ML19308A845

Ro:On 771107,analysis of Raw Water Supply Samples Collected in July,Aug & Sept 1977 Showed Tritium Concentration Exceeding Control Level by Greater than Ten Times

ML19308A845
Person / Time
Site:	Oconee
Issue date:	11/10/1977
From:	Parker W DUKE POWER CO.
To:
References
NUDOCS 7912120635
Download: ML19308A845 (2)

Text

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$7 Vict PetteDtest TEL E*=c es t:Asta 704 S eta = Peoowerios. 373 4ces Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Suite 1217 l 230 Peachtree Street, Northwest Atlanta, Georgia 30303 RE: Oconee Nuclear Station Docket Nos. 50-269, -270, -287

Dear Mr. O'Reilly:

Pursuant to the requirements of Oconee Nuclear Station Technical Speci-fication 6.6.2.2.d, this report is submitted describing a condition in which a measured level of radioactivity exceeded the control level by

• greater than ten times.

On Novenber 7, 1977 analytical results of composited raw water supply

, grab samples collected in mid-July, August, and September 1977 were reviewed. A summary of the pertinent results of the radioactivity con-f centrations in these samples is given below:

Sample Location, Tritium Concentration 004.1 Seneca (Control) < l.lE-7 pCi/ml 006.1 Clemson (2.9 + 0.2)E-6 pC1/ml Tritium concentrations in downstream water samples are dependent upon the tritium concentrations of liquid effluent released from the station.

Fo- the period July 1 - September, 1977 a total of 456 curies of tritium

! wtre released from the station in liquid effluents. The average release

! rate for the period was 5.0 Ci/ day.

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 dispersion only. Conservatism was used in selecting parameters for substitution in the instantaneous release equa-tion to determine the concentration of effluents at Clemson water intake.

These assumptions were (1) the elevation of Laks Hertvell is 654.00 feet, (2) the flow of the Keowee River is 1100 cfs, the yearly average, and

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Novemb:r 10, 1977 - -

(3) an instantaneous release of 5.0 Ci of tritium is made each day several days prior to sampling. The peak concentration which would result at the 006.1 sample point is approximately 2.4E-6 pCi/ml.

The calculated tritium concentration is comparable to the observed value of 2.9E-6 pCi/ml. Therefore, the observed concentration is within the limits of conservative calculated values.

The Final Environmeatal 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 making the most important contribution to dose at these locations is tritium (more than 50%)". The dose estimate for any indivi-dual consuming Clemson water containing 2.9 x 10-6 pCi/ml of tritium is 0.29 mrem / year if these tritium concentrations were maintained over the year. This estimate of dose is less than 0.3% of the dose from natural background and less than 0.06% of the limits of 10CFR20. Therefore, it is concluded that the observed anomalous tritium concentration does not adversely affect public health and safety.

Ver truly yours, w k L) o_u et .

William O. Parker, Jr. ,

RLG:ge l

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