ML20236D467

Discusses Issue Raised During Review for 10CFR50,App R Audit on Guidance in Generic Ltr 86-10 Re high-low Pressure Interfaces.Concludes Problem Outside Requirements of Generic Ltrs 86-10 & 81-12 as Evidenced by 821230 Safety Evaluation

ML20236D467
Person / Time
Site:	Quad Cities
Issue date:	07/23/1987
From:	Johnson I COMMONWEALTH EDISON CO.
To:	Murley T Office of Nuclear Reactor Regulation
References
3387K, GL-81-12, GL-86-10, NUDOCS 8707300462
Download: ML20236D467 (2)

Text

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Ch Commonwealth Edison-l

? One First National Plaza, Chicago, Illinois

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] Address R; ply to: Post Office Box 767 y/ Chicago, Illinois 60690 0767 July 23, 1987

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i Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation-j U.S. Nuclear Regulatory Commission Washington, DC 20555 l

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Subject:

Quad Cities Station Units 1 and 2 i

"10 CFR 50, Appendix R Requirements For High-Low Pressure Interfaces" l

NRC Docket Nos. 50-254 and 50-265__

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Dear Mr. Murley:

1 In preparation for the 10 CFR 50, Appendix R audit, Commonwealth l

Edison Company (CECO) is performing a review of the Quad Cities Station's I

Appendix R Safe Shutdown Analysis. One of the issues raised by this review

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concerns the' applicability of the guidance provided in Generic Letter 86-10, Section 5.3.1, regarding the analysis of multiple " hot shorts" in electrical circuits involving high-low pressure interfaces, to the solenoid operated reactor relief valves, 1(2)-203-3A, B, C, D and B, the active components of the Automatic Blowdown System (ABS).

It is the position of CECO that the relief valves do not constitute a

Thus, high-low pressure interface for the purposes of Appendix R analysis.

analysis of these valves is not subject to the consideration of multiple " hot l

shcrts" in the individual valve control circuitry or ADS circuitry as required by Genet!c Letter 86-10.

The basis for this' position is contained in the The guidance provided by NRC in Generic Letter 81-12 and its clarification.

Staff's concern with high-low pressure interfaces is that a single fire could cause redundant reactor coolant boundary valves to open, resulting in a fire-initiated LOCA through the subject interface. This concern does not exist in regard to the relief valves for two reasons. First, the i slief valves are not redundant coolant system isolation valves. The opening of any individual relief valve will create a flow path for reactor coolant th" >qh the valve to the suppression pool located in the pressure-suppression et m ~

(torus) portion of primary containment. The second reason the valves are

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high-low pressure interfaces is this flow of reactor coolant does not constitute a LOCA since the coolant is maintained in a recoverable location (i.e., the torus which is expressly designed for this purpose) within primary containment.

Thus, no fire-induced LOCA is possible due to spurious operation of the relief

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valves and therefore the valves are not considered to be high-low pressure interfaces for the purpose of Appendix R analysis.

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The' response.to Generic Letter.81'-12 was provided by Ceco for the..

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Qucd Cities Station'by' letter dated July?l, 1982.'.As stated there,."The only~

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iidentified high-to-low pressure interface with dual. motor operated isolation =

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" valves....are located on-the Residual Heat Removal System shutdown cooling pump' suction' lines...."-'In order to prevent a fire-induced spurious

' operation from causing:a LOCA through.this interface, it was proposed that

.the normally closed RHR shutdown' cooling valve-be' locked in a deenergized

position at'the; appropriate motor control center. The NRC staff reviewed

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the: response and-found<it" acceptable, as' documented-in the December'30, 1982

. Safety Evaluation Report, Section 3.4.3.

.In conclusion,gitLis',CBCo's' position.that the consideration of

"- : multiple'" hot shorts".:in electrical circuitsLinvolving high-low pressure e,

' interfaces to the ABS and'related solenoid operated relief valves is outsideM the: requirecients'of Generic Letters 86-10 and 81-12.

We further'believe-

0 that yours staff has accepted this position'in the past

as evidenced in your December 30,.1982,.' Safety Evaluation.

~Please 6irect any.. questions'you may have regarding.this matter to

.this' office.

-Very truly yours, y

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I. M. J h on Nuclear Licensing A nistrator

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cc: NRC Regional Administrator NRC Resident Inspector - Quad Cities

.j T.'Ross - NRR p

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I 3387K l

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