ML17037C165

Letter Enclosing Noble Gas and Iodine Activity Data in Response to the June 10, 1975 Letter

ML17037C165
Person / Time
Site:	Nine Mile Point
Issue date:	07/07/1975
From:	Rhode G Niagara Mohawk Power Corp
To:	Lear G Office of Nuclear Reactor Regulation
References
Download: ML17037C165 (8)

Text

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NRC DISTRIBUTION FOR PART 50 DOCKET MATERIAL (TEMPORARY FORM)

CONTROL NO 734 FILE FROM: Niagara Mohawk Power Cor DATE OF DOC DATE R EC'D LTR TWX RPT OTHER Syracuse, N.Y. XX TO: ORIG CC OTHER SENTNRC PDR Hr. G ~ Lear l-signed. SENT LOCAL PDR xxxx CLASS UNC LASS P ROP-INFO INPUT NO CYS REC'D DOCKET NO:

XXXX 50>>220 DESCRIPTION: ENCLOSURES:

Ltr trans the following: Noble Gas Activity Data ACKNO>VL,ED"VV

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NIAGARA MOHAWK POWER CORPORATION 4I'M, NIAGARA ~) MOHAWK 300 ERIK BOULEVARD WEST SYRACUSE. N. Y. 13202

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Mr. G. Lear, Chief Operating Reactors Branch 83 ~<~4 ~~~< iy Division. of Reactor Licensing 41/yW>>

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U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Re: Nine Mile Point Unit 1 Docket No. 50-220

Dear Mr. Lear:

The attached noble gas and iodine activity data for Nine Mile Point Unit 1 is provided in response to your letter of June 10, 1975. It is representative of normal operation for the plant.

Very truly yours, NIAGARA MOHAWK POWER CORPORATION Gerald . R de Vice President En neering Attachment 7343

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Nine Mile Point Unit 1 NOBLE GAS AND IODINE ACTIVITY DATA Noble Gas Activit Data Only the following limited data is available for noble gas activity in the drywell during operation. The best sample taken occurred when the offgas (summation of the six principal fission gases) l ~ amounted to 200,000 pCi/sec at the Steam Jet Air Ejector (SJAE).

Drywell Gas Sample Offgas Sample at SJAE Fission Gas Ci/cc pci/cc Xe-133 6.0 x 10 (-5) 2.0 x 10 (-1)

Xe-135 4.0 x 10 (-5) 5.5 x 10 (-1)

Iodine Activit Data The following is a table of sample results over the last few years showing a comparison between I-131 in the drywell atmosphere, I-131 in the reactor water, and the offgas activity (summation of the six principal fission gases) I ~ at the SJAE.

Drywell I-131 Reactor Water I-131 Offgas .at SJAE Date Ci/cc Ci/ml 10-16-73 4.1 x 10(-9) 5.2 x 10(-3) 4.9 x 10(+4) 3-27-74 4.9 x 10(-9) 2.2 x 10(-3) 6.8 x 10(+4) 11-13-74 5.9 x 10(-'10) 9.1 x 10(-4) 7.3 x 10(+4) 12-5-74 4.7 x 10(-10) 8.9 x 10(-4) 7.9 x 10(+4) 12-13-74 2.4 x 10(-9) 9.3 x 10(-4) 3.2 x 10(+4) 12-20-74 1.1 x 10(-9) 8.1 x 10(-'3) 5.9 x 10(+4) 2-3-75 4.4 x 10(-9) 1.2 x 10(-3) 8.'2 x 10(+4) 3-20-75 4.1 x 10(-9) 4.3 x 10(-3) 1.0 x 10(+5)

,4-11-75 1.5 x 10(-7) j:5.j 4.4 x 10(-3) 1.2 x 10(+5)"

6-17-75 2.0 x 10(-9) 4.3 x 10(-3) 1.7 x 10(+5)

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Notes

[1] At sample time,'-131 concentration in the reactor water was approximately 4.0 x 10(-3) pCi/ml.

[2] Fision gases include: Kr-85m, Kr-88, Kr-89, Xe-133, Xe-135, and Xe-138. There is approximately a five minute delay between the reactor and SJAE.

[3] Leakage of reactor water into the drywell floor drain system was nominally <0.5 gpm for most of the sample periods.

[4] Experience has shown that a "Distribution Factor" of 1,000,000 is appropriate to approximate airborne I-131 levels during times of normal reactor water leakage, i.e.:

Reactor Water I-131 Ci/ml Distribution Factor = Drywell I-131 (pCi/cc)

[5] Sample taken prior to a drywell purge preceeding reactor shutdown due to high leakage rate of reactor water into drywell floor drain sump.

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