ML022410043

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Supplement to Nuclear Regulatory Commission Request for Additional Information Regarding Containment Structure Conformance to Design Basis Requirements
ML022410043
Person / Time
Site: Cook  
Issue date: 08/23/2002
From: Greenlee S
Indiana Michigan Power Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP:NRC:2520-01, FOIA/PA-2005-0075, TAC MB3603, TAC MB3604
Download: ML022410043 (4)


Text

Indiana Michigan Power Company 500 Circle Drive Buchanan, MI 49107 1395 INDIANA MICHIGAN POWER August 23, 2002 AEP:NRC:2520-01 10 CFR 50.90 Docket No.:

50-315 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-P 1-17 Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Units 1 and 2 SUPPLEMENT TO NUCLEAR REGULATORY COMMISSION REQUEST FOR ADDITIONAL INFORMATION REGARDING CONTAINMENT STRUCTURE CONFORMANCE TO DESIGN BASIS REQUIREMENTS (TAC NOS. MB3603 AND MB33604)

Reference:

1 Letter from J. F. Stang (NRC) to A. C. Bakken III (I&M), "Donald C. Cook Nuclear Plant, Units 1 and 2 Request for Additional Information, Regarding Containment Structure Conformance to Design-Basis Requirements (TAC Nos. MB3603 and MB3604),"

dated May 31, 2002 2

Letter from S. A. Greenlee (I&M) to U. S. Nuclear Regulatory Commission Document Control Desk, "Response to Nuclear Regulatory Commission Request for Additional Information Regarding Containment Structure Conformance to Design Basis Requirements (TAC Nos. MB3603 And MB3604),"

dated July 16, 2002 This letter provides supplemental information in response to a Nuclear Regulatory Commission (NRC) request for additional information regarding conformance of the containment structures at Donald C. Cook Nuclear Plant to design basis requirements.

In Reference 1, the NRC noted that Indiana Michigan Power Company (I&M) had used values for rebar yield strength obtained from certified material test

U. S. Nuclear Regulatory Commission AEP:NRC:2520-01 Page 2 reports (CMTRs) in containment structural calculations at Donald C. Cook Nuclear Plant. The NRC requested that I&M provide justification for use of the CMTR yield strength values in lieu of nominal specified code properties.

I&M provided its response to the NRC request in Reference 2. In that response, I&M identified the structural calculation for the ice condenser endwalls as one of the calculations in which CMTR data had been used for rebar strength. I&M also stated that the ice condenser endwall structural calculation contained overly conservative inputs and assumptions, and that revision of these inputs and assumptions was expected to eliminate the need for reliance on CMTR values for rebar strength.

I&M committed to provide the NRC results of the revised endwall calculation with respect to required rebar yield strength. Background information pertaining to the revision and the results of the revision are provided below.

To support completion of containment structural calculations in the first half of 2001, I&M elected to use preliminary pressure values in some of the calculations, including the ice condenser endwall calculation. Prior to approving the endwall calculation, I&M confirmed that the preliminary pressure values bounded the final pressure values. However, the results determined by the approved calculation continued to be based on the preliminary pressure values.

Using the preliminary pressure values, the calculation determined that the required endwall capacity could only be achieved by crediting as-built CMTR values for the rebar strength.

Consistent with the commitment made in Reference 2, I&M has revised the ice condenser endwall structural calculation to incorporate the final endwall differential pressures and to use only the nominal specified code rebar strength of 40 ksi. This revision demonstrates that the ice condenser endwall meets the required capacity without reliance on as-built rebar strength.

There are no new commitments made in this letter.

Should you have any questions, please contact Mr. Gordon P. Arent, Manager of Regulatory Affairs, at (269) 697-5553.

AEP:NRC:2520-01 U. S. Nuclear Regulatory Commission Page 3 Sincerely, Scot A. Greenlee Director of Nuclear Technical Services JRW/jen c:

K. D. Curry J. E. Dyer MDEQ - DW & RPD, NRC Resident Inspector R. Whale

U. S. Nuclear Regulatory Commission AEP:NRC:2520-01 Page 4 bc:

G.P. Arent A. C. Bakken III P. B. Cowan S. A. Greenlee S. B. Haggerty D. W. Jenkins J. A. Kobyra J. E. Pollock J. F. Stang, Jr., - NRC Washington, DC T. R. Stephens T. K. Woods