ML20138E790

NPDES Noncompliance Notification:On 970319,approx 300 Gallons of Waste Water Was Drained from Millstone 3 Reactor Plant Closed CWS & Discharged Via Dsn 001C-9

ML20138E790
Person / Time
Site:	Millstone
Issue date:	04/14/1997
From:	Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
To:	Dinoia M CONNECTICUT, STATE OF
References
SES-97-GN-065, SES-97-GN-65, NUDOCS 9705050147
Download: ML20138E790 (2)

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Northeast 7 8"" 8'"" 8"uo, a 06037 Utilities System Northeast UtiBtles Service conipany P.o. Boz 270 Hartford, cT 06141-0270 (203) 66s-5000 April 14,1997 j

SES-97-GN-065

D11003 Ms. Michele DiNola Bureau of Water Management Department of Environmental Protection 79 Elm Street P.O. Box 5066 Hartford, CT 06106-5127

Dear Ms. DiNola:

Millstone Station 2

NPDES Permit No. 0003263 Notification Pursuant to Northeast Nuclear Energy Company's NPDES permit, Millstone Station is authorized to discharge non-contarninated closed cooling water system drainage through DSN 001C-9. On March 19,1997, approximately 300 gallons of waste water was drained from the Millstone 3 Reactor Plant Closed Cooling WcW Wem and discharged via DSN 001C-9.

However, as reported to you by phone on April 9,1997, and as discussed below, we have become aware that this discharge may have contained small amounts of dichlorodifluoromethane ("R-12"). While we do r.ut believe this discharge endangered human i

health or the environment, we are, neverthelest reporting this event to you in accordance with 4

Subsection (j)(11)(D) of Section 22(a)-430-3 of the Regulations of Connecticut State Agencies.

By way of background, the Reactor Plant Closed Cooling Water systems at Millstone Unit 3 consist of several closed systems. One such system is the Reactor Plant Chilled Water system which uses R-12 as a refrigerant. The Reactor Plant Chilled Water system is a three loop system which provides cooling water to various components throughout the Millstone 3 Reactor Plant. Each loop is equipped with a shell and tube heat exchanger where heat is transferred from the system cooling water (tube side) to the R-12 (shell side). The heat exchanger tubes within the Reactor Plant Chilled Water system are tightness tested I, periodically by means of Eddy Current testing. The frequency of this testis based on k U

recommendations by the vendor performing the test. The most recent Eddy Current test was performed in May of 1996. All tubes were found to be tight at that time. Since there is no present indh:ation of a loss of freon, we believe the presence of R-12 in the Reactor Plant Chilled Water System is the result of historicalleaks in the system.

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9705050147 970414 -

PDR ADOCK 05000423 S PDR

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The presence of R-12 was discussed with the Department in late 1996. At that time, it was I agreed that Reactor Plant Chilled Water drainage was to be collected and properly disposed of I off-site rather than discharged. However, at the time of the March 19,1997 discharge, it was not fully understood that the Reactor Plant Closed Cooling Water system may also contain R-

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1 12 due to past heat exchanger leaks and/or quarterly safety testing requirements during which 1

the Reactor Plant Closed Cooling Water system and the Reactor Plant Chilled Water system l are cross-connected. As a result, the 300 gallons of Reactor Plant Closed Cooling Water, that

is the subject of this letter, was inadvertently discharged rather than collected for off-site  ;

4 disposal. Subsequent to this discharge, prior sampling results for the Reactor Plant Closed Cooling and Chilled Water Systems were reviewed. This, in turn, led to the resampling of i these systems on April 1,1997. On April 8,1997, the laboratory results revealed the presence )

, of R-12 in the A and B loops of the Reactor Plant Closed Cooling Water system at 44.8 ppb  !

and 60.7 ppb respectively and in the Reactor Plant Chilted Water system at 98.5 ppb.

While the presence of R-12 in these two closed systems is not necessarily indicative of the d

presence of R-12 above detectable levels at the point of discharge of waste water into Long Island Sound, guidance is now in place instructing Millstone personnel to collect all Reactor Plant Closed Cooling Water drainage and Reactor Plant Chilled Water drainage in containers l for off-site disposal. Further, to monitor for the potential presence of R-12 in the Radioactive

{ Waste system as a result of system leakage, all discharges via DSNs 001C-2 and 001C-3 will l be sampled.

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Should you have any questions regarding this matter, please contact Mr. Paul Jacobson at l

(860) 447-1791 extension 2335.

Very truly yours, i NORTHEAST NUCLEAR ENERGY COMPANY QW

! S. Scace

Director- Nuclear Engineering Programs  !

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! cc: M. Harder i J. Gder i NRC i

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