ML20245G487
| ML20245G487 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/10/1989 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CP-86-41, TXX-89544, NUDOCS 8908160019 | |
| Download: ML20245G487 (2) | |
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Log # TXX-89544 File # 10110(CP-86-41)
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1UELECTRIC William J. Cahill, Jr.
Execwive Mce President U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET N05. 50-445 AND 50-446 SMALL BREAK LOCA MODE 4 OPERATION SDAR: CP-86-41 (INTERIM REPORT)
Gentlemen:
On May 28, 1986, TV Electric verbally informed your Mr. I. Barnes of s deficiency involving the evaluation of the effect of a small break LOCA during Hede 4 operation. This is an interim report of a potentially reportable item under the provisions of 10CFR50.55(e). The most recent interim report was logged TXX-89058 dated February 13, 1989.
Following the NRC Regulatory Staff's decision not to accept the Westinghouse Owners Group (WOG) plan to apply Leak Before Break technology in resolving the issue of a small break LOCA during either Mode 3 or 4 operation, the WOG developed a new approach, identified in the interim report transmitted with TU Electric letter TXX-80258, dated February 29, 1988.
The work in support of the large break LOCA portion of this apprcach has been completed. The results of the structural reliability and risk assessment analysis show that the probability of a large break LOCA occurring in Mode 3 or 4 is lower than for Mcde 1.
In addition, it has been shown that the probability of core damage is less in Mode 3 or 4 than in Mode 1.
The small break LOCA portion of the WOG approach has been extended to include an analysis of a small break LOCA with the RHR tross-tie valve closed.
This additional analysis is expected to demonstrate that the calculated results for l
this degraded flow case are acceptable both with regard to the operator l
actions necessary to actuate ECCS and the need to open the RHR cross-tie I
valve.
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- l TXX-89544 Augustfl0, 1989 Page 2 of.2'
- Since the need for the additional small break LOCA analysis was agreed upon only recently, submittal to the NRC of the report addressing a small break LOCA'in Mode 3 or 4 is not expected until sometime in-the summer of 1990.
Based.on that schedule. TU Electric anticipates suhsitting its next report on this matter by August 13, 1990.
Sincerely.
f*..
William J. Cahill, Jr.
RLA/smp c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3) l 1
.