ML19312C158

Forwards Addl Info Re Electrical Equipment Which May Become Submerged Following Postulated Loca,In Response to Question 4 of NRC 760406 Ltr Re ECCS Analysis

ML19312C158
Person / Time
Site:	Oconee
Issue date:	06/04/1976
From:	Parker W DUKE POWER CO.
To:	Rusche B Office of Nuclear Reactor Regulation
References
NUDOCS 7912060734
Download: ML19312C158 (4)

Text

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.- SPA Mr. Benard C. Rusche

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%%,U 13 4,'.m:'yr e Director of Nuclear Reactor Regulation '. . N G'g ' ' T/

U. S. Nuclear Regulatory Commission -

.7 Washington, D. C. 20555 ,

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Attention: Mr. R. A. Purple, Chief .

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Operating Reactors Branch No. 1 Re: Oconee Nuclear Station Docket Nos. 50-269, -270, -287

Dear Mr. Rusche:

In response to your letter dated April 6, 1976 which requested additional information regarding the ECCS analysis for Oconee Nuclear Station Units 2 and 3, the attached information is provided to supplement my May 13, 1976 submittal. This information is the response to Question 4 con-cerning electrical equipment which may become submerged following a postulated loss-of-coolant accident.

Mr. R. A. Purple's letter dated October 15, 1975 indicated concern for the possibility of water hammer in the Low Pressure Injection System and recommended that valves LP-21 and LP-22 be changed to normally open valves.

The Oconee 2 operating procedures will be revised, prior to startup, to require that valves LP-21 and LP-22 be normally open during unit operation.

Very truly yours,

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William O. Parker, Jr.

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. ~ f. .n MST:vr Attachment 6736 i

89i20607)

g 9 RESPONSE TO MR. R. A. PURPLE'S LETTER DATED APRIL 6, 1976 Question 4: /

Identify all electrical equipment, both safety and non-safety, that may become submerged as a result of a LOCA. For all such equipment that is not qualified for service in such an environment, provide an analysis to determine the following: (1) the safety significance of the failure of the equipment (e.g., spurious operation, loss of function, loss of accident / post-accident monitoring, etc.) as a result of flooding, (2) the effects of Class IE electrical power sources serving this equip:nent as a result of such failures, and (3) the proposed design changes resulting from your analysis. Your response to item (2) should specifically address breaker and fuse coordinction

, and the irolation capabilities of this aspect of your design.

RESPONSE

Identification of Submerged Electrical Equipment All electrical equipment, both safety and non-safety, which may become sub-merged as a result of a postulated loss-of-coolant accident is identified in the attached Table 1.

Evaluation of Safety Significance A review of the electrical equipment identified in Table 1 has been performed to determine the safety significance of the failure of this equipment. The failure of valves which could become submerged (identified by *) has previously been analyzed in attachment 4 to our July 9, 1975 submittal and in the response to question 2 in attachment 2 of our October 31, 1975 submittal. The remaining items are not considered necessary to place the reactor in a shutdown condition nor to mitigate the consequences of a loss-of-coolant accident. Therefore, it j is considared that the failure of this equipment has no safety significance.

4 Evaluation of Effects on Class lE Power Sources All electrical equipment listed in Table I is supplied from Non-Class lE power sources with the following exceptions:

a. Reactor Coolant Pump 011 Tank Level Detectors (4)

b. Letdcen Cooler LA Isolation Valve HP-3

c. Letdown Cooler 1B Isolation Valve HP-4

d. Quench Tank Suction Valve CS-5 Based on the analysis of the above-mentioned equipment that is powered from Class lE power sources, it has been determined that existing circuit breaker and fuse coordination will protect the Class lE power sources such that the safety function of other Class lE equipment is not rendered inoperative.

However, a situation has been identified in wnich the flooding of limit switches on valves b, c, and d (above) could possibly result in the loss of normal control power (manual control function) to ES Cabinet 8. This would not affect the required safety function of the equipment associated with

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2-ES Cabinet 8. However, Inodifications will be made to assure that the manual control function of eauipment supplied by ES Cabinet 8 is maintained.

Proposed Desian Channes To preclude the possibility that the flooding of limit switches on valves b, c, and d (above) could result in a loss of normal control power (manual control function) to ES Cabinet 8, fuses will be installed in the circuits from the valve limit switches to ES Cabinet 8. An analysis has shown that fuses will provide the necessary coordination to assure that ES Cabinet 8 retains its normal control power (manual control function).

. . ,. ~ - a TABLE 1 ELECTRICAL EQUIPMENT LOCATED BELOW THE LOCA FLOOD LEVEL Steam Generator lA Level Detector (5)

Steam Generator 1B Level Detector (5)

Reactor Coolant Pump Oil Tank Level Detector (4)

Reactor Coolant Pump Standpipe Level Detector (4)

• Letdown Cooler lA Inlet Valve HP-1

• Letdown Cooler lA Isolation Valve HP-3

• Letdown Cooler 1B Inlet Valve HP-2

• Letdown Cooler 1B Isolation Valve HP-4

• Letdown Cooling Inlet Valve CC-1

• Letdown Cooling Inlet ' Valve CC-2 Letdown Cooling Component Cooling Outlet Temperature Detector (2) l Qucacu 'ank Level Detector Quench Tank Press Detector Quench Tank Heat Exchanger Discharge Temperature Detector Quench Tank Temperature Detector

• Quench Tank Suction Valve CS-5 Quench Tank Heat Exchanger Inlet Valve CC-49 Position Indication Quench Tank Heat Exchanger Outlet Valve CC-53 Position Indication Quench Tank Cooler Inlet Valve CS-13 Position Indication Quench Tank Cooler Outlet Valve CS-14 Position Indication Quench Tank Outlet Valve CS-3 Position Indication

• Core Flood Tank 1A Outlet Valve CF-1 Controller Core Flood Tank 1A Level Detector (2)

Core Flood Tank 1B Press Detector Reactor Building Normal Sump Temperature Detector Reactor Building Normal Sump Level Detector Reactor Building Emergency Sump Level Detector Lighting Panels EL1 and WL1 Reactor Vessel Water Level Detector Telephones PA Speakers PA Amplifier PA Power Supply I l

'1 CSafety significance previously addressed in W. O. Parker'r letters of July 9, j 1975 and October 31, 1975.

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