ML20126E249

Informs of Licensee Intentions of Replacing Existing Reactor Water Level Sensors REO 9A,REO 9B,REO 9C & REO 9D W/Remotely Located Level Sensors During Feb-Mar 1970 Outage.Drawings Encl

ML20126E249
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	02/24/1970
From:	Haueter R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Morris P, Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8101150657
Download: ML20126E249 (5)

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• Area Code 517 788+0560 February 24, 1970 Dr. Peter A. Morris, Director Re: Docket 50-155 Division of Reactor Licensing DPR-6 ZEK United States Atomic Energy Commission Washington, DC 20545 .-Regulatory File Cy.

Dear Dr. Morris:

Attention: Mr. D. J. Skovholt This informational letter will confirm our intention of re-placing the existing reactor water level sensors (REo 9A, REO 9B, REO 9C and REO 9D) with remotely located level sensors during the February-March 1970 outage at Big Rock point. These present magnetic float switch-type pressure switches will be replaced using level ele-ments (constant head chambers) with the indicator switch devices for each element being located outside of the recirculation pump room to provide better accessibility for calibration and maintenance.

Previous work functions performed on this system include yearly calibration, valve and switch maintenance.

The present level switches, valves and piping (Attachment No 1) are located approximately 36 feet above the recirculation pump room floor and are inaccessible during power operation. The level switches are accessible during shutdown only by way of a vertical ladder leading to the service platform. The general radiation field on the platform near the switch location averages approximately 500 mR/h. Several localized radiation hot spots of three to four R/h exist in this area due to the accumulation of crud deposits in surrounding headers and associated piping. Because of high radiation exposures to manpower, while performing calibration checks and nec-essary maintenance and due to the poor accessibility to the system, Consumers Power Company has decided to replace the existing level sensors with a remote system.

The new remote level sensor system (Attachment No 2) vill consist of four stainless steel constant head chambers, tubing, valves, viring and four Yarway units with self-contained relays and terminal boards. This system vill be similar to the existing drum level sensors system which has shown proven reliability (over seven years of service).

/

THIS DOCUMENT CONTAINS ,,

E POOR QUAUTY PAGES _

8mMM57 .

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Dr. Peter A. Morris 2 Att: Mr. D. J. Skovbolt February 24, 1970 .

9 The installation of the level elements and readout sensor units will be in accordance with Yarway specifications and the fol-loving criteria:

1. The indicators vill be calibrated with appropriate t

. suppression.

2. Tubing and/or piping for the respective instruments vill be run close together with long radius bends providing for ex- .

pansion. l 3 All tubing and/or piping vill be installed to permit  !

free drainage with the absence of nondraining ' pockets.  ;

4. No existing system trip or set points will be changed. .f

.l' General Electric Company has studied our preliminary design criteria and has given Consumers Power Company tentative approval.

The final design criteria vill be presented to General Electric Company for their approval. .i Consumers Power Company believes that the new' level sensor system will improve plant reliability through greater flexibility for calibration .d maintenance and will.also reduce substantial radiation exposure to plant personnel. In our opinion, the new level sensor system vill not result in any additional hazards to plant personnel or the prJolic and vill improve the present plant safety system.

Yours very truly,

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V ERC/ck Robert L. Haueter Electric Production CC: GFiorelli Superintendent - Nuclear EJBrunner

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DATE R!CEIVED NO.

r;ou' Consumers Powe Compaar lDATE OF DOCUMENT Jackson,alichiama 49201 .

2-34-3 k-a7-D 594 m ,,,,,, , ,,,, o7, ,,,

Bobett L. Esueter , ,

yo: ORIO.s CCa OTHEA Dr Pater A. Morris 1 signed & M oonf4 ACTIdM NECESSARY O CONCURRENCE O DATE ANSWERED NO ACTION NECESSARY O COMMENT O av CLA44t F: POST OFFICE FILE CODES a REO.NO:

50-155 DE3CRIPTION: (Must Be Unclassified) REFERRED TO DATE RECElVED BY DATE Ltr informing of intention to replace Ziemann the existing reactor water level sensors 3-e *lt

,fg gy, fa, ,,gga,i (REO 9A,9B,90,9D) w/ remotely located leval sensors during Feb-Mar 70 outage. "

DIJfRIBUTION:

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