ML20041B325

Ro:On 820111,unit Tripped Due to Freezing of Steam Generator Pressure Sensing Lines.Analysis of Reactor Coolant Sample Showed Activity of 1.01 Uci Dose Equivalent I-131.Later Sample Showed 0.935 Uci Dose Equivalent

ML20041B325
Person / Time
Site:	Point Beach
Issue date:	02/09/1982
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 8202230528
Download: ML20041B325 (2)

Text

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.f MSC0nsin Electnc eowra couesur 231 W. MICHIGAN, P.O. BOX 2046. MllWAUKEE. WI 53201 February 9, 1982 1

Mr. J. G. Keppler, Regional Administrator Office of Inspection and Enforcement, Region III U. S. NUCLEAR REGULATORY COMMISSION Y '

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799 Roosevelt Road //

W Glen Ellyn, Illinois 60137 g

Dear Mr. Keppler:

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DOCKET NO. 50-266 E gesu[%

REACTOR COOLANT ACTIVITY LIMITATION '

POINT BEACH NUCLEAR PLANT, UNIT 1 i[. D

(~ ' .

.}d This letter serves as notification of a reportable occurrence at Point Beach Nuclear Plant, Unit 1, in accordance with the Confirmatory Order of November 30, 1979 as modified.

At 9:50 p.m. on January 11, 1982, Unit 1 experienced a reactor trip due to freezing of steam generator pressure sensing lines (this event is covered in detail in Licensee Event Report No. 82-001/03L-0). In accordance with our admini-strative procedure to fulfill the primary coolant sampling requirenents of the Confirmatory Order, a reactor coolant sample was obtained and analyzed at 12:18 a.m. on January 12, 1982.

Analysis showed a specific activity of.l.01 pCi/g dose equivalent I-131, exceeding the limitation of 1.0 pCi/g dose equivalent I-131 contained in paragraph IV.2 of the November 30, 1979 Confirmatory Order. As required by the procedure, another primary coolant sample was taken and analyzed later the same shift at 1:42 a.m.

The specific activity of this sample was 0.935 pCi/g dose equivalent I-131. The specific activity of the primary coolant is conserva-tively estimated to have exceeded 1.0 pCi/g dose equivalent I-131 from the time of reactor trip to the time of the second sample

.which is slightly less than four hours. Detailed results of the specific activity analyses are as follows:

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o ei Mr. J. G. Keppler February 9, 1982 Concentration Dose Equivalent I-131 Time Component UCi/cc UCi/cc 12:18 a.m. 1-131 0.641 I-133 1.040 I-132 0.471 I-134 0.136 I-135 0.838 3.130 Total 1.01 Total 1:42 a.m. I-131 0.605 I-133 0.964 I-132 0.386 I-134 0.052 I-135 0.657 2.660 Total 0.935 Total During the 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to the reactor trip, the reactor was operating at 1305 MW thermal power, letdown flow through the mixed bed demineralizer was 37.gpm, and no degassing operations were taking place.

As of January 1, 1982, the fuel burnup by core region is as follows:

Region, Avg Burnup, MWD /MTU 8A 10,094 9 32,404 10 25,482 11 15,803 12 7,378 12A 546 13 613 This occurrence is an example of iodine spiking following a power reduction or reactor trip. Similar occurrences have been observed frequently in pressurized water reactors in the past.

Westinghouse Topical Report WCAP-8637 dated November 1975 has presented a discussion and analysis of this phenomenon. Subsequent to this reactor trip and iodine spike, the Point Beach Unit 1 primary coolant activity returned to its normal operating level of approximately 0.1 pCi/g dose equivalent I-131 within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Very truly yo rs, hj / ,

Assistant Vi'ce President C. W. Fay Copy to NRC Resident Inspector