ML20235G900

Submits Rept Re 870814 Oil Spill at Facility.Oil Spill Caused by Hydrogen Seal Oil Vacuum Tank Malfunction Causing Overflow Through Vent Line & Onto Maint Shop Roof

ML20235G900
Person / Time
Site:	Millstone
Issue date:	09/25/1987
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	ENVIRONMENTAL PROTECTION AGENCY
Shared Package
ML20235G904	List: ML20235G900 ML20235H185
References
D01624, D1624, NUDOCS 8709300281
Download: ML20235G900 (5)

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-1. . >< ..ua mta ;wa HARTFORD CONNECTICUT 06141-0270 L L J ['J.'l'J.[lg;;;;; (203) ees-5000 September 25,19S7 D01624 Mr. Michael Deland, Regional Administrator U. S. Environrnental Protection Agency Region 1 J. F. Kennedy Federal Building Boston, Massachusetts 02203

Reference:

Letter (D01530), E. 3. Mroczka to M. Deland, dated June 2,19S7.

Dear Mr. Deiand:

Millstone Nuclear Power Station Oil Spill Report Northeast Utilities Service Company (NUSCO), on behalf of Northeast Nuclear Energy Company (NNECO) and in accordance with 40CFRil2.4(a), submits a report concerning the oil spills at NNECO's Millstone Nuclear Power Station.

There have been three spills at Millstone within a 12-month period: January 22, 1937, March 26,19S7, and August 14, 1937. A report on the first two spills was submitted with the refercoced letter.

Therefore, pursuant to 40CFRil2.4(a), NUSCO hereby submits the following information for the August 14,1937 spill:

1. Name of Facility:

Millstone Nuclear Power Station

2. Name of the Owner or Operator of the Facility:

Northeast Nuclear Energy Company P. O. Box 270 l Hartford, Connecticut 06141-0270 )

3. Location of the Facility:

The facility is located on a Si5-acre site at Millstone Point on Long Island Sound, Waterford, Connecticut, h

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Mr. Michael Deland D01624/Page 2 September 25,1987

4. Date and Year of Initial Facility Operation:

The station was first placed into operation in December 1970 with the commercial operation of Unit 1.

5. Maximum Storage and Handling Capacity of the Facility and Normal Daily Throughput:

The Millstone site has a total oil storage capacity of approximately 550,000 gallons. This storage is located in many tanks, no one of which is larger than 35,000 gallons, and includes lubricating oil, transformer oil, diesel fuel, home heating oil, and jet fuel. All site deliveries of oil are by trucks having a maximum capacity of 8,000 gallons. Transfer operations of greater than 16,000 gallons per day are rare.

Norrnal daily oil usage is approximately 5,260 gallons.

6. Description of Facility Millstone Nuclear Power Station is a three-unit facility located on a $15-acre site at Millstone Point on Long Island Sound in Waterford, Connecticut. The site boundary includes Route 156 on the north, Long Island Sound on the south, Jordan Cove on the east, and Niantic Bay on the west. See attached map for general layout (Enclosure 1).

7. A complete copy of the SPCC Plan with any Attachments:

See attached (Enclosure 2).

8. The Causes of the Spills, including a Failure Analysis of the System or Subsystem in which the failure occurred:

The causes of the spills occurring on January 22,19S7 and March 26,19S7 have been explained in the June 2,1937 submittal.

The spill on August 14, 1937 occurred when the Unit I hydrogen seal oil vacuum tank malfunctioned. This caused an overflow through a vent line and onto the Maintenance Shop roof. The oil entered the roof drain which connects to the catch basin. The catch basin discharges into Long Island Sound.

The float valve on the hydrogen seal oil vacuum tank is the root cause of this incident. Efforts by NNECO to recreate the failure of the valve and entire system have been futile, The system was tested at various pressures and flows, and in each :.use, the valve properly responded. Visual inspections of the valve and float mechanism provided no abnormal findings. Since this is the only makeup source to the tank, the conc!v9n is that the float valve's malfunction is random in nature.

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Mr. Michael Deland l

D01624/Page 3 September 25, 1987 )

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9. Corrective Action and/or Countermeasures Taken, Include a Description of Equipment Repairs and/or Replacement:

Upon discovery of the spill, absorbent material's were placed in the catch basins and on the maintenance shop roof. An absorbent boom was used to contain, and absorbent pads were used to collect the floating oil. East Coast Environmental Services participated in the clean-up efforts, which were completed by 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />, August 14,1987.

10. Additional Preventive Measures Taken or Contemplated to Minimize the Possibility of Recurrence:

In NUSCO's letter of June 2,1987, a commitment was made to conduct an oil flush of the turbine lube oil system during Unit l's 1987 refuel outage.

This was a corrective action item for the March 26, 1987 spill. The flush has been done. An inspection of the seal oil tank was done after the ]

August 14, 1987 spill. Increased amounts of particulate were found in the ,

i tank bottom. This is attributed to the oil flush and could have contributed to the malfunctioning of the vacuum seal oil tank float valve.

Test of the float valve and system failed to recreate the malfunction ,

f causing the August 14,1987 spill. It must be anticipated, then, that this occurrence could happen again. To prevent this, several actions have or will be taken to preclude an overflow from reaching Long Island Sound. l They are: l f

A 275 gallon catch tank was set up on August 25,19S7, to capture 1) any overflow. This tank is located at ground level as opposed to the previous 55 gallon drum which was on the roof. This facilitates a routine checking of the tank.

2) Operations personnel check the overflow tank every four hours for any oil accumulation.

3) A replacement float valve will be ordered, and upon receipt, installed. The current valve has been cleaned and reinstalled.

4) The vacuum tank will be cleaned of particulate when the system can be removed from service.

The SPCC Plan is currently being reviewed by NNECO personnel to determine if revisions are needed, if the Plan is revised, it will be certified by a Professional Engineer and a copy will be sent to you.

By copy of this letter, NNECO, pursuant to 40CFRll2.4(c) and Section 22a-450 of the Connecticut General Statutes, is providing the Water Compliance Unit of the Depat tment of Environmental Protection with a copy of all information sent j to the EPA Regional Administrator.

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,;.O Mr. Michael Deland D01624/Page 4 September 25,1987 If you have any questions, please cal! Ms. Cynthia L. Karlic, NUSCO Generation Facilities Licensing, at (203) 665-3740.

Very truly yours, NORTHEAST UTILITIES SERVICE COMPANY As Agent for Northeast Nuclear Energy Company b ,D , at t es E. J. Mroczka 4 Senior Vice President L 'U 6L2. .

By: C. F. Sears Vice President Enclosures cc: w/ Enclosures Mr. Richard Barlow, Director Water Compliance Unit Department of Environmental Protection 122 Washington Street Hartford, Connecticut 06106 U. S. Nuclear Regulatory Commission Atto: Document Control Desk Washington, D. C. 20555 USCG Station Port Safety Detachment c/o Fort Trumbull New London, Connecticut 06320-5593 Attn: Petty Officer Walsh i

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