooler unit with the same cooling water flow rate. Reducing the single unit heat transfer rate by 10% provides additional conservatism. Using the methodology described above, the spectrum of LOCA and MSLB accidents described in USAR Section 6.2, " Containment Systems," was reanalyzed. The peak containment pressure following a LOCA was calculated to be 47.3 psig. This value, obtained for a double ended reactor coolant pump suction guillotine break with minimum safety injection (Figure 1), IL the same as the current USAR analysis. The peak pressure following a LOCA remains below the peak pressure of 48 psig specified in Technical Specification 3/4.6.1.2, " Containment Leakage," for Local Leak Rate Tacting and Integrated Leak Rate Testing required by Appendix J to 10 CFR 50. As shown by Figure 1, the post-LOCA containment pressure fallt to below 50% of the peak vglue wi*hin 24 hours as specified by Standard Review Plan Section 6.2.1.1.A. Therefore, no change to this section of Technical Specifications is required and there is no impact on the offsite radiological dose consequences due to a postulated LOCA as described in the USAR. 6 ForanMgLB,thepeakpressurewascalcule'.edtobe48.9psigforCase9 a 0.80 ft split rupture at 502 power (Figure 2). This is slightly higher (0.8 psi) than the preyiously calculated peak pressure of 48.1 psig for Case 12, a 0.66 ft split at 251 power, but remains well telow the containment design pressure of 60 poig. The peak containment pressure following an MSLB is not contained in the Technical Specification Limiting WCAP-7907-P-A, "LOFTRAN Code Description," Gurnett, T. W., et al., April, 1984 NUREG-800, " Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants," Revision 2, July 1981 s Case numbers refer to Table 6.2.2-56 of the WCGS USAR

v Attachmsnt II.to.ET 91-0135 Phge 5 of 10-s Conditions for. Operations or Surveillance requirements and therefore, no changes. are required as a result of this increase. The revised peak l containment pressure following an MSLB is reflected in proposed changes to j Technical Specification Bases sections 3/4.6.1.4, " Internal Pressure,' and 3/4.6.1.6. ' Containment Vessel Structural Integrity,' i The results.of the revised analyses of containment peak pressure-are i summarized below. l i Containment Pressure (psig) Current USAR New Analyses l LOCA 47.3 47.3 MSLB 48.1 48.9 I Containment l Design Pressure 60.0 f i 'The revised peak containment temperature analyses showed that the LOCA l events continue to be bounded by the MSLB events as described in the current t USAR analyses. For an MSLB the calculated peak containment temperature was 386.5 F which occurred for Case 7, a full double ended rupture at 50% power (Figure 3). This is a; slight increase (1.6 F) fromghepreviouslycalculated j peak temperature of 384.9 F for Case 6, a 0.84 ft split at 75Z power. Review of environmental qualification documentation for equipment located t inside the containment has concluded that the equipment remains fully qualified for the revised containment environmental conditions. In addition to the proposed reduction in required cooling water flow in the [ post-accident mode, this proposed change includes deletion of the current . requirement for periodic verification of a specified minimum cooling water f flow ir the normal CCS operational alignment. In its normal operating mode j the cooling water flow to the ESWS is supplied from the non-safety related SWS. In this mode the cooling water flow rate to components supplied by the ESWS are dependent on the pressure in the SWS, the position of throttle valves in the ESWS return line to the SWS, and-specific component configurations within the ESWS. These parameters-may vary greatly due to seasonal temperature changes. As a result, the cooling water flow rate to. the containment coolers in their normal alignment also varies significantly. Cooling water flow rate variations of up to. 300 gpm per j cooler group are frequently observed as a result of such variations in. -operating conditions. Therefore, the measurement of the normal cooling l water flow rate to the containment cooling units does not provide an i appropriate indication-of the capability of the coolers to perform their j safety function or allow meaningful data trending to detect potential flow -i degradation. L As discussed above, the capability of the containment coolers to perform their. safety function is . adequately verified by the surveillance requirements of Technical Specification 4.6.2.3.b. This

test, which is l

i - performed at least. once per 18 months, measures the cooling water flow rate r l to the containment coolers with the ESWS and its supplied components in [ l their post-accident alignment. This test configuration provides a constant t ESWS backpressure and allows an accurate assessment of the flow capability [ of the' containment cooling units. l L k

Attachment II to ET 91-0135 1 Page 6 of 10 In addition, the performance of the containment cooling units, along with other safety related heat exchangers, is routinely monitored to detect any flow degradation due to pipe fooling or tube plugging as part of the program required by Generic Letter 89-13, ' Service Water System Problems Affecting Safety-Related Equipment". This monitoring program includes as periodic periodic measurement of flow and pressure differential as well testing to measure the heat transfer capability of the cooling units. The surveillance testing required by the proposed revision to Technical Specification 4.6.2.3.a.2 together with the routine performance monitoring of these heat exchangers provides assurance that the containment coolers will function as required following any postulated accident. During nornal operations the containment coolers also serve to maintain the containment conditions consistent with the assumptions of the safety analyses and suitable for safety related equipment located in the containment. This is adequately verified by the requirements of Technicsl Specification 3/4.6.1.5, ' Containment Systems - Air Temperature," which requires vegification that the average containment air temperature does not exceed 120 F at least once per 24 hours. Potential degradation of the containment coolers could be identified by monitoring cooler leakage. Leakage from the coolers is identified by the Nuclear Plant Information System that monitors level tcansmitters associated with the leak detection standpipes for each cooler. The surveillance requirement for the CCS with revised surveillance requirement 4.6.2.3.a.2 provides a level of assurance comparable to the surveillance requirements for other safety related equipment. For example, the surveillance requirements associated with Technical Specification 3/4.7.4, Essential Service Water System and 3/4.7.3, Component Cooling Water System require a valve position verification every 31 days, an automatic ensure the pump starts and valves are correctly positioned every action to 18 months and inservice testing in accordance with Technical Specification s 4.0.5, Based on the above discussion, both the normal and post-accident functions of the CCS are adequately verified by other testing. Therefore, since the testing currently required by Technical Specification 4.6.2.3.a.2 does not provide an appropriate indication of capability of the CCS, this testing requirement is being replaced by a proposed requirement to perform a periodic verification of proper valve posicions in the cooling water flow path. conclusions The effect of the proposed reduction in the minimum required cooling water flow rate to the containment coolers Las been evaluated and shown to have no significant effect on the consequences of postulated accidents. For a LOCA, the calculated peak containment pressure is unchanged and the containment pressure response remains consistent with the* assumptions used to evaluate the potential offsite radiological consequences of a LOCA due to leakage from the containment. For an MSLB event, the contninment pressure remains well below the design pressure of the containment and the safety related equipment located within the containment has been evaluated and found to remain fully qualified for the revised containment conditions. The deletion g

- -~.- - -.

6 91-0135 Attachment'II to ET I Page:7 of 10 f of the surveillance requirement for flow measurement during normal -{ operations does not adversely affect the reliability of the CCS since + ongoing performance monitoring of these heat exchangers provides a more } appropriate indication of. potential - degradation. In addition, a [ surveillance requirement to periodically verify proper valve positions in j the. cooling water. flow path has been added to provide additional assurance i that the flow path 10 functional. On these bases, it is concluded that the l probability of occurrence or consequences of equipment malfunctionn or j accidents previourly evaluated in the USAR are not increased. f The CCS serves to mitigate the consequences of postulated accidents, but is [ act associated with the initiation of design basis events and has no direct impact on the Reactor Coolant-System or other structures or systems associated with-the initiation of postulated accidents. Therefore, the possibility of a new accident that is different from aty already evaluated j in the USAR is not created. I The proposed reduction in required cooling trater flow is acceptable based on revised accident analyses. For a LOCA the containment peak pressure and temperature were not increased. Although a slight increene in the MSLB peak j containment pressure does occur as a result of this proposed change, the revised value remains well below the containment design pressure. The [ margin of safety between the containment design pressure and the pressure at { whicn the containment would ultimately fail is ut. changed by this proposed j amendment. Therefore, it is concluded that there is no reduction in the margin of safety as described in the bases of any technical specification. f i ~ i ? t f i i i l f r 5 I \\

gy < spa 0 - ,g CONTAINMENT PRESSURE RESPONSE TO POSTULATED C DEPSG LOCA WITH MINIMUM SAFETY INJECTION E "i s0 e Peak Pressure = 47.3 psig 5 @ 140 seconds t4 g 30 j-O / b 8 \\ m 8 20 n. I i 10 \\% 1 ol ,,,,,r ,,,,,1 a ,...,,1 . m,.i .t 0.1 1 10 100 1000 10000 100000 1000000 Time (seconds) Figure 1

ggc E g-3 e,$ - CONTAINMENT PRESSURE RESPONSE TO 8: POSTULATED MSLB CASE 09 I 60 C. 6 C 50 ^.9 mQ. vg eg Peak Pressure = 48.9 psig ~ @ 1800 seconds 2 Q. 30 E m E 4 C E 20 c 0 MSLB Case 09 o 50% Power Level 10 0.80 f t2 Split Break I I 0 O 500 1000 - 1500 2000 Time (sec) Figure 2 -.r -y .c. v. ~w. w~,- w ov,.m,r,-e-+% =-o st e m -e wr-rv--- a w, ew x-v ow e-e---n-4-v.- n-*w w+ ,-r----+++- -e s u~,ive-r--i.<e-e -s- .+-

gy

  • a og-O3 CONTAINMENT TEMPERATURE RESPONSE TO POSTULATED MSLB CASE 07 1

400 ~ 4 Peak Temperature = 386.5 F @ 125 seconds b 5 Spray Activated M u. v 3 300 E.- E 9 250 Ee E _C 200 3 5 MSLB Case 07 0 50% Power Level ,3, ~ Full D.E. Break I l I 100 O 500 1000 1500 2000 Time (sec) FIGURE 3 t:

AttechmbntIIItoET 91-0135 Page 1 of 3 ATTACIMENT III REVISED SIGNIFICANT IIAZARDS CONSIDERATION Dl; TERMINATION. i 9 + b ? t

.. Attachment III;to ET 91 0135 i ,Pago 2 of 3 l SICNIFICANT HAZARDS CONSIDERATION DETERMINAii)N This proposed change has been reviewed per the standards provided in i 10 CFR 50.92. Each standard is discussed separately below. i g l Standard I Involves a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated. j i This amendment ~ request proposes to reduce the minimum cooling water flow -[ requirement for the containment cooling system (CCS) for post-accident conditions. In addition, a surveillance requirement to verify a specified t minimum flow rate in the normal operating mode of the CCS is deleted and } replaced with a requirement for periodic valve position verification. The + effect of.the proposed reduction in the minimum required cooling water flow rate to the CCS has been evaluated and shown to nave no 91;nificant effect on the consequences of postulated accidents. For a ptstalated Loss of f Coolant Accident (LOCA), the calculated peak contaitsent pressure is f unchanged and the etiatainment pressure response remains contiotent with the i assumptions used tc evaluate the potential offsite radiological consequences { of a LOCA due tofleakage from the containment. For a postu?ateo Main Steam l Line Break (MSLB)- event', the containment pressure remains well below the I design pressure of the containment-and safety related equi tent located l within-the containment has been evaluated and found to remain fully qualified for the revised containment conditions. The deletion of the .i surveillance requirement for flow measuremont-during normal operations does not. adversely. affect the reliability of the CCS since the proposed requirement :for perindic valve position verification along with ongoing Lperformance monitoring-of these heat exchangers provide more reliable -indications of system performance. On these-bases, it is concluded that l there will be no significant increase in the probability of occurrence or consequences'of previously evaluated accidents. l 9 f Standard -II - Create the Possibility of a New or Different Kind of Accident From any-Previously Evaluated. The CCS serves to mitigate the consequences of postulated accidents, b

  • is

+ unot associated with the initiation of design basis eventa and has no direct -l impact on) the Reactor Coolant -System or other structures or systems j associated-_ with the initiation of postulated accidents. Therefore, this . proposed technical specification revision does not create the possibility of { a new or different kind of accident from any previously evaluated. l Standard III - Involve a Significant Reduction in the Mkrgin of Safety, f I The proposed reduction in required cooling water flow has been shown to be acceptable based (ni revised accinent analyses. For a LOCA the containment peak pressure and temperature were not increased. Although a slight i increase in the MSLB peak containment pressure does occur as result of this proposed change, the revised value remains well below the containment design pressure. The_ margin of safety between the containment design 1 pressure and the pressure at which the containment would ultimately fall is [ unchanged by this proposed amendment. Therefore, it is conclu6ed that there is no-significant reduccion in the margin of safety as described in the bases of any technical specification, j i I ~ ~

Attachment'III.to ET 91-013fi ,Page'3 of 3 Based on the'above, the-requested technical specification change does --not involve a significant. increase in the-probability or consequences of a... ~ previously evaluated accident, create the possibility of'a new or different kind-' of accident, or involve a significant reduction in the margin of safety. Therefore, the requested license amendment does not involve a significant hazards consideration in accordance with 10 CFR 50.92. p i-l l-e.. ;

Attachmsnt IV to ET 91-0135 ,Page 1 of 2 1 t ATTAC1 MENT IV REVISED ENVIRONMENTAL IMPACT DETERMINATION F F 't t f e 4 h l

i. Attachmsnt IV to ET 01-013$ page 2 of 2 FNVIRONMENTAh 3MPACT DETERMINATION This amendment request meets the criteria specified in 10 CFR $1.22(c)(9). Specific criteria contained in this section are discussed below. (1) the amendment involver no significant har.ards consideration. Ae demonstrated in Attachment II, this proposed amendment does not involve any significant hazards considerations. (11) there is no significant chango in the typee or significant increase in the amounts of any effluents that may be released offeite. The proposed change reduces the minimum flow requirements for cooling water to the containment cooling system under post-accident conditions. The proposed change also replaces a requirement to verify a specified minimum flow under normal system alignment with a requirement to periodically verify proper valve alignment. The reduction in the minimum required flow to the containment cooling system will increase the available service water system flow rate margin. This will provido adequate margins for future flow balancing and redistribution to assure adequate flow is provided to the various safety related components served by the service water system. There are no changse to the methods of operations an a result of this amendment and the system will continue to provide adequate flow for the required cooling of necessary systems and components. (iii) there le no significant increano in individual or cumulative occupational radiation exposure. Other than the proposed reduction in minimum required flow to the containment cooling system, the proposed amendment does not affect the method of operation of the service water system or containment cooing system. The proposed amendment does not involve systems which contain radicactive materials and will have no aftect on levels of radiation normally present in the facility. Therefore, there will be no significant increase in individual or cumulative radiation exposure associated with this proposed amendment. Based on the above, there will be no significant impact on the environment resulting from this chenge and the change meets the criteria specified in 10 CFR 51.22(c)(9) for a categorical exclusion from the requirements of 10 CPR 51.21 relative to a specific environmental assessment by the Commission. ..}}

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