ML18057A962
| ML18057A962 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/07/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18057A961 | List: |
| References | |
| NUDOCS 9106140216 | |
| Download: ML18057A962 (6) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION RELATED TO THE PALISADES NUCLEAR PLANT RETENTION OF CONTAMINATED SOIL ONSITE INTRODUCTION In reference (1), Consumers Power Company (CPCo) requested approval pursuant to Section 20.302 of Title 10 of the Code of Federal Regulations (CFR) for the disposal of licensed material not previously considered by the NRC in the Palisades Final Environmental Statement (FES), dated June 1972.
The petition submitted contains a detailed description of the licensed material (i.e.,
contaminated soil) subject to this 10 CFR 20.302 request. The 6,000 cubic feet of onsite contaminated soil contains a total radionuclide inventory of 5.1 mCi, based on radioactive material that was deposited in the soil due to the flooding of the South Radwaste Building. The contaminated area is located inside the security fences, and is on company controlled land.
This area (South Radwaste Area) is fenced in, within the plant's south security fences.
Thus it is inaccessible to the public (see Figures 1 and 2).
In the submittals (References 1-5), the licensee addressed specific information requested in accordance with 10 CFR 20.302(a), provided a detailed description of the licensed material, thoroughly analyzed and evaluated the environmental effects relative to retention of the contaminated soil onsite, and committed to follow specific procedures to minimize the risk of unexpected exposures.
Although the environmental impact of the proposed action is well within the dose criteria contained in the Commission's Below Regulatory Concern (BRC) Policy Statement, dated July 3, 1990, the licensee has not requested, and the staff has not considered, th~ actions described herein to be exempt from NRC regulation.
CPCo plans to dispose of the 6,000 cubic feet of contaminated soil onsite pursuant to 10 CFR 20.302.
The area, known as the South Radwaste Area, has been contaminated by several cooling tower overflows (three times in an eight-year period), and has subsequently been redistributed by heavy rain showers.
The cooling tower overflows were caused by instrument failures that opened the cooling tower bypass valve during normal operation. This valve is now electri-cally isolated during cooling tower operation.
The licensee conducted a soil survey because the South Radwaste Building was in the main path of the water overflows from the cooling tower.
Survey results indicated that radioactive material was deposited in the soil. Although the majority of the radioactive material has been packaged as radwaste and will be subsequently shipped offsite (16 boxes each having a volume of 98 cubic feet, containing 85% of the estimated activity), a large volume of low level contaminated soil is contained in the fenced area described as the South Radwaste Area.
9106140216 910607 PDR ADOCK 05000255 P
PDR The specific area contaminated is noted as Area B on the survey grid map (see Figure 2). The total activity of this area (5.1 mCi) is based on 6,000 cubic feet of soil contaminated with the spoils from the South Radwaste Building.
Table 1 lists the principal nuclides identified in the contaminated soil. The activity in this table is based on measurements in 1987; see data from a recent submittal (Reference 5) shows that activity concentrations in the contaminated area have decreased by approximately 10 percent. The radionuclide half-lives, which are dominated by 30-year Cs-137, meet the staff's 10 CFR 20.302 guidelines (Reference 6, which applies to radionuclides with half-lives less than 35 years).
Nuclide Co-60 Cs-137 RADIOLOGICAL IMPACTS Table 1 Average Concentration (pCi/g) 0.05 30 Total Total Activity (mCi) 0.079 5.0 The licensee has evaluated the following potential exposure pathways to members of the general public from the radionuclides in the contaminated soil:
(1) external exposure caused by direct radiation from radionuclides in the soil; and (2) internal exposure from inhalation of resuspended radionuclides.
The staff has reviewed the licensee's calculational methods and assumptions and finds that they are consistent with NRC Regulatory Guide 1.109, "Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I, 11 Revision 1, October 1977.
The staff finds the assessment methodology acceptable.
The dose assessments are based on the followi~g:
- 1.
5.1 mCi of contaminated soil distributed over 12,000 square foot planar source having a thickness of 0.5 feet (6000 cubic feet source volume).
- 2.
Direct radiation exposure of 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> per year.
- 3.
Inhalation exposure based on 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> per year is minimized due to six-inch layer of gravel (which inhibits wind erosion.)
- 4.
Groundwater not considered because there are no domestic wells in the area down-gradient from the plant.
Doses calculated from these pathways are shown in Table 2.
The total dose of 0.85 mrem per year is within the staff's guideline of 1 mrem per year (Reference 6).
Pathway Groundshine Inhalation Groundwater Ingestion Table 2 Whole Body Dose Received by Maximally Exposed Individual (mrem/year) 0.85 0.00081 0.0 TOTAL 0.85 The above doses are a small fraction of the 300 mrem received annually by members of the general public in the United States and Canada from sources of natural background radiation (Reference 7).
Based on our review of the proposed disposal of contaminated soil onsite, we conclude that:
(1)
The radioactive material will be disposed in a manner such that it is unlikely that the material will be recycled; (2)
Doses to the total whole body and any body organ of a maximally exposed individual (a member of the general public or a non-occupationally exposed member) from the probable pathways of exposure to the disposed material will be less than 1 mrem per year; (3)
Doses to the total whole body and any body organ of an inadvertent intruder from the probable pathways of exposure will be less than 5 mrem per year since the burial location is on company-controlled land; (4)
The radiation exposures to the nuclear station workers are small compared to the routine occupational exposures at the Palisades Plant; (5)
The possible radiation risks to members of the general public as a result of such disposal are well below regulatory limits and small in comparison to the doses they receive each year from natural background radiation.
The licensee's procedures and commitments as documented in the submittal are acceptable, provided that they are permanently incorporated into the licensee Offsite Dose Calculation Manual (ODCM) as an Appendix, and that future modifications be reported to NRC in accordance with the applicable ODCM change pro to co 1.
REFERENCES (1)
CPCo's letters, T. C. Berdine to NRC Document Control Desk, November 12, 1987 and January 25, 1988.
(2) Memorandum from L. J. Cunningham, DREP to T. R. Quay, T. V. Wambach, "Request for Additional Information (RA!)," March 15, 1988, April 7, 1989, and January 12, 1990.
(3)
CPC0 1s supplement to Reference (1), J. L. Kuemin to NRC Document Control Desk, June 27, 1988.
(4)
CPC0 1s supplement to References (1, 2), G. B *. Slade to NRC Document Control Desk, August 31, 1990.
(5)
CPCo's letter, T. P. Neal to B. Holian, October 13, 1990.
(6)
E. F. Branagan, Jr. and F. J. Congel, "Disposal of Slightly Contaminated Radioactive Wastes from Nuclear Power Plants," presented at CONF-860203, Health Physics Considerations Decontamination Deconmissioning, Knoxville, TN, February, 1986.
(7) National Council on Radiation Protection and Measurements, "Exposure of the Population in the United States and Canada from Natural Background Radiation," NCRP Report No. 94, Bethesda, MD. December 30, 1987.
Principal Contributor: J. L. Minns
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