ML20206H129

Clarifies Flow Path Requirements & Acceptable Independence Requirements for RHR Subsystems Per LER 86-03.Plant Meets Limiting Condition for Operation 3.5.2.e If Valves MO-8809 a & B & MO-8812 Locked Open in Modes 1-3

ML20206H129
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	06/17/1986
From:	Varga S Office of Nuclear Reactor Regulation
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
TAC-61523, NUDOCS 8606250536
Download: ML20206H129 (3)

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June 17, 1986 Docket No. 50-344 DJSTRIBUTION

\ Docket File NRC PDR Local NRC PAD- 3 Rdg.

MEMORANDUM T0: Dennis F. Kirsch Division Director K. Johnston Division of Reactor Safety Projects, RV T. Chan C. Vogan FROM: Steven A. Varga, Project Director S. Varga PWR Projects Directorate #3

SUBJECT:

CLARIFICATION ON TROJAN TECHNICAL SPECIFICATION 3.5.2, FLOW PATH REQUIREMENTS FOR THE RESIDUAL HEAT REMOVAL On March 31, 1986, Portland General Electric (PGE) issued Licensee Event Report (LER) No. 86-03 for the Trojan Nuclear Plant. LER 86-03 reported that valve M0-8809A (RHR pump discharged valve / cold leg injection) was taken out of service for preventive maintenance while Trojan was at 100% power. LER 83-03 stated that removal of this valve from service degraded the ECCS injection function of the RHR system based on the analysis in the UFSAR and that TS 3.5.2 "ECCS Subsystems - Tavg greater than or equal to 350 F" had been incorrectly interpreted and the interpretation had been incorporated in plant maintenance procedures.

By memorandum dated May 19, 1986, you requested that NRR provide clarification regarding what are the flow path requirements and minimum acceptable independence requirements for each RHR subsystem.

A. RHR Flow Path Requirements TS 3.5.2 requires two independent ECCS subsystems to be operable, each subsystem being comprised of "an operable flow path capable of taking suction from the RWST on a SI signal and transferring suction to the containment sump during recirculation phase of operation." One subsystem can be inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in Mode 1. As noted in the LER, the licensee interpreted this as allowing M0-8809A to be taken out of service for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. However, with M0-8809A closed, low head SI flow to RCS loops 1 & 2 is isolated.

The Tro.ian ECCS design assumes low head SI flow to all four loops during the injection phase of a LOCA. Therefore, an operable flow path would require M0-8809 A and B to be open during Modes 1, 2, and 3. With M0-8809A closed, Trojan did not meet TS 3.5.2.

8606250536 860617 PDR ADOCK 05000344 S PDR

B. RHR Independence Requirements A review of Figure 5.4-7 in the Trojan FSAR would indicate that the Trojan low head SI system lacks redundancy not only with regard to valves M0-8809 A & B but also with regard to RHR pump suction isolation valve M0-8812.

However, FSAR Section 6.3.3.13.1 indicates that valves M0-8809 A & B and M0-8812 are normally open, with control power lockout provided in the control room, thus effectively provided double isolation of the control power. Therefore; two independent spurious events would be required to energize the contactor coil, thereby causing unintentional valve operation. Testing of control circuitry would not change the valve position provided that the control circuit and lockout feature are intact.

This design meets Branch Technical Position PSB BTP .18, " Application of the Single Failure Criterion to Manually-Controlled Electrically-Operated Valves."

We therefore conclude that the Trojan design meets the intent of LC0 3.5.2.e providing valves M0-8809 A & B, and M0-8812 are maintained in the locked open position during Modes 1, 2, and 3.

Steven A. Varga, Director PWR Directorate #3 Division of PWR Licensing-A, NRR i

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• SEE PREVIOUS PAGE FOR CONCUR PAD-3* PAD-3 PAD- - .

i C. Vogan K. slohns on T. Chan S. V ga 06/11/86 06/4/86 06/4/86 06f 6

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Section 6.3.3.13.1 indicates that valves M0-8809 A & B and M0-8812 are normally open, with control power lockout provided in the control room, thus ffectively providing double isolation of the control power. Therefore, two i ependent spurious events would be required to energize the contractor coil, thereby causing unintentional valve operation. Testing of control circy'itry would not <

change the valve position providing that.the control circuit an'd lockout feature are intact. ThisdesignmeetsBranchTechnicalPosiyionPSBBTP18,

" Application of the Single Failure Criterion to Manually-Controlled Electrically-Operated Yalves." /

We therefore conclude that the Trojan design meets the ntent of LCO 3.5.2.e providing valves M0-8809 A & 3, and M0-8812 are maint ned in the locked open position during Modes 1, 2, and 3.

Steven A. Vayga, Director PWR Directov ate #3 Division f PWR Licensing-A, NRR l

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t PAD-3 b PAD 3 PAD-3 PAD-3 C. Vogan K Johnston T. Chan S. Varga 06/8/86 / /86 06/ /86 06/ /86 i

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