ML18144A015
| ML18144A015 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 11/08/1985 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Varga S Office of Nuclear Reactor Regulation |
| References | |
| 85-499A, NUDOCS 8511150094 | |
| Download: ML18144A015 (2) | |
Text
VIRGINIA ELECTRIC AND PowER CoMl'ANY RICHMOND2 VIRGINIA 23261 W. L. STEWART VICE PRESIDENT NucLEAB OPERATIONS November 8, 1985 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation Attn:
Mr. Steven A.Varga, Chief Operating Reactors Branch No. 1 Division of Licensing U.S. Nuclear Regulatory Commission Washington DC 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT NOS. 1 AND 2 PROPOSED TECHNICAL SPECIFICATIONS CHANGES Serial No.
E&C/NAS/ap Docket Nos.
License Nos.
85-499A 50-280 50-281 DPR-32 DPR-37 On August 9,
1985 we submitted a request to change the Technical Specifications for Surry Power Station, Unit Nos. 1 and 2 (Serial No.85-499).
The proposed changes would impose a minimum temperature for criticality of 522°F.
On October 2, 1985, a telephone conference was held between Vepco (Mr.
J,
- Hegner, Mr.
N.
Smith and Mr. K. Basehore) and NRC (Mr. T. Chan and Ms. M.
Chatterton) to provide additional background information pertaining to this submittal. The following provides a summary of this additional information.
The proposed minimum temperature for criticality of 522°F was established based on a detailed evaluation of the safety and plant operational impact of achieving criticality at temperatures below the nominal hot zero power temperature of 547°F.
The evaluation considered the impact of the reduced temperatures on the FSAR Chapter 14 accident analyses, including the effects on core kinetics parameters and peaking factors, reactor protection and control systems
- response, and on fuel performance and NSSS/balance of plant integrity.
The results of our evaluations showed that certain of the core-physics-related parameters which can significantly influence the accident analysis results (e.g. ejected rod worths and power peaking factors) do in fact become more limiting at reduced temperatures.
The minimum temperature limit was chosen such that all of the existing accident analysis assumptions remain bounding for the current operating cycles. Future reload evaluations will explicitly account for the possibility of achieving criticality at temperatures as low as 522°F.
It should be noted that the 522°F limit does not represent a condition below which the accident analysis results would be unacceptable.
In fact, Vepco
'41 I
t Mr. Harold R. Denton Page 2 studies have shown that acceptable results can be demonstrated at temperatures substantially below this limit. However, the 522°F limit was chosen to provide a reasonable degree of assurance that accident re-analyses will not be required for future cycles.
Under the existing Technical Specifications, no clearly defined minimum temperature for criticality exists which can be readily correlated with accident analysis assumptions.
The proposed changes rectify this situation by establishing a limit which would be reflected in the reload safety analysis process for all future cycles.
Please contact us at your convenience if you have any additional questions.
~~
W. L. Stewart cc:
Dr. J. Nelson Grace Regional Administrator Mr. Charles Price Department of Health 109 Governor Street Richmond, Virginia 23219 Mr. D. J. Burke NRC Resident Inspector Surry Power Station