ML20097G705
| ML20097G705 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 06/10/1992 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CP-88-34, TXX-92263, NUDOCS 9206170246 | |
| Download: ML20097G705 (2) | |
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- TXX-92263 55 Fi e # 10110 L
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TUELECTRIC June 10, 1992 William J. Cahill, Jr.
Gremp Vue PresisLeet U. S. Nuclear Regulator., Commisslon Attn: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET no. 50-446 RHR HEAT EXCHANGER SUPPORT DESIGN SDAR: CP-88 '4 (FINAL REPORT - UNIT 2)
Gentlemen:
On October 6, 1988, TU Electric's report logged TXX-88724 notified th-NRC of a reportable deficiency in the support configuration of the residual heat removal (RHR) heat exchangers. The last correspondence on this issue was TXX-89259 dated May 17, 1989, which provided a supplemental report for Unit 1 and an interim report for Unit 2.
TXX-89259 indicated t ri&' a final report for Unit 2 would be submitted prior to Unit 2 fuel load.
Tnis information is provided below.
DESCRIPTION The purchase specification supplied to the Nuclear Steam Supply System (NSSS) vendor indicated that the RHR heat exchangers would be mounted on rigid supports.
However, design validation of the RHR heat exchanger supports indicated that the final design and as-built co.istruction of the supports were not rigid.
An analysis was performed to determine if the RHR heat exchangers could still be qualified when considering the stiffness of the as-built support arrangement.
This analysis showed that the heat exchanger support arrangement resulted in an overstressed condition in the heat exchanger shells.
This deficiency was caused by failure of the original design organization to design rigid supports for the RHR heat exchangers.
SAFETY IMPLICATION The RHR heat exchangers are utilized to establish and maintain cold shutdown conditions following postulated events.
A failure in t% shells of both RHR heat exchangers following a seismic event may have resulted in the inahility to achieve and maintain a cold shutdown condition.
9206170246 920610 N
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+.y Attachment to TXX-92263 Page 2 of 2
[QRRECTIVE ACTION As previously discussed in correspondence for Unit 1, correction of this deficiency required the. identification of modificatiorc to restore the.
necessary degree of rigidity to the 5 eat exchanger support structure.
These modifications required analysis by the heat exchanger vendor to ensure elimination of the overstress condition in the heat exchanger shell followed-by a final reconciliation of support loads.at several levels in the heat-exchanger support structure.
The same modifications required for resoletion of this defic ency in Unit 1 have been implemented for Unit 2, and final reconciliation of the support loads is in progress. Although not expected by Engineering, if the need for-any additional modifications is identified during final reconciliation,-you will be notified of these modifications and the modifications will be implemented prior to Unit 2 fuel load.
Sincerely, y
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William J. Cahill, Jr, CBC/JAA/tg c - Mr. R. D. Martin, Region IV Resident Inspe-tors, CPSES (2)
Mr= T. A. Cerg.ian, NRR Mr. B. E. Holian, NRR
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