ML19322B603
| ML19322B603 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/31/1976 |
| From: | Parker W DUKE POWER CO. |
| To: | |
| References | |
| NUDOCS 7912040631 | |
| Download: ML19322B603 (3) | |
Text
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Powan Duttomo 422 Socin Caucen Srazzr, Cnez.orrz, N. C. maa4a wlLU A 84 Q. PA R M C R, J R, ViCC htssognt Tttgmonc Anga 70s Steam Paoouction 37 > 408 3 March 31, 1976 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 Specification 6.6.2.2, this report is submitted describing a condition in which measured levels of radioactivity exceeded the control levels by greater than ten times.
A description of a condition in which a measured level of radioactivity exceeded the control level by greater than four times, but less than ten times is also provided.
On March 26, 1976, semiannual analytical results of bottom sediment and aquatic vegetation samples collected on February 17, 1976 were reviewed.
Listed below is a summary of the pertinent results:
Sample Location Type of Sample Radionuclide Concentrations 006.2 Clemson Water Bottom Sediment Mn-54 < 2E-2 pCi/gm (dry)
Intake Co-58 < 2E-2 pCi/gm (dry)
Hartwell Reservoir Co-60 < 2E-2 pCi/gm (dry)
(Control)
Cs-134 2.59E-1 1 0.34E-1 pCi/gm (dry)
Cs-137 4.27E-1 1 0.43E-1 pCi/gm (dry) 1-131 < 7.0E-2 pCi/gm (dry) 000.4 Near Liquid Bottom Sediment Mn-54 3.10E-1 1 0.36E-1 pCi/gm (dry)
Effluent Co-58 9.04E-1 1 0.90E-1 pCi/gm (dry)
Release Point Co-60 4.31E-1 1 0.45E-1 pCi/gm (dry)
)
Cs-134 3.67E-1 1 0.37E0 pCi/gm (dry) l Cs-137 6.38E0 1 0.64E0 pCi/gm (dry) 1-131 3.52E-1 1 1.18E-1 pCi/gm (dry) 000.5 1 mile radius Aquatic Co-58 < IE-1 pC1/gm (wet) l of site Vegetation Cs-134< IE-1 pCi/gm (wet)
Lake Keowee Cs-137< IE-1 pCi/gm (wet)
(Control)
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005.2 Hwy. 127 Aquatic Co-58 1.03E010.10E0 pCi/gm (wet)
Bridge Vegetation Cs-134 1.16E0 1 0.12E0 pCi/gm (wet)
Cs-137 2.30E0 1 0.23E0 pCi/gm (wet)
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:
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S = 2.5E-3 x T xC x W x (1 - e
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f W - stream width factor - 0.2 TL - station life T - half life of radionuclide i g
C' - concentration of radionuclide i in water in pCi/1 A - decay constant of radionuclide i g
Using this formula, it is possible to calculate the expected concentrations in bottom sediment samples collected downstream of the liquid effluent release point. The specific information required to perform this calculation is the tailrace concentrations of the same radionuclide as found in the sediment samples, discharged as radioactive waste.
The concentrations are based on effluent discharges for January and February 1976.
These tailrace concentrations were a factor of ten greater than those presented in Table 111-12 of the FES for anticipated annual tailrace concentrations.
The following table summarizes this data and provides a comparison of expected and actual concentrations:
Expected Actual Radionuclide Water Concentration Sediment Concentration Sediment Concentration pCi/ml pCi/g pCi/g J
54Mn 1.41E-10 1.92E0 (3.10 1 0.36)E-1 58Co 2.76E-09 9.85EO (9.0410.90)E-1 60Co 6.56E-10 1.99E0 (4.31 1 0.45)E-1 I
Cs 2.58E-09 5.80E0 (3.67 1 0.37)E0 137Cs 4.13E-09 6.87E0 (6.38 i 0.64)E0 131 1 5.57E-09 2.24E0 (3.52 i 1.18)E-1
Mayc@ 3B, B97M Pcgn 3 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 for this calculation is:
1.
The tailrace concentrations of those radionuclides which were 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 '.tological accumulation factors for the radionuclides found in the aquatic vegetation samples. The biologic.al 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:
Bioaccumulation Expected Actual Isotope gOConc.
Factor Vegetation Conc.
Vegetation Conc.
Ci/ml pCi/g wet we.
pCi/g wet wt.
-9 134 2.58 x 10 25000 64.5 (1.16 1 0.12)E0 Cs 137 4.13 x 10-25000 103 (2.301 0.23) E0 Cs
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58 2.76 x 10 2500 6.9 (1.03 1 0.10)E0 g
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.
The calculated concentrations of radionuclides in bottom sediment and aquatic vegetation are based on tailrace concentrations a factor of ten greater than those presented in Table 111-12 of the FES. The tailrace concentrations are high due to an error in the method for calculating effluent release rates as discussed in NRC/01E Inspection Reports No. 269/76-2, 270/76-2, and 287/76-2.
The method for calculating effluent release rates has been corrected; in the future, the concentrations of radionuclides in bottom sediment and aquatic vegetation samples should level off or decrease due to this correction.
Very truly yours, su. d ik ~
William O. Parker, Jr.
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