ML20045D396
| ML20045D396 | |
| Person / Time | |
|---|---|
| Issue date: | 04/19/1993 |
| From: | Surmeier J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Chernoff A ENERGY, DEPT. OF |
| References | |
| REF-WM-61 NUDOCS 9306280324 | |
| Download: ML20045D396 (5) | |
Text
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O Mr. Albert R. Chernoff, Project Manager Uranium Mill Tailings Remedial Action Project Office U.S.' Department of Energy Albuquerque Operations Office P.O. Box 5400 Albuquerque, New Mexico 87115
Dear Mr. Chernoff:
The U.S. Nuclear Regulatory Commission has received the Department of Energy's i
(DOE) March 25, 1993, response to our remaining open issues and comments on I
the final Remedial Action Plan (RAP) for the Gunnison Uranium Mill Tailings l
Remedial Action Project.
Those issues and comments were transmitted by our i
i letters of December 17, 1992, and February 25, 1993.
i The comments and most of the open issues have been resolved by DOE's response; however, seven issues still require additional information.
Those issues and the NRC staff's reasons for requesting revised responses are discussed in the enclosure. Note that one of the previous comments has been elevated to an open issue.
When replacement pages for the final RAP and the Remedial Action Inspection j
Plan are received that provide adequate response to all the open issues, we will issue our final Technical Evaluation Report and concur in the RAP.
Since remedial action activities are planned to resume shortly, these remaining issues need to be resolved promptly. However, the seven open issues involve processing site cleanup, disposal cell cover, and ground-water monitoring, none of which would preclude hauling tailings to the disposal cell.
If you i
have any questions on this review, please contact me at FTS 8-301-504-3439, or 4
the NRC Project Manager, Elaine Brummett at FTS 8-301-504-2533.
Sincerely, e~ - -
nef"$1GNED @
At l
John J. Surmeier-Uranium Recovery Branch Division of Low-level Waste Management-and Decommissioning Office of Nuclear Material Safety and Safeguards
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l Nuclear Regulatory Commission Staff Discussion of the Department of Energy's Response to Open Issues on the Gunnison Remedial Action Plan I
i draft Technical Evaluation Report Open Issue No. 9:
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After several discussions with the Department of Energy (DOE), the Nuclear Regulatory Commission staff narrowed.this issue to a request for Atterberg limit testing for radon barrier material during construction.- Although DOE's response does not present an Atterberg Limits testing program of the extent proposed by the staff, we generally agree that the mitigating factors, as stated by DOE, should provide conservatism in construction.
The limited testing proposed by DOE will provide some assurance that the design Atterberg limits can be achieved in production of the radon barrier layer.
Since DOE's proposed testing procedure will verify Atterberg limit values for production material in a logical manner, the methods are. considered satisfactory for this project. Conversely, the procedures proposed should not be applied generically to other sites.
Specific consideration is necessary for any programs that are less than the guidelines provided in Section 3.2.5 I
of the Staff Technical Position on Testing-and Inspection Plans. DOE should revise the Remedial Action Inspection Plan to incorporate the proposed procedures and include the revision with the Remedial Action Plan (RAP)_ page q
changes.
i draft Technical Evaluation Report Open Issue No. 23:
l DOE provided some site-specific information on the procedure for determining Ra-226 and Th-230 content of cobbly soil (bulk averaging) for RAP Section 6.5.3.
It states that thirty-three tests pits were constructed to determine the average mass partition function, but incorrectly refers to this procedure as Site Verification Alternative 2.
This sentence should be corrected to identify the activity as Statistical Mass Partition Function Alternative 1.
Apparently Site Verification Alternative 2 is to be used at this site. When the site correction factor (partition function) is used instead of determining the factor for each grid, DOE should provide discussion in the Completion
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Report to demonstrate that the test pits are representative of the cobbly i
areas.
t DOE also should indicate in the RAP if the 33 test pits contructed to determine the site partition function include the 28 test pits evaluated in i
calculation 612-01-01.
If this earlier data, which indicates that the average measured Th-230 content of the cobbles fraction is S.5 pCi/g, has not been considered, an explanation for its exclusion should be provided.
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Final RAP Open Issue No. 2:
NRC staff requested site-specific justification for a Th-230 supplemental standard allowing Th-230 deposits to remain that exceed the projected 1000-year Ra-226 standard.
The DOE proposal that any Th-230 deposit below the 4
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a water table not be excavated is inappropriate, unless it includes adequate justification. Any Th-230 in excess of the accepted supplemental standard (1000-year projected Ra-226 standard) that DOE proposes to leave in place, should be evaluated with an ALARA analysis that considers future land use and potential exposure pathways. The cost and hazards of excavating below the water table would be evaluated against potential health and environmental risks due to the deposit. The RAP should indicate that such an analysis and a recommendation would be provided in a Project Interface Document, if elevated Th-230 is found below the water table.
Final RAP Open Issue No. 5:
DOE's response (Part 1) states that all contaminated wetland areas referenced by Note 13 on Drawing GUN-PS-10-0212 will be excavated. NRC staff anticipates that this change in the excavation plan will be handled by a Class I PID since the Plans for Implementation did not include revision of the drawing.
NRC staff understands that the excavation plan was changed becausc these areas did not meet the official designation of protected wetlands. The RAP should indicate that DOE uses the term " wetlands" to describe wet land and is not referring to designated (protected / regulated) wetlands.
Part 2 of the DOE response indicates that an application for supplemental standards will be made for the north-south runway on the basis of cost to remediate and the infrequent use of the area.
Since the runway is apparently on a vicinity property, this information would not be part of the RAP.
If this supplemental standard would include some wetlands, that was not indicated.
Final RAP Open Issue No. 6:
NRC staff agreed in the telephone conference of January 11, 1993, that requiring a minimum of five percent bentonite be incorporated into the radon barrier material is acceptable if adequate quality control measures are taken during testing. The DOE response provided a procedure for verifying the 3
application of the required percentage of bentonite, but it is only applicable if mixing beds are used. Specification Section 02228 Part 2.2.A has been revised to require a pugmill or other mechanical means for mixing soil and bentonite; therefore, mixing beds are no longer acceptable according to the specifications. A procedure to verify the bentonite content, based on the current specifications, should be provided.
i Final RAP Open Issue No. 7:
Our February 25, 1993, letter to DOE requested two additional revisions to the Gunnison final RAP. These two requests were:
(1) revise the list of hazardous constituents to include nitrate and silver, and (2) revise specific text references to the designed radon barrier hydraulic conductivity as being lx10'8 cm/sec. The NRC staff agrees with DOE's response and implementation 2
1 plans for the hydraulic conductivity revision; however, the response and implementation plans for the hazardous constituents are not wholly adequate.
Part 192 (a)(3) of Title 40 specifically requires that DOE conform to the ground-water protection provisions of 40 CFR 264.92 through 264.95 when l
establishing the list of hazardous constituents and their respective concentration limits.
Part 264.93(a) specifically identifies a hazardous constituent as a listed element or compound (Appendix VIII, Part 261; or Table l
A, Part 192.02) that has been detected in ground water in the uppermost i
aquifer underlying a regulated unit and that is reasonably expected to be in, or derived from waste contained in a regulated unit. The NRC staff has reviewed laboratory results for both nitrate and silver provided in Appendix A to Attachment 3 of the RAP (Tables 3.4; 3.7; 3.8; and 3.11).
Nitrate has been identified in the tailings pore water, and the ground water 1
(both upgradient and onsite/downgradient) at the processing site. The nitrate detected in the upgradient wells, which characterize the background conditions, is not likely the result of milling operations since nitrate is j
commonly associated with agricultural contamination sources.. Lysimeter i
i samples have identified nitrate in the tailings pore water in 1984 and 1990.
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Unfortunately, more recent confirmation of these results were not possible, due to limited sample volumes collected in the lysimeters. Nitrate has been detected in numerous onsite and downgradient wells during sampling episodes in 1983, 1985, 1990, and 1991. The data presented in Appendix A to Attachment 3 do not provide a clear indication of the amount that nitrate from the tailings has impacted the ground-water in the uppermost aquifer, given the likelihood of contaminant contributions from non-milling sources.
Regardless, the explicitness of Part 264.93(a) requires that nitrate should be added to the list of hazardous constituents. The concentration limit for nitrate can i
either be the background level or the Maximum Concentration Limit, as
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designated in Part 264.94 and Table A, Part 192.02.
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Silver has been detected in lysimeter samples collected in 1990 and 1991; however, the results provided in Appendix A to Attachment 3 indicate that many of these results may be suspect because of interference with other metal ions also in solution. Silver had not been detected in previous lysimeter sampling episodes (1984) nor in the ground water upgradient, onsite, or downgradient of the processing site. NRC staff agrees that silver should not be added to the i
list of hazardous constituents, due to the absence of silver in the ground water beneath and downgradient of the processing site and the inexactness of the recent sampling results.
In summary, DOE must include nitrate as a hazardous constituent for ground-water monitoring at the Gunnison disposal site, and provide an appropriate concentration limit in order to demonstrate compliance with 40 CFR 192.02(a)(3).
Previous Comment on the Remedial Action Selection Report Executive Summary:
The second paragraph on page one of the Executive Summary states that asbestos and other hazardous materials are stored on the processing site. NRC had requested (Section 7 of the draft Technical Evaluation Report) information on 3
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the disposal plans for these stored materials. ~The DOE response:(Enclosure'3, i
March 25, 1993) indicated that the stored materials _would be relocated to the i
permanent repository..Because disposal of " hazardous materials" in the
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disposal cell creates the potential _ for regulatory. issues, NRC. staff considers the designation of these materials an open issue. DOE should. revise.the j
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second paragraph of the Executive Summary to indicate that these stored materials meet the criteria of residual radioactive material. and are not regulated as hazardous waste.-
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