ML20211A948

Informs of Completion of Analysis of Heat Transfer in Cooler During Fan Coast Down & Concludes That Potential Exists for Steam Foundation,Under Conditions Where Dcw Sys Flow Is Lost Prior to Full Isolation Valve Closure

ML20211A948
Person / Time
Site:	Grand Gulf
Issue date:	08/12/1999
From:	Byrd R ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-06, GNRO-99-00043, NUDOCS 9908240177
Download: ML20211A948 (4)

Text

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O Ente gy perrtions, Inc.

Port Gibson. MS 39150 Tel 601437 2800 August 12, 1999 U.S. Nuclear Regulatory Commission Mail Station P1-37 Washington, D.C. 20555 Attention: Document Control Desk

Subject:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Generic Letter (GL) 96-06 GNRO-99/00043 Gentlemen:

On October 7,1998 members of the Grand Gulf staff contacted Mr. James Tatum, of your staff to discuss NRR's concerns with the Grand Gulf response to GL 96-06 dated September 15,1998. In that telephone conversation Mr. Tatum stated the reason for the questions was to allow him to reach closure based on reasonable analysis that would support the Grand Gulf conclusion that there is no bases to support steam formation in the Drywell Chilled Water (DCW) system under the postulated conditions. Therefore there would be no water hammer concern at Grand Gulf.

Mr Tatum stated that it appeared that Grand Gulf had only analyzed heat transfer through the DCW piping and agreed that no water hammer concern could be reasonably assumed from heat transfer through the piping. He asked if Grand Gulf had analyzed heat transfer in the cooler itself during the fan coast down following loss of power and if under those conditions could steam formation occur. Grand Gulf indicated that heat transfer in the cooler had not been considered in the above submittal.

Mr. Tatum then requested that Grand Gulf provide additional information to allow closure of his concerns. Mr. Tatum indicated that there were at least two possible ways to address these issues and that both had been previously acceptable to the commission.

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Grand Gulf has completed the analysis of heat transfer in the cooler during fan coast down and has concluded that under conditions where the DCW system flow is lost prior to full isolation valve closure a potential exists for steam formation in the DCW piping under the

, i postulated LOCA conditions. Grand Gulf intends to modify procedural guidance to address the potential water hammer concern under the postulated conditions.

Yours truly,

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4 GNRO-99/00043 Page 3 of 4-cc: Ms. J. L. Dixon-Herrity, GGNS Senior Resident (w/a)

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