ML20235C636

Informs That Since Issuance of Staff Status Repts on Vendor ATWS Evaluations,Industry Raised Concerns Re Lack of Specificity of Guidelines Applied in NRC Review.Div Ltr to AIF on ATWS Guidelines Encl.W/O Encl

ML20235C636
Person / Time
Issue date:	08/31/1976
From:	Heineman R Office of Nuclear Reactor Regulation
To:	Sherwood G GENERAL ELECTRIC CO.
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References
FOIA-87-40 NUDOCS 8707090489
Download: ML20235C636 (1)

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r M2 AUG 3 1 876 Dr. Glenn G. Sherwood, Manager Safety and Licensing General Electric Company 175 Curtner Avenue San Jose, California 95114

Dear Dr. Sherwood:

1 Since the issuance of the staff status reports on the vendors'  !

AWS evaluations, the industry has raised concerns with what they f believe to be lack of specificity of the guidelines applied in j the staff review. In this regard, the staff met with the Atomic l Industrial Forum's Cometittee on Reactor Licensing and Safety on June 24, 1976 and discussed the industry concerns with the staff

, requirements and alternative proposals for timely resolution of. j i

this issue. Although we believe that the status reports provide l l specific AWS acceptance guidelines, we agreed to provide a '

l summary of these guidelines to the industry. The enclosed copy of our letter to AIF on AWS guidelines is provided for your information. We intend to apply the status report guidelines ,

in the review of your AWS submittals.

Sincerely, ,

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Robert E. Beineman, Director j Division of Systems Safety l Office of Nuclear Reactor Regulation

Enclosure:

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FEB 1 1 19fil 7,8,S,1011:12.1 i 2 3 4.5,"6

! MEMORANDUM FOR: M. Bender, Chairman, ACRS FROM: Denwood F. Ross, Jr., Assistant Director for Reactor.

Safety, DSS ,

SUBJECT:

BWR R0D DROP ACCIDENT (GENERIC ITEM IIA-2)

The latest letter from Birkhofer, et al, (enclosed) to the General Electric Company on the analysis of the central rod drop accident does not cause us to modify the conclusion stated in our report of 1 June 1976 that GE's analysis method is suitable even though it does not consist of a full three-dimensional representation.

The following brief comments may assist your review of this material.

1. The comparison of the spatial vs po, int kinitics results are basically irrelevant because, while the G.E. method is in a sense point kinetics in nature, the German po' int kinetics differs in detail from that of G.E., thus invalidating any direct comparison. ,

2. The nature of the problem, especially the important .

limiting G.E. cases, make any 2D-XY calculations and comparisons also irrelevant. -

3. Only the 3D-XYZ central vs asymmetric rod cases are of interest. These show a small increase (about eight percent) in peak energy for the asymmetric rod vs the central rod. However, as in the original report, the

. calculation is confused by the requirement to maintain a given rod reactivity worth in both cases. This implies (the information presented is insufficient in this area) that a somewhat different rod geometry must have been used for the two cases since the " correct" identical j

areas would not have given the same reactivity worth at the two radii. Thus, the comparison is of uncertain value. The eight percent difference, if valid, however, would not, in any case, significantly alter our previous

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. FEB 11577 H. Bender i

4. As indicated in our report, we are continuing our '

generic review of this area. The Staff and BNL efforts to get the MEKIN code operational.are still underway.

, We hope to be able to carry out some of our own

• calculations in the near future.

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l c Denwood F. Ross, Jr., Assistant Director for Reactor Safety l Division of Systems Safety F.nclosure:

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