ML20056F374

Requests That ABB-CE Comprehensively & Systematically Evaluate Potential Design Alternatives Proposed to Reduce Probability of SGTR Containment Bypass Accident Sequences

ML20056F374
Person / Time
Site:	05200002
Issue date:	08/12/1993
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Matzie R ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
References
NUDOCS 9308270065
Download: ML20056F374 (2)

Text

,

August 12, 1993 l

Docket No.52-002 l

Mr. Regis A. Matzie l

Vice President Nuclear Systems Licensing ABB-Combustion Engineering, Inc.

1000 Prospect Hill Road

)

Windsor, Connecticut 06095-0500

SUBJECT:

CE SYSTEM 80+ PROTECTION AGAINST CONTAINMENT BYPASS DURING A STEAM GENERATOR TUBE RUPTURE (SGTR)

More than a year ago, the NRC staff asked whether features could be provided in the System 80+ design to reduce the probability of SGTR containment bypass accident sequences.

Although ABB-CE has studied this matter, the staff has seen virtually no design improvements to address this important safety issue.

The use of Inconel 690 for steam generator (SG) tube material, although an important j

improvement, is not sufficient by itself to reduce staff concerns.

Despite improvements in SG circulating ratio, the staff is not convinced that the tube degradation phenomena in the System 80 SG are fully understood to conclusively rule out applicability to the CE System 80+ SG design. Assuming an SGTR frequency of 10'2 per reactor-year (as many years of experience show) and heavy reliance upon operator actions to prevent subsequent core damage, the staff does not have high confidence that the large-release guideline of 10~6 per-reactor year can be met with the current System 80+ design.

The staff requests that ABB-CE comprehensively and systematically evaluate potential design alternatives that ABB-CE proposes to deal with this issue.

These design alternatives, among which are use of nitrogen-16 monitors and automatic primary depressurization, were discussed during previous meetings between NRC staff ana ABB-CE staff.

Efforts to resolve similar containment bypass issues (interfacing-systems loss-of-coolant accident (ISLOCA)) have been highly successful. Although the ISLOCA resolution required substantial effort by both parties, the staff is prepared to treat the SGTR containment bypass issue in a similar manner and encourages ABB-CE to adopt this approach in order to maintain current scheduleddginalShnodgg Dennis M. Crutchfield, Associate Director for Advanced Reactors and License Renewal Office of Nuclear Reactor Regulation cc:

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0FFICIAL RECORD COPY:

9308270065 930812 7

DOCUMENT NAME:

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PDR ADOCK 05200002 M

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ABB-Combustion Engineering, Inc.

Docket No.52-002 cc:

Mr. C. B. Brinkman, Acting Director Nuclear Systems Licensing ABB-Combustion Engineering, Inc.

1000 Prospect Hill Road Windsor, Connecticut 06095-0500 Mr. C. B. Brinkman, Manager Washington Nuclear Operations ABB-Combustion Engineering, Inc.

12300 Twinbrook Parkway, Suite 330 Rockville, Maryland 20852 Mr. Stan Ritterbusch Nuclear Licensing ABB-Combustion Engineering 1000 Prospect Hill Road Post Office Box 500 Windsor, Connecticut 06095-0500 Mr. Sterling Franks U.S. Department of Energy NE-42 Washington, D.C.

20585 Mr. Steve Goldberg Budget Examiner 725 17th Street, N.W.

Washington, D.C.

20503 Mr. Raymond Ng 1776 Eye Street, N.W.

Suite 300 Washington, D.C.

20006 Joseph R. Egan, Esquire Shaw, Pittman, Potts & Trowbridge 2300 N Street, N.W.

Washington, D.C.

20037-1128 l