ML18138A043

Forwards Responses to NRC Questions Re LOCA-ECCS Analysis for Amend to License DPR-37 & Proposed Tech Spec Change 78. Will Provide Info Re Low Head Safety Injection Flow Tests at Later Date

ML18138A043
Person / Time
Site:	Surry
Issue date:	02/20/1980
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8002220398
Download: ML18138A043 (5)

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Vx::ao1;NlA ELECTlUc AND PoWER COM.PA.NY RXCHMOND, VIRGXN.lA 23261 February 20, 1980 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation Attn!

Mr. Albert Schwencer, Chief Operating Reactors Branch, No. 1 Division of Operating.Reactors U. S. Nuclear Regulatory Conrritlssion Washington, D. C.

20555

Dear Mr. Denton:

Serial No. 388B FRD/WCB:

• plc Docket* No. 50-281 License No. DPR-37 SUPPLEMENTARY INFORMATION FOR AMENDMENT. TO OPERATING LICENSE SURRY POWER STATION UNIT NO. 2 PROPOSED TECHNICAL SPECIFICATION CHANGE NO. 78 provides our responses to the Nuclear Regulatory Commission (NRC) staff questions on our Surry Unit 2 LOCA-ECCS analysis transmitted by.my letter to you, Serial No. 388, dated May 31, 1979.

These questions were provided informally by Mr. J. D. Neighbors (tele-copy from J. D. Neighbors (NRC) to D. W. Speidell (Vepco) ~ dated January 2, 1980).

As discussed with Mr. Neighbors on February 11, 1980, we will be providing final information in then.ear future on the Low Head Safety Injection flow tests discussed in my letter to you, Serial No. 388A, dated October* 25, 1979.

If you have further questions or require additional information, please contact us.

Very truly yours, b,_)/J1. ~LM:tttv;7,r' C. M. Stalli_ngs Vice President,*. Power Supply and Production Operations Attachment cc:

Mr. James P. O'Reilly, Director Office of Inspection and Enforcement Region II

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Question 1 Response 1 Appendix K of 10CFR 50 requires that LOCA analyses be performed with a spectrum of possible pipe breaks.

In the current submittal, *the licensee has provided the results of the analysis performed with only one break and stated* that this break size "was verified" to be limiting.

Before we can proceed with our review, we need detailed information on how the "explicit verification" was made.

Verification of the limiting break size (i.e., CD = 0_.4) was accomplished by performing two additional analyses using the same input and models as the CD= 0.4 case with en= 0.6 and en= 1.0.

As has been the case in previous submittals (Refs.

1,2,3), the limiting break was found to be en = 0.4.

Table 4*of Reference 4 contains a summary of results for the non-limiting analyses with CD= 0.6 and CD= 1.0.

,I Question 2 Response 2 e

In the submittal, the licensee states that the analytically predicted total peaking factor values stay below the LOCA predicted limit during Condition I plant operation.

The licensee also states that the analytical results justify the new axial flux difference limits which are less.con-servative than the previously approved values.

Provide the description and give the results of the relevant analyses.

The analytically predicted maximum values for the total peak-ing factor, FQ(73), were determined using the "3-case" analysis methodology documented in Reference 5.

These predicted total peaking factor values lie below the Technical Specifications limit of 2.19 X K(~) which is described in Reference 4.

Thus, no potential violations of the proposed Technical Specifications limit for FQ(~) exist during Condition I plant operation in Surry 2 Cycle 5, and the current Technical Specifications requirement for frequent axial power distri-bution surveillance is no longer necessary.

The axial flux difference (AFD) limits applicable for Cy"cle 5 are*the generic values developed by Westinghouse based upon the Constant Axial Offset Control (CAOC) analysis* methodology (+/-5 llI band) which is described in WCAP-83856 and in Reference 5.

The predicted values for F Q-(~) were computed using. these generic Westinghouse AFD limits in the specific CAOC analy-sis for Surry 2, Cycle 5.

1.

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References

1.

Letter from C. M. Stallings (Vepco) to H. R. Denton (NRC), Serial No.

736, dated December 26, 1978.

2.

Letter from C. M. Stallings (Vepco) to E. G. Case (NRC), Serial No.

303, dated May 26, 1978.

3.

Letter from C. M. Stallings (Vepco) to B. C. Rusche (NRG), Serial No.

219/082776, dated October 29, 1976.

4; Letter from C. M. Stallings (Vepco) to H. R. Denton (NRC), Serial No.

388, dated May 31, 1979.

5.

Letter from Westinghouse (C. Eicheldinger) to NRC "(J. F. ** Stolz) dated April 6, 1978, Serial No. NS-CE-1749.

6.

T. Morita, et. al., "Power Distribution Control and Load Following Procedures, "WCAP-8385, Westinghouse Electric Corporation, September, 1974.