ML19322B693

Ro:On 770124,review of Composite Water Supply Samples Collected Oct-Dec 1976 Showed Excessive Levels of Radioactivity.Anomalous Tritium Concentrations Present No Safety Hazard

ML19322B693
Person / Time
Site:	Oconee
Issue date:	01/28/1977
From:	Parker W DUKE POWER CO.
To:
References
NUDOCS 7912050698
Download: ML19322B693 (3)

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.. ww o. ..n.c a. s n. January 28, 1977 SCr Pots,ctwt Tt 6 t *= C w t:Asta 704 S'taan Peoowevion 273-4083 Mr. Norman C. Moseley, Director U. S. Nuclear Regulatory Commission Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 Re: Oconee Nuclear Station Docket Nos. 50-269, -270, -287

Dear Mr. Moseley:

Pursuant to the requirements of Oconee Nuclear Station Technical Specifica-tion 6.6.2.2 e and d, this report is submitted describing conditions in which measured levels of radioactivity exceeded the control levels by greater than ten times, and describing conditions in which measured levels of radioactivity exceeded the control level by greater than four times, but less than ten times.

On January 24, 1977 analytical results of composite water supply samples col-lected in October, November, and December.1976 were reviewed. Given below is a suc: mary of the pertinent results of the radioactivity concentration of these samples:

Sample Location Type Sample Tritium Concentration 004.1 Seneca (Control) Raw Water (1.90 0.70) E-07 uC1/ml 006.1 Clemson Raw Water (1.85 : 0.13) E-06 uCi/ml 012 Anderson Raw Water (7.70 0.80) E-07 uCi/ml 004.1 Seneca (Control) Finished Water (1.70 0 0.70) E-07 uCi/ml 006.1 Clemson Finished Water (1.62 t 0.13) E-06 uCi/ml 000.3 Bridge N. of Site on Surface _ Water (3.60 t 0.90) E-07 uC1/ml Hwy. 183 Connecting Canal (Control) 000.7 Bridge S. of Site on Surface Water (3.01 ! 0.18) E-05 uCi/ml Hwy. 183 005.2 Hwy. 27 Bridge at Surface Water (3.58 0.28) E-06 uC1/ml Newry y912050h<P g

Mr. Norman C. Mocalsy Pag 2 Two January 28, 1977 Sample Location Type Sample Tritium Concentration 013 Hartwell Reservoir, Surface Water (1.84 0.17) E-06 uCi/ml 5.8 Miles S. of Keowee Dam Tritium concentrations in the water samples collected are dependent upon the tritium concentrations of liquid effluent released from the station. For the months of October, November, and December, 1976 a total of'461 Curies of tri-tium were released from the station in liquid effluents. The maximum tailrace concent.4 tion of tritium was 3 x 10-3 pCi/ml. The average tailrace concentra-tion of 'aci*ium was 1.52 x 10-6 uCi/ml. The station's objective (Technical Specification 3.9) in making effluent releases is to maintain the average con-centration of tritium in liquid effluents upon release from the Restricted Area to not more than 5 x 10-6 uCi/ml. Technical Specification 3.9.2 speci-fies that the quarterly average concener RestrictedAreashallnotexceed1x10gtionoftritiumreleasedfromthe uCi/ml. Therefore, it can be seen that the average tritium concentration for the quarter in liquid effluents is within the objective concentration and well below the specified quarterly average concentration.

Dilution and dispersion of tritium in liquid effluents between Oconee Nuclear Station and the Clemson water intake has been calculated using the equation for instantaneous release taken from the U. S. Geological Survey Paper No.

443-B, " Dispersion of Dissolved or Suspended Materials in Flowing Streams" by Robert E. Glover (1964), p.5. This equation accounts for longitudinal dis-persion only. Conservatism was used in selecting parameters for substitution in the instantaneous release equation to determine the concentration of effluents at the Clemson water intake. These assumptions were (1) the ele- ,

vation of Lake Hartwell is 654.00 feet and (2) the flow of the Keowee River is 1100 cfs, the yearly average. Listed below are the resulting calculated l concentrations of tritium at the Clemson water intake using the above method. I October 1.95 x 10-6 pCi/ml '

November 1.72 x 10-6 uCi/ml l December 0.93 x 10-6 uCi/ml )

Average 1.53 x 10-6 uCi/mi  ;

These calculated tritium concentrations are nearly the same as those observed; with water samples collected over October, November, and December, 1976 at the Clemson water intake having an average tritium concentration of about 1.53 x 10-6 pCi/ml. Therefore, the observed concentrations are within the limits of conservative calculated values.

I The Final Environmental Statement for Oconee states that "the largest estimates of dose to the individuals from liquid effluents are at Clemson and Pendleton where drinking water is withdrawn from the Keowee River. The radionuclide

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Mr. Norman C. Mocalcy .

Page Three I January 28, 1977 l making the most important contribution to dose at these locations is tritium (more than 50%)." The dose estimate for any individual consuming Clemson water containing 1.53 x 10-6 uCi/ml of tritium is 0.15 mrem / year if these '

tritium concentrations were maintained over the year. This estimate of dose is less than 0.5% of the dose from natural background and less than 0.1% of i

the limits of 10CFR20. Therefore, it is concluded that the observed anoma-l lous tritium concentrations do not adversely affect public health and safety.

VGy truly yours,

~uj l.) . L William O. Parker, Jr. '

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