ML20134M170

NPDES Noncompliance Notification:On 961106,discovered Water in Turbine Bldg Sump That Overflowed Onto Floor.Caused by Open Drain Line from C Hotwell.Water Remained in Sump & Trench & No Discharge to Environ Occurred

ML20134M170
Person / Time
Site:	Millstone
Issue date:	11/15/1996
From:	Scace S NORTHEAST NUCLEAR ENERGY CO.
To:	Grier J CONNECTICUT, STATE OF
References
D10506, SES-96-GN-046, SES-96-GN-46, NUDOCS 9611220254
Download: ML20134M170 (2)

Text

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Rope Ferry Rd. (Route 156), Tcterford, CT 06385 l._ Northeast Nucl:ar Energy will. cone Nuclear Power station bl g

Northeast Nuclear Energy Company

P.O. Box 128 Waterford. CT 06385-0128 (203) 447 1791 1 Fax (203) 444-4277 November 15,1996 m Northe t Utilitie. sy. tem SES-96-GN-046 D10506 4

Mr. James Grier Principal Sanitary Engineer Bureau of Water Management Permitting, Enforcement and Remediation Division Department of Environmental Protection

79 Elm Street

! Hartford, CT 06106 Dear Mr. Grier; i Millstone Nuclear Power Station NPDES Permit CT 0003263 Information on Discharge Event via DSN 001C-8 and 001C-4 As requested, the following describes the discharge of Millstone Station Unit 3 (" Millstone") ,

I feedwater system wet lay-up drainage as discussed with you on Thursday, November 7,1996.

By way of background, plant personnel were preparing to place the Unit 3 condensate and feedwater system in a dry lay-up configuration. To remove the last volume of wet lay-up water

. from the three sectional hotwells, portable pumps were used to transfer the contents of the A and B hotwells to the C hotwell. From the C hotwell, the wet lay-up drainage was to be discharged via DSN001C-8, o authorized under Millstone's NPDES Permit. 1 On November 6,1996, shortly after pumping started, plant personnel found that water had flowed into a turbine building sump and overflowed onto the floor. It was discovered that a 1.5 inch drain line from the C hotwell had been left open, causing approximately 500 gallons to drain to the sump and adjoining trench (the " sump water"). However, there was no discharge to the environment; this water remained in the sump and trench.

c Analyses performed on the sump water were as follows:

i Temp: 68"F pH 9.39 ,'D TSS 18.4 ppm pfjd y

Iron 0.95 ppm Hydrazine 0.012 ppm ETA Non-detectable 9611220254 961115 PDR ADOCK 05000423 S PDR osse 24 mrv. im 220053 1

., Mr. James Grier SES-96-GN-046/D10506 l November 15,1996 Subsequently, on the morning of November 7,1996, a small volume of water from the sump and trench was being transferred to the Makeup Waste Neutralization Tank (MWNT), which discharges to DSN 001C-4. Upon learning of this action, chemistry supervision stopped the l transfer, pending environmental review.

l After discussing this issue with you on Thursday, November 7,1996 and, after reviewing with l you the discharge descriptions in our August 8,1991 Revised Form 2s and the station NPDES l Permit issued December 14,1992, it was agreed that feedwater lay-up water containing hydrazine could be directed te DSN 001C-8, or to the MWNT, if the ETA concentration was less than detectable. Accordingly, the station transferred the remaining sump contents to the MWNT on Friday, November 8,1996. Discharge of the MWNT via DSN001C-4 occurred November 12, and 13,1996. Analyses for this batch discharge are as follows:

Discharge Volume 50,700 gallons pH 7.0 .

Hydrazine 5.8 p.p.m.

TSS 10.8 p.p.m.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY b ._ h b't S. E. Scace (d.H.BYothersforS.E.Scace)

Director of Nuclear Engineering Programs cc: M. DiNioa, CT DEP M. Harder, CT DEP NRC l

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