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UNITED STATES
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x NOV 2 1984 Docket Nos. 50-424/50-425 MEMORANDUM FOR:
Charle's A. Willis, Leader Effluent Treatment Systems Section Meteorology & Effluent Treatment Systems Branch, DSI FROM:
Robert A. Jachowski, Acting Leader Hydrologic Engineering Section Environmental & Hydrologic Engineering Branch, DE
SUBJECT:
LIQUID RADWASTE TANK FAILURE EVALUATION FOR V0GTLE UNITS 1 AND 2 We have evaluated the consequences of a failure of the Waste Evaporator ConcentrateHoldupTank(WECHT)atthenearestunrestrictedarea. The radionuclide concentrations were evaluated for a spring that is about 2800 feet southeast of the Unit 1 containment. The spring is on the applicant's property. The nearest unrestricted area is the Savannah River and the nearest potable water supply is Beaufort / Jasper County, 112 miles downstream.
Hyd'raulic Conductivity (Permeability) is the important parameter used in determining groundwater travel time.
The FSAR lists a wide range of values for the water table aquifers.
Field permeability tests, which.are more indicative of average aquifer characteristics, ranged from 60 to 350 ft/ year.
Values from laboratory tests, which only reflect on a small disturbed sample of the aquifer, ranged from 10 to 20,000_.ft/ year.
It is our judgement that the appropriate value of hydraulic conductivity to be used to determine groundwater travel time over a significant distance is 350 ft/ year. Using a hydraulic conductivity of 350 ft/ year, the computed travel time to the Spring, 2800 feet southeast of the plant, is 338 years.
This travel time would reduce the concentrations of all the radionuclides listed in your memorandum of October 11, 1984 to small fractions of the 10 CFR Part 20 limits. Since the FSAR lists point values of hydraulic conductivity that are considerably greater than 350 ft/ year, we also computed an ultra-conservative groundwater travel time of 14.8 years using a hydraulic conductivity of 8000 ft/ year. With this conservative groundwater travel
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Charles A. Willis EE-time, all of the radionuclides except Co 60, Cs 134 Cs 137 and Sr 90 will be less than the 10 CFR Part 20 requirements at the spring. We further considered the effects of sorption on radionuclide travel time for the four critical radionuclides. We used conservative distribution coefficients of 100 for Co 60, Cs 134 and Cs 137 and 10 for Sr 90. The resultant concentrations at the spring are small fractions of the 10 CFR Part 20 requirements.
I We also considered the effects of dilution in the Savannah River. The combined groundwater and river dilution is about 140,000 which is sufficient to reduce all radionuclides to small fractions of the 10 CFR P' art 20 requirements.
Based on the above information, we conclude that the accidental failure of the WECHT would result in radionuclide concentrations, at the nearest
' unrestricted area, that are small fractions of the 10 CFR Part 20 requirements.
Questions concerning t,his review should be addressed to Gary B. Staley (X28003), cognizant engineer assigned to this facility.
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' Robert A. Jachowski, Acting Leader Hydrologic Engineering Section Environmental & Hydrologic Engineering Branch Division of Engineering cc:
R. Ballard W. Johnston W. Gammill C. Nichols G. Staley DISTRIBUTION:
Dockets EHEB Rdg RAJachowski I
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- 11/ A/84 0FFICIAL RECORD C0PY x.:.- -. -.-.
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