ML19275E724

Forwards Supplemental Safety Evaluation Supporting Licensee 800125 Response.Peak Containment Pressure Will Remain Below Design Pressure Even W/Addition of Auxiliary Feedwater at Run Out Flow

ML19275E724
Person / Time
Site:	05000000, Millstone
Issue date:	05/09/1980
From:	Check P Office of Nuclear Reactor Regulation
To:	Novak T Office of Nuclear Reactor Regulation
Shared Package
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References
FOIA-80-515, FOIA-80-555 TAC-42410, NUDOCS 8005300388
Download: ML19275E724 (2)

Text

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MQ 9 ' m Docket No. 50-336 MEMORANDUM FOR:

Thomas M. Novak Assistant Dimetor for Operating Reactors, DL FROM:

Paul S. Check, Assistant Director for Plant Systems, DSI

SUBJECT:

STAFF EVALUATION OF MILLSTONE, UNIT 2 RE: CONTAINMENT OVER-PRESSURIZATION POTENTIAL DUE TO AUXILIARY FEEDWATER PUMP Ri>N-0UT FLOW FOLLOWING A MSLB By letter dated December 21, 1979, the staff requested Northeast Utilities, the licensee for the Millstone Nuclear Power Plant. Unit 2 to provide certain additional information. Specifically, the licensee was to assess the potential for containment overpressurization due ter the anticipated continuous addition, at pump mn-out flow, of auxiliary feedwater to the affected steam generator following a postulated main steam line break (MSLB) accident.

The staff's interest in this issue resulted from the recomendation of the Three Mile Island, Unit 2 (TMI-2) Lessons Leamed Task Force to automate initi-ation of the auxiliary feedwater systems. Automating the auxiliary feedwater system would cause an increase in energy released to containment after a MSLB; thereby, increasing the containment pressure response to a MSLB.

By letter dated January 25, 1980, Northeast Utilities responded to the staff's letter cited above.

Thethe original MSLB analysis by Northeast Utilities, no consideration was given to auxiliary feedwater pump run-out. % licensee has since perfonned an analy-sis that demonstrates that the addition of auxiliary feedwater at the run-out flow condition will not cause containment pressure to rise above the initial blowdown peak.

The staff concurs with the licensee's finding that the peak containment pressure will remain below the containment design pressure even with the addition of aux-iliary feedwater at run-out flow. An SER on this matter was prepared by the Containment Systems Branch and is enclosed.

In the course of our review of the postulated MSLB with auxiliary feedwater pump at run-out flow, we noted that the licensee had not considered the consequences of postulated single failures such as failure of the main feedwater control valve

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~290 Thomas M. Novak to close. To satisfy current criteria, the MSLB accident would have to be' re-analyzed assuming single active failures. We suggest that you may wish to have the licensee rannalyze the containment resoonse transient in a manner consistent with current criteria at an appropriate time.

Paul S. Check, Assistant Diractor for Plant Systems Division of Systems Integration

Enclosure:

As stated cc:

R. Clark E. Conner O. Parr W. Butler J. Shapaker P. Hearn Central files CSB Rdg NRR Rdg PCheck e

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/80 NRC FORM 318 (9-76) NRCM O240 DU.S. GOVERNMENT PRINTING OF ICE: 1979 289-369