ML20151W778
| ML20151W778 | |
| Person / Time | |
|---|---|
| Site: | 07001201 |
| Issue date: | 09/08/1998 |
| From: | Allsep T FRAMATOME COGEMA FUELS (FORMERLY B&W FUEL CO.) |
| To: | Lamastra M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20151W780 | List: |
| References | |
| TAC-L30746, NUDOCS 9809160096 | |
| Download: ML20151W778 (5) | |
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QQl0I FRAMATOME COG EMA FU ELS September 8,1998 Mr. Micheal Lamastra Licensing Section 2 Licensing Branch Division of Fuel Cycle Safety & Safeguards, NMSS United States Nuclear Regulatory Commission Washington, D.C. 20555
SUBJECT:
Wet Weather Stream Release (TAC No. L30746)
Docket No. 70-1201, SNM-1168
Dear Mr. Lamastra:
The additional information requested concerning the subject project in your July 8,1998 letter is enclosed. During preparation of the response, additional surveys and/or remediation work necessary to demonstrate that the subject area is ready for release were identified. As appropriate, the additional work required is identified in the enclosure. Attached to the enclosure, please find a revised table of data, Table 6-2, originally included with our April 29, 1998 :.tbmittal. The table has been revised in conjunction with your request for additional informat on.
i The enclosed document states the additional work we plan to perform to demonstrate the subject area suitable for release.
We are continuing to develop the final details of the actual survey /reme diation work required. To ensure that the work will be cost effective, we will delay submittal of the final work plan for your review and approval until such time that your final review of the information submitted on April 29,1998 and the information provided with this letter is complete.
If you have any technical questions regarding the information submitted please call me at (804) 832-5202.
l Sincerely,
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4 Tim V. AIlsep k
E$N ONoNot Acting Manager, Safety & Licensing I
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Enclosure k
Framstome Cogoma Fuels F R AM ATO M E ro. Box 11646. Lynchburg, VA 24506-1646 TECHHOLOOIE5 Telephone: 804 832 5000 Fax: 804-832 5167
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Responses to NRC Requests for Additional Information From Submittal Dated April 29,1998 i
1.
Table 6-2 of the Survey Report (enclosure of the submittal dated April 29, 1998) provides the weighted averages of total uranium in soil for each 30 x 30 ft (9 x 9m) grid block. This table indicates that grids B3, Q7, R7, R8, S6, S8, T6, T8, T10, U7, U9, U10, and U11 have uranium concentrations that exceed 30 pCi/g. As specified in Section 8.5.2 of NUREG/CR-5849, " Manual for Conducting Radiological Surveys in Support of z
License Termination," the average activity in each 100 m contiguous area containing measurements between 30 and 90 pCi/g must be less than 30 pCi/g in order to show compliance with the guideline value. Therefore, you have not demonstrated that these areas are suitable for unrestricted release.
Please provide additional data to demonstrate that the average uranium concentration is less than 30 pCi/g in the 100 m' contiguous area surrounding the locations where elevated levels of total uranium (30 to 60 pCi/g) were measured. Data from the 1991 or 1994 surveys may be used where appropriate. If this information cannot be provided, additional remediation or sampling will be necessary.
FCF Response FCF does not currently possess sufficient data to demonstrate that the average uranium concentration is less than 30 pCi/g in the 100 m' contiguous area surrounding the locations where elevated levels of total uranium between 30 and 90 pCi/gm have been identified. A survey /remediation plan is being developed that will include additional evaluations of these areas. As a minimum, the plan will include a review of all grid blocks and hot spots identified above the guideline value of 30 pCi/gm (This review will be performed using revised data. See FCF response to item 2 for more information concernmg revised data.). After additional review of the survey data obtained in March 1998 (as revised), FCF agrees that more careful application of the requirements in section 8.5.2 of NUREG/CR-5849 is necessary.
2.
In Section 5.3 of the Survey Report, you indicate that a factor of 25 would be used to convert gamma spectroscopy measurements of U 235 to total uranium, which assumes a mass U-235 enrichment of 4%. Because the mass enrichment of uranium discharged to the Wet Weather Stream varied to values less than 4%, this conversion factor could be higher. In fact, the uranium alpha spectroscopy measurements provided in Attachment 2 of your April 29 submittal indicate an average factor of 36, not 25. Justify the use of the i
factor of 25 or revise the data analysis in the Survey Report using the factor of 36 to calculate total uranium concentrations.
i FCF Response The conversion factor of 25 was selected based on the assumption that the residual uranium in the Wet Weather Stream was enriched in the Uranium-235 isotope to approximately 4% by mass. FCF has evaluated the ORISE alpha spectroscopy results for the samples that were collected and relinquished to the NRC during the March 1998 l
survey. Based on this evaluation, a conversion factor of 33 is more appropriate. Table 6-2 of the Survey Report, which reports the average total uranium concentration measured
i in each grid, has been revised to reflect this conversion factor. Table 6-2 and the data to support the derivation of the conversion factor are included as Attachment I for your review.
- 3. of your Survey Report provided the soil sampling results. Data on elevated areas designated B3, B3-C3, C3, R7, and T8 indicate that the uranium concentration in soil is higher outside of the established elevated area " boundaries" as determined through the gamma walk-over surveys. We assume that this is due to subsequent remediation of these areas. liowever, because the uranium measurements outside the boundaries are greater than 30 pCi/g, this data seems to indicate that the gamma survey did not accurately determine the extent of the elevated areas. (This is of panicular concem due to the presence of vegetation and obstacles greater than 2 inches in height covering 5 to 60% of the surface area of each grid.) Also, several areas of elevated activity were found in the 1994 sampling plan that were not identified as elevated areas in the final status survey, including areas in grids J3, R9, T10, Tl1, V8, and V12.
Please provide greater detail on how the extent of all elevated areas was determined, including survey maps of the elevated areas. This information is also necessary to verify your conclusion that the elevated uranium concentrations in soil samples meet the criteria of 30 pCi/g * [(A/100), as discussed in Section 8.5.2 of NUREG/CR-5849.
FCF Response Gamma scan surveys were performed, using sodium iodide detectors, to identify areas of elevated radioactivity and to establish the boundaries of those areas. The areal extent of areas of elevated radioactivity was estimated by determining the points surrounding the center of the elevated reading where the detector response dropped off to the ambient levels. Appendix D-2 of the Survey Report provides d: tailed maps for areas of elevated radioactivity including the dimensions for each location. Ilowever, the maps do not adequately address the contamination outside the areas designated as " elevated".
As stated in Section 5.2 of the Survey Report, the detection sensitivity of sodium iodide gamma scans to measure the residual total uranium is approximately 140 pCi/ gram (according to NRC estimates published in NUREG/CR-1507.) As such, the implemented gamma scan technique is insensitive to the boundaries of areas less than or equal to 30 pCi/ gram.
Sodium iodide c'etectors are commonly used to perform gamma scans of residual uranium radioactivity in support of release for unrestricted use, despite their sensitivity limitations, because they are close to if not the best available technology. If fact, Appendix D to NUREGICR-5849, Sample Final 9tatus Survey Reportfor the Reference Uranium Fuel Fabrication Plant, an example of a final status survey report, lists sodium iodide detectors as the gamma scan instrumentation for scans of affected area grounds with potential low-enriched uranium contamination.
FCF considers the use of sodium iodide detectors an important part of the survey methods available to discern the boundary of the elevated areas. Due to the sensitivity limitations l
imposed by the detector design, additional survey techniques (e.g., soil samples and/or gamma spectroscopy measurements) may be required to more adequately define localized
areas of elevated radioactivity.
'Ihe revised data table and a more comprehensive review of the soil samples indicate that additional measurements may be required to verify that the contamination found outside the remediated areas is in compliance with the applicable criteria specified in NUREG/CR-5849.
The areas identified as elevated in 1994 that were not identified likewise in the 1998 survey will be given specific attention during the subsequent survey work planned for the area. The difference in classification is most likely due to the variation in techniques used for the two survey campaigns, soil-sampling in 1994 and direct measurements in 1998.
4.
Table 6-2 of the Survey Report indicates that grid blocks Q7 and R8 have average uranium concentrations in excess of the guideline value of 30 pCi/g. Please provide survey data for the area beyond the northwestern perimeter of these grid blocks to demonstrate that it is not necessary to include this adjacent area in the "Affected Area."
Also, from the survey maps it appears that the "Affected Area" does not extend to the discharge point of the Wet Weather Stream at the St. James River. Please provide information to demonstrate that this area is not expected to be contaminated.
FCF Response With the revision of the values expressed in Table 6-2 of the Survey Report, a review is necessary to ensure that all areas above the guideline value have been adequately evaluated to demonstrate compliance with the requirements in NUREG/CR-5849.
Additional surveys may be required to evaluate areas above the guideline value which lie on the edge of the "affected area", such as the areas adjacent to grid blocks Q7 and R8. If necessary, the "affected area" will be expanded as required by survey results.
Measurements obtained during initial survey work in 1983 found contamination present only in the first 700 meters downstream of the discharge point. Beyond this point, the discharge stream continues into a 4 to 8 foot deep gully until it reaches a dirt road. The stream goes under ground for about 30 feet to a ravine on the other side of the road. The ravine is about 20 to 30 feet deep and ends at the James River. At that time, soil samples from this area did not reveal contamination above the guideline value. These initial surveys were used to define the 75 grid blocks that now are identified as the "affected area". That notwithstanding, additional measurements will be obtained in the area where the stream exits the "affected area", continuing toward the James River to ensure that the "affected area" boundary is adequately defined.
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Responses to NRC Requests for AdditionalInformation Attachment I Calculation of Activity Ratio of Total Uranium to Uranium-235 in Residual Uranium at Framstome Cogema Fuels Wet Weather Stream Prepared by Cabrera Sen' ices,Inc. under contract to Framatome Cogema Fuels I
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