ML20210V095

Forwards Rev 0 to Emergency Plan Implementing Procedure EP-2320, Emergency Technical Assessment, in Response to Util 851104 Commitment to Revise Core Damage Evaluation Procedures & NRC Re NUREG-0737,Item II.B.3

ML20210V095
Person / Time
Site:	Davis Besse
Issue date:	10/02/1986
From:	Williams J TOLEDO EDISON CO.
To:	Stolz J Office of Nuclear Reactor Regulation
Shared Package
ML20210V101	List: ML20210V095 ML20210V113
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.3, TASK-TM 1295, NUDOCS 8610100500
Download: ML20210V095 (2)

Text

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i TOLEDO

%se EDISON JOE VVILLIAMS. JR.

Docket No. 50-346 Sermar Vcc Prescers - Actear (419]243 2300 License No. NPF-3 14' S1 4 " 2 '3 Serial No. 1295 October 2, 1986 Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz PWR Project Directorate #6 Division of PWR Licensing-B United States Nuclear Regulatory Commission Washington, D. C. 20555

Dear Mr. Stolz:

Under cover letter (Serial No. 1066) dated August 14, 1984, Toledo Edison provided your office with a copy of Attachment 4, Core Damage Evaluation from Radiochemistry Analyses, and Attachment 5, Core Damage Evaluation from Containment Radiation Plots, to procedure EI 1300.07, Technical Support Center Activation, for the Davis-Besse Nuclear Power Station.

This submittal was in response to your letter (Log No. 1553), dated July 19, 1984 concerning NUREG-0737, Item II.B.3, Post-Accident Sampling System (PASS).

On November 4, 1985, a telephone conference call was held between Toledo Edison representatives and the NRC Staff. During the telephone call, Toledo Edison committed to revise the core damage evaluation procedures to include consideration of core temperature data, hydrogen concentration in containment, and other relevant physical parameters. The core damage assessment procedure was upgraded to include the data available from Class 1E post-accident monitoring instrumentation as well as confirmatory data available from PASS samples. The core damage assessment procedure has been incorporated into Emergency Technical Assessment Procedure, EP-2320, and is enclosed for your review.

The revision of this procedure accompanies the overall effort to upgrade the PASS. By telephone call on July 21, 1986, Mr. A. W. DcAgazio of your staff requested that a summary of the PASS upgrade be provided with the submittal of the revised procedure.

The PASS upgrade resulted from recommended actions of Toledo Edison's System Review and Test Program. The following summarizes the current upgrade:

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• Deckat No. 50-346 License No. NPF-3 Serial No. 1295 October 2, 1986 Page 2 A. A time-motion study was conducted in early 1986 using the sampling procedures approved for use at that time. The previous time-motion study used preliminary procedures and did not incorporate all the required sampling steps. The_reviaed time-motion study using the NUREG-0737, II.B.2 source term (100% noble gas, 50% halogens, 1%

particulates, decayed one-hour), indicated that the dose to the operator, in a post-accident situation, exceeded GDC-19 guidelines.

This was reported to the NRC in Licensee Event Report No. 86-20. To correct this situation, two modifications have been implemented:

1. The process piping on the PASS skid, where the sample is drawn, is separate from the PASS control panel. A shield wall has been constructed between the skid and the control panel to significantly reduce the dose to the operator.

2. Repeater gauges for monitoring sample flow and temperature have been mounted in a low dose area adjacent to the PASS control panel. This will allow the operator to monitor system function during long sample purges, while remaining away from the panel.

With these modifications, the estimated operator doses are below GDC-19 guide) *.nes.

B. .In addition to the above two modifications, the sampling system design was significantly modified to minimize the radiation exposure during sampling and to facilitate the sampling of both liquid and the off-gas from the liquid. The original design called for drawing a 30 ml liquid sample and did not provide for sampling of the gases evolved from a depressurized liquid sample. In the new design, both the liquid and off-gas samples are collected in separate 4 ml vials.

This small sample volume provides an additional reduction of dosage to the operator.

C. Applicable sampling procedures were revised to address system design changes and to integrate the analysis of PASS data into the overall post-accident assessment scenario.

The PASS and supporting procedures were successfully demonstrated to the NRC in the Emergency Exercise on September 23, 1986.

Very truly yours, d;)

WD:plf cc: DB-1 NRC Resident Inspector i

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