ML20086E220

Ro:On 750209 & 10,excessive Level of Heat Rejected to Connecticut River & Filter Paper Sample Whisked from Numbed Technician Hand by Wind,Respectively.Events Caused by Lack of Communication & Wind,Respectively

ML20086E220
Person / Time
Site:	Vermont Yankee
Issue date:	03/10/1975
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
VYV-3755, NUDOCS 8312060430
Download: ML20086E220 (3)

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, '. O ~O b VERMONT YANKEle NUCLEAR POWER CORPORNPTON SCVCNTY SCVCN OROVC GTRCCT RirrLANo, VimMONT 03701 VYV-3755 e '$xis7 a

VERNON. VERMONT oS354 March 10, 1975 .

United States Nuclear Regulatory Commission A Office of Inspection and Enforcement [ r ,- f co b, Region I /O '

(/ 'h 631 Park Avenue pf j f/ f.N3'

/ > 8g/jf D King of Prussia, Pennsylvania 19406 4 Dc-ATTENTION: James P. O'Reilly, Director

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REFERENCE:

Operating License DPR-28 .#~' % ir'4 NT Docket No. 50-271 ., gy *If ,Q/

Dear. Sir:

. D-This letter is to inform you of two events that occurred during the month of February, 1975. The first involves _a_regnfra - r af Appendix B to our Technical Specifications and the second is an item of

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missed _ surveillance.

1. Technical Specifications Appendix B, Section 1.1.A.3, requires that discharges of heated water to the Connecticut River shall -

,- be controlled so that the rate of change due to operations shall not exceed 0.5'F per hour from May 1 through October 31, nor l'F per hour from November 1 through April 30, as meas,ured at.-

the upstream and downstream monitors. -

Prior to the event, Vermont Yankee was operating at a steady 100% power 1cvel and rejecting appro::imately 70% heat to the .

Connecticut River under our NRC approved Phase II Study program.

At approximately 1100 on February 9, 1975, the Vermont Yankee operator learned from.the Vernon hydroelectric station that'their scheduled full load operation for the previous 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> had been canceled and that during this period they had operated at.-

minimum lead. The Vermont. Yankee operator immediately began to' -

reduce the amount of heat being rejected to the river by. opening ,

the rceirculation gate in increments _of one hour duration.

8312060430 75'0310 PDR ADOCK 05000271 K b} O-g4

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• VERMONTh) NKEE NUCLEAR POWER CORPORAT

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Office of Inspection and Enforcement March 10, 1975 Page 2 By 0700 on February 10, 1975, Vermont Yankee was operating entirely on closed cycle. Two hours later, at 0900, the Vernon hydrocicctric station returned to full load operation. The cumulative effects of impounding the relatively high heat rejection rates while Vermont Yankee returned to closed cycle operation, coupled with the rapid change in the hydroelectric station's return to full load, resulted in an indicated rate of change at the downstream monitor of 1.3*F/ hour. Technical Specifications Appendix B, Section 1.1.A.3, allows a maximum rate of change of 1.0*F/ hour. ,,

In evaluating the observed 1.3*F/ hour-rate of change, the following statistical analysis should be considered. During Phase I of the open cycle river study in 1974, a statistical correlation based on historical natural variation of the maximum mixed river temperatures as measured at the upstream and downstream monitors was performed. This analysis covered four years of river temperature data. From the resulting regression equation, it can be shown ,

that at a 99% confidence limit for 32*-34*F river water temperature (winter conditions)~ the natural variation between the two river-temperature monitors may be as high as 10.9'F. Theretore, tne observed 1.3*F/ hour rate of change may not have been completely attributable to operations at Vermont Yankee and the Vernon hydroelectric station.

It was concluded, however, that the corrective actions taken to . ,

reduce the heat rejection rate in this instance were correct and proper.

2. Table 3.9.1 of the Technical Specifications requires that an air particulate sample from the environmental monitoring stations be analyzed for gross beta activity weekly. Once each week a technician collects the filter paper sampic from ca'ch monitoring station and the sample is later analyzed by an independent

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laboratory. On February 10, 1975, . a windy and cold day, the' technician made his normal rounds. While changing the 47 mm diameter filter paper at Station AT 2.1, the wind whisked the!

sample from his numbed fingers and blew it irretrie@ ably out of reach. It should be noted that the use of gloves during this delicate procedure is impractical. Station AT 2.1 is-a Zone II station which provides a ' distant ~ running background which makes uit possible to distinguish significant radioactivity introduced into-the environment by operation of Vermont Yankee from that'

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o VERMONT Y KEE NUCLF:"AR POW;iP COR"0 J.a' 463 Office of Inspection and Enforcement March 10, 1975 Page 3 4

introduced by other sources. Plant management has discussed with those individuals responsibic for conducting the surveillance sampling the need for employing the utmost possible care to '

prevent a. recurrence of this nature in the future.

f Very truly yours,

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Bradford W. Riley l Plant Superintendent BMB/kbd l

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