ML20128N125

NPDES Noncompliance Notification:On 930103,cooling Tower Blowdown Water Overflowed from Discharge 001 Pipeline & Flowed Into Possum Hollow Creek.Caused by Failure to Throttle Unit 2 Bypass Valves.Procedure Changed

ML20128N125
Person / Time
Site:	Limerick
Issue date:	02/17/1993
From:	Doering J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Feola J PENNSYLVANIA, COMMONWEALTH OF
References
NUDOCS 9302230054
Download: ML20128N125 (3)

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{ C . PIIILADELPIHA ELECTRIC COMPANY LIMERICK GENERATING STATION P. O. BOX 230)

SANA'IDGA, PA 19464-2300 (215) 3271200 EXT,2000 J. OoERING, JR.

[yy[fc7[,wwa sw,cw February 17, 1993 Mr. Joseph A. Peola Pennsylvania Department of Environmental Resources Regional Water Quali- Manager Lee Park, Suite 6010 555 North Lane L'nshohocken, PA 19428

Subject:

Limerick Generating Station, Units 1 and 2 Noncompliance with NPDES Permit No. PA-0051926

Dear Mr. Feola:

DESCRIPTION OF NONCOMPLIANCE On January 3, 1993, a noncompliance of the NPDES permit for the Limerick Generating Station occurred when Unit 1 and Unit 2 Cooling Tower blowdown water overflowed from the Discharge 001 pipeline and flowed into the Possum Hollow Creek resulting in an unpermitted discharge. This condition resulted in the release of chemically treated water from an unmonitored discharge point.

Following the automatic shutdown of Unit 2 at 1615 hours0.0187 days <br />0.449 hours <br />0.00267 weeks <br />6.145075e-4 months <br /> on January 3, 1993, operations personnel reduced the Unit 1 Cooling Tower blowdown flow to 1500 gpm. At 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> operations personnel diverted circulating water flow from the Unit 2 Cooling Tower trays into the Unit 2 Cooling Tower basin. At this time operations personnel observed water discharging from a manhole on the Cooling Tower blowdown line (Discharge 001 pipeline) and flowing into the Possum Hollow Creek. At 1905 hours0.022 days <br />0.529 hours <br />0.00315 weeks <br />7.248525e-4 months <br />, Operations personnel reduced the Unit 2 Cooling Tower blowdown flow to terminate the overflow from the manhole. An estimated 250 gallons of circulating water was discharged into the Possum Hollow Creek. The combination of the Unit 1 and the Unit 2 Cooling Tower blowdown flow resulted in momentarily exceeding the Cooling Tower blowdown line capacity.

The chemical makeup of the water that discharged into the Possum Hollow Creek was determined by analysis to have a pH of 220015 ,

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• Page 2c ap roximately-8;l and total zinc concentration of;0.5' ppm.-TThe-PECO 5 usage rate for the Unit 1 Cooling Tower was being:

maintained atqwell below 4496 lbs/ day. All values were within' the permit limits for discharging from outfall 001.

CAUSE OF THE NONCOMPLIANCE The cause of the noncompliance was a failure to adequately-throttle the Unit-2. Cooling Tower cold weather bypass valves to prevent blowdown flow from exceeding the capacity of the' Cooling Tower blowdown line. Operations personnel, while aware of1the need to maintain combined. blowdown flow to less than 10,000 gpm; did not have specific guidance in System (S) operating procedure' S09.0.B, " Cold Weather Operation of the Cooling Tower," to successfully maintain the required blowdown..=Also. throttling the Cooling Tower cold weather bypass valves;to-prevent. overflow is difficult because the operator must manually open.the seventy-eight inch valves in a confined space while maintaining communication with operators in the Main Control' Room.- The number of actions required of the Main Control Room operators following the automatic-shutdown of'a reactor-exacerbates the-difficulty of preventing blowdown flow from exceeding the capacity of the Cooling Tower blowdown line.

PREVENTION OF PUTURE OCCURRENCES Procedure SO9.0.B was temporarily changed on January 20, 1993 to enhance the guidance to prevent exceeding 10,000 gpm:in the blowdown line and causing an unpermitted discharge of waterfto Possum Hollow Creek through a manhole. The temporarily changed Procedure SO9.0.B was used to place the Unit'2 Cooling-Tower into Cold Weather Bypass on January 21, 1993, and there was no-unpermitted discharge'from the manhole. Procedure SO9.0.B will be permanently changed by March 15, 1993 to include the enhanced' guidance.

An engineering evaluation of'possible-modifications 1to prevent recurrence of a similar. event has been completed. The ._

alternatives are undergoing a cost benefit analysis. LA decision-a on the alternatives will be made by June L30, 1993.

If you have any questions please contact Mr. Gil J. MadsenLat-(215) 327-1200.

Sincerely, L h2 JLP:cah /

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cc U.S..iluclear Regulatory Commission

- Document ~ Control 1 Desk'

- Docket Nos. 50-352/50-353:- -

Washington,; D.C. 20555

- T. T. Martin Administrator, Region I, USNRC. i'

- Docket Nos.-50-352/50-3.53-T. J.' Kenny _

USNRC Senior Resident _ Inspector,_ LGS' -

Docket Nos. 50-352/50-353 Program Management Section-(3WM52)

Permits Enforcement Branch '

Water Management Division Environmental--Protection Agency-Water Permits Section ' '

Region-III _

841 Chestnut Building Philadelphia, PA'19107 '

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