ML20247G470
| ML20247G470 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 07/24/1989 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CP-89-017, CP-89-17, TXX-89487, NUDOCS 8907280085 | |
| Download: ML20247G470 (2) | |
Text
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3 lllllllllll"llllllllllll Log # TXX-89487 File # 10110
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Ref. # 10CFR50.55(e)
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1UELECTRIC July 24, 1989 ENEek'$r'aD!ch U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
L 5M S
E b ER LEAKAGE SDAR: CP-89-017 (FINAL REPORT)
Gentlemen:
On June 23, 1989, TV Electric verbally notified the NRC of a deficiency involving control room HVAC system damper leakage. After further evaluation, this deficiency has been determined to be reportable under the provisions of 10CFR50.55(e). The required information follows.
DESCRIPTION During the closure of open items and final review of confirmation required assumptions associated with the control room habitability Design Basis Document (DBD) and calculations, potential unfiltered air leakage paths into the control room were identified.
Zero leakage had been assumed for these flow paths when they included more than one closed damper.
The deficiency involved use of dampers in lieu of bubble tight butterfly valves for isolation of air ducts which connect to outdoor makeup and exhaust.
These dampers allow unacceptable leakage into the control room.
This design deficiency is unique to the control room HVAC system.
SAFETY IMPLICATIONS Engineering evaluation has determined that the estimated leakage rates due to the subject potential unfiltered leakage paths, when combined with the unfiltered infiltration rates previously assumed in the control room dose analysis, could cause the whole body and thyroid dose limits specified in General Design Criteria (GDC) 19 of 10CFR50, Appondix A to be exceeded.
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-TXX-89487-July 24, 1989
_ Page 2 of 2 This condition' represents a significant deficiency in the design of CPFES which, in the event it-had remained uncorrected, could havo affected adversely the safe operation of the plant. Therefore, this issue is reportable under-the
- provisionsof10CFR50.55(e)
CORRECTIVE ACTION'
- To correct this deficiency, design modifications in the ductwork have been identified as follows:
1.
Unfiltered leakage into the' control room through the makeup path will be eliminated by ensuring that any potential leakage must pass through the filters prior to entering the control room.
2.
Unfiltered leakage through the exhaust path will be eliminated by exhausting directly from.the room rather than the return duct.
During accident conditions when the exhaust system is not operating, air leakage into the control room via the exhaust path will be prevented by maintaining the control room envelope at a positive pressure.
The implementation of these design modifications will be completed prior to the respective fuel load date for Units 1 and 2.
Sincerely, 6
William J. Cahill, Jr.
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DEB /vid c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3) t L__________-
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