ML19343D414

Interim Deficiency Rept Re Heating,Ventilation & Air Conditioning Cooling Sys,Initially Reported on 810330. Engineering Studies for re-evaluation of Sys Design for CPSES to Be Completed by 810630

ML19343D414
Person / Time
Site:	Comanche Peak
Issue date:	04/24/1981
From:	Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Madsen G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, TXX-3307, NUDOCS 8105040437
Download: ML19343D414 (2)

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TEXAS UTILITIES GENERATING COMinNY soon navAN mwen LALLAM, TEXA8 75203

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April 24, 1981 TXX-3307 p J'3- -

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Mr. G. L. Madsen, Chief g (>

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Reactor Projects Branch U. S. Nuclear Regulatory Commission Office of Inspection & Enforcement 611 Ryan Plaza Dr., Suite 1000 Docket Nos. 50-445 Arlington, Texas 76012 50-446 COMANCHE PEAK STEAM ELECTRIC STATION HVAC COOLING SYSTEM FILE N0: 10110

Dear Mr. Madsen:

In accordance with 10 CFR 50.55(e), we are submitting this interim report concerning identified deficiencies associated with the HVAC System supplying cooling to the rooms containing vital AC power con-verters and the DC battery chargers. This matter was verbally reported to your Mr. R. G. Taylor on March 30, 1981.

The attached report addresses the technical aspects of the deficiency.

Our QA staff, in conjunction with the AE's QA staff, is currently examining the QA program aspects. We expect to complete this evaluation by June 30, 1981, at which time we will be in a position to file a final report on this matter.

If we can provide any additional information, please advise. ,

Very truly yours, f.

R. J. Gary RJG:kh cc: NRC Region IV - (0 + 1 copy)

Director, Inspection & Enforcement - (15 copies) c/o Distribution' Services Branch, DDC, ADM.

U. S. Nuclear Regulatory Commission Washington, D. C. 20555 i I

810 5 0.4 0 '/J-7 S l

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• April 24, 1981 TXX-3307 Attachment HVAC Design

Description of the Deficiency The UPS and Distribution Rooms contain the Class IE static invertersTh and battery chargers.

Access Area Ventilation System. It has been determined that this system as designed isg incapable of maintaining room temperaturg at design levels (less than 104 F during normal plant operation and 122 F post-accident environment for the duration required). The deficiency occurred because

• of increased heat rejection into the UPS and Distribution Rooms due to increased size of electrical equipment (resulting from increased demand for uninterruptible power supply), without subsequent redesign of the HVAC System to provide additional cooling capacity.

Safety Implication Analysis In the event that the static inverters and their connected loads become inoperable due to the deficiency described above and this event occurs in both A and B trains (as in the case of loss of off-site power), the reactor and turbine would trip, and all instrumentation required to verify In shutdown (and follow cooldown) conceivably could become unavailable.

the postulated loss of battery chargers, DC power would be available for up to four hours, after which breaker control and emergency lighting would be unavailable.

Corrective Action The existing ventilation system will be replaced with a new class IE air conditioning system that will be capable of maintaining the temperature in the UPS and Distribution Rooms to equipment design levels. The air conditioners will perform this function during all modes of plant opera-tion including normal and post-accident conditions. The chiller units will be powered by safety related busses that are loaded on the diesels in the event of loss of off-site power. The remainder of the system, such as dampers and ductwork, will also be seismically qualified. Design, fabrication and installation activities are expected to be complete prior to fuel load.

Ewineering studies are currently in progress for other plant areas to

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re-evaluate the HVAC design for CPSES. The initial phase of this evalua-tion is scheduled for completion by December 1,1981. In the event that significant problems are uncovered by these reviews, they will be handled in accordance with standard reporting requirements.