ML20216B558
| ML20216B558 | |
| Person / Time | |
|---|---|
| Issue date: | 03/06/1998 |
| From: | Joseph Holonich NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Rael G ENERGY, DEPT. OF |
| References | |
| REF-WM-62 NUDOCS 9803130116 | |
| Download: ML20216B558 (6) | |
Text
!
George Rael, Dir:cto:
U.S. Dep rtm:nt of Energy Albuquerque Operations Office ERD /UMTRA P.O. Box 5400 Albuquerque, NM 87185-5400
SUBJECT:
REVIEW OF COMPLETION REPORT FOR RIFLE, COLORADO, VICINITY l
PROPERTY RF-475 l
Dear Mr. Rael:
The U.S. Nuclear Regulatory Commission staff has reviewed the Rifle, Colorado, Vicinity Property Completion Report (VP CR) for property RF-475, south of Highway 6. This VP CR, dated February 19,1997, was submitted by the U.S. Department of Energy (DOE) under letter dated July 17,1997. Concurrence by the NRC on this VP CR is required because special circumstances resulted in supplemental standards being invoked during rernedial action.
4 Because the use of supplemental standards is the reason for the NRC's review, the NRC staff I
review has been limited to those parts of the VP CR related to the use of supplemental standards. The staffs review comments on the VP CR are presented in the enclosure.
The NRC staff concludes that additional information is required to determine whether compliance with the U.S. Environmental Protection Agency cleanup standards has been achieved. Most importantly, site-specific dose and as low as reasonably achievable (ALARA) analyses for the areas of thorium-230 contamination must be provided, to support the DOE assertion that the cleanup standards used for thorium-230 contamination are ALARA. This and other issues of concern related to the use of supplemental standards are more fully described in the enclosure.
If you have any questions concerning this letter or the enclosure, please contact the NRC Project Manager, Janet Lambert, at (301) 415-6710.
Sincerely,
$sh"l.bol'cNb,biek Uranium Recovery Branch Division of Waste Management ll Office of Nuclear Material Safety and Safeguards g[, k
Enclosure:
As stated cc: F. Bosiljevac, DOE Alb
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WASHINoTON, D.C. 20666 0001 k,.....,o March 6, 1998 George Rael, Director U.S. Department of Energy Albuquerque Operations Office ERDIUMTRA P.O. Box 5400 Albuquerque, NM 87185-5400
SUBJECT:
REVIEW OF COMPLETION REPORT FOR RIFLE, COLORADO, VICINITY PROPERTY RF-475
Dear Mr. Rael:
The U.S. Nuclear Reaulatory Commission staff h&s reviewed the Rifle, Colorado, Vicinity Property Completion Report (VP CR) for property RF-475, south of Highway 6. This VP CR, dated February 19,1997, was submitted by the U.S. Department of Energy (DOE) under +
dated July 17,1997. Concurrence by the NRC on this VP CR is required because spie e circumstances resulted in supplemental standards being invoked during remedial action.
Because the use of supplemental standards is the reason for the NRC's review, the NRC staff review has been limited to those parts of the VP CR related to the use of supplemental standards. The staff's review comments on the VP CR are presented in the enclosure.
The NRC staff concludes that additional information is required to determine whether compliance with the U.S. Environmental Protection Agency cleanup standards has been -
achieved. Most importantly, site-specific dose and as low as reasonably achievable (ALARA) analyses for the areas of thorium-230 contamination must be provided, to support the DOE assertion that the cleanup standards used for thorium-230 are ALARA. This and other issues of concem related to the use of supplemental standards are more fully described in the enclosure.
If you have any questions concerning this letter or the enclosure, please contact the NRC Project Manager, Janet Lambert, at (301) 415-6710.
Sincerely, k
M.
L Joseph J. Holonich, Chief Uranium Recovery Branch Division of Waste Management Office of Nuclear Material Safety and Safeguards
Enclosure:
As stated cc: F. Bosiljevac, DOE Alb E. Artiglia, TAC Alb
k U.S. NUCLEAR REGULATORY COMMISSION STAFF REVIEW OF CO,MPLETION REPORT FOR RIFLE VICINITY PROPERTY RF-475 NRC staff reviewed the Vicinity Property Completion Report (VP CR) (MK-F 1997a) submitted to the NRC. This VP CR describes the remedial actions (radiological cleanup) and verification activities performed at the Rifle vicinity property (VP) RF-475. This site is west of and adjacent j
to the New Rifle processing site, and thus contains residual radioactive material that has migrated from the processing site. According to the RAP for the Rifle sites, some of the contaminated material on VP RF-475 was transported off the New Rifle site by surface drainage of water and sediments (DOE 1992).
As for the New Rifle site, Th-230 contamination was a concem at this VP, and the generic Th-230 protocol (Chemoff 1993) was used to provide supplemental standards for assessing the j
adequacy of Th-230 cleanup. For most areas of Th-230 contamination, cleanup was performed L
to meet the generic criterion of the 1000-year Ra-226 concentrations not exceeding the EPA L
standards for Ra-226 concentrations in soil. For one verification grid, this generic criterion for Th-230 contamination was exceeded.
Because the reason for t'he NRC's review of this VP CR is that supplemental standards were used at the VP, the NRC staff review has been limited to areas related to the use of supplemental standards for the VP.
l COMMENT 1, USE OF GENERIC TH-230 CRITERlON AS SUPPLEMENTAL STANDARD l
There are many verification grids on the VP for which remedial action was perfomied for Th-230 contamination in soils or for which verification was performed to show that residual concentrations of Th-230 in soils were acceptable. There is no indication in the VP CR that a supplemental standard for Th-230 contamination was used in these areas to determine the
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adequacy of remedial action or the acceptability of residual levels of Th-230.
Discussion in section 3.1.3, on page 6, of the VP CR, it is iadicated that the southeast comer of the VP was i
remediated fer Th-230, and that about 465 veri 6 cation samples in that area were analyrad for Th-230. The Th-230 concentrations were then used, along with the Ra-226 concentrations, to estimate the Ra-226 concentration that would be present in 1000 years (called the 1000-year Ra-226 concentration). The VP CR further indicates that these 1000-year Ra-226 concentrations were compared to the EPA Ra-226 standard of 15 pCi/g above background (for material deeper than 15 cm), presumably to determine if remadial action was complete or if the existing Th-230 levels were acceptable. The criterion of comparing the 1000-year Ra-226 concentrations to the EPA standard for Ra-226 is one criterion that was suggested in the DOE's generic Th-230 protocol (Chemoff 1993). The NRC staff interpret this criterion to be a L
supplemental standard for Th-230 contamination that was used for determining the adequacy of Th-230 cleanup and the acceptability of existing Th-230 concentrations at the Rifle sites and associated vicinity properties. It is considered a supplemental standard because there was a hazard associated with Th-230 contamination at the Rifle sites (hence the remedial action) and because there is no standard for Th-230 in the EPA standards and the EPA regulations require the development of a supplemental standard.
NRC Review of VP CR for RF-475 1
February 1998 Enclosure
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In a number of locations in the VP CR, the descriptions of the use of supplemental standards indicate only one verification grid for which supplemental standards were used, a grid where the generic criterion (comparing the 1000-year Ra-226 concentration to the EPA standards for Ra-226) was exceeded. These descriptions in the VP CR occur, at least, in section 1.0, on page 5; section 3.1.3, on page 6; and section B.2, on page B-4 of Appendix B.
Recommendation The DOE should revise the wording in the referenced sections of the VP CR, and any other similar sections, to indicate that a supplemental standard for Th-230 was used in many areas of the VP to determine the adequacy of Th-230 cleanup or the acceptability of existing Th-230 j
concentrations.
COMMENT 2, LACK OF SITE-SPECIFIC DOSE ANALYSIS FOR TH-230 AREAS The VP CR does not provide a site-specific dose analysis for the residual levels of Th-230 in soil or a discussion of how the Th-230 contamination has been reduced to levels that are ALARA.
Discussion in its approval of the generic Th-230 protocol, the NRC imposed additional conditions, one of which is applicable to the Rifle sites. The NRC's approval letter (Holonich 1994) indicated that "Because the generic thorium protocol does not consider the volume of Th-230 contamination, or the additional hecith risk from any residual uranium, implementation of the protocol for each site should include a site-specific analysis of the health risk, and should emphasize reducing the Th-230 to ALARA levels." The NRC also noted that the DOE's dose assessment (to support the generic protocol) included some assumptions that the NRC staff thought may not be conservative for all sites, one of which was the assumption that the contaminated area involved 2
only one 100 m grid.
The VP CR does not contain a site-specific dose analysis for the residual levels of Th-230 or a discussion of how the Th-230 contamination has been reduced to levels that are ALARA. As described above, the southeast part of the VP was remediated for Th-230 contamination in soil, and residual Th-230 concentrations were compared to a supplemental standard to determine the adequacy of the Th-230 cleanup or the acceptability of the residual Th-230 levels. The NRC staff briefly reviewed the Th-230 verification results in Table 3.2 of the VP CR (MK-F 1997a),
and from this review it is clear that many verification grids had Th-230 concentrations greater than 15 pCi/g above background for backfilled soils. (At Th-230 concentrations lower than this value, comparison to a supplemental standard for Th-230 from the generic Th-230 protocol would not be needed because such concentration levels would be reasonably expected to occur in association with Ra-226 concentrations at the EPA cleanup standard, with the assumption that Th-230 is roughly in equilibrium with Ra-226 in tailings materials.) These were not just isolated verification grids; there is a large cluster of similarly affected grids in the seutheast part of the VP. Pecause of the large cluster of affected grids, the NRC staff concludes that the analyses performed by the DOE to support the generic Tn-230 protocol (which assumed one contaminated grid) are not applicable to the residual Th-230 at this VP, and a site-specific dose analysis is necessary.
NRC Review of VP CR for RF-475 2
February 1998
d Recommendation The DOE must perform a site-specific dose analysis (or refer to a previous analysis) for the cluster of verifiedtion grids with elevated Th-230, and must provide additional information in the VP CR, including a description of the site-specific dose analysis and results and a brief discussion of how residual Th-230 has been reduced ALARA. The analyses may rely on (or essentially replicate) the analyses provided in the revisions (Arp 1997a, Arp 1997b) to the completion report for the Rifle sites (MK-F 1997b).
COMMENT 3, JUSTlFICATION FOR NONROUTINE USE OF SUPPLEMENTAL STANDARD FOR TH-230 CONTAMINATION IN SOIL Appendix B of the VP CR describes a recommended use of supplemental standards for the
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area of verification grid K-16-10 of the VP. This grid contains primarily Th-230 contamination in soil, with the 1000-year Ra-226 concentration exceeding the supplemental standard used i
routinely at the VP (that the 1000-year Ra-226 concentration should not exceed the EPA l
standards for Ra-226, based on the DOE's generic Th-230 protocol). The concentrations for 1
this grid, based on an average of the verification sample results and results of a quality assurance duplicate analyzed by Barringer Laboratories (from Table 3.3 of the VP CR), are 3.1 i
pCi/g Ra-226,45.5 pCi/g Th-230, and 18.0 pCi/g for the 1000-year Ra-226 concentration. This 1000-year Ra-226 concentration is only slightly higher than the generic protocol value (15 pCi/g above background, or 16.2 pCi/g for the Rifle sites). The NRC staff considers the justification provided in Appendix B, for considering this area to meet a supplemental standard for Th-230, to be insufficient.
Discussion in using supplemental standards for cleanup of Th-230, under criterion (h) of 40 CFR 192.21, remedial actions are required to reduce the residual radioactivity (of the radionuclides other than Ra-226) to levels that are as low as reasonably achievable (ALARA). The health risk analysis in section B.3.1 of Appendix B only considered exposures from gamma radiation, though other pathways, especially radon infiltration into a structure built abovo the area, could also be important. Thus, from the information presented in Appendix 3 of the VP CR, it is not clear to the NRC staff that the Th-230 contamination has been reduced ALARA.
However, the DOE's generic Th-230 protocol (Chernoff 1993) provides for two options that relate to the conditions for this grid at this VP. One option indicated for deeply buried materials is that the 1000-year Ra-226 concentrations are acceptable if the radon progeny concentrations in a home built above the area would not be greater than 0.02 WL. Another option indicates that for contaminated materials in the saturated zone it is reasonable to assume that the radon
' generated within the saturated zone generally will not diffuse to the surface.
An undated memorandum (included in Appendix A of the VP CR) from R.R. Fencil, the Rifle site health physics manager, indicated that the residual contaminated material was within the saturated zone and thus measurable radon emanation was not expected. The memorandum 4
also indicated that the grid in question was within the area of the developed wetlands of the VP at the site. For this reason, the NRC staff considers it appropriate to also assume that it would be extremely unlikely for any habitable structure to be constructed above the grid in question.
Thus, the NRC staff concludes that the cleanup of the Th-230 in grid K-16-10 has met the intent of the options described in the generic Th-230 protocol and therefore is considered to have met a supplemental standard for Th-230 cleanup.
NRC Review of VP CR for RF-475 3
February 1998
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Recommendation The DOE should revise the discussions in Appendix B of the VP CR to describe some of these additional' reasons (above) for considering that grid K-16-10 has met a supplemental standard for Th-230.
REFERENCES i
Arp S.J.1997a. Letter to J.J. Holonich, Uranium Recovery Branch, Office of Nuclear Material Safety and Safeguards, U.S Nuclear Regulatory Commission, dated November 17,1997, with enclosed page changes for the Rifle, Colorado, UMTRA Project sites completion report.
U.S. Department of Energy, Albuquerque Operations Office, Environmental Restoration Division, Uranium Mill Tailings Remedial Action Team, Albuquerque, New Mexico.
Arp S.J.1997b. Letter to J.J. Holonich, Uranium Recovery Branch, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, dated December 8,1997, with enclosed page changes for the Rifle, Colorado, UMTRA Project sites completion report.
U.S. Department of Energy, Albuquerque Operations Office, Environmental Restoration Division, Uraniu..: Mill Tailings Remedial Action Team, Albuquerque, New Mexico.
Chemoff A.1993. Letter to J.J. Surmeier, Uranium Recovery Branch, Division of Low-Level Waste Management & Decommissioning, Office of Nuclear Material SMety and Safeguards, U.S. Nuclear Regulatory Commission, regarding thorium-230 cleanup protocol, dated December 22,1993. U.S. Department of Energy, Albuquerque Field Office, Uranium Mill Tailings Remedial Action Project Office, Albuquerque, New Mexico.
DOE (U.S. Department of Energy).1992. Remedial Action Plan and Site Design for Stabilization of the Inactive Uranium Mill Tailings Sites at Ri!Ie, Colorado, Final, Volume II-Appendices D and E. February 1992.
Holonich J.J.1994. Review of UMTRA Project Thorium-230 Genetic Protocol. Letter to A.R.
Chemoff, Uranium Mill Tailings Remedial Action Project Office, U.S. Department of Energy, dated July 5,1994. U.S. Nuclear Regulatory Commission, Office of Nuclear Material Safety and Safeguards, Division of Waste Management, High-Level Waste and Uranium Recovery Projects Branch, Washington, D.C.
MK-F (MK-Ferguson Company and Rust Federal Services, Inc.).1997a. Vicinity Property Completion Report at RF 475, Rifle, Colorado. February 19,1997.
MK-F (MK-Ferguson Company).1997b. Rit'e, Colorado, NRC Copy, Final Completion Report.
April 1997.
NRC Review of W CR for RF-475 4
February 1998