ML20058K068

NPDES Noncompliance Notification:On 931118,daily Outfall 001 Free Chlorine Sample Indicated 0.2 Mg/L Free Chlorine.Caused by Circulating Water Supplying to Much Chlorine.Mod to Plant Will Decrease Chlorine to Svc Water

ML20058K068
Person / Time
Site:	Davis Besse
Issue date:	11/24/1993
From:	Jeffery Wood TOLEDO EDISON CO.
To:	Plotts R OHIO, STATE OF
References
GA-93-125, NUDOCS 9312140385
Download: ML20058K068 (4)

Text

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TOLEDO 1$

EDISON l A Centerer Erergy Cornpany l November 24, 1993 EDISON PLAZA ._

300 MADtSON AVENUE i TOLEDO. OHIO 43652-o001 i I

Hr. Robert Plotts l Environmental Specialist j Division of Vastevater r Ohio Environmental Protection Agency Northwest District Office i 347 North Dunbridge Road P. O. Box 466 r Bowling Green, Ohio 43402-0466 [

1 i Subj ect: Noncompliance with Ohio Environmental Protection Agency  ;

National Pollutant Discharge Elimination System Permit Number 2TB00011*ED Maximum Daily Free Available Chlorine Duration l Limit for Outfall 001. .

Dear Mr. Plotts:

This notification.is being provided in accordance with Part III,  !

Section 12(D) of the Ohio Environmental Protection Agency (EPA) [

National Pollutant Discharge Elimination System (NPDES) Permit Number. i 2IB00011*ED for the Davis-Besse Nuclear Power Station.

On November 18, 1993, at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br />,.the daily Outfall 001 free 4 chlorine grab sample indicated.0.2 mg/L free available chlorine.

Subsequent analyses vere then performed every fifteen minutes until i 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br />, when free chlorine vas no longer present. Siner this '

location is.only monitored once a day by grab sample, the exact-duration of chlorine discharge could not be determined. An investigation was conducted to determine the cause of the discharge and _1 to estimate the probable duration, since the maximum allowable daily j duration is two hours for any detectable amount of free chlorine. '

On November 15, 1993, a shock chlorination procedure had been performed-on the circulating vater system to disinfect the condenser water boxes ,

prior to a maintenance activity. Following chlorination, the  :

circulating water system vater was r -irculated until free chlorine was  !

no longer detectable. Once no free .lorine was detected, the i circulating vater system vater was dischargrd through Outfall 001. The '!

shock chlorination of the circulating vater system is performed ~in this  ;

method to prevent exceeding the free chlorine maximum contaminant. level ,

and duration limitations. In addition to this non-routine shock  :

chlorination of the circulating water system, the circulating water >

chlorination pump routinely injects chlorine into the circulating vater system four times a day for thirty minutes at a time to remove i microbial contamination and debris from the circulating vater system. l g.',

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9312140385 931124 P - .

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The service water system free chlorine concentration was also higher ,

than it had been during past shock chlorination procedures. These i chlorine levels are now required to be kept at a higher level since this chlorination point supplies vater to the site's drinking vater i plant as well as the service water system. Drinking water chlorine levels are required to be kept at much higher levels than in the past ,

to ensure adequate contact time is maintained to prevent waterborne i diseases. ,

i This occurrence has been compared with the previous shock chlorinations of the circulating vater system where releases of free chlorine did not occur. This evaluation concluded that the only significant change that has been made is the increased chlorine concentrations in the service water system. Normally, this higher chlorine concentration vould be  ;

consumed in the combined circulating water and rav unchlorinated intake water discharge prior to discharge through Outfall 001. In this case, ,

however, the circulating vater system surfaces had already been highly chlorinated, to remove the microbial contamination and debris which  ;

reduced the demand. As a result, although the circulating water showed no detectable chlorine prior to discharge, when the service water and circulating vater chlorination pumps were returned to service, they ,

supplied more chlorine than could be consumed in the system at that time. ,

Following the shock chlorination procedure and the holding period, the l service water chlorination system was returned to service at 1715 hours0.0198 days <br />0.476 hours <br />0.00284 weeks <br />6.525575e-4 months <br /> on November 17, 1993. The circulating water chlorination system was then returned to service at 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br /> on November 17, 1993. As a result, cFlorine vould only have been supplied from the circulating water chlorination system twice prior to the discovery of the detectable chlorine level at Outfall 001, once at approximately 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> and once at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on November 18, 1993.  ;

Vorst case conditions vould show that chlorine may have been discharged from 1715 hours0.0198 days <br />0.476 hours <br />0.00284 weeks <br />6.525575e-4 months <br /> on November 17, 1993, until 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on November 18,

. 1993, due to chlorination of the service water system. It is more 1 likely, however, that this discharge only occurred as a result of the thirty-minute chlorination of the circulating water system at 0200 ,

hours and 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br />. This is because the service water and circulating vater chlorination systems independently have not previously resulted in the discharge of chlorine; it is only the combination of the two that seems likely to have caused this occurrence. Therefore, the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> limit was likely not to have been exceeded, but this conclusion can not be reached with certainty 4

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once the discharge was discovered, the service water chlorination system was removed from service and the service water return was.

switched from the circulating water system, which discharges to Outfall  !

001, to the intake canal, which recirculates back into the system to prevent further discharges. -A subsequent free chlorine analysis at i 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br /> on November 18 shoved that chlorine was again below the detectable limit. No further free chlorine has been detected at Outfall 001 since this event occurred. ,

j Following this incident, telephone notification was made to the Ohio EPA Emergency Response Center in accordance with section 12(B) for the.

potential violation of a maximum daily discharge limit. This event was 1 given incident number 9311-48-4752.  ;

A modification to the site's drinking vater plant is currently in l progress which vill decrease the amount of chlorine which must be added

o the service water system. This modification vill provide a separate l chlorination point for the drinking vater plant, thereby permitting the i service water chlorination level to be reduced. This should reduce the  ;

likelihood of chlorine being added in excess of the amount consumed in  !

the system. i Should you have any questions regarding this matter, please contact Mr. Villiam T. O'Connor, Hanager - Regulatory Affairs, at (419) 249-2366.

Sin erely yours, N [D John K. Vood Plant Manager Davis-Besse Nuclear Power Station TKV/amb

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• l November 24, 1993 r E 2.8 GA 93-1025 i

Subject:

Submittal of the National Pollutant Discharge Elimination System (NPDES) Permit Free Available Chlorine Unauthorized Discharge l FOR INFORMATION ONLY:

I cc: A. F. Gephart (IND216)  ;

f J. J. Ilolden (3043) '

S. C. Jain (3085)

T. J. Myers (3387) '

V. T. O'Connor (3065)

H. E. O'Reilly (1660) '

K. C. Prasad (3105)

R. J. Scott (1041) '

R. J. Slyker (3065) -

S. Stasek (4030)

L. F. Storz (3080) -

J. C. Sturdavant (3065)

J. K. Vood (2101) '

T. K. Vasch (3360) ,

CNRB (3030)

SAR-Up (3065) '

NRM (3020)

US NRC/ Document-Control Ohio EPA /Z. A. Clayton U. 5. EPA / Region V f.

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