ML20197D184

Provides Addl Info in Response to Questions 13 & 15 in Re Leakage Rate from Spent Fuel Pool Liner, Surface Dose Rate as Spent Fuel Pool,Potential Impact of Proposed Spent Fuel Pool Mod Re Gaseous Effluents

ML20197D184
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	11/08/1978
From:	Naughton W COMMONWEALTH EDISON CO.
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 7811210410
Download: ML20197D184 (3)

Text

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November 8, 1978 Director of Nuclear Reactor Regulation U.S. Nuclear Reg 11atory Commission Washington, D.C. 20555 1

Subject:

Zion Station Units 1 and 2  ;

Additional Information on Proposed ,

Expansion of Spent Fuel Storage Capacity l

.NRC Docket Nos. 50-295 and 50-304 I Reference (a): October 24, 1978 letter from William F.

Naughton to Director of Nuclear Reactor l Regulation responding to NRC request for additional information

Dear Sir:

Per conversations with Messrs. J. N. Donohew and G. Zech of the NRC Staff, Commonwealth Edison Company was requested to provide additional information with regard to its responses to Questions 13 and 15 in Reference (a). This information is provided below.

Additional Information on Response to Question 13 a) During the preoperational test period at Zion Station, the leakage rate from the spent fuel pool liner was found to be 50 gallons / day.

Currently, observations of the six sight glasses installed in the drain lines indicate that this leakage rate has remained unchanged since the initial test period.

b+c) The surface dose rate at the spent fuel pool is less than 2 mrem /hr during normal operations.

To date, failed fuel has not been a problem at Zion Station. Due to the low levels observed, failure rates have been difficult to quantify.

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. k Commonw:alth Edis n NBT Docket Nos. 50-295/304 Director of Nr. clear Reactor Regulation November 8, 3978 Page 2 The spent fuel pool filters are changed once oer year, usually just prior to a refueling outr3e.

This provides maximum filtration capacity during fuel movemente and precludes potential delays in the outage schedule necessitated by a filter change. Thus, the filters are changed on an operational basis, not due to a loss of filtration capacity.

Additional Information on Response to Question 15 9"

in stored a) The fuel is Kr8,5* which is an inert gas.

most significant To date, Kr 85 has barely been detectable at Zion Station because there have not been any significant fuel failures at Zion Station. This situation is not expected to change in the futuse as Zion Station does not expect any degradation in Suel performance.

Therefore, in assuming a potential impact of the proposed spent fuel pool modification with regard to gaseous effluents from the pool, the following assumptions were made:

1. Each fuel assembly contains about 8500 curies (Ci) of Kr85 with 100% contained in fuel-clad gap (Zion FSAR, Page 14A.3-3 Table A.3-2, in-dicates that the activity of the highest rated discharge assembly at time of reactor shutdown is 8500 curies with 27.3% expected in the fuel-clad gap) ;

2. Only 0.1% of the additional 1244 stored assemblies (2112-868) are leakers; and

3. Leakage rate of 0.1% per year since all the fuel in the pool will not leak simultaneously.

Based on these assumptions, a potential increase of about 11 Ci per year is calculated for Zion Station.

Since Zion Station released a total of 13,117 Ci between January and June 1977 (less than 10% of the allowable Zion Technical Specification limit), this potential incremental, increase of 11 Ci is considered negligible.

.. . . , 4-. _ ..

Ceminonwacith Edison - NRC Docket 'Nos. 50-295/304

[ Director: of Nuclear Reactor Regulation-

~

November-8',~ 1978 '

Page 3:

b4c) All leakage.from the spent fuel pool is. collected.

_'This leakage, which.is 50 gallons per day (approximately 18,000- gallons - per year) , is not expected to" increase as a result'of the. proposed modification ~. All of this-leakage is combined with other boric acid containing1wasta. streams ~and treated

=by, evaporators as_part of.the radwaste' system. This

-leakage.accountscfor'approximately 0.3'Ci contained'

.in al solid' discharge of about 300 lbs. of boric acid per. year.

1 i-One (1) _ signed original and thirty-nine (39) copies are l

-provided_for.your:use. l Very truly yours,

/t. M F4 o L 1 W.F.Naughhon Nuclear _ Licensing Administrator

- Pressurized-Water Reactors.

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