ML20129K117

Responds to 850613 Request for Addl Info Re NUREG-0737,Item II.F.2, Inadequate Core Cooling Instrumentation. Class 1E Platinum Resistance Temp Detectors Will Be Used to Measure Ref Junction Temp for Backup Displays

ML20129K117
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	07/19/1985
From:	Withers B PORTLAND GENERAL ELECTRIC CO.
To:	Butcher E Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM TAC-45175, NUDOCS 8507230404
Download: ML20129K117 (3)

Text

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um same N General MCoirpaily r - E:

m.m Bart D Wthers Vce Presdent July 19, 1985 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation ATTN:

Mr. E. J. Butcher, Jr., Acting Chief Operating Reactors Branch No. 3 Division of Licensing U.S. Nuclear Regulatory Commission Washington DC 20555

Dear Mr. Butcher:

NUREG-0737, Item II.F.2 Inadequate Core Cooling Instrumentation Your letter of June 13, 1985 requested information in addition to that contained in our March 12, 1984 and January 4, 1985 submittals concerning the Core Exit Thermocouple System, the subcooling margin monitors, and the Reactor Vessel Level Instrumentation System. The requested information is attached.

Sincerely, 2

Bart D. Withers Vice President Nuclear Attachment c:

Mr. Lynn Frank, Director State of Oregon Departiaent of Energy Mr. John B. Martin Regional Administrator, Region V U.S. Nuclear Regulatory Commission R87 a M%*

Ro01 121 S W Sa! mon Sneet, Per ond Oregon 97204 g

Trojan Nuclear Plant Mr. E. J. Butcher, Jr.

Docket 50-344 July 19, 1985 License NPF-1 Attachment Page 1 of 2 REQUEST FOR ADDITIONAL INFORMATION FOR INADEOUATE CORE COOLING INSTRUMENTATION NRC Request PGE has committed to upgrade the existing Core Exit Thermocouple (CET)

System and it is still in process to finalize the CET System design with respect to either qualifying the existing reference junction box (RJB) or removing RJB to outside of the Containment.

Provide a block diagram of the final CET System (primary and backup), including the qualification status of the components and schedule for modification, if any.

PGE Response Our letter of January 4, 1985 provided the environmental and seismic qualification status of the final CET System. At that time, it was unknown as to whether the reference junction boxes would remain in Containment or would be relocated.

It has since been determined the reference junction boxes in the final CET System will be located inside the control room (a mild environment). Seismically qualified, Class 1E platinum resistance temperature detectors will be used to measure the reference junction temperature for the backup displays.

With regard to the block diagram of the system, several tcaign alterna-tives are still being considered which make it inappropriate to forward a block diagram at this time. The conformance of the system deb ;n, quali-fication, and schedule for installation to the NRC requirementK nee ade-quately described in our January 4, 1985 letter as supplemented herein.

NRC Request PGE has used the two current subcooling margin monitors (SNMs) as its i

backup CET displays. Although the SNMs will have qualified input upon completion of CET upgrade, the SNM displays are not seismically quali-fled. PGE has also insisted in its two previous submittals dated March 18, 1983, and January 4, 1985 that it does not plan to upgrade SNK displays based on the short-term requirements of NUREG-0578. The Staff has responded to the PGE proposal in our February 2,1984 evaluation that the requirements of NUREG-0578 have been superseded by specific design requirements given in NUREG-0737, Item II.F.2.

Based on our review, PGE's proposal to use nonqualified SMMs as the backup displays for the CETs does not meet the requirements of NUREG-0737, Item II.F.2.

In addition, the backup SMM instrumentation channel should be seismically and environmentally qualified, electrically independent from the primary SMM channel and energized from an independent station Class 1E power source, and should satisfy the single-failure criterion. Therefore.

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Trojan Nuclear Plant Mr. E. J. Butcher, Jr.

Docket 50-344 July 19, 1985 License NPF-1 Attachment Page 2 of 2 provide the schedule and plan to upgrade the existing SMMs or provide an alternate instrumentation scheme which meets design requirements for SMMs and backup CET display.

PCE Response As part of the CET upgrade, the two channels of the SMM will be upgraded to be electrically independent of one another and of the primary CET display. The SMMs are located in a mild environment and as such are not subject to environmental qualification requirements. The SMMs will be seismi*cally qualified in accordance with IEEE 344-1975. Each SMM channel will be energized from an independent Class 1E power source. The SMM satisfies the single-failure criterion as follows:

a.

The two SMM channels are redundant and are powered from separate trains of Class 1E power.

b.

The two SMM channels will not share any common inputs.

c.

The SMMs will be electrically isolated and independent from the primary CET display.

NRC Request PGE has stated that the RVLIS will be operational by July 1, 1985 upon completion of the modification. Please describe and provide details of the modification and the schedule for submitting the implementation letter report, which was described in our February 2, 1984 evaluation.

PGE Response As noted in our January 4, 1985 letter, problems were being experienced with the RVLIS regarding maintaining system fill. A modification was completed during the 1985 refueling outage to replace many of the system's mechanical joints with welded joints and to weld the caps on the three-way valves in the system.

It is still our intent to submit the implementation letter report by September 1, 1985 as described in our March 12, 1984 letter.

SAB/3kal 1095G.785