ML19351F369
| ML19351F369 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/06/1981 |
| From: | Cross J TENNESSEE VALLEY AUTHORITY |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| 1183-4164, NUDOCS 8101120331 | |
| Download: ML19351F369 (2) | |
Text
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TENNESSEE VALLEY AUTHORITY
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CHATTANOOG A. TENNESSEE 37401 El 500A Chestnut Street Tower II 9,
January 6, 1981
-,ER Director of Nuclear Reactor Regulation Attention:
Mr. A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing U.S. Nuclear Regulatory Cossaission Washington, DC 20555
Dear Mr. Schwencer:
In the Matter of
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Docket No. 50-327 Tennessee Valley Authority
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As agreed in a telephone conversation with C. Stahle of your staff on December 16, 1980, enclosed is a mvised page for volume 2 of TVA's report on the Core Degradation Program for Sequoyah Nuclear Plant. This page is revised to address the NRC staff's concern regarding the polyurethane foam insulation in the ice condenser.
Very truly yours, TENNESSEE VALLEY AUTHORITY f16~
J. L. Cross Executive Assistant to the Manager of Power Sworn to d subscr bed before me j
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this /O ' day of f 1981 Y
()Al Notary Public g'
My Comunission Expires /
Enclosure a
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REPLACE LAST PARAGRAPH ON PAGE VIII-8 (Continued on Page VIII-9)
IN VOLUME 2 WITH THE FOLLOWING:
As an added note, the air ducts are multilayer steel panels which totally encapsulate the foam insulation behind them. The entire wall panel structure, which includes the wall panels, polyurethane foam insulation, and supporting hardware to the containment wall steelliner plate 'has been qualified by testing to a pressure of 19.0 PSIG. The structural compressive strength of the wall panel design is dependent on the polyurethane foam insulation behind it.
As noted above, the polyurethane foam has a minimum compressive strength of 30.0 PSIG. Shrinkage of the polyurethane foam is considered insignificant (on the order of 1/2 o" 1%). This was determined by Westinghouse during initial development of the wall panel / foam design concept by testing foam samples from accelerated aging tests, the foam does not shrink as long as the proper propor-tions of the chemical constituents are combined and batched proper-ly. This has been verified by Westinghouse research test work and polymer insulation information for this particular polyurethar.e foam.
It should be noted that Westinghouse implemented and maintained a very stringent Q.A. program during the entire foam insulation installation operation at the Sequoyah Site to have the highest degree of confidence that the insulation was batched and installed properly.
Even if shrinkage in the foam insulation were postu-lated, the wall panels would simply deflect and deform under the pressure loads until they bottomed on the polyurethane foam insu-lation. The postulated LOCA or hydrogen burning pressures trans-mit compressive loads against the wall panels. Without taking any credit for the pressure equalization that would occur in the panels during the postulated events, the nature of the wall panel loadings are such that a loading mechanism does not exist which could cause a failure mode in the supporting hardware such that the wall panels would become detached and expose the polyurethane foam insulation. Therefore, the ice condenser wall panel design provides adequate protection for the polyurethane foam to prevent any localized burning of the foam during a hydrogen burn event.
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