ML20196H643

Informs That Util Is Seeking Approval to Discharge Chlorinated Blowdown from Bearing Cooling Tower for More than 2 H Per Unit as Specified in Special Condition 10 of Vpdes Permit.Meeting During Wk of 981214,requested

ML20196H643
Person / Time
Site:	North Anna
Issue date:	12/03/1998
From:	Birckhead R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Kregloe W VIRGINIA, COMMONWEALTH OF
References
NUDOCS 9812090127
Download: ML20196H643 (2)

Text

e

" Innsbrook lichntcal Center e

, 5000 thorninion ihndet*ard Glen Allen. Virginia 23060 l

1 VIRGINIA POnTR December'3,1998 I

I Mr. William L. Kregloe l DEO-Valley Regional Office , l 4411 Early Road P. O. Box 1129 Harrisonburg, Virginia 22801 -

j RE: North Anna Power Station - Bearing Cooling Tower Blowdown

Dear Mr. Kregloe:

I As previously discussed, wo are seeking approval to discharge chlorinated blowdown from the bearing cooling tower for more than two hours per unit as specified in Special Condition i No.10 of the VPDES permit.

)

For years, the bearing cooling tower has been chlorinated on a continuous basis, but has not been blown down. Due to the lack of blowdown, the calcium concentration has increased in the system, resulting in scale buildup. The bearing cooling tower needs to be blown down continuously to reduce this concentration. i Other options have been evaluated. Reducing the normal chlorine feed to two hours per day was investigated along with shocking the unit with larger doses of chlorine for short periods.

A representative of the Calgon Corporation makes inspections of the bearing cooling tower approximately once per week. It is his opinion that a small residual of chlorine must be maintained in the bearing cooling tower at all times to control biological growth. Based on their operating experience, station chemistry personnel agree that a continuous or near continuous feed of chlorine is necessary. Chlorine in the system is maintained at a level below the discharge limit of 0.2 mg/l monthly average.

Installation of a dechlorination system was also evaluated. There is no practicable way to inject the dechlorination chemicals into the discharge line, in addition, this would result in another chemical being introduced into the lake. ,

i.x U

From an environmental standpo:nt, the discharge of chlorinated blowdown would have a negligible impact. The estimated flowrate for the blowdown is 150 gpm to 200 gpm. This is an intemal discharge that discharges into .he circulating water tunnel where it mixes with as much as 2,000,000 gpm of lake water before being discharged into the discharge canal and cooling lagoons. By comparison, our permit allows the discharge of reverse osmosis reject water directly to the lake with a total chlorine residual of up to 4.0 mg/l. i 9812090127 981203 "

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PDR ADOCK 05000338 j p PDR L l

The Steam Electric Guidelines include a provision allowing the state to provide relief from the chlorination restriction for cooling tower blowdown.

We wouId like to meet with'you and/or Mr. Pandey the week of December 14 to further discuss this matter. I will be calling you in several days to schedule a meeting. In the

, meantime, if you have any questions, please call me at (804) 273-2992.

Sincere ,

e Ron Birckhead cc:

U.S. Nuclear Regulatory Commission -

Region 11 Atlanta Federal Center 61 Forsyth Street, SW Suite 23T85 Atlanta, GA 30303 RE: North Anna Units 1 and 2 Docket Nos. 50-338/50-339 License Nos. NPF-4/NPF-7 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE: North Anna Units 1 and 2 Docket Nos. 50-338/50-339 License Nos. NPF-4/NPF-7 Mr. M.J. Morgan NRC Senior Resident inspector North Anna Power Station bc: