ML20128B728

Responds to Request for Addl Info Re Verbal Request for back-up Calculations for Gpu Nuclear TDR 713, OCNGS Upper Drywell Shield Wall Thermal Analysis

ML20128B728
Person / Time
Site:	Oyster Creek
Issue date:	11/18/1992
From:	Devine J GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20128B732	List: ML20128B728 ML20128B742 ML20128B759
References
TASK-03-07.B, TASK-3-7.B, TASK-RR 5000-92-3080, C321-92-2270, TAC-M76879, NUDOCS 9212040065
Download: ML20128B728 (2)

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-J, GPU Nuclear Corporation

[' a i pa ,e Jersey 07054 201-316-7000 TELEX 136-482 Writer's Direct Dial Number November 18, 1992 5000-92-3080 C321-92-2270 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Gentlemen:

Subject:

OYSTER CREEK NUCLEAR GENERATING STATION (OCNGS)

DOCKET NO. 50-219 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION SEP TOPIC III-7B RELATE') TO DRYWELL TEMPERATURE (TAC NO.m76879)

This letter is in response to your verbal request for the back-up calculations for GPU Nuclear Technical Data Report (TDR) No. 713, entitled "0CNGS Upper Drywell Shield Wall Thermal Analyses", which was transmitted to yuu via our letter of November 15, 1990. Since the TDR was written, we have undertaken a more comprehensive evaluation of the structurel integrity of the Reactor Building, including the upper drywell shield wall. This evaluation included the following components: (1) all paperwork relating to cor. crete issues was reviewed to assess trends; g2) the structure was walked down sevecal times by our staff in an effort to _eek out anv signs of unexpected degradation; (3) the cracks observed in Girder RE and che underside of the slab at elevation 75' beneath the spent fuel pool were examined using NDE techniques (Reference 2); and (4) a comprehensive analysis of the ncrth half of the Reactor Building was completed to predict cracks and correlate to observed cracks and to reevaluate the structure for the design basis loads and load combinations with respect to the AC: Code requirements.

The analysis of the north half of the Reactor Building was performed using an ANSYS finite element model. The model extends from Column Line R4 to R7, from Column Line RA to RF and from elevation 23' to 119'. It includes the drywell shield wall, spent fuel pool and supporting girders and columns, floor slabs at elevations 51', 75', 95' and 119', and the east, west and north exterior walls. The analysis incorporates findings from the first three (3) components of the evaluation listed above and includes all design basis loads. The analysis procedure allows for concrete cracking and subsequent redistribution of internal forces.

E, a n A D 4 9212040065.921118 PDR ADOCK 05000219 P PDR gO GPU Nuclear Corporation is a subsidiary of General Pubhc Utihties Corporat:on I I}

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• EThe:resultsJof the. analysis are discussed in the att;ched GPU Nuclear Topical-

. Report No. 088. Based:on the analysis and the other components-of the evaluation, we have concluded: -(l) the- paperwork did not' indicate an adverse -

trend relating to concrete degradation; (2)~ the walkdown did not. reveal:any unexpected degradation; .(3) the cracks in Girder RE are confined-to the surface and the crack in the slab at elevation 75' is through:the thickness-(i.e., the crack penetrates the entire thickness.of the clab) and was found to be acceptable. It was concluded in the analysis that the Reactor Building complies with the ACI Code for all design basis loads and load combinations (attached Report). Further, uwe are able to explain the origins of virtually i

all the observed cracks in the structure, If you have any questions regarding the information provided in this letter.

and/or the attached report, please call Mike Laggart, Manager, Corporate Licensing,zat (201) 316-7968.

Very tr yqurs, a- \LF -

J.C.beVine,Jr.

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l L Vice President and Director Technical Functions JCDV/YN:1ga Attachment cc: Administrator, Region 1 NRC Senior Resident Inspector C;' ster Creek NRC: Project Manager i

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G :ll Nuclear OYSTER CREEK NUCLEAR GENERATING STATION i STRUCTURAL EVALUATION OF THE

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GPU Nuclear Corporation ABB Impell Corporation One Upper Pond Road 770 Cochituate Road Parsippany, NJ 07054 Framingham, MA 01701 I

Report No. 0370-1341

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