ML20148H239

Summary of 780904 Meeting W/Util Re Asymmetric LOCA Loads,Generic Task A-2 & Related SEP Topic.Attendance List Encl

ML20148H239
Person / Time
Site:	Yankee Rowe
Issue date:	10/02/1978
From:	Burger A Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
REF-GTECI-A-02, REF-GTECI-RV, TASK-A-02, TASK-A-2, TASK-OR NUDOCS 8011170464
Download: ML20148H239 (5)

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Docket " . 0-29 OCT 0 21978  :

LICE!iSEE: Yankee Atomic Electric Company (YAEC)

FACILITY: Yankee Nuclear Power Station (Yankee-Rowe)

SUMMARY

OF SEPTD!BEP, 4,1978 !!EETIf1G C0!1CERf1ING _ ASYMMETRIC LOCA LOADS .

On September 4,1978, the NRC staff met with representatives of YAEC to discuss information needed ;for resolution of' asymmetric LOCA loads, generic task A-2, and relater'. Systematic Evaluation Program (SEP) y;.

topic. . p A list of attendees is attached. h I

By letters dated January 25, 1978, and June 7, 1978, we requested YAEC to perfom an assessment of potential daaage to the reactor coolant

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system and reactor vessel internals from postulated asymmetric LOCA i loads. It was also requested that this assessment be extended to include the potential effects of such loads on other safety related facility featurest YAEC was requested to submit a detailed schedule for the evaluations which would. result in resolution or the problem within two years. YAEC's response in letters dated February 21, 1978 and June 21: 1970, was that our request for additional o 'luations reprcrents a change of the design basis for Yankee-Rowe; namely, a conservatively designed reactor coolant system, backed by an emergency core cooling system and an analysis that shows that even if a fission product release were assummed from a major accident (hypothetical accident), the calculated doses at the exclusion boundary are below the guideline values in 10 CFR Part 100. Since A this is the design basis upon lwhich Yankee-Rowe is licensed to be operated, YAEC did not believe they should be required to purfom specific analyses of LOCA related effects o,n structures and components; ,

however, if new bases are to be imposed it should be done as a part of , E the Systematic Evaluation Program.

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During the meeting YAEC expanded on its position that evaluation of effects of asymmetric LOCA loads is not necessary because the Yankee-Rowe reactor coolant system piping was designed to ASME B.31.1 criteria which provides thicker pipe walls resulting in lower stresses compared to piping designed to the current AS!iE Section III criteria.

Therefore, a pipe break should rot need to be considered likely. We indicated, however, that based on all information available to us to date we cannot conclude that a break of a large reactor coolant system pipe is not a credible event. Therefore, YAEC's position is not acceptable to us and the evaluations identified in our January 25, 1978 request are required for Yankee-Rowe. Furthermore, we indicated that resolution of the problem within about two years, as a generic .y task (rather than an SEP topic), is required by the Conrnission because l we could not justify based on probabilistic arguments that a large pipe break is an acceptable risk beyond about two years. We explained mj how the results of this generic task would be integrated into the SEP "

review of Yankee-Rowe. We 61so explored possible methods for integrating this effort with seismic considerations and pipe breaks inside contain- =

y ment, both SEP issues. ,

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In summary, we indicated that: (1) the asynmetric LOCA loads issue ..

will be evaluated in the generic task A-2 and will be coordinated with '

cur SEP review of Yankee-Rowe because of seismic considerations, and I (2) we require that YAEC perfom and provide us the results of t- ,

analyses of the e~ffects of asynraetric LOCA loads. '

YAEC indicated that they will meet with their consultants to evaluate H the effort involved to meet our requirenents. YAEC will advise us as soon as possible of their intent to proceed with the evaluations i identifying the scope and schedule for completing the efforts within about two years.

Wrd ensd 'O hlfredCurger,ProjectJ!anager '

Operati~ng Reactors Bram;b #2 ,'

Divisio,n of Operating R,eactors, Enctiosure :

1. Attendance List cc w/ enclosure:

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i cc w/ enclosure:

Mr. Lawrence E. Minnick, President ..2 Yankee Atomic Electric Company 20 Turnpike Road ,

Westboro, Massachusetts 01581 1 Greefield Community College 1 College Drive Greenfield, Massachusetts 01301 Yankee Atomic Electric Company -

ATTN: Mr. Robert H. Groce -

Licensing Engineer 1 20 Turnpike Road -

Westboro, Massachusetts 01581 l.: :b j I i

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i ATTENDANCE LIST

!!EETIltG WITH YANKEE ATOMIC ELECTRIC CO'1PNtY ASYtf1ETRIC LOCA LOADS Yankee Atomic Electric Company ..

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J. Hoffman il J. Stacey D. Hansen 1

fiRC 77Curger K. Jabbour H. Schierling ..

S. Hosford :l R. Snaider .l l

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