ML20205T596
| ML20205T596 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 06/09/1986 |
| From: | Tucker H DUKE POWER CO. |
| To: | Harold Denton, Youngblood B Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20205T600 | List: |
| References | |
| NUDOCS 8606160094 | |
| Download: ML20205T596 (3) | |
Text
&
Duxt: Pownsit GoMi>m 18.0.150X 3318f)
CilAllLOTTE, N.C. 28242 HAL H. TUGEER 1 P.tE PHONE (704) 3y3 4531 vnarer.sorwr m m. e m
June 9, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
/TTENTION:
B.J. Youngblood, Director PWR Project Directorate #4
Subject:
McGuire Nuclear Station Docket Nos. 50-369, -370
Dear Mr. Denton:
By letter dated April 30, 1986, the NRC staff forwarded an ACRS letter regarding operation of McGuire without Upper Head Injection Systems dated April 16,1986, and requested a Duke response.
The Advisory Committee on Reactor Safeguards suggestion that Duke consider maintaining the disconnection of the Upper Head Injection System (UHIS) on a reversible basis until further calculations show operating conservatisms of McGuire without UHIS are similar to non-UHIS plants was prompted by the Sandia presentation which included, for information, a comparison of "best estimate" analyses for McGuire and a standard Westinghouse plant.
It was pointed out that the comparison was not conclusive due to variations in important input assumptions used in the Sandia TRAC-PF1/ MODI analysis for McGuire and the TRAC-PD2 analysis of the standard plant. The apparent lack of "best estimate" analyses which could be compared directly and the conser-vative nature of evaluation model analyses which hamper their use to provide comparisons of actual plant behavior, apparently led to the ACRS suggestion regarding additional analyses.
In response to this suggestion, Duke provides the attached evaluation. This evaluation is based upon available analytical predictions and LOFT test results and demonstrates that the operating conservatisms for McGuire without UHI are similar to those which exist for non-UHIS plants. The evaluation model and "best estimate" analyses predict similar plant responses during blowdown for McGuire without UHIS and the non-UHIS plants. The refill /-
reflood behavior is slightly different between the two plant designs but the evaluation model predicts similar clad temperature responses while the "best estimate" analyses show a clad reheating for McGuire which is greater than that which is predicted for the non-UHIS plant. The refill /reflood clad reheating and higher blowdown clad temperature predictions from the Sandia h
[
h D
I i P
H.R. Denton June 9, 1986 4
Page 2 analysis compared to the TRAC-PD2 standard plant analysis are shown to result from the significant differences in assumed linear heat generation rates used in the two analyses.
This conclusion is supported by a review of the IDFT experiments L2-2 and L2-3.
Upon review of the evaluation model analyses, "best estimate" analyses, and IDFT data, Duke believes the existing predic-tions and data are adequate to demonstrate that the operating conservatisms for McGuire without UHIS are similar to non-UHIS plants and that no further analyses are necessary.
The McGuire units will be operated during the upcoming cycles (1986-1987) with the UHIS isolated but not physically removed. In order to fully benefit from the analytical and licensing actions which resulted in the May 13, 1986 SER and thus reduce plant maintenance, startup delays, and radiation exposure to personnel, the removal of the UHIS, including capping reactor vessel penetrations and removal of piping and components is currently scheduled for the 1987 refueling outages at McGuire.
Very truly yours, i%
Hal B. Tucker RLG/j gm Attachment xc:
Mr. Darl Hood, Project Manager Division of Licensing Office of Nuclear Regulatory Commission Washington, D.C.
20555 Mr. W.T. Orders i
NRC Resident Inspector McGuire Nuclear Station 1
Dr. J. Nelson Grace U.S. Nuclear Regulatory Commission - Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Paul Boehnert 4
ACRS i
a
H.R. Denton June 9, 1986 Page 3 bxc: N. A. Rutherford J.B. Day J.G. Torre S.A. Gewehr P.B. Nardoci R.O. Sharpe T.L. McConnell E.O. McCraw W.D. Reckley B.
McIntyre (W)
P.
Studer (TVA)
MC-801.01