ML20209B322
| ML20209B322 | |
| Person / Time | |
|---|---|
| Site: | 07003073 |
| Issue date: | 06/18/1999 |
| From: | Lux J KERR-MCGEE CORP. |
| To: | Brown S NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 9907060381 | |
| Download: ML20209B322 (5) | |
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O_*(mKERR-McGEE CORPORATION EERR-MCGEE Cf NTER e OttLAHOMA CITY. OKLAHOMA 7312S June 18,1999 Mr. Stewart Brown Low-Level Waste & Decommissioning Projects Branch Division of Waste Management Office of Nuclear Materials Safety & Safeguards U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Re:
Docket No. 70-3073 License No. SNM-1999
Dear Mr. Brown:
Kerr-McGee Corporation (KMC) met with NRC on June 16,1999, to review KMC responses to NRC's Request for Additional Information dated May 6,1999. KMC provides the following clarification requested by NRC. The requests are italicized. NRC did not provide these requests in writing, and the requests are stated as understood by KMC.
- 1. Provide assurance that the estimated dose to a trar.sportation worker (as presented in Appendix B) hauling radioactively contaminated soil is less than that estimatedfor a radiation worker.
Calculated doses to transportation personnel would be less than calculated doses to radiation workers due to the fact that the drivers will be transporting sealed containers - the most likely
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route of exposure would be direct exposure in the cab of the vehicle. Therefore, the worker scenarios presented in Attachment B of the June 4,1999 letter include and exceed the range
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1 of potential exposures that might result from waste transportation.
- 2. Clanfy that the estimated dose to a radiation worker (as presented in Appendix B) was calculatedforfuture decommissioning operations.
The estimate was based upon work to be performed in the future and utilized upper ranges for
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radioactive materials in air and soils / sludges at the facility. It is therefore considered to be an upper bound estimate for potential doses to workers during the decommissioning project.
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- 3. Providejustipcationfor the cited 9.6 nr'/ day of air that a member of the public would inhale lF$
or recalculate the dose based on an air intake of1.2 m'/hr.
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g The value cited is for a typical radiation worker breathing at a rate of 1.2 m'/hr for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, and should reflect the time of exposure for a member of the public, which is assumed to be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Corrected pages B-7, B-8, B-12 are submitted as an attachment to this letter with s
the appropriate values and calculations. The modifications yield an estimate of 0.15 mrem to a member of the public for the off-site transportation accident scenario. The corrections do u
not affect the concibsions of the evaluation in that this estimated dose is insignificant.
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- 4. ' Please clarify KMC's position regarding debris and/or rubble outside of RMA-11.
KMC.will perform surface contamination measurements on "large" debris and/or rubble, such as brick, sheet steel, etc. All material that' exceeds surface contamination limits
- specified in Section 3.2.3.2 of the Site Decommissioning Plan will be shipped to an off site licensed disposal facility. KMC may not be able to justify the use of surface contam'mation measurements for some debris and/or rubble (e.g., pieces are too small or irregular). Such debris and/or rubble will be segregated in a separate area until KMC and NRC agree on an appropriate measurement method and criteria for this' material.
$ Provide additional information regarding analyses of air samples and actions taken as a result of those analyses.
Air samples are typically analyzed at approximately twelve hours and two weeks after sample
- collection. Air samples are' classified as "Open" or " Closed". Air samples are not considered " Closed" until the second or final count is performed, the results are loaded into the dosimetry database, the data record is printed, and the record is reviewed / signed by the HP lead Technician'(HP Lead).
Each day air samples are analyzed, an air sample report is generated from the dosimetry database. This report has two parts. The first lists results from all "Open" air samples. The second lists year-to-date DAC-hrs for ea::h individual. The second part includes exposures based on both " Closed" air samples and any "Open" air samples assigned to that individual.
The HP Lead compares workplace concentration levels listed in the first part of the report with concentration-based action levels, and then compares year-to-date exposures listed in the second part with bioassay action levels. If an "Open" air sample has a significant impact on any specific individual, the HP lead may pursue further action, such as re-counting the air sample to quantify naturally occurring short lived radon daughters. Air samples may therefore be counted at additional intervals besides 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and 14 days after sampling. As long as the anticipated radon decay appears to be the cause of elevated concentrations, no work-related actions are triggered, If you have any questions or comments, please call me at (405) 270-2694.
Sincerely, Jeff Lux Project Manager xc:
C. L. Cain, NRC Region IV Blair Spitzberg, NRC Region IV Cushing Citizens' Oversight Committee Earlon Shirley, ODEQ Darrell Shults, ODEQ
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J significantly overestimate the. actual doses that would be received, due to the conservative assumptions utilized and the fact that no credits were assumed for the use of personal protective gear during the cleanup effort.
Off-Site Radletonical Accident Scenario-Member of the Public The member of the public is assumed to be at a distance of 1 km from the spill, and is constantly in the plume centerline in the downwind direction. The atmospheric stability will be assumed as extremely stable, Class F. The spill will be modeled as a point source, with emission rates as defined for the cleanup worker scenario.
The basic atmospheric dispersion equation for a ground level source at the plume centerline is:
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- X = Q + (2n)(c )(a,)(u).
y Sigma y and sigma z were picked from Figures 3-2 and 3-3 in Reference 5, using Class F atmospheric stability curves. The wind speed is assumed to be 1 m/s.
. The concentration of airborne total uranium, x, is calculated-x = 7.1 E-12 Ci/s + (2n)(34 m)(14 m)(1 m/s) = 2.4 E-15 Ci/m' The effective dose can be calculated using the dose conversion factors from EPA Federal Radiation Guidance Report No.11 (Reference 3). The dose conversion factors
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for U-234, U-235, and U-238 are similar. Therefore, simplification of the problem can 1
be achieved through the use of the dose conversion factor for U-234, which is the most
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conservative.
Inhalation Class Y is assumed for the resuspended material.
The breathing rate is assumed to be 9.6 m'/ day.
Effective Dose to the Member of the Public from total U
= (2.4 E-15 Ci/m') (1.2 m /hr) (24 hr) {3.58 E-05 Sv/Bq) 3 6
(3.7 E+09 mrem / Ci per Sv/Bq)(10 pCi/Ci)
= 9 E-03 mrem CEDE Cushing Decommissioning Plan B7 Response to General Comnwnt #2
y v.,
Effective Dose to the Member 1of the Public from Th-232
= (2.4 E-15 Ci/m') (1.2 m'/hr) (24 hr) (4.43 E-04 Sv/Bq)
(3.7 E+09 mrem /pCi per Sv/Bq) (10* pCi/Ci)
= 0.113 mrem CEDE Effective Dose to the Member of the Public from total Th-228
= (2.4 E-15 Ci/m') (1.2 m /hr) (24 hr) (9.23 E-05 Sv/Bq) 8 6
(3.7 E+09 mrem /pCi per Sv/Bq) (10 Ci/Ci)
= 0.023 mrem CEDE Total CEDE to the Member of the Public from all nuclides
= 0.15 mrem Note that the TEDE is equivalent to the CEDE as there is no anticipated direct exposure to a member of the public resulting from the accident scenario.
The upper estimate of dose to the member of the public is 0.15 mrem, which is i
insignificant.
This estimate utilized conservative assumptions of wind speed and stability class and placed the individual in the plume centerline for the entire duration of the cleanup. In addition, no shielding or dilution effects were considered as is normally done to account for shelter of the individual.
On-Site Radiolonical Accident Scenarlo-!!(adiation Worker This scenario assumes that a single container holding 7.5 ft' of waste soils is spilled.
The concentrations of total U, Th-232, and Th-228 within the spilled material are each 200 pCi/g. The spill covers an area of 15 ft to a depth of 6 inches (15 cm). The 2
calculations can be performed utilizing the same methodology as for the Off-Site Scenario-Cleanup Worker. The cleanup is assumed to take 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
Emission Rate (E) = 0.01 [a A K C L' V'] based upon Reference 1.
= (0.01)(0.41)(52)(1.0)(20)(0.7)(1.0) = 2.98 tons / acre-y Cushing Decommissioning Flan B-8 Response to General Comment #2 L
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i of spilled radioactive material.
estimated doses for the three scenarios, as follows: Conservative assump i
Off-site Radiological Accident Scenario-Worker:35 mrem TEDE Off-site Radiological Accident Scenario-Public: 0.15 mrem TEDE
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On-site Radiological Accident Scenario-Worker:11 mrem TEDE These dose estimates are considered to represent upper bounds of dose.
The calculations demonstrata that the radiological consequences of accidents involving radioactive waste spillage are insignificant for members of the public, and will result in doses to cleanup workers that are well within the regulatory requirements.
References
- 1. Colorado Department of Health, Interoffice Communication, Fugitive Dust 1
Emissions, September 30,1981.
- 2. Radiological Health Handbook, U.S. Department of Health, Education, and Welfare, Public Health Service, Revised 1970.
- 3. Enviromnental Protection Agency, _" Limiting Values of Radionuclide Intake and Air '
Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion," EPA-520/1-88-020, Federal Guidance Report No.11, September,1988.
- 4. U.S. NRC, NUREG/CR-5512, PNL-7994, " Residual Radioactive Contamination from Decommissioning", Volume 1, Reprinted June,1994.
- 5. Turner, D.
B.,
" Workbook of Atmospheric Dispersion Estimates," U. S.
Department of Health, Education, and Welfare, Cincinnati, OH,1969.
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. Cushing Decommissioning Plan B-12 Response to General Comment #2
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