ML19220C418

Forwards Draft Suppl to SER Re Applicants Revised Analysis of Available Net Positive Suction Head for Containment Spray Sys Pumps.Accepts Proposal to Throttle Spray Pumps

ML19220C418
Person / Time
Site:	Crane
Issue date:	03/23/1978
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	Vassallo D Office of Nuclear Reactor Regulation
References
NUDOCS 7905010237
Download: ML19220C418 (6)

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I'SE 2 3193 Docket No. 50-320 MS10RN!DUM FOR:

D. Vassallo, Assistant Director for Light Water Reactors, DF:t FRGt:

R. L Teuesco, Assistant Director for Plant Systems, DSS

SUBJECT:

DRAFT SUPPLEEIT TO THE SAFETY EVALUATION REPORT FOR Tl'REE MILE ISLMD NUCLEAR STATIO:i, U LIT 2 Plant Name: Three Mile Island Nuclear Station, Unit 2 Docket Numner: 50-320 Milestoaa Number: 24-04 Licensing Stage: CL NSSS Supplier: Babcock & Wilcox Architect Engineer: Burns & Roe Contaircent Type: Dry Responsible Branch & Project Manager: LWR-2; II. Silver Requested Coupletion Date: H/S Review Status: Incomplete-Enclosed is a draft Supplement to the Safety Evaluation Report (SSER) for the Three Mile Island Heclear Station, Unit 2, addressing the applicnet's revised analysis of tne available net positive suction head (NPSH) for the contairment spray systes pumps. The impact of the proposed administrative controls for adjusting spray system flow rates on the previously accepted containcent depressurization analysis and contain:::ent analysis for the ECCS performance evaluation are also addressed.

During the course of pre-operatie al testing, it was discovered that one of the contaira:ent spray system pumps did not meet the pump head curve supplied by the vendor ' Babcock & Wilcox Canada. Ltd).

Both pump impellers were teturned to the vendor, and the pump bead curves and NPSH requirements were redetemined. The test results showed that the required NPSii would exceed the available NPSH under punp runout conditions. The applicant therefore, pecposes to rely on operator action to throttle the pumpa to assure that the ay311able NPSH would be adequate for the spray ptops.

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3. Vassallo NAR 2 g 3,3 We have ccmpleted our evaluation of the applicant's proposal to tnrettle the spray pumps, and based upon the available tir.c margins for operator action, we conclude that it is an acceptable solution.

We and our consultant plan to centinue reviewing the available test data, to confirm the safety cargins for allowing operator action or determine the need for additional pump testing to provide greater assurance of pump reliability when operating in a cavitating mode, or determine the need for syste design changes.

Oddcal si.~,.o.g 5 d L. Tedesco Robert L. Tedesco, Assistant Director for Plant Systems Division of Systems Safety Enclorure:

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