ML20094N290

Documents Info Presented During 920326 Telcon Re Util Commitments for Monitoring Crack Growth Rate Conditions in RCS Using Data Obtained from Crack Arrest Verification Sys During Cycle 8 Operation

ML20094N290
Person / Time
Site:	Brunswick
Issue date:	03/30/1992
From:	Starley R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NLS-92-102, TAC-M81880, NUDOCS 9204060274
Download: ML20094N290 (9)

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C9&L C$rolina Power & UgM Company a,-u.o steam f.eette tsant eosn,an. w wsue w March 30,1992 RUS$tLL tt $Y AOKLY. J H, l'uma c af Petuett SERIAL: NLS 92102 United States Nuclear Ro0ulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO.1 DOCKET NO. 50 325/ LICENSE NO. OPR-71 FEEDWATER NOZZLE N4D SAFE END UT INDICATION (NRC TAC NC. M81880)

Gentlemen:

The purpose of this letter is document information presented to the NRC Staff durin0 a telephone conference call conducted on March 26,1992. This telephone call related to Carnlina Power & Light Company's commitments for the monitoring of crack growth rate conditions in the reactor coolant system using data obtained from the crack arrest verification system (CAVS),

By letter dated Janucry 10,1992 (Serial: NLS-91335), CP&L provided Information concoming the Company's intended actions based on the crack arrest verification system monitoring. On May 16,1991, CP&L initiated crack arrest verification system dats to validate the crack Drowth law model used to justify operation for the current operating cycle. On March 21.1992, operations personnel observed an increase'in Unit 1 reactor coolant system leakage as monitored through ihe primary containment (drywell) floor drain. AlthoLgh the soecific origin of the leakage was unknown, the leaka0e is believed to be the result of a packing leak on one or more reactor coolant system valves. The Unit 1 Technical Specifications limit the amount of unideritified reactor coolant system leaka00 to the following:

A 2 gpm increase in unidentified leakage wittiin any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period 5 Oprn unidentified leaka0e over any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period.

As a result of this increasing Unit 1 dtywell floor drain leakage, the B32 F013 containment isolation valve was closed. Closure of this valve did result in a decrease in observed flow to the drywell floor drains and supported the belief that the leakage is the result of a packin0 l eak on the B32-F019 valve. Closure of the C00033 9204060274 920330 '

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. Document Control Desk NLS 92102 / Page 2 B32 F019 valvo isolates flow to the 3/4 lach sampio line that providos reactcr I

- coolant system flow to the crack anost verification system Thora are no alternato means of providing reactor coolant samplo flow to the crack arrost verification system; therefore, monitoring of reactor coolant system crack Drowth roto conditions cannot be continued at this timo, The enclosed tablo (Tablo 1) dividos crack arrest verification monitoring for Unit 1 Cycle 8 operation into five distinct periods. For parlod 1 (2/22/91 to 5/1G/91),

continuous crack arrest verification system monitoring was not performed; therefore, the maximum averago crack arrest verification system growth rato (2.45E 5 inches / hour) was assumed. For the second period (5/16/91 to 3/13/92),

crack arrest verification system measuromonts Indicated a growth rate of l 1.1E 5 inches / hour t'or a total of 0.0715 inches of Growth as shown in l

- Enclosuro 3. For the third period (the current operational parlod for Unit 1), crack '

arrest verificatlor, system monitoring cannot be continued due to isolation of the  !

- 832-F019. valve; therefore, the maximum average crack arrest verification system I growth rate was assumed. For the fourth period (G/05/92 to G/21/92), Unit 1 will I be t. hut down for a surveillance testin0 outage; therefore, no crack arrest  ;

verification system growth will occur or be recorded. For the fifth period (6/22/92 to 9/11/92), the maximum overage crack arrest verification system growth rato

, was conservatively assumed, although the crack arrest verification system will be rostored to service. Those assumptions are conservativo based on the observed i

. ton months of crack arrest verification system datormined crack growth rate for

- parlod 2. Roactor coolant system chemistry is not expected to change appreciably during the current cycle, thereby ensurin0 that the crack Drowth rate for the balance of the current operatin0 cyclo romains conservatively bounded.

. The total crack hirest verification system Orowth measured and conservatively _

projected from the five periods discussed is 0.1946 inches compared to the ASME Codo ,Section XI flaw limit's allowable growth of 0.3219 inches, Thorofore, best on conservativo projection of crack arrest verification system and corresponding foodwater nozzlo flaw Orowth, continued operation of Brunswick i

- Unit 1 until a achaduled survcillance testing outa00 in June 1992 without the availability _'of tho_ crack arrest verification system is justified and has no adverso impact on the health and safety of the public.

At present, a throo week outa00 is scheduled to begin either May 30,1992 or

, June 6,1992 to perform rnut_ino surveillanco tests. During this outa00, the Company intends to repair the B32-F019 valvo, thereby allowin0 rostoration of

_ reactor coolant system sample flow to the crack arrest verification system followin0 unit re start. Until the planned surveillance testing outago, the Company intends to perform the alternato crack Drowth monitoring by inferring the ,

inconol 182 crack propagation rate on a monthly basis using tne averago ,

I p 9,g.-+-9 a %,ep v.,me,.e--yp. 'yg-- p,w,, - w u e y- , e.d,,,,m ,,,me,.,w.~sy,him-....c,mo9%.,,W,n v,-.-- .%c. ,.ir,t =e=.-mue-.r., w e , enn., -e. . - * , - . . , - , - . - + w~aw--**.--*,w -w- e--

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. Docudient Control Desk Ni S 92102 / Page 3 conductivity.and a calculational model found in EPRI draf t report RP200617. The model yields the throo curvos shown in Enclosure 2. The top curvo represents the Brunswick Plant situation based on an incor 01182 ECP of 120 130 mVSHE. For exarnplo, at 0.20 ps/cm the growth rato is 1.2BE 8 cm/ soc or 1.81E 5 inches / hour.

- This sooms to comparo well to crack arrest verification system data for this environment and providos additional assurance to the 10 months of crack growth i history accurnulated since the Company's commitment to monitor crack arrest l verification data. If the calculation yloids a growth rato that exceeds the analyzed value of 2.45E 5 inchos/ hour, then accolorated monitoring would be performed as described in our previous commitment lotter. The averago Unit 1 conductivity for the year to dato is 0.125 ps/cm and is 0.175 ps/cm for the cycle to date.

The Com;)any requests the NRC Staff provide verbal foedback at their earliest

- convenienco on the acceptability of the alternato crack growth rato monitorin0 method described herein pending repair of the 032 F019 valvo.

Please refer any questions ro0arding this submittal to Mr. W. R. Murray at (919) 546-4661.-

Yours very truly, N l R. B. Starby, r.

L WRM/wrm_ (bnp1cav.wpf)

Enclosures i

i cc: Mr. S. D. Ebneter Mr.N.B.Lo L Mr. R. L. Provatte L W

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ENCLOSURE 1 BRUN3 WICK STEAM ELECTRIC PLANT, UNIT 1 NRC DOCKET NO. 50 325 OPERATING LICENSE NO. DPR 71 FEEDWATER NOZZLE N4D SAFE GND UT INDICATION (NRC TAC NO. M81880)

GuidMARY OF ORUNSWICK PLANT, UNIT 1 CRACK ARREST VERIHCATION SYSTEM MONITORING DURING CYCLE 8 OPERA flON

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TABLE 1 BRUNSWICK PLANT, UNIT 1 CAV MONITORWG t

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CORRET,PONOWG  !

'l PREDICTED FW ,  ;

TOTAL OPERATING

• CAV PAW l PERIOD HOURS HOURS REMARKS AA UNCHES) AA UNCHES) )

2/22/91 -5/16/91 197G 1004 Start of Operating (0.0261) 0.0070 l I Cycle (Assumed  !

Maximum Growth i i Rate) t .  ;

5/16/91 -3/13/92 7220 6445 ' CAV Monitor in 0.0715 0.02~ 8 Service  !

'1 3/13/92 - 6/05/92 1992 1992 CAV Monitor Not in (0.0483) 0.0153 l l Seivice [

(Assume Maximum i Growth Rate) 6/O5/92- 6/21/92 408 0 SurveiF.ance ] O O l Testing Outage  !

i 6/22192 - 9/11/92 1968 1938 Remaining (0.0482) 0.0173  ;

Operating Cyc!e (Assume. Maximum l Growth Ratei }

f p TOTAL 13.564' 11.469 0.1946- 0.0612  ;

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ENCLOSURE 2 BRUNSWICK STEAM El.ECTRIC PLANT, UNIT 1 i NRC DOCKET NO. 50 325 l l OPERATING LICENSE NO. DPR 71 i FEEDWATER N0ZZLE N4D SAFE END UT INDICATION i

(NRC TAC NO. M81880) ,

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ENCLOSURE 3 BRUNSWICK STEAM ELECTRIC PLANT, UNIT 1 NRC DOCKET NO. 50-325 OPERATING LICENSE NO. DPR-71 FEEDWATER NOZZLE N4D SAFE END UT INDICATION (NRC TAC NO. M81880)

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. y BRUNSWICK UNIT 1.C'. A. N. SYSTEM DATA .

, INCOMEL'182 SPECIMEN CRACK GROWTH  :

0.34  :

0.32 -

0.3 -  :

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0.26 -

g 0.24 -

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CAV SYSTEM HOURS THROUGH 1/25/92 l ACTUAL LENGTH ASSUMED . LENGTH '-

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