ML18141A325

Advises That Reduction of Boron Concentration in Storage Tanks & Safety Injection Piping Would Result in Reduction of Approx 136 Manrem in Annual Radiation Dose.Method for Establishing Manrem Reduction Estimate Provided

ML18141A325
Person / Time
Site:	Surry
Issue date:	01/18/1984
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Harold Denton, Varga S Office of Nuclear Reactor Regulation
References
025, 25, NUDOCS 8401250044
Download: ML18141A325 (2)

Text

e e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 W. L. STEWART VICE PRESIDENT NucLEAR 0PERATXONS January 18, 1984 Mr. Harold R. Denton, Director Serial No. 025 Office of Nuclear Reactor Regulation NO/WDC:jab Attn: Mr, Steven A, Varga, Chief Docket Nos. 50-280 Operating Reactors Branch No. 1 50-281 Division of Licensing License Nos. DPR-32 U. S. Nuclear Regulatory Commission DPR-37 Washington, D. C. 20555 Gentlemen:

MAN-REM DOSE ESTIMATES - REDUCED BORON CONCENTRATION SURRY POWER STATION In our meeting with the Nuclear Regulatory Commission on September 21, 1983, Vepco committed to provide information on radiological dose savings estimated to result from reducing the boron concentration. Although exact measurements of radiation exposure reduction due to reduced boron concentration cannot be made, it is estimated that the reduction of boron concentration in the storage tanks and safety injection piping would result in a reduction of approximately 136 man-rem in annual radiation dose at Surry Power Station.

The man-rem reduction estimate was established as follows:

1. Actual station doses associated with concentrated boric acid piping received during the first 10 months of 1983 were approximately 365 man-rem on the Boric Acid Flats and 53 man-rem at the Boron Injection Tanks.

2. A conservative estimate of dose rate resulting from boron concentration in the tanks at a minimum of 7% versus 11.5% in 1983 (concentration 60% of current) is 90% of the dose rate experienced in 1983. Subsequent flushing of tanks and reduction of crud concentrations could be expected to provide even further reduction in general area dose rates.

3. Manhour expenditures for maintenance are estimated to be reduced by 25% due to lower boron concentration and resultant lowered heat tracing temperature requirements.

4. Man-rem exposure (1983) = Dose Rate (1983) x Maint. Manhours (1983).

Man-rem exposure at reduced CB= .9 Dose Rate (1983) x . 75 Maint.

Manhours (1983) = .675 x man-rem exposure (1983).

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e e VIRGINIA. ELECTRIC A.ND PowER CoMPANY To Mr. Harold R. Denton

5. Based on 418 man-rem received January through October in 1983, a man-rem exposure due to concentrated boric acid piping, the man-rem exposure expected with the reduced boron concentration would be 418 x .675 or 282 man-rem. Thus, using the ten month data above without credit for the additional two months; man-rem exposure reduction would be at least 136 man-rem per year.

Should you have any further questions, please contact us.

Very truly yours, Ql.~~

W. L. Stewart cc: Mr. James P. O'Reilly Regional Administrator Region II Mr. D. J. Burke NRC Resident Inspector Surry Power Station Mr. J. Don Neighbors NRC Project Manager - Surry Operating Reactors Branch No. 1 Division of Licensing