ML19322B608

Ro:On 760409,water Sample Radioactivity Levels Exceeded Control Level by Greater than Ten Times & by Greater than Four But Less than Ten Times.Caused by Excessive Effluent Release.Calculation Method for Effluent Release Corrected

ML19322B608
Person / Time
Site:	Oconee
Issue date:	04/16/1976
From:	Parker W DUKE POWER CO.
To:
References
NUDOCS 7912040635
Download: ML19322B608 (5)

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DUKE PowEn COMPANY ,

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422 Sourn Cuuncu Srazzr, CuAnwitz, N. C. maa.sa mw o. en n a t a. s a.

April 16, 1976 Ttt t >=ou t:Anta 704 Vict Pettiotat 3 7 3-4 C 6 3 Setaa. Paoowction Mr. Norman C. Moseley, Director .

U. S. Nucicar Regulatory Commission Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 RE: Oconee Nuclear Station Docket Nos. 50-269, -270, -287 bear Mr. Moseley: .

Pursuant to the requirements of Oconee Nuclear St'ation Technical Specifica-tion 6.6.2.2, this report is being submitted describing conditions in which measured levels of radioactivity exceeded the control level by greater than ten times, or by greater than four times but less than ten times. Summarized herein are the results of water samples and an aquatic vegetation sample analysis collected during February, 1976.

On April 9, 1976, tritium concentration analytical results for a composite water sample collected over the month of February, 1976 were reviewed and compared with similar results for the control sample collected over the quarter October 1, 1975 to December 31, 1975. Given below is a summary of the pertinent results of the radioactive concentrations of these samples.

As indicated, the measured level of tritium concentration exceeded the control level by greater than ten times. .

Sample Location Type Sample Tritium Concentration 000.3 Bridge N. of Site on Surface Water (1.8 1.3) E-7 pCi/mi Hwy. 183 Connecting Canal (Control 000.7 Bridge S. of Site on Surface Water (2.25 0.23) E-5 uci/mi Hwy. 183 During the month of February, 1976, 300 Curies of tritium were released from the station in liquid offluents. The maximum tailrace concentration of tritium was 3 x 10-3 UCi/ml. The average tailrace concentration of tritium was 2.89 x 10-6 uCi/ml. The station's objective (Technical Specification 3.9) in making effluent releases is to maintain the average concentration of tritium in liquid effluents upon release from the Restricted Area to not more than 5 x 10-6 uCi/ml. Also, Technical Specification 3.9.2 specifies that t t ,.

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mm Apr,11 16, 1976 quarterly average concentration of tritium released from the Restricted Area shall not exceed 1 x 10-5 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 concen-tration.

Additionally, on April 9, 1976,, gross beta activity analytical results for water samples collected during the month of February, 1976 were reviewed.

Given below is a summary of the pertinent results of the radioactivity of these samples, showing comparison to control samples.

Sample Location Date Collected Type of Sample Gross Beta uCi/ml 000.3 Bridge North 2/3/76 Surface ,

1.85E-9 5.24E-10 of Site (Control) ,

000.7 Ilwy. 183 Bridge 2/3/76 Surface 2.57E-8 1.15E-9 005.211wy. 27 Bridge 2/3/76 Surface 9.71E-9 1 7.87E-10 -

004.1 Seneca (Control) 2/3-2/24/76 Raw < 8.83E-10 2/3-2/24/76 Finished < 8.83E-10 l 006.1 Clemson 2/3-2/24/76 Raw 6.28E-9 6.79E-10 2/3-2/24/76 Finished 9.46E-10t 4.87E-10 Cross beta concentrations in the water samples collected are dependent upon the corrosion and fission product concentrations in liquid effluents released from the station. For the month of January, 1976, 1.90 Curies of corrosion and fission products were released from the station in liquid effluents; the maximum tailrace concentration was 3.92 x 10-6 pCi/ml; the average tailrace concentration was 1.66 x 10-8 pCi/ml. For the month of February, 1976, 1.64 Curies of corrosion and fission products were released from the station in liquid effluents; the maximum tailrace concentration was 5.07 x 10-6 uCi/ml; the average tailrace concentration was 1.58 x 10-8 pCi/ml.

As indicated in Technical Specification 3.9, the station's annual objective in making effluent releases is to maintain the average concentration of corrosion and fission products in liquid effluents upon release from the Restricted Area to not more than 2 x 10-8 pCi/ml.

Technical Specific:. tion 3.9.3 specifies that the instantaneous concentration of radioactive materials released from the Restricted Area shall not exceed 10CFR20, Appendix B limits, for average annual release rates. For the most ir'-

restrictive case in which the isotopic concentrations are not know, this limit is 1 x 10-7 UCi/ml. Due to a procedural error in the method for calculating effluent release rates the corrosion and fission product concen-trations for January and February, 1976 in liquid effluents exceeded this i i

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", April 16, 1976 limit for instantaneous concentrations. This deficiency has been corrected and will be addressed further in Reportable Occurrence Report R0-269/76-4.

Otherwise, -c can be seen that the objective average release concentrations for January and February, 1976 were not exceeded.

At Location 000.7, Hwy. 183 Bridge, near the effluent discharge point, the gross beta activity, standardized against the beta energy of Cesium-137, should compare favorably to the average activity released from the station.

Similarly, the gross beta activity in samples collected further downstream such as 005.2, Hwy. 27 Bridge, and 006.1, Clemson Water Intake, should decrease with dilution and dispersion. Dilution and dispersion of corrosion and fission products in liquid effluents between Oconee Nuclear Station and the Clemson Water Intake have been calculated using the equation for instan-taneous release taken from the U. S. Geological Survey Paper No. 433-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 effluent at the Clemson Water Intake. These assumptions were (1) the elevation of Lake Hartwell is 654.00 feet and (2) the flow of the Keowee River is 1100 CFS, the yearly average. The resulting " worst-case" calculated corrosion and fission product concentrations at the Clemson Water Intake are as follows:

January 2.97 x 10-8 uci/ml February 3.84 x 10-8 pCi/ml These calculated concentrations are a factor of ten higher than those observed. j l

Note, also that although the raw water gross beta activity exceeds the control i location activity by four times, the finished water gross beta activity at Clemson compares favorably with the control location activity.

On April 12, 1976, semiannual analytical results of an aquatic vegetation sample collected on February 22, 1976 were reviewed. Listed below is a summary of the pertinent results.

Date Radionuclide Sample Location Collected Concentrations (pci/gm)

~

000.5 1-mile radius of site 2/17/76 MN-54 < l. E-01 Lake Keowee (Control CO-58 < 1. E-01 CO-60 < 2. E-01 1-131 < 4. E-01

, CS-134 < l. E-01 CS-137 < l. E-01 000.4 Near Liquid Effluent 2/22/76 MN-54 (6.54 0.66) E 00 Release Point CO-58 (3.84 0.38) E 01 CO-60 (1.36 0.14) E 01 I-131 (1.66 0.63) E 00 t.

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. April 16, 1976 CS-134 (1.69 0.17) E 01 CS-137 (2.89 0.29) E 01 CS-136 3.80 2.38 E-01 AG-110M 5.06 1.23 E-01 The expected buildup of activity in organisms living in station effluents is discussed on pp. 130-133 of the Final Environmental Statement for Oconee Nuclear Station. From the information provided in FES, it is possible to calculate the concentrations one would expect to see in aquatic vegetation samples collected from the vicinity of the liquid effluent release point; the specific information required is:

1. The tailrace concentrations of the radionuclide found in the aquatic vegetation samples, discharged as radioactive waste. . (These concentrations are based on effluent discharges for January and February, 1976. The tailrace concentrations are a factor of 10 greater than those presented in Table 111-12 of the FES for anticipated annual tailrace concentrations.)

2. The biological accumulation factors for the radionuclides found in the aquatic vegetation samples. (The biological accumulation factors used in the calculation of expected concentrations in aquatic vegetation are those found in Table V-7 of the FES. The biological accumulation factor for Ag-110m is taken from UCRL-50564 Rev. 1, 1972.

The following table summarizes this data and provides a comparison of expected and actual concentrations:

Bioaccumulation Expected Actual Isotope H2O Concen. Factor Vegetation Concen. Vegetation Concen.

pC1/ml pCi/g wet wt. pCi/g wet wt.

54 g 1.92 x 10-10 35000 6.72 6.59 0.66 58 C0 3.23 x 10-9 2500 8.08 38.4 3.8 60 Co 6.08 x 10-10 2500 1.52 13.6 1.4 131 7

5.27 x 10-9 200 1.05 1.66 0.63 134 * *

• Cs 137 Cs 136 1.25 x 10-10 25000 3.13 0.38 0.24 ,

Cs 110m 1.94 x 10-11 200 3.88 x 10-3 0.51 1 0.13 Ag I

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With aquat.ic vegetation samples, the calculated or expected concentrations )

of nuclides, based on effluent releases, are in most cases greater than or nearly equal to those actually determined by laboratory analysis. The i

• April 16, 1976 water concentrations used to calculate the concentrations of these radionu- .

clides in aquatic vegetation are average concentrations. The maximum water concentrations are a factor of ten higher so the actual vegetation concen-trations for any one sample could be higher also. This may account for instances in which the actual vegetation concentration is greater than the expected calculated value.

The calculated concentrations of radionuclides in aquatic vegetation are based on tailrace concentrations, a factor of ten greater than those presented in Table 111-12 of the EES. The tailrace concentrations are high due to the previously mentioned procedural error in the method for calculating effluent release rates. In the future, the concentrations of radionuclides in aquatic vegetation samples should level off or decrease due to corrective actions taken.

Ver truly yours, -

t.a_c4 M . ,

William O. Parker, Jr.

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