RBG-29152, Advises That Util Installed Sys for Injecting Dechlorinating Chemical Into Cooling Tower Blowdown,Per 880830 Proposed Changes to Asiatic Clam Control Program.Environ Impact of Change Considered Insignificant

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Advises That Util Installed Sys for Injecting Dechlorinating Chemical Into Cooling Tower Blowdown,Per 880830 Proposed Changes to Asiatic Clam Control Program.Environ Impact of Change Considered Insignificant
ML20195D813
Person / Time
Site: River Bend Entergy icon.png
Issue date: 10/31/1988
From: Booker J
GULF STATES UTILITIES CO.
To:
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RBG-29152, NUDOCS 8811070140
Download: ML20195D813 (3)


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  • GULF STATES UTILITIES COMPANY Oh ww , v +.,,; .

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October 31, 1988 RBG- 29152 File Nos. G9.5, G10.2.7 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:

I River Bend Station - Unit 1 Docket No. 50-458 Gulf States Utilities Company (GSU) submitted for your review and approval proposed changes to its Asiatic Clam Contro' Program (ACCP) on March 30, 1988. One of the proposed changes was that the normal service water system will now be chlorinated year round at a concentration of at least 0.6 parts par million total residual chlorine (TRC). This change is expected to enhance the effectiveness of the ACCP to assure that asiatic clams will not survive and grow to fouling size in the normal service water system. So that waste water discharge permit limitations can be complied with for the discharge of residual chlorine to the Mississippi River, GSU has installed a system for injecting a dechlorinating chemical into the cooling tower blowdown.

The reducing agent GSU is using to react with TRC is amonium bisulfite.

Approximate 1v 5 parts per million of the bisulfite is maintained in the blowdown. This represents a slight excess of the amount necessary to totally dechlorinate the concentrations of TRC remaining at the point of blowdown wi thdrawal . This margin is necessary to account for the variability of TRC concentrations and blowdown flows. The reactions between TRC and the bisulfite produce mainly sulfate and chloride salts. The contribution of these salts from dechlorination represents a small percentage of the total concentration of these constituents in the blowdown. According to Section 5.5 of the River Bend Station Environmental Report - Operating License Stage, the concentratior of these constituent salts will meet state water quality standards and will be within 0.1 parts per million of the ambient river water content after 16 dilutions of blowdown with Mississippi River water. It is estimated that a d.'lution factor of 16 will be effected within 50 feet downstream of the discharge outfall. Any unreacted amonium bisulfite will likewise be quickly d1 Nted.

The Environmental Protection Agency (EPA) idcognizes(1) the toxicity of chlorine and regulates its discharge in power plant effluents through 40CFR423. River Bend Station's wastewater discharge permits contain the standard permit limitations for chlorine in cooling tower blowdown. The toxicity of amonium bisulfite, as well as other dechlorinating agents and l 8811070140 001031 I I PDR ADOCK 05000450 P PNU

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  • NRC Page 2 their reaction products, is such that their discharge is not regulated by the EPA, nor does the state of Louisiana specify water quality standards for ,

dechlorinating agents and their reaction products. In fact, the EPA encourages or requires dechlorination of other chlorinated waste streams, particularly municipal sewage treatment effluent.

Dechlorination has been found to reduce the acute toxicity of chlorinated .

waters to certain aquatic species.(2,3) One study found that ,

chlorination-dechlorination of sewage treatment effluent with hisulfite reduced the toxicity of fish below that of unchlorinated effluent.(4)

Dechlorinating agents have also the ability to reduce the mutagenic activity

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of chlorinated waters.(5)

Because the chemical products from dechlorination will not tignificantly affect the composition of the blowdown and therefore will not significantly alter the environmental assessmer,t in the NRC's Final Environmental Statement -

l (NUREG-1073) Section 5.3.2.3, and because the toxicity of the blowdown will

not be increased, GSU consioars the environmental impact of this change to be insignificant.

If further information is required, please contact Mr. James took at (504) 381-4151. ,

Sincerely, ,

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J. E. Booker Manager-River Bend Oversight

, River Bend Nuclear Grnup JEB/l JWC/ C KCH ch ,

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References:

(I)47 Fedcral Register 52300 (2)Ha11 L.W. at al. "Effluents of Dechlorination on Early Life Stages of l Striped Bass (Morone saxatilis)", Environmental Science and Technology

  • 15:573-578(1981) L (3hrd, R.W., and G.M. DeGraeve. "Residual Toxicity of Several Disinfectants in Domestic and Industrial Wastewaters", Journal of Water Pollution ,

Control Federation 50: 2703-2722(1978) l (4)Esvelt, L. A., et al. "Toxicity Assessment of Treated Municipal Wastewaters", Journal of Vater Pollution Control Federation [

45:1558-1572(1973)

(5)Cheh, A.M., et al. "Nonvolatile Mutagens i Drinking Water: Production by i Chlorination and Destruction by Sulfite". Science 20:90-92(1980) {

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  • cc: U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 NRC Sanfor Resident Inspector P.O.. Box 1051 St. Francisville, LA 70775 Mr. Walt A. Paulson RBS Project Manager Document Control Desk Washington, D.C. 20555

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