ML20037A170

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Forwards Staff Positions Re Fuel Assembly Response to Asymmetric Loads Resulting from Seismic & loss-of-coolant Accidents & Draft Ltr to B&W Requesting Expanded Rept Covering All Current B&W Fuels
ML20037A170
Person / Time
Site: Midland
Issue date: 11/15/1978
From: Tedesco R
Office of Nuclear Reactor Regulation
To: Vassallo D
Office of Nuclear Reactor Regulation
Shared Package
ML111090060 List: ... further results
References
FOIA-80-515, FOIA-80-555 NUDOCS 7811280163
Download: ML20037A170 (6)
v • d • e


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UNITED STATES j

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W ASHINGTON. D. C. 20555 O[/

NOV 151978 MEMORANDUM FOR:

D. B. Vassallo, Assistant Director for Light Water Reactors, DPM FROM:

R. L. Tedesco, Assistant Director for Reactor Safety, DSS

SUBJECT:

STAFF POSITIONS ON FUEL ASSEMBLY ASYMMETRIC LOADING ANALYSIS FOR MIDLAND 1 AND 2 The Reactor Fuels Section of the Core Performance Branch has prepared a staff position (Attachment 1) on fuel assembly response to asymetric loads resulting from seismic and loss-of-coolant accidents for the Midland plant, Units 1 and 2, whic' contain Mark B fuel.

Please note that an earlier set of draft questions on this subject was sent to the Mechanical Engineering Branch (memo: Meyer to Bosnak, September 12,1978) for incorporation with related questions from other branches. Those-questions (on the fuel analysis) are generic in nature,- --

cover the fuels consideration comprehensively, and do not acknowledge that Midland submitted any related analysis; of course they did (in the FSAR). Consequently those questions should not be issued without the background given in this memorandum; and the questions should be used in the ultimate (POST OL) resolution of this issue.

Note further that the fuel response to asymmetric loads is being reviewed as a generic item and that we have returned (memo: Ross to Varga, April 4,1978) Babcock & Wilcox's generic report on Mark-C fuel (BAW-10133) for revision because it did not contain sufficient infor-mation for review. We now believe that the B&W report should be d

expanded to cover all current B&W fuels (alternatively a separate report on Mark-B fuel could be submitted) and we have drafted a letter to this effect (Attachment 2) that you can send to B&W.

We intend to complete our generic review of fuel assembly response to asymmetric loads for B&W following the receipt, review, and acceptance of a revised version of BAW-10133 or other generic reports.

It is our understanding that this procedure will not impact the licensing schedule for Midland, so long as the utility comits to a post-OL resolution of the matter in accordance with the guidelines of NRR Generic Activity A-2, because the FSAR contains a seismic and LOCA

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analysis that is based on previously reviewed and accepted criteria.

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.m Core Performance Branch Staff Position on Fuel Assembly Response to Asymmetric Loading in Midland Units 1 and 2 231.34 Section 4.2.3.5.2, "LOCA and/or Seismic Loading," of the (4.2.3.5)

Midland 1 & 2 FSAR refers to fuel assembly analysis methods presented in Babcock and Wilcox report, " Fuel Assembly Stress and Deflection Analysis for Loss-of-Coolant Accident and Seismic Excitation," BAW-10035, dated December 1972. BAW-10035, Rev.1 is the non-proprietary version of BAW-10008, Part 2, Revision 1, dated January 1972. These reports were previously reviewed and accepted (see Topical report evaluations, R. R.

Maccary to R. C. DeYoung, August 30 and September 5,1972, and February 28,1973).

Notwithstanding the prior review and acceptance of these referenced reports, the FSAR does not provide adequate treatment of this concern for the following reasons:

1.

The review of BAW-10035, Rev.1 (and BAW-10008, Parts 1 and 2), focussed primarily on the response of the core internals to asymmetric loading, not the fuel response (except in the sense of how the fuel affects the core internals).

2.

The review of BAW-10035, Rev.1 (and BAW-10008, Part 2), was conducted prior to the emergence of the North Anna asymmetric loading issue (NRC memorandum, V.Stello, Jr.

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-2 to R. J. Mattson, " Category A Technical Activity Task A-2, Asymmetric LOCA Loads).

In the period prior to North Anna, only vertical loads were considered signi-ficant. Analyses of these vertical loads were checked against test results. Our current understanding of potential LOCA loading, however, is that lateral loadings of significant magnitude are possible. Therefore, additional analyses, accounting for the effects of lateral loads, must be perfonned.

It should be noted that Babcock & Wilcox has submitted a generic report which deals with the analysis of Mark C fuel assembly response to asymmetric loads (BAW-10133, " Mark C Fuel Assembly, LOCA-Seismic Analysis, dated October 18,1977).

We performed an acceptance review of this report and found it to be unacceptable for review in its current form because it did not contain sufficient technical information (NRC memorandum, D. F. Ross to D. B. Vassallo, April 4, 1978).

We requested that the report be revised to include substan-tially more technical information, examples of which we provided. We believe that this report could be revised

' further to include an analysis of Mark B fuel, or alterna-tively, that a separate Mark B fuel analysis could be provided.

In either case, further analysis, accounting l

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.. for the effects of lateral loads must be performed for Mark B fuel that is being used in new plants.

The current treatment in the FSAR is sufficient to proceed with issuance of an Operating License because it is based on the best available methodology and criteria, and that is all that is required at this stage according to the guidelines of NRR Generic Activity A-2.

The applicant must, however, commit to perform an evaluation of their facility following staff approval of the generic analysis methodology and criteria, should the knowledge developed from our generic review warrant such reevaluation.

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Proposed Letter to Babcock & Wilcox Earlier this year,we performed an acceptance review of your report that dealt with the analysis of Mark C fuel assembly response to asymmetric loads (BAW-10133, " Mark C Fuel Assembly, LOCA-Seismic Analysis, dated October 18,1977). We found that the report did not contain sufficient information to begin a full-fledged review, and we asked you to revise that report to include substantially more technical information, examples of which were pro'ided (letter, v

S. Varga (NRC) to J. Taylor' (B&W), April 14,1978).

More recent work on the Midland review (the Midland units will contain 1

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Mark B,15x15 fuel assemblies) has revealed that the FSAR treatment of Mark B fuel assembly response to asymmetric loads is inadequate because it references an old (circa 1972) analysis (BAW-10035) that was performed prior to our more recent understanding of the issued related to the North Anna asymmetric loadings. Therefore, in addition to our earlier request for additional information, please expand BAW-10133 to cover all current B&W fuel designs, or, alternatively, submit a similar separate analysis on Mark-B fuel that is applicable to the Midland units. This should not impact the review of the Midland FSAR, so long as the utility commits to a post-OL resolution of the matter in accordance with the guidelines of NRR Generic Activity A-2.

If you have any questions about this request, please call Dr. Michael Tokar of the Core Performance Branch at(301)492-7603.

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