ML20128F347

Submits Preliminary Review of Licensee Position on SEP Topic III-7.B Re Seismic Category I Structural Design Criteria. Related Topics Identified.Recommended Actions,To Address SEP Evaluations Completely,Listed

ML20128F347
Person / Time
Site:	Yankee Rowe
Issue date:	03/08/1985
From:	Stilwell T CALSPAN CORP.
To:	Carrington M NRC
Shared Package
ML20128F323	List: ML20128F347
References
CON-NRC-03-81-130, CON-NRC-3-81-130, RTR-NUREG-0828, RTR-NUREG-828, TASK-03-05.A, TASK-03-05.B, TASK-03-06, TASK-03-07.B, TASK-3-5.A, TASK-3-5.B, TASK-3-6, TASK-3-7.B, TASK-RR NUDOCS 8507080214
Download: ML20128F347 (3)

Text

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FRANKUN RESiARCH ' CENTER DIVISION OF AltVIN'CALSPAN March 8, 198 6 i

U.S. Nuclear Regulatory Cour.ission ,

Washington, D.C. 20555 Attention: Mr. M. Carrington (MS-540) l Project Officer

Reference:

1. FR0 Project C5506

2. NRC Contract NRC-03-81-130

3. FRC Assignment No.18

4. FRC Task No. 438 .

5. TER-5257-316, Design Codes, Design Criteria, and Loadings Combinations, Yankee Rowe Nuclear Power Station 4

6. Yankee SEP Integrated Assessment, December 1982 y

Dear Mr. Carrington:

FRC has conducted a preliminary review of the Licensee's submittal [Ref.

6) concerning Topic III-7.B for the Yankee Rowe Nuclear Power Station. The gist of this response is the Licensee's position that compliance with Systematic Evaluation Program (SEP) Topic III-7.B follows automatically once all other SEP topics have been addressed.

SEP Topic III-7.B is charged with the comparison of structural design criteria in effect when SEP plants were constructed and those in effect today as they apply to Seisnic Category I plant structures. Two aspects of these criteria are included within its scope:

1. Analytical design req;irements of the zajor codes for plant building and containments. ,

2. Load and load combinetion requirements.

Both of these, somewhat diverse, aspects are included within one SEF topic to provide a mechanisn within the SEF where their rutual and concurrent effects upon perceived margins of safety in plant structures may receive attention.

Other related SEP topics address individual aspects of plant structural integrity in detail. For example, Topic III-6 assesses plant seisric integrity: Topics III-5.A and III-5.B assess plant integrity in the event of a LOCA. Neither, however, addresses the possibility and consequence of the sir'iltaneous occurrence of these events. Current design criteria require such consideration. This requirement is erbodied in the loading combinations now s W ried; therefor *. its SEP review falb within the scope of Topic III-7.B.

2c m a RAct sTatrt$ M.ADEWA PA 19103 Tm 710 6701889 TE 015 ut 1000 8507080214 850703 PDR ADOCK 05000029 P PDR

Mr. Carrington Page 2 March 8, 1985 Another example, which is referred to in Ref. 6, is the extrese environmental snow load. SEP Topic II-2.A identifies on a plant-specific basis the magnitude of this load, but is not charged with asses' sing the -

capacity of plant structures to sustain it. This is addressed unSer Topic III-7.B. Buildings for which this load has been designated Scale A are to be reviewed for their ability to support the designated snow load.

In order that SEP evaluations of the adequacy of plant structures at the Yankee Rowe plant can be completed, we recommend that Yankee Atomic Electric ' ~~'^

Company be requested to take three actions:

1. Review individually all Seismic Category I structures at the Yankee Rowe plant to see if any of the structural elements listed in Section

. 13 of TER-C5257-316 occur in their designs. These are the structural elements for which a potential exists for margins of safety to be less than originally computed, due to critieria changes since plant design and construction. For structures which do incorporate these features, assess the actual impact of the associated code changes on margins of safety.

2. Reexamine the margins of safety of Seismic Category I structures under loads and load combinations which correspond to current criteria. Only those load combinations assigned a Scale A or Scale Ax rating in Section 10 of TER-C5257-316 need be considered in this review.

If the load combination includes individual loads which have themselves been ranked A orxA , indicating that they do not conform to current criteria, update such loads.

Full reanalysis of these structures is not necessarily required.

Simple hand computations or appropriate modifications of existing resalts can qualify as acceptable means of demonstrating structural adegaary.

3. Review Appendix A of TER-C5257-316 to confirr that all items listed there have no impact on safety sargins at the Yankee Rowe plant.

With respect te this recommendation, the Licensee ind2 cater that the acceptance criteria for structures at the Yankee Rowe plant was described in their reevaluation and retrofit criteria doecment as including:

AISC, 8th edition ASME Beiler and Pressare Vessel Code,1977 [Section not stated: Section III ought to have been used)

ACI 318-1977.

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l Mr. Carrington Page 3 March 8, 1985 For Topic III-7.B review, FRCbelievesthecodeslistedindection9of TER-C5257-316 to be proper.

Very truly yours, Thomas C. Stilwell TCS:sf cc: D. Persinko C. I. Grimes

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