ML20205K035

Informs That Certain Addl Corrections Warranted for 990121 SER for Amend 163 to License DPR-28 Re Suppression Pool Water Temp.Suggested Corrections Listed

ML20205K035
Person / Time
Site:	Vermont Yankee
Issue date:	03/31/1999
From:	Leach D VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-99-45, NUDOCS 9904120301
Download: ML20205K035 (2)

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.n VERMONT YANKEE y NUCLEAR POWER CORPORATION <

185 Old Ferry Road, Brattleboro, VT 05301 7002 (802) 257-5271 March 31,1999 BVY 99-45 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC '20555

References:

(a) Letter, USNRC to VYNPC, " Correction to Safety Evaluation for Amendment No.163 Regarding Suppression Pool Water Temperature - Vermont Yankee '

Nuclear Power Station (TAC No. MA1721)," NVY 99-06, dated January 21,1999. 1 (b) Letter, USNRC to VYNPC, " Issuance of Amendment to Facility Operating {

License No. DPR-28, Vermont Ya:.kee Nuclear Power Station (TAC I No. MA1721)," NVY 98-170, dated December 28,1998. I (c) Letter, VYNPC to USNRC, " Technical Specincation Proposed Change No. 204, Suppression Pool Water Temperature," BVY 98-69, dated May 8,1998.

Subject:

Vermont Yankee Nuclear Power Station l

License No. DPR-28 (Docket No. 50-271) i Reauest to Correct Safety Evaluation Report for License Amendment No.163 l

In Reference (a), the Staff provided corrections to the Sefety Evaluation Report (SER) for License i

Amendment No.163 (Reference (b)), which modined the Technical Specification requirements for suppression pool water temperature. Vermont Yankee (VY) has reviewed the revised SER and believes that certain additional corrections are warranted.

I On page 2 of the corrected SER, the phrase "when used with the 2 sigma adder" was added to the sentence "The ANS 5.1 1979 decay heat model has been found to be acceptably conservative." It would  ;

not be accurate to describe the 2-sigma uncertainty as an adder in our suppression pool water temperature analysis. It was not "added" to the calculated decay heat. Rather, the 2-sigma uncertainty was combined statistically with the 2% thermal power uncertainty, as fully described in Reference (c), Attachment 1, Section 2.2.1.1, page 4.

l A more accurate statement would be "The ANS 5.1 1979 decay heat model has been found to be l acceptably conservative when a 2-sigma uncertainty is applied." ,

i Likewise, on page 3 of the corrected SER, the phrase "and the use of the ANS 5.1 1979 decay heat model l with a 2 sigma adder" was cided to the last sentence of the Erst paragraph. A more accurate statement (N -O would be"and the use of ths (NS 5.1 1979 decay heat model with a 2-sigma uncertainty applied." -

As a Snal item, the SER in Reference (b) makes several statements with regard to the ' requirements' of l the Standard Review Plan,(SRP). Speci0cally, Page 3 of the SER contains "...these reauirements assure  !

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• P. ."*""Y^**N" " 3*""" Courournos BVY'99-45 / Page 2 that the approved Appendix K evaluation model..." and "... meets many of the reauirements detailed in the SRP."

i Since VY is a pre-General Design Criteria and pre-SRP plant, the guidance contained within the SRP is not a requirement for VY. Accordingly, the statements should be revised to reflect that the guidance of the SRP has substantially been followed.

If you have any questions on this transmittal, please contact Mr. Thoroas B. Silko at (802) 258-4146.

i Sincerely, VERMONT Y' KEE NUdLEAR POWER CORPORATION )

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Vice P esident, Engineering cc: USNRC Region 1 Administrator USNRC Resident Inspector- VYNPS USNRC Project Manager- VYNPS Vennont Department of Public Service 1

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