ML20235Z535

Forwards Addl Info in Response to NRC Request Re Safety Enhancement Program.Questions Re Direct Torus Vent Sys Deferred Until Addl Modeling & Analytical Work Completed

ML20235Z535
Person / Time
Site:	Pilgrim
Issue date:	10/08/1987
From:	Bird R BOSTON EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8710210186
Download: ML20235Z535 (5)

Text

I ocT es 87 15:17 BOSTON EDISON P.2

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I SEP Program

?0R N:0RVE ON OU aeli1 Boston, Massa:husetts 02199 j

Ralph G. Bird RC Sener Vi:e President - Nuclear BECo 87-2$

i U. S. Nuclear Regulatory Commission

>S Document Control Desk w

Washington DC 20555 Docket 50-293 A55E55HENT Of PILGRIM SAFETY ENHANCEMENT PROGRAM l

Reference:

1. NRC letter, S.A. Varga to R.G. Bird

" Initial Assessment of Pilgrim Safety Enhancement Program."

l dated August 21, 1987.

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2. BEco letter, R.G. Bird to S.A. Varga l

" Information Megarding Pilgrim Station Safety Enhancement Program," Letter No.87-111 dated July B. 1987.

Dear $1r:

The purpose of this letter is to provide additional information in response to the NRC staff's request (Reference 1) regarding the Pilgrim Safety Enhancement Program (SEP), as submitted in Reference 2.

The information contained in the attachment to this letter responds to the staff's requests except for those related to the Direct Torus Vent System.

Based on discussions between Mr. J. E. Howard (6oston Edtson) and the NRC staff during the period September 23 and 24, 1987, we are deferring our

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res xnse to the staff's question regarding the Ofrect forus Vent System until suci time as we can complete additional modeling and analytical work.

If you have any questions or require any additional information, platse contact us.

R?A 21868k 8?a886 p

PDR R. G. Bird

Attachment:

Assessment of Ptigrim Safety Enhancement Program MGL/jcp/1159 g

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l Mr. R. H. Wessman. Project Manager cc:

Division of Reactor-Projects I/II Office of Nuclear Reactor Regulation i

U.~S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, MD 20814 U. S. Nuclear Regulatory Commission

. Region I-

.631 Park Avenue King of Prussia, PA 19406 Senior NRC Resioent Inspector Pilgrim Nuclear Power Station 4

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I CCT 00 '87 15217 BOSTON EDISOM P.4 Attachment Lu BECu Let%er No. 5/-

Assessment of Pilerim Safety Enhancement Procram 1

1.

Sect. 3.4 - Additional Sources of Water for RPV Iniection and Containment SEAX NRC Reauett The staff recuests clarification regarding the modification to the RHR system to provide acditional sources of water for RPV injection and containment spray. This modification may require a change to the Technical Specifications. As described in the enclosure, the valves.to be added to the RHR system become part of the reactor coplant pressure boundary during.

operation of the RHR system and, consequently, are $Ubject to surveillance testing.

BECo Resnonse i

No changes are required to the Technical Specifications due to the addition of gate valve 10-HO-511 and check valve 10-CK-510 to the RHR system.

dZ Gate valve 10-H0-511 and check valve 10-CK-510 are not part of the O

reactor coolant pressure boundary. The reactor coolant pressure boundary consists of all those pressure-retaining components connected to the g

reactor coolant system, up to and including the outarmost containment o

isolation valve in system p

containment per 10CFR50.2.pi sing which penetrates primary reactor late valve 10-HO-511 and check valve 1

g 10-CK-510 are connected to tte RHR system outside the outermost g

containment isolation valve and are located outside the reactor coolant g

pressure boundary.

k These valves are connected to tha RHR system pressure boundary but will 3

be maintained in a closed position during all events or conditions analyzed in.the FSAR. The original plant design inc'orporated a similar g.

connection to the RHR system from the salt service water system. The valves in this interconnection are also maintained in a closed position and are nnt included in Technical Speetfications. The integrity of the RWR system pressure boundary is verified by hydrostatic pressure testing in accordance with the Pilgrim Nuclear Power Station Inservice Inspection Program.

2.

Sect. 3.7 - Ra dun Witronan tunniv tvatam MRC Raeustt The staff requests clarification regarding the function of one valve in the backup nitrogen supply system. As described in the enclosure, valve AD-4356 appears to be a containment isolation valve and, consequently, would be appropriate for inclusion in the Technical Specifications.

REco Ratnente Cheek valve $1-CM-167 is the primary containment isolation valve in the nitrogen supply line, not valve A0-4356 which is upstream of check valve 31-CK-167. Class C lines as defined by FSAR Section 7.3.2 require only one primary containment isolation valve; this is check valve 31-CK-167. -

OCT 08 '87 15:88 BOSTON EDSSON P.5 Attachment %o BECo Le9ter No. 87-Annessment of Pilarim Safety Enhancement Procram FSAR Table 5.2-5 incorrectly lists A0-4356 as a primary. containment isolation valve. The table will be corrected in the next revision of the FSAR. Table 1 of Reference 2.1 also incorrectly lists A0-4356 as a primary containment isolation valve. Therefore. A0-4356 need not be tested in accordance with 10CFR50 Appendix J.

A0-4356 is not included in Pilgrim Technical Specifications.

Reference 2.1 BECo letter (J.E. Howard) No. 76-11 to NRC (D.L. Ziemann)

" Additional 10CFR50 Appendix J Evaluation", dated January 27, 1976.

3.

Sect. 312 - 14adifica" ion to Raaetor core Isolatien coeltne svntam Turbine Erhaust "rin Satooint

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NRC #squggi The staff still has questions regarding the proposed modification to the reactor core isolation cooling (RCIC) system. Prior to ilnplernenting this

' modification the staff requests that Bete conduct an assessment of hydrodynamic loads on the RCIC piping and supports, based ren the proposed exhaust. pressure of 46 psig, and make the results of that assessment available to the staff.

RFca Rannonse RCIC steam turbino discharge at higher back pressure up to 46 psig is acceptable for the following reasons:

Starting transients and air clearing loads are Ibw. The RCIC e

turbine has approxisiately a 10 second start up time. A gradual start up over such a long time will not produce high air clearing loads or dynamic effects.

Flow rates through the RCIC exhau t line are 10w. Steam flow at 25 a

psig back pressure is 12.3 lbs/ft sec (i.e.16,350 lba/hr in an 8" line, Reference PSAA Section 4.7) and would not change appreciably as back pressure is increased'to 46 psig, The pi e stresses and support / penetration loads for the Reactor Core a

IsolatfonCooling(RCIC)exhaustpipinghavepreviouslybeen h

evaluated for the combined loads of the Mark I Containment Program.

2 The maximum stresses and loads from that prograa occurred during the o

simultaneous application of Condensation Oscillation (00) shell p

loading C0 drag loads applied to the submerged piping, SSE loads.

.c thermal, loads, and weight loads. This load combination controlled the pipe stresses in the Mark I Program because the sinusaldal C0 forces occurred in a frequenc;r range where the piping has high o

dynamic amplification. This ts a severe condition that bochds any Lt..

forces related to continuous steam condensation at the low flow E

rates associated with RCIC operation.

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OCT 08 '87-15:19 BOSTON EDISON P.6 Attachment to BEco Letter No. 87-Annessment of Pilarim Safety Enhancement Proaram Although preseures and frequencies associated with RCIC~ discharge o

cannot be precisely determined, they are bounded, at PNPS, by data from safety relief valve' tests. Data-recorded in the Monticello Ramshead Tests showed steam condensation leads of s 6 psid or less.

This differential pressure is approximately pressures-due to tio LOCA C0 design load, y equal to the cyclic I

and as discussed above the C0 frequencies are in a range of typically high pipe response. The

-fact that the penetration and su) ports for the RCIC exhaust piping

' j meet all Code requirements for tie CO loads combination clearly demonstrates its ability to withstand the discharge forces associated with its own operation.

The design pressure of the RCIC turbine discharge piping is 100 psig, which is well above the proposed back pressure setpoint of 46 psig.

FOR N:0RMA"0t QN!_Y.

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