ML19341C238
| ML19341C238 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 01/06/1981 |
| From: | Mazur D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, GO-81-02, GO-81-2, NUDOCS 8103020508 | |
| Download: ML19341C238 (5) | |
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Mr. R. H. Engelken, Director January 6, 1931 f4RC Region V G0-1-81-02 Suite 202 Walnut Creek Plaza 19C0 ?l. California Blvd.
Walnut Creek, California 94595 P .
Dear Mr. Engelken:
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Subject:
Washington Public Power Sucply System WP?SS Nuclear Projects tios. 1 at4 'BN g/'gg2 Occke: :;os. 50-450 and 50-513 k^ 7J ggA 2(-
ICCFR50.55(e)
Interia Report On Diesel Generator k./ %G '
Cercustion Air Intake Desicn Deficiency g p Mr. D. F. Kirscn, Principal Region V Inspector for WriP-1/4, was verbally notified of tnis reportaole condition on Cecemcer 8,1930.
The attatnment to tnis letter contains tne i!PPSS interim report 01 the subject condition. Foiicwing evaluation of proposed design fixes a final report will be issued by June 1,1931.
Yours very truly,
'\
4 D.W. Mazur '
Program Director CWM:LCO:sh Attachment cc: CR Bryant, Bonneville Pcwer Administration JR Lewis, Eonneville Power Administration V Stello, Director, tiRC Office of Inspection and Enforcement
' V Mani, Uni ted Engineers & Constructors, Phila.
AD Toth, ::eclear Regulatory Comission, Region V, U?tP-2 ECC Files - 1/4 FCCC G. D. Ecuchey - ?!uclear Safety Director ik '
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8103020SM s '
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ATTACH!iENT ,
REPORTABLE DEFICIEL.lCY IN THE DESIGil .
OF THE HVAC SYSTEM FOR THE EMERGENCY DIESEL GEllERATOR AREA
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Project:
' Washington Public Power Supply System (WPPSS), Units WNP-1 & WNP-4 flame - Address of Licenses:
Washington Public Power Supply System (WPPSS)
'3000 George Washington Way-Richland, Washington 99352
-Date of Construction Permit Issued:
WNP'-l'- December 23,.1975 WNP_-4'- February- 21, 1978_ .
I f Problem Cescriotion: i o
- 1. Two(2) independent safety-related emergency diesel generators (DG) are located in the General Services Building (GSB) between column lines D-J and:1-4, at elevation 399';-0". Each DG supplies standby power to the redundant Class1 1E emergency buses, which feed the plant service auxil-iary loads-required for hot an! cold shutdown, and pnstulated plant acci-dents,-including- complete Loss oi Off-Site Power (LOOP).
In the current plant design, the emerency ~DG-combustion air intakes are part of. the Heating, Ventilation, and An "onditioni.ng (HVAC) . System
. air intake- for the- DG area. The air intakes are separate and independent, takingicombustion- air from a common plenum. rhis' plenum also provides outside air. to the.other safety-related HVAC systems listed below:
- a. Component.Coolino and Makeup Pump Area
- b. Non-Contam.inated Service Area
~ c. Contamina ted Service Area I Jd. Electrical'and Piping Tunnels
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' e'. - Control
- Room - .
- f. Switchgear, Battery, and Cable Spreading Area l
. The plenum has a . fixed louver,3cunted on the outside wall of the GSB;
'the intake ducts-are ' protected by a missile barrier and tornado check valves.
The ductwork for_ the HVAC' systems is : designed to withstand 12" W.G. The iattached diagram. illustrates the ' combustion air intake- and HVAC air -intake.
sys tems (see. Sketch 1121580)'.
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Recor2ble Deficiency In The Design Of The ;VAC 5j. p For The Sergency Diesel Generator Area Page Z Problen Descriotion__(cont'd) in the event of a tornado, the potential regative pressure (-1.5 osi or '2" '. .G.), outsice the builcing, uill cause the check valves to close to protect the HVAC ductwork and the internals of the building feca the negative cressure. However, under the existing arrangement, should the postulated tornado also lead to a loss of Off-Site Power (LCCP) and, simultaneously, decressurize the air intake side of the G33, tne automatic starting of the DG .ould cause the tornado check valves to open, by the higher suction pressure of the DG air intake, and subiect the HVAC ducts to the negative ambient pressure of the tornico, for which they are not designed. This could lead to a fail-ure of :ne cuct..or< and, sutsecuently, a failure of the DG HVAC system ara. cassibly, otner safety-related HVAC systems.
- 2. Secondly, it was also ciscovereo tnat tne current air-intake louver cesign cust be imorovec to assure prevention of ice accumulation.
Should tne current cesign of tne louvers not ce improved, potential ice accumulation coulo resuit in an increased air flow resistance throut.n tne louvers and a cossible malfunctioning of the emergency Diesei Generators and the safety-related HVAC systems.
Safetv :molications:
- 1. The ooten;ial failure of tne ductwork could cause loss of combustion
-air in acaition to the loss of cooling to safety related HVAC areas of the G53 anc loss of function of the Diesel Generators. This would lead to tne loss of standby cower supply for the emergency loads.
- 2. Patential ice accu.nulation on tne louver system could lead to malfunc-tioning of the Diesel Generators and the safety-related HVAC systems sucn tnat the design environmental conditions for safety-related equip-nent ::ay be violated.
It is conciuced that these ceficiencies, if uncorrected, could present un-acceptable safety consequences to the plant, and are therefore considered to represent deficiencies in design that could lead to a violation of the safety design bases for the construction permit.
Correctr,e e ticn .
o The following cesign changes are currently being evaluated.
- 1. :epiration of tne ducts for CG Corbustion Air Intakes from tne intake for the nVAC system in the DG area, and placing of the CG coroustion air intakes ahead of the tornado check valves.
This could ensure that tne starting of the DG, under a tornado condition, would not affect the integrity of the ventilation
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o f the sys tems.
Reportable Ceficiency In The Design' Of- The HVAC System For The Emergency Diesel Generator Area Page 3 Corrective Action (co_nt'd):
- 2. Designing the Combustion Air Intake ducts to withstand the negative 1.5 psi, under a tornado condition.
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- 3. Replacing of the existing louvers with a type which would sub-stantially reduce rain and snow carry-over into the intake area, and evaluation of provision of heat tracing for louvers to pre-vent ice or snow buildups.
o The above design evaluations will be completed prior to June 1,1981.
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