ML20077D870

NPDES Noncompliance Notification:On 910512,cooling Tower Experienced Failure,Causing Large Vol of Cooling Tower Water to Bypass Normal Blowdown Discharge Pathway.Cooling Tower Will Be Inspected During mid-yr Outage

ML20077D870
Person / Time
Site:	Limerick
Issue date:	05/17/1991
From:	Doering J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Bauer R PENNSYLVANIA, COMMONWEALTH OF
References
NUDOCS 9106050248
Download: ML20077D870 (4)

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3917077730 PHILADELPHI A ELECTRIC COM PANY LIMERICK GENER ATING ST ATION ' /'

P. O. BOX A I [F S AN ATOG A. PENNSYLV ANI A 19464 _.

(215) 327 1200 car.acoo J. DOE RtteG JR.

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g g yg9 Mr. Robert Bauer, Jr. -

Department-of Environmental Resources

Bureau of-Water Qualit'y Management Suite 6010, Lee ~ Park 555 North Lane ~

Conshohocken, PA 19428

Subject:

. Unanticipated Bypass of Unit 1 Cool:ng Tower. Blowdown Limerick Generating Station NPDES _ Permit No..;PA-0051926

Dear Mr. Bauer:

On May 12, 1991, at approximately'1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> the Unit 1~

l Cooling Tower experienced a. failure of a joint-between two concrete sections on the top of the outer wall of the lower raceway section of the. tower. This failure allowed =a_large volume of Cooling Tower water to_ bypass.the normal blowdown discharge pathway (Discharge-.001).-- The overflowing water.ran across_the ground to a-storm water runoff drain that directed the flow down an old-stream bed and under the-site boundary fence._ +

The failure was discovered by security. personnel during: routine ~

l rounds at~1600 hours. Upon. verification of the' failure;at

'approximately'1605 hours0.0186 days <br />0.446 hours <br />0.00265 weeks <br />6.107025e-4 months <br /> the Main Control-Room. Shift Supervisor

' initiated reduction:of-the. circulating water l flow inithe section- ~

of the-raceway where'the' damage-occurred. _~At11620 hours,-

Operations began reducing Unit l reactor poweriso total -

circulating water flow through the cooling tower could be' -

-decreased. -By 170G hours,Ltwo of the ci'rculatingtvater' pumps that send: flow to'the cooling' tower were' removed from' service.

As'a result of:these actions,; the amountiof overflow (through the-failed concrete- join'. decreased = to approximately -100-300 gallons per minute.

~

.Alleoverflow from the. tower was-terminated byf150'0 hour0 days <br />0 hours <br />0 weeks <br />0 months <br />.s on-May.13, 1991,1whenLa: Maintenance-work group isolated the1 area.of-  ;

the racewayLin;the; vicinity lof.the-failednjoint-:with sand bags.x Maintenance _ personnel evaluated the extent;of the damsge..,

commenced repair. work, and' initiated:aTrooticause? investigation.-

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Repair work consisted of replacing the two concrete sections to their original positions, and securing them with anchoring cables (2 each) attached to the corresponding inner wall section j

of the Cooling Tower raceway. The seals between the sections were also repaired. Unit 1 was restored to full power at 1523 hourt on May 15, 1991.

Routine sampling and analysis of Unit 1 circulating water was performed by Chemistry personnel on May 12 and 13, 1991. The results indicated that our permit limits (at Discharge 001) were-not exceeded in the cooling tower basin on either of these days.

On May 13, 1991, we performed a visual inspection of the overflow area, the storm drain, the connecting outfall, and areas

downstream to ascertain if any obs;rvable environmental impact had occurred. There were no signs of any detrimental environmental effects on the aquatic life where the outfall entered the Schuylkill River or any place downstream within 100 yards. Additionally, there were no visible erosion or flooding i effects. To check for thermal impact on the river, temperature o readings were taken upstream, downstream, and within the outfall flow. The corresponding temperatures were 69 degrees F upstream and downstream, and 75 degrees F in the outfall stream.

A 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> notification was made to Mr. David Burke of the

• Pennsylvania DER at 1408 hours0.0163 days <br />0.391 hours <br />0.00233 weeks <br />5.35744e-4 months <br /> on May.13, 1991, in accordance with the requirements of NPDES Pe.-it, No. PA-0051926- since this incident is considered to be an unanticipated bypass ofcthe normal cooling tower discharge. This. follow up report is being submitted in accordance with the same permit. Based on our observations and analytical results, we conclude that no permit i

limits were exceeded.

The cause of the discharge was.the_ unexpected' failure of the Cooling Tower concrete sections. .We are investigating the1cause of the failure in accordance with our in-house event investigation process. Corporate Engineering, the Cooling Tower-vendor (Marley), and' site Maintenance and' System Engineers'are involved in the causal investigation.. The investigation process will determine the root cause(s) and ensure appropriate

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.i corrective measures. A visual inspection of the Unit 2 Cooling Tower will be conducted prior to completion of the current Refuel Outage. An inspection of the Unit _1 Cooling Tower is planned for the upcoming niid-cycle outage.

If you have any questions or require further information

please contact Dan Shutt (x3465) of ny uttff.

I Very tIJ1y yours, i  %

/

DCS/cah cc: .. U . S .1 Nuclear-_ Regulatory Commission. 4 Jocument Control Desk Washington, D.C. 20555.

Administrator Region I

( U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia,_PA 19406 Senior Resident Inspector, USNRC

, T.J. Kenny, Limerick, M/C A2-5 Ptogram Management Section (3WM52)

Permits F.forcement Branch Water Management Division-Environmental Protection Agency Water Permits Section Region III 841 Chestnut Building Philadelphia,-PA 19107

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S23-1 G. J. Beck -

63D-3 G. M. Morley -

S9-2 R. W. Dubiel -

A5-1 i R. W. Boyce -

AS-1 T. J. Jackson - SB3-3 G. J. Madsen -

SB3-4 Commitment Coordinator - 52A-5

, PA DER BRP Inspector - 334 Correspondence Release Point - T2-4 DCC - 340 t

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