ML19260B020

Submits Addl Response to IE Bulletin 79-01A.Coils in Solenoid Actuated Unloader Valves for MSIV Hydraulic Sys of Both Units Observed to Be Enviromentally Unqualified for Existing Temp Ambient.No Safety Hazard Involved

ML19260B020
Person / Time
Site:	Calvert Cliffs
Issue date:	12/01/1979
From:	Ash R BALTIMORE GAS & ELECTRIC CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
IEB-79-01A, IEB-79-1A, NUDOCS 7912060358
Download: ML19260B020 (3)

Text

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,, BALTIMORE GAS AND ELECTRIC s

CHARLES CENTER . P.O. BOX 1475 BALTIMORE, MARYLA*JD 21203 December 1, 1979 ELtcTRic ENGINEERING e

• DEPARTMENT -

Office of Nuclea'r Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attn: Mr. Robert W. Reid, Chief Operating Reactors Branch #h Division of Operating Reactors

Subject:

Calvert Cliffs Naclear Power Plant Units Nos. 1 & 2, Dockets Nos. 50-317 & 50-318 Environmentally Unaualified Electrical Eauiument heference: (a) NRC IE Bulletin 79-01, 2/8/79 (b) BG&E letter dated 11/5/79 from A. E. Lundvall, Jr.

to R. W. Reid, IE Bulletin 79-01/01A Gentlemen:

In our continuing effort to identify electrical equinment which does not have evidence of nroper environmental qualification nursuant to Reference (a) and as last reported in Reference (b), our staff identified a specific connonent on November 29, 1979 which did not anpear to be qualifie.d for its environment. Additional research that day and the next has led us to conclude that the coils in the solenoid actuated unloader valves ft the main steam isolation valve (MSIV) hydraulic systems in both units at Calvert Cliffs are not properly qualified for existing ambient temperatures in their installed locations. This finding was reported to our NRC Pro,iect Manager on November 30, 1979 by telephone. That telenhone message and this letter constitute our 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ret, ort pursuant to Reference (a ) .

Comnonent Identification and Function The solenoid-actuated unloader valve is located downstream of the high pressure pump which is used to (a) pressurize the MSIV accumulator upon receipt of a low-pressure actuation signal, and (b) to provide fluid directly to the MSIV actuator to maidain the valve in a shut position.

When the solenoid is energized, and t.ne punn is oneratine, tM valve closer causing the pumn discharge cressure to increase and thus forcing the fluid through to the MSIV or into the accumulator, as reauired. The system vill reset when accumulator pressure is restored. When the solenoid is not energized and the pumn is operating, fluid is recirculated through the normally open valve back to the reservoir. The solenoid coils, rated as Class "B", are only qualified for an ambient temperature of 700F. The location of the valves recuires that the coil be que.lified for ambient ~

temneratures of up to 1200F.

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Mr. R. W. Reid December , 1979 Safety Analysis We have performed an analysis of the potential consequences of a failure of an unloader valve solenoid to function properly. We have concluded that there is no immediate safety concern associated with this deficiency. This conclusion is based on the following points:

1) The coils are normally deenergized and not required for normal functioning of the MSIV hydraulic system as long as accumulator pressure is above the high pressure pump actuation signal;

2) An alarm warns the operator if the high pressure hydraulic pumn does not maintain discharge pressure, as it would not if the solenoid coil was to fail to operate;

3) If the accumulator nressure can't be restored, the license Technical Specifications nrovide Action Statements to ensure plant safety (T.S.3.7.1 5 MSIV operability);

h) The MSIV's and hydraulic system are exercised monthly to ensure operability;

5) System design as described precludes the possibility of a need to shut the MSIV's concurrent with the existence of inadequate hydraulic pressure to shut the valves;

6) The vicinity of the plant where the unloader valves are located is normally exnected to be in an ambient temoerature range of 8co-900F and is not expected to exceed 1200F; T) The plant operators have been alerted to the notential problem with the unloader valve solenoids and vill monitor their operation until the deficiency is corrected.

Continued Plant oneration Based on the analyses summarized above, we feel there is ample assurance that both Calvert Cliffs units can continue to coerate without any degradation of overall ulant safety while a resolution to this problem is determined. We are actively investigating the purchase of new, environ-mentally-qualified valves since the original valve supplier, Control Concepts Corporation, does not manufacture environmentally-qualified coils ,

and another brand of environmentally-qualified coil assembly will not fit into the existing valves due to dimensional limitations.

We vill keep you informed of our progress in correcting this deficiency.

ry rul yo

. F. Ash e:

Chief Nuclear Engineer Electric Engineering Department

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air. R. W. Reid December 1, 1979 cc: J. A. Biddison, Esquire G. F. Trowbridge, Esquire Mr. E. L. Conner, Jr.

Mr. J. W. Brothers - Bechtel Director itegion I Office of Insuection & Enforcement U. S. Nuclear Regulatory Comission 631 Park Avenue King of Prussia, PA 19106 4

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