ML20023C062
| ML20023C062 | |
| Person / Time | |
|---|---|
| Issue date: | 04/21/1983 |
| From: | Higginbotham L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Page R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-3 NUDOCS 8305090582 | |
| Download: ML20023C062 (3) | |
Text
{{#Wiki_filter:wg_ 3 weza DISTRIBUTION 3hg Nn NMSS r/f (Return to WM, 623-SS WMLLr/[f TECHNICAL EVALUATION REQUEST /1 WM s/f
- SMNeuder EFHawkins REBrowning APR 211983 PDR WM
MEMORANDUM FOR: R. G. Page, Chief Uranium Fuel Licensing Branch Division of Fuel Cycle and Material Safety FROM: L. Higginbotham, Chief Low-Level Waste Licensing Branch Division of Waste Management
SUBJECT:
REQUEST FOR TECHNICAL EVALUATION ON RADIONUCLIDE TRANSPORT IN GROUND WATER We have reviewed the subject request from the Atlantic Research Corporation to allow on-site disposal of soil contaminated with strontium-90. According to the information supplied by the licensee, approximately 2000 cubic feet of earth, contaminated with 1 millicurie of Sr-90, has spread aoout 15 feet vertically and 12 feet radially in all soil directions. The contaminated material is on a slope of a hill in an area zoned industrial. The site is approximately 600 feet from the nearest private residence situated on the far side of small stream, approximately 300 feet from the contamination. The residence is at a higher elevation than that of the site and there are ao water wells or agricultural activities in the immediate area. In order to assess the potential radiological hazards from the contaminated soil remaining in place, we have considered the primary exposure pathways to be (1) drinking water from a nearby well which is contaminated via the ground water pathway, (2) living on and consuming food grown on the disposal area (intruder-agriculture scenario), and (3) drinking water from an "on-site" well constructed after land release for unrestricted use. For the nearby-well scenario we have calculated a potential 50 year dose commitment to the bone of 1.9 mrem and a wnole-body dose equivalent of 0.25 mrem due to 1 year ingestion of drinking water from a well located 250 feet from the contaminated area. By way of comparision, this is less than the annual whole-body dose equivalent limit of 4 mrem set by EPA for public drinking water systems. For the intruder-agriculture scenario, 0FC : NAME : DATE,.:83/04/19 8305090582 830421 PDR WASTE WM-3 PDR
TECHNICAL EVALUATION REQUEST /1 assuming a uniform concentration of 11 pCi/gm soil contaminant, the potential annual dose to the bone due to ingestion, inhalation, and direct radiation has been calculated to be 0.61 mrem. For the "on-site" groundwater scenario, i.e., for a well located anywhere on or near the contaminated soil, the potential 50 year dose commitment to the bone will not exceed 2 mrem provided that a 250-foot restriction zone for water withdrawal is maintained around the site'for at least 30 years. Details of the modeling are summarized separately (see attached). We conclude that, with the contaminated soil remaining in place, the potential dose commitment to man will be limited to less than 2 mrem to the bone provided that drinking-water withdrawal points are not permitted within at least 250 feet of the contaminated area over the next 30 year period. In addition, we suggest that restricted access to the contaminated area and appropriate posting be maintained thoughout the entire period. Please contact Dr. Stan Neuder of my staff on this matter, should any questions arise. Original Signed By Leo Higginbotham, Chief Low-Level Waste Licensing Branch Division of Waste Management
Enclosure:
As stated cc: RCunningham, FC EShuni, FCML WMLL (L OFC : -{fe, NAME : SNe LHigginbotham
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DATE :83/04'/19
- 83/04/j)D a6
.~ TECHNICAL EVALUATION REQUEST /1 Ground Water Scenario Methodology: Modified USGS Solute Transport Code (NUREG/CR-2502) Disposal Dt cription For modeling purposes, assume an inverted conical-shaped volume, 15 ft depth, 12 ft base radius, with apex at the top of saturated zone. Surface soil 2 area 452 ft, average cross-sectional area 151 2 ft, equivalent contaminated square area 12 ft x 12 ft. Parameter Values: Activity 1 mci Sr-90;- recharge. 5 in/yr; _ dispersivity 20 ft; dispersivity ratio 0.2; leach rate 0.25 per year; distribution coefficient 3; hydraulic conductivity 5 x 10 5 ft/sec; effective porosity 0.2; saturated thickness 10 ft; distance to withdrawal well 250 ft. Addition Assumptions: Two liters drinking water per day ingested for_ a 1 year period. Ingested concentration-assumed to be 2/3 peak value. Intruder Scenario Methodology: 10 CFR Part 61 methodology Volume: Contaminated Volume 2000 ft3 Concentration: 11 pCi/gm-soil, uniform distribution Scenario: Contaminated soil was previously excavated and is distributed on the surface. Intruder then inadvertently resides and consumes food grown on the site. Exposure to the individual is due to inhalation of suspended contamination; direct radiation and consumption of contaminated food. OFC : NAME : DATE :83/04/19
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