ML19312C618

Ro:On 770812,composite Surface Water Samples Collected from Apr-June 1977 Showed Tritium Concentration Exceeding Control Level by 50 Times.No Threat to Public Safety & No Corrective Action Planned

ML19312C618
Person / Time
Site:	Oconee
Issue date:	08/18/1977
From:	Parker W DUKE POWER CO.
To:
References
NUDOCS 7912190811
Download: ML19312C618 (2)

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.Af7 wew - e.,4anca.sa. August 18, 1977 Vict PatSicCNT TELCP=0NE: Aata 704 Seta Peooucwo= 37 3-40 e 3 Mr. James P. O'Reilly, 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. O'Reilly:

Pursuant to the requirements of Oconee Nuclear Station Technical Speci-fication 6.6.2.2.d, this report is submitted describing conditions in which measured levels of radioactivity exceeded the control levels by greater than ten times ar.d conditions in which measured levels of radioactivity exceeded f.he control level by greater than fifty times.

On August 12, 1977, ant.lytical results of composite surface water samples collected ear?.y in April, May, and June, 1977 were reviewed.

Given below is a sur. nary of the pertinent results of the radioactivity concentrations of these samples:

Sample Location Type of Sample Tritium Concentration 00.3, Hwy. 183 Bridge N. of Surface (1.1 1 0.9)E-7 pCi/ml site (Control) 000.7, Hwy. 183 Bridge S. of Surface (>50x) (1.6 1 0.1)E-5 pCi/ml Site 013 Hartwell Reservoir 5.8 Surface (>10x) (1.6 1 0.2)E-6 pCi/ml mi. S. of Keovee Dam Tritium concentrations in water samples collected are dependent upon the tritium concentrations of liquid effluent released from the station immediately prior to and during sampling. For the period March 15, 1977 through June 7, 1977, a total of 540 curies of tritium were released from the station in liquid effluents. The average release rate for the '

period was 6.35 Ci/ day.

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My. James P. O'Rsilly, Director '

Paga Two .]

August 18, 1977 -

Based on the curies released and the continuous sampler design at location 000.7, it is calculated that the activity in the sample should have been approximately 5E-5 pC1/ml. This concentration compares favorably with the observed value at location 000.7 near the effluent discharge point.

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 equation to determine the concentration of effluents at the Clemson water intake. These assumptions were (1) the elevation of Lake Hartwell is 654.00 feet, (2) the flow of the Keowee River is 1100 cfs, the yearly average and, (3) an instantaneous release of 6.35 Ci per day. Using this method, the average concentration of tritium at the Clemson water intake should be approximately 1.lE-6 uCi/ml. The calculated tritium concentration is approximately the same as that observed in Hartwell Reservoir just upstream of the Clemson water intake.

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 making the most important contribution to dose at these locations is tritium (more than 50%)." The maximum dose estimate (using the Regulatory Guide 1.109 model) for any individual consuming Clemson water containing 1.1E-6 uCi/ml of tritium is 0.11 mrem / year if these tritium concentrations were maintained over the year. This estimate of dose is less than 0.1% of the dose from natural background and less than 0.05% of the limits of 10CFR20. Therefore, it is concluded that the observed anomalous tritium concentrations do not affect public health and safety in any way.

Very truly yours, William O. Parker, Jr.  %

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