ML19317D575
| ML19317D575 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 09/21/1976 |
| From: | Parker W DUKE POWER CO. |
| To: | |
| References | |
| NUDOCS 7912060820 | |
| Download: ML19317D575 (3) | |
Text
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hMI DUKE Powcu Godmurn
[6 ")d f Powzu 13usi.oswo 422 SouTn Cuuncu STurer. CHARI,oTTE, N. C. as24a j70 wituam o. paaaca,sa.
SOPtember 21, 1976 Act Patsectur Tctromong; Anta 704
$rca.e PmOOwCYiON 373-4083 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 radio-activity exceeded the control level by greater than four times, but less than ten times.
On September 13, 1976, analytical results of aquatic vegetation and bottom sediment samples collected in July, 1976 were reviewed.
Given below is a summary of the pertinent results of the radioactivity concentration of these samples.
Sample Location Type of Sample Radionuclide Concentrations pCi/g (dry) 000.5 1-mile radius of Aquatic Vegetation Cs-137
< 3.40E + 00 site and Leak Keowee Mc-54
< 4.21E + 00 (Control)
< 5.55E + 00 Co-58
< 5.00E + 00 Cs-134
< 4.00E + 00 000.4 Near Liquid Aquatic Vegetation Cs-137 5.2
.33E + 01 l
Effluent Release Mn-54 4.17!.33E + 01 Point Co-60 6.8
.40E + 01 Co-58 1.77
.12E + 02 Cs-134 3.26.30E + 01 000.5 1-mile radius of Bottom Sediment Co-58
< 2.50E - 01 site and Lake Keowee Cs-134
< 2.10E - 01 (Control) 000.4 Near Liq.uid Bottom Sediment Co-58 1.76
.19E + 00 Effluent Release Cs-134 2.93
.24E + 00 Point
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791206o 20
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Page 2 Suprembsr 21, 1976 -)
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s The expected buildup of activity in sediment downstream from the station effluent release point has been calculated using the following formula from WASH 1258, p. F25:
Si = 2.5E-03 x Ti x Ci x W x (1-e
)
W - Steam Width Factor - 0.2 TL - Station Life (20 years)
Ti - Half Life of Radionuclide i in Days C1 - Concentration of Radionuclide i in Water, pCi/l Ai - Decay Constant of Radionuclide i Using this formula, it is possible to calculate from the tailrace concentra-tions, the concentrations to be expected in sediment samples collected down-stream of the liquid effluent release point; The concentrations are based on effluent discharges for January through June,1976.
The following table summarizes this data and provides a comparison of expected and actual concentrations:
Expected Actual Radionuclide Water Conc.entration Sediment Concentration Sediment Concentration ~
~~~
~~~
uC1/ml pC1/g pCi/g 58 6.95E-07 2.49E+01 (1.76 0.19)E0 60 134 2.36E-07 8.72E+01 (2.93 0.24)E0 Cs 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.
Frcm the information provided in FES, it is possible to calculate the concentrations one would expect to see in aquatic vegetation t
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 through June, 1976.
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 following table summarizes this data and provides a comparison of expected and actual concentrations:
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Page 3 cSept:aber 21, 1976 Bioaccumulation Expected Actual Isotope H O Conc.
Factor Vegetation Conc.
Vegetation Conc.
2 pCi/ml
~
pCi/g dry wt.
pCi/g dry wt.
54 3.17E-08 35000 4.99E+01 (4.17 ! 0.33)E+01 g
134 2.36E-07 25000
' 2.65E+02 (3.26 0.30)E+01 Cs 137 3.57E-07 25000 4.00E+02 (5.20 0.33)E+01 Cs 58 6.95E-07 2500 7.83E+01 (1.77 t 0.12)E+02 Co 60 1.20E-07 2500 1.35E+01 (6.8 0.4)E+01 Co With both bottom sediment and aquatic vegetation samples, the calculated or expected concentrations of radionuclides, based on effluent releases, are greater than those actually determined by laboratory analyses for all radio-nuclides except Seco and 60 o.
The tailrace concentrations in the past have C
been high due to an error in the method for calculating effluent release rates as disclosed in NRC/0IE Inspection Reports No. 269/76-2, 270/76-2, and 287/76-2.
The method for calculating effluent release rates has been corrected; and in the future, the concentrations of radionuclides in bottom sediment and aquatic vegetation samples should level off or decrease due to this correction.
/
V 'ry truly yours, a.
w*
William O. Parker, Jr EDB:ge I
l i
y.
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