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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK BACKGROUND HISTORY OF THE NFSS RESIDUES In about 1942, the Mallinckrodt Chemical Works in St. Louis, MO, began extracting uranium from very rich Belgian Congo ores received from the African Metals Corporation of Belgium (AMCB) for use in the Manhattan Engineering District Project. The residues remaining after uranium extraction (classified as K-65 residues; see Table 1) contain many of the uranium decay products that had been in secular equilibrium with the 238U and 235U isotopes. The 234U was recovered with the uranium product, thus removing an important member of the decay chain. In addition, the extraction process resulted in separation (i.e., removal) of some 230Th from the residues. The residues were returned to the AMCB until April 1949, after which time they were sent to the Lake Ontario Ordnance Works (LOOW) in Lewiston Township, upstate New York, for storage in a large silo. The residues were classified, as shown in Table 1, based on U3O8 content of the ores from which they were recovered. The present area of the LOOW, much reduced in size, is now known as the Niagara Falls Storage Site (NFSS); the storage silo was located in the northeast panhandle of the site (Figure 1). When the storage silo at NFSS was full, the remaining K-65 residues were sent to the Feed Materials Production Center, now designated as the Fernald Environmental Management Project (FEMP), at Fernald, OH, where they were stored along with K-65 residues shipped directly from Mallinckrodt and with K-65 and other residues produced by uranium recovery operations performed at the FEMP site. Although a different uranium separation process was used at the FEMP site than was used at the Mallinckrodt Chemical Works, the K-65 residues at the two sites are essentially the same in chemical and radiological properties. At the NFSS, approximately 3,510 metric tons of residues were stored in a silo, a volume of about 11,000 m3. The residues contain approximately 520,000 pCi/g of 226Ra and 54,000 pCi/g of 230Th. The concentrations of these isotopes in the K-65 residues stored at the FEMP site are somewhat lower, and have a somewhat lower ratio of radium to thorium because of the different separation process used. The residues also contain a low concentration of unseparated uranium, as well as other elements such as barium (which was added during processing by Mallinckrodt), lead, and molybdenum, and minor amounts of rare earth elements and noble metals. In addition to the K-65 residues, there are large amounts of other radioactive contaminated materials from uranium ore processing stored at NFSS (Table 1). At NFSS, a distinction is made between “residues” and contaminated materials with high 226Ra concentrations, whereas the term “wastes” is used for all other contaminated materials at the site. The residues other than those classified as K-65, together with the wastes, have much lower concentrations and total
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK TABLE 1. Inventory of Radium-226 and Thorium-230 in NFSS Residues and Wastes (after Bechtel National, Inc., 1994a, Table 3-1, p. 3-15) Classification a Volume,(m3) 226Ra Inventory,(Ci) 230Th Inventory, (Ci) Residues K-65 3,000 1,881 195 L-30 6,000 87 87 F-32 500 0.2 0.2 L-50 1,500 6 6 Contaminated Wastes R-10 residues and soil 45,000 5 5 Remaining Contaminated soil 134,500 3 3 Totals 190,500 1,982 296 K-65 residues -- from processing ore containing 35-60% U3O8 L-30 residues -- from processing ore containing ~ 10% U3O8 F-32 residues -- from processing ore containing unknown precentage of U3O8 L-50 residues -- from processing ore containing ~ 7% U3O8 R-10 residues -- from processing ore containing ~ 3.5% U3O8
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 1. Location Map for Niagara Falls Storage Site (NFSS), NY (Bechtel National, Inc., 1994a)
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK amounts of 226Ra and 230Th than do the K-65 residues. An important feature of the K-65 residues is that the concentration of 226Ra in them is much higher than the concentration of 226Ra in what are classified as “uranium mill tailings” from processing of typical uranium ores from the United States. For example, the uranium concentration in the original Belgium Congo ores from which the K-65 residues were derived ranged from 35 to 60 percent U3O8, whereas the concentration of uranium ores in sandstone deposits such as are found on the Colorado Plateau is from 0.2 to 0.4 percent U3O8. The other residues of concern stored originally at other locations at the NFSS were produced by processing of less concentrated ores at the Linde Ceramics Plant at Tonawanda, NY. These residues, called L-30, F-32, and L-50 residues, also have substantial concentrations of 226Ra and 230Th, exceeding those from common uranium mill tailings. The term “high-level” residues is used here to denote the K-65, L-30, F-32, and L-50 residues, or any combination thereof. The R-10 residues, produced at Linde by the processing of ore containing about 3.5 percent U3O8 were inadvertently intermixed with soil during ground surface storage at NFSS and subsequent mixing during site cleanup, and are now classed by DOE as a waste (U.S. Department of Energy, 1986, Table 3.5, p. 3-14). In 1982 DOE initiated interim measures to consolidate and store all radioactive materials on the site and adjacent properties. From 1983-1985, the K-65 high-level residues were transferred by hydraulic mining from the storage silo to the reinforced concrete cellar of a previously existing building (numbered 411 in Figure 2). The other high-level residues (classified L-30/F-32 and L-50) also currently reside in this and adjacent reinforced concrete cellars of previously existing buildings (numbered 410, 413, and 414 in Figure 2). In 1986 the entire area holding the residues and waste (called the Wastes Containment Structure) was covered with what DOE has designated as an interim facility cap (Figure 2 and Figure 3). The cap is designed to retard radon emissions and to reduce rainwater intrusion into the residues and wastes (Bechtel National, Inc., 1986a and 1986b). In September 1986, the DOE issued a Record of Decision (ROD) (Office of Federal Register, 1986) for remedial actions at the NFSS that stated the following: Decision: For the radioactive wastes at the NFSS, the DOE has selected long-term in place management consistent with the guidance provided in the Environmental Protection Agency (EPA) regulation for uranium mill tailings (40 CFR 192) [Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings]. For the radioactive residues at NFSS, it is the DOE intent to provide for long-term in place management consistent with future applicable EPA guidance. If future analyses show that in place management cannot meet EPA guidance, long-term in place management of the residues would need to be replaced by another option which meets EPA guidance and is environmentally acceptable. Further NEPA [National Environmental Policy Act] review is anticipated subsequent to additional
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 2. Plan View of the Waste Containment Structure (WCS), Showing Location of Cellars of Buildings 410, 411, 413, and 414 that Contain Residues (after U.S. Department of Energy, 1986)
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK TABLE 2. Management Alternatives for NFSS Residue and Wastes (U.S. Department of Energy, 1986) Alternative Name 1 No Action 2a Long-Term Management at NFSS: Modified Containment 2b Long-Term Management at NFSS: Modified Containment plus Modified Form 3a Long-Term Management at Arid Site (Hanford) 3b Long-Term Management at Humid Site (Oak Ridge) 4a Long-Term Management of Residues at Hanford, Wastes at NFSS 4b Long-Term Management of Residues at Hanford, Ocean Dispersal of Wastes 4c Long-Term Management of Residues at Oak Ridge, Wastes at NFSS 4d Long-Term Management of Residues at Oak Ridge, Ocean Dispersal of Wastes From U.S. Department of Energy, 1986
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK design of the long-term in place management project for the radioactive residues. The resulting remedial actions at NFSS are described in the 1986 FEIS. The New York State Department of Health and Environmental Protection and the U.S. Environmental Protection Agency (EPA) have expressed concern over the plan of action put forth in an exchange of letters with DOE (letters included in U.S. DOE, 1986, Appendix K). The central point of these letters was that the concentration of 226Ra in the K-65 residues was so high that 40 CFR 192 was not applicable, and that the management of these residues should follow 40 CFR 191 (Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastess). The letters expressed lesser concern with the lower-level radioactive residues and wastes. This does not address the issue of how the NFSS residues should be defined based on current regulations, however. 1986 FINAL ENVIRONMENTAL IMPACT STATEMENT (FEIS) DOE and its contractor have delineated and compared alternatives for managing the NFSS residues and wastes and have described conceptual design and technical aspects of addressing the alternatives (U.S. Department of Energy, 1986, pp. 2-1 through 2-30 and Appendixes C,D, and E). Table 2 lists the alternatives for NFSS considered in the FEIS. The environmental impacts associated with each alternative were analyzed in the 1986 FEIS in terms of three time periods, both for radiological and non-radiological materials. The time period designations and periods chosen are: 1) Action Period: approximately 10 years; 2) Maintenance and Monitoring Period: 10 to 200 years; and 3) Long-Term Period: 200 to 1000 years. Two cases identified for the Long-Term Period were: Case A - Loss of Monitoring, Maintenance, and Corrective Action; and Case B - Loss of All Controls. The 10 to 200 years maintenance and monitoring period was used by DOE as the reference for the analysis made in the 1986 FEIS. Implementation of any of the alternatives was projected to permanently commit some land to management of at least the NFSS residues and, in some alternatives, the NFSS wastes as well. The near-surface burial of the NFSS wastes and residues was stated by DOE to commit “the federal government (or its successor) to perpetual care of the burial sites because the residues and wastes would remain hazardous for thousands of years” (U.S. Department of Energy, 1986, p. 2-26). In all cases, extended care costs were projected through the end of the Maintenance and Monitoring Period (200 years), ranging from $8.6 to $26 million total, and with a sinking fund of $8.6 to $26 million for the Long-Term Period (beyond 200 years). The following information concerning alternatives, radon release, transportation, risks, and selection of primary alternative represents a very brief summary of the material primarily found in the 1986 FEIS (U.S. Department of Energy, 1986) and the 1994 Failure
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK Analysis Report (Bechtel National, Inc., 1994a). It is included to provide background for the rest of the report. Alternatives Alternatives 1, 2a, and 2b (Table 2) leave the wastes and residues at NFSS. Alternative 3a moves the residues and wastes to the Hanford Reservation, Richland, WA. Alternative 3b moves the residues and wastes to Oak Ridge National Laboratory, Oak Ridge, TN. Alternatives 4a and 4b move the residues to the Hanford Reservation, with the wastes disposed at NFSS or by ocean disposal, respectively. Alternatives 4c and 4d move the residues to Oak Ridge, with waste disposed at NFSS or by ocean disposal, respectively. Only Alternative 2b requires substantial modification of the residues. In one modification option, the residues are processed to recover resources present in them (uranium, cobalt, nickel, molybdenum, and lead). The vitreous slag from this process is presumed to contain most of the radioactivity (U.S. Department of Energy, 1986, p. C-4). Other options are direct vitrification of the residues, in-situ vitrification, and solidification in bitumen, resins, or concrete. In the vitrification option, the vitrified material and precipitates containing the radium and thorium would be re-buried in the diked containment area at NFSS. The 1986 FEIS identifies numerous uncertainties associated with residue modification, including resource recovery efficiencies, radioactive contamination of recovered resources, and characteristics of all waste products from the recovery process. The alternatives and their effects that were presented in the 1986 FEIS are summarized below for convenience; the 1986 FEIS and related documents should be consulted for more complete and detailed information. Alternative 1 - No Action. Erosion of the interim protective cap is expected to occur after the cessation of maintenance and monitoring. It is projected that after 1,000 years there would be increased 222Rn release due to loss of cap integrity; however, these releases are expected to present insignificant health effects. The predominant health threat after 1,000 years would be to the “resident intruder ” who might build a house in the contaminated materials, inhale air containing 222Rn gas and its radioactive decay daughter products, eat contaminated food grown in an on-site garden, and drink contaminated water from a well located at the edge of the contaminated area. A projected dose of 8,000 rem/year to the bronchial epithelium from the inhaled radon and its daughter products would likely result in death of such a resident intruder within a few years. Migration of radiological and chemical contamination of ground water at NFSS would possibly be slow and localized. In the long term, the subsurface clay cutoff wall surrounding the buried residues and wastes would likely provide little or no retardation of contaminant migration. Alternative 2a - Long-Term Management at NFSS: Modified Containment. A long-term cap would replace the interim cap and the site would be maintained and monitored for 200 years. The site would be reduced in size to 16 hectares (0.16 km2), with the
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK remaining 61 hectares (0.61 km2) to be released by DOE for other use. The 1986 FEIS states that if controls cease at 200 years, the long-term cap would delay exposure of the contaminated materials. After 1,000 years, even after the most erosive land use, there likely would be a cover over the contaminated materials. As in Alternative 1, doses to the public would be from 222Rn, and are expected to be very small. The potential resident intruder would receive the same high radiation dose as in Alternative 1. The integrity of the cap could be jeopardized by “gullying”, slumping, extended drought, severe earthquake, or biotic intrusion. Migration of contamination of ground water at NFSS by 226Ra and by other hazardous chemicals would probably be slow and localized. Alternative 2b - Long-Term Management at NFSS: Modified Containment plus Modified Form. The interim cap would be removed and the residues excavated and processed. The residues in modified form would then be re-buried on site. This alternative would result in increased 222Rn and particulate releases during excavation and processing. As a result, the radiation doses to the general public and the concomitant health effects would be greater than in Alternatives 1 and 2a. Assuming that 222Rn emissions from the modified residues are reduced by a factor of 10, the dose to the resident intruder would be reduced proportionately, although still critical. However, cumulative doses to critical organs of workers and the general public would likely result in negligible health effects. There would be more transportation-related injuries and deaths and radiation health effects associated with occupational exposures than for the alternatives that do not involve handling and processing the residues, however. Processing the residues would not markedly change impacts on ground water, which would be about the same as for Alternative 2a. Alternative 3a - Long-Term Management at Arid Site (Hanford). Both the residues and the wastes would be excavated from the NFSS containment area and transported by trucks to a DOE waste management site at Hanford Reservation. This alternative would result in increased 222Rn and particulate releases which would affect the general public surrounding NFSS, at the Hanford site, and along the route followed between the two sites. However, radiological health effects to the general public are expected to be insignificant. Radiological health effects to workers are expected to be higher than those to the general public, but would also be negligible. Releases of 222Rn from the arid soil-covered trenches at Hanford would be much higher than from the clay-covered containment at NFSS, but the health effects would still be expected to be negligible. Because the burial area at Hanford is larger than at NFSS, and because the residues will not be concentrated in one area as at NFSS, the resident intruder 's bronchial epithelium dose would be less at Hanford than at NFSS. Nonetheless, a resident intruder at Hanford could have a significant health risk. There will be more transportation-related injuries and deaths than for the alternatives that do not involve transporting the residues. Removal of the residues will markedly reduce future impacts on ground water at NFSS. Alternative 3b - Long-Term Management at Humid Site (Oak Ridge). Both the residues and the wastes would be excavated from the NFSS containment area and transported by trucks to a DOE waste management site on the DOE reservation near Oak Ridge, TN, for
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK burial. This alternative would result in increased 222Rn and particulate releases which would affect the general public surrounding NFSS, at the Oak Ridge site, and along the route followed between the two sites. The resulting health effects to both the public and resident intruder would be virtually the same as for Alternative 2b. Vertical migration of radiological and chemical contaminants from residues and wastes would be expected to be very slow at the Oak Ridge site. Because of the larger ground water flow at Oak Ridge than at NFSS, the ground water contaminants would likely be diluted more than at NFSS, unless the ground water becomes saturated in both cases as it flow through the radium and thorium salts. It is predicted that ground water contamination will not occur in 1,000 years. No significant non-radiological ground water contamination is expected. Alternative 4a - Long-Term Management of Residues at Hanford, Wastes at NFSS. The residues that underlie the wastes (Figure 3) would be excavated, packaged, and transported to the DOE Hanford site (as in Alternative 3a) and the wastes would remain at NFSS. Because only the residues would be moved from NFSS, only one-tenth as many truck trips would be required as in Alternative 3a. Because the residues contain about 99 percent of the radionuclide inventory at NFSS, the radiological impact of this alternative would be about the same as that for moving both residues and wastes. [The Committee notes that this is not necessarily true; the fact that the residues are about 10 times as concentrated means that the dose would be higher during each shipment, and the resultant exposure dose rate and total dose to an individual would be higher.] The number of additional adverse health effects is expected to be extremely low. The risk to the resident intruder at NFSS would be substantially reduced because only the wastes would remain at NFSS. Alternative 4b - Long-Term Management of Residues at Hanford, Ocean Disposal of Wastess. The residues would be excavated, packaged, and transported to the DOE Hanford site, as in Alternative 4a. All remaining wastes would be excavated and transported in bulk by trucks to a dock in New York or New Jersey where they would be loaded onto barges and transported to the 106-Mile Ocean Wastes Disposal Site for disposal [Site 106, managed by the EPA, is a designated waste-disposal site 110 nautical miles (204 km) southeast of the entrance to the New York harbor and 90 nautical miles (167 km) east of Cape Henlopen, DE]. The impacts at Hanford would be the same as those for Alternative 4a for all time periods. However, the total population doses to the general public would be greater for this alternative than for any of the other alternatives, due to the assumed particulate releases from the NFSS wastes as they are transported through the densely populated New York metropolitan area. Nonetheless, the impact would be insignificant. The concentrations of both radiological and chemical contaminants from the wastes is expected to be negligible and generally indistinguishable from the naturally occurring concentrations of these elements in the ocean.
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 3. East-West Cross Section Through Building 411 of Interim Waste Containment Structure (after Bechtel National, Inc., presentation to Committee, October 1994)
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 7. North-South Cross Section of Bedrock Geology in Vicinity of NFSS (Bechtel National, Inc., 1984)
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 8. Generalized Near-Surface Geological Column (Bechtel National, Inc., 1984)
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK Ground water underlying the NFSS does not provide a viable source of potable water at the present because in the shallow unconsolidated sediments it is of poor quality and because bedrock units underlying the area which contain ground water typically have low permeability. Also, at present there is an abundance of potable water available to the area from other sources (Lakes Erie and Ontario, and the Niagara River). A few wells have been registered in the area, but none are presently used for drinking water. Horizontal ground water gradients in the water bearing units at the NFSS, of which two have low permeabilities and one contains poor quality water, indicate a flow direction toward the north-northwest, perpendicular to the strike of the Paleozoic rock units, at a rate of less than 0.3 m/year. However, the Committee understands that the effects of pumping at the Modern Landfill facility just to the east of the NFSS, begun in 1991, have been noticed in the NFSS monitoring wells, and may lead to changes in the flow direction. CURRENT MAINTENANCE AND MONITORING For the Maintenance and Monitoring Period (10 to 200 years), DOE has committed programs to ensure that the Wastes Containment Structure (WCS) is maintained, radioactive releases to the environment are monitored, and periodic corrective remedial actions will be taken, as necessary. The programs also provide surveillance of the NFSS to protect against human intrusion into the contaminated materials, and to minimize unfavorable interactions between the NFSS and the surrounding communities and neighbors. The 1986 FEIS recommends continued site investigations to determine seasonal variations in the environment and the geohydrology of the sediments underlying the Wastes Containment Structure, noting that such investigations are difficult to perform in the heterogeneous conditions at the NFSS (U.S. Department of Energy, 1986, p. 4-68). Both performance monitoring and environmental monitoring programs have been instituted at the NFSS. The performance monitoring program, which has a limited duration, and which is distinct from the environmental monitoring program, was established to test the validity of the main engineering elements of the WCS function to minimize rainfall infiltration, to prevent pollution of ground water, and to prevent radon emanation (Bechtel National, Inc., 1990). The environmental monitoring program at NFSS includes sampling networks for radon concentrations in air, external gamma radiation exposure, and total uranium and 226Ra concentrations in surface water, sediments, and ground water (Bechtel National, Inc., 1994b); results are reported annually. The primary concern of both programs is with 222Rn gas escaping from the WCS. However, monitoring wells at several depths are also monitored to see if radioactive materials are moving underground with water movement. Non-radioactive, toxic substances such as lead and barium are not monitored. Table B-6 (Appendix B) shows the existing monitoring network (Bechtel National, Inc., 1994a).
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK Recent data indicate that certain types of monitoring for radioactive materials in ground water at the NFSS have been curtailed. In 1993 and 1994, there were 43 ground water sampling locations (Figure 9), of which only 9 were sampled for total uranium content, and only 11 were sampled for 226Ra. Of the 43 locations, 13 were located at the perimeter of the WCS, and 28 were on-site but outside the WCS. The Committee was told that the reductions in sampling frequency were due to lack of detection of 226Ra above background levels. [Data in the 1994 Failure Analysis Report (Bechtel National, Inc., 1994a) indicate that 226Ra is not expected to migrate beyond the perimeter of the WCS until the 5,000 to 10,000 year time frame.] The Committee was also told that installation of the permanent cap would result in loss of the 13 WCS perimeter sampling locations. Thus, materials moving in ground water would have to traverse longer distances before detection in the 28 sampling locations now outside the WCS, or in new wells to be installed. LONG-TERM MAINTENANCE AND MONITORING In its September 1986 Record of Decision (ROD) for remedial actions at the NFSS, DOE selected long-term in-place management of the residues and wastes in the WCS, consistent with appropriate federal guidance and regulations. For the Long-Term Period (200 to 1,000 years) following the earlier periods during which the residues and wastes will continue to be managed, DOE has considered two cases involving different degrees of loss of control over the NFSS site (U.S. Department of Energy, 1986). In both cases, monitoring, maintenance, and corrective actions would cease after 200 years, but in one alternative, DOE would lose control over access, land use, and ownership as well. Potential impacts beyond 1000 years and needs for their management were not addressed due to uncertainties relative to such factors as degree of control, location and density of populations, environmental conditions, and limits on current predictive capabilities (U.S. Department of Energy, 1986, p. 4-7). Although the cessation of maintenance and monitoring starting at 200 years was selected as a reference point for purposes of analysis, DOE has strongly indicated the intent of the federal government to take perpetual care of the NFSS residues and wastes (U.S. Department of Energy, 1986). Nevertheless, the provision of maintenance and monitoring over the thousands of years that the residues and wastes would remain radioactively hazardous was stated to be an unreasonable assumption, and 100 years has been selected as the boundary for application of administrative controls after closure at high-level radioactive waste repositories (40 CFR Part 191). The adverse impact of death from doses to resident intruders at the NFSS could only be prevented if controls are maintained for many thousands of years or if a different method of long-term management (e.g., greater confinement) was implemented (U.S. Department of Energy, 1986, p. 4-7).
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 9. Monitoring Well Locations (Bechtel National, Inc., 1991)
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK The Committee notes with interest DOE's establishment of a Long-Term Surveillance and Maintenance (LTSM) Program of “off-site” DOE radioactive waste disposal sites, including those under the Uranium Mill Tailings Remedial Action Program (UMTRAP) and the Formerly Utilized Sites Remedial Action Program (FUSRAP), that appears to be applicable to NFSS. DOE's Grand Junction, Colorado, Projects Office was designated as the LTSM Program Office. The draft guidelines are not clear as to whether the degree of custodial surveillance, monitoring, maintenance, and corrective actions would be equivalent to DOE's present activities at the NFSS, nor what the expected duration of the LTSM Program would be (200 years, 1,000 years, or longer). ADJACENT SITES The NFSS is bounded on two sides by major waste disposal facilities, the Chemical Wastes Management (CWM) Chemical Services, Inc. (formerly Model Cities Landfill), and Modern Landfill, Inc (Figure 4). The CWM site is a repository for hazardous waste regulated under RCRA, and Modern Landfill receives wastes not classified as hazardous wastes under RCRA but not necessarily materials without health risk. Current site plans and ongoing monitoring do not address the present or long-term potential impacts of these sites on the residue and waste storage at NFSS. This is particularly important, given the time frame (perpetual care), uncertainty of hydrology, and the potential public health impacts of the wastes at these sites. The Committee found no evidence that these sites are impacting the waste at NFSS at the present time. However, there is currently no routine testing done to monitor pollutant migration which may impact the NFSS, and little information available on the current or long-term health risks posed by these neighboring sites. RADIOACTIVE CONTENT OF RESIDUES AT NFSS As has been mentioned previously, “residues” are distinguished from “wastes” at the NFSS, the term “residues” being applied to those contaminated materials that have a high 226Ra concentration. The average concentration, inventory, and distributions of 226Ra and 230Th are given in Table B-7 (Appendix B). Of primary concern from a long-term health risk potential are the 1,974 Ci of 226Ra and the 288 Ci of 230Th located in the high concentration K-65, L-30/F-32 and L-50 residues. Most of the radioactivity (1,881 Ci of 226Ra and 195 Ci of 230Th) is in the K-65 residues, with concentrations of 226Ra at 100 to 200 times the concentration of radium present in more common uranium tailings. The ratio of curie content of 226Ra to 230Th in the K-65 residues is about 9.6 to 1, due to removal of thorium from the K-65 ores during processing. In other residues the radium and thorium are in secular equilibrium, i.e., with curie ratios of 1 to 1.
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK The projected total inventories of 226Ra and 230Th in the Wastes Containment Structure (WCS) over the next 10,000 years, based on radioactive decay, are given in Table B-8 and Table B-9 (Appendix B), assuming that the residues remain in place. In the next 1,000 years, the total 226Ra inventory in the WCS will decay from 1,982 to 1,388 Ci; after 10,000 years, the 226Ra inventory will decay to 294 Ci. Due to its much longer half-life, the total 230Th inventory will decay from 296 to 294 Ci in the next 1,000, and to 272 Ci after 10,000 years. Thus, by 10,000 years from now about 93 percent of the 226Ra remaining in the WCS would be that produced by thorium in secular equilibrium. The Committee has also considered how the removal of selected residuals from the NFSS (e.g., for disposal) would affect the radioactive content of the WCS (Table B-10 and Table B-11, Appendix B). Removal of the K-65 residues alone would reduce both the 226Ra and 230Th contents to about 100 Ci; with further removal of L-30/F-32 and L-50 residues, the contents would be further reduced to about 8 Ci. The associated volume of the removed residues ranges from 3,000 m 3 (~ 3,900 yd3) for the K-65 residues to 11,000 m3 (~ 14,400 yd3) for the K-65, L-30/F-32 and L-50 residues. The R-10 residues, mixed with soil and having low concentration of radioactivity, have been classified as wastes and were not considered for removal by the Committee. The effects of selected removals on 226Ra and 230Th inventories are shown in Figure 10 and Figure 11 for the K-65 and L-30/F-32 combined residues (the L-50 values would be approximately identical to the bottom curve in each figure and were not shown in the interest of clarity). FERNALD RESIDUES The DOE site at the Fernald Environmental Management Project (FEMP) has K-65 and other residues similar to those at the NFSS, as given in Table 3. The residues at the FEMP site are stored in large, cylindrical storage facilities (silos). All of the K-65 residues at the NFSS and in Silo 1 at the FEMP site were produced at the Mallinckrodt Chemical Works in St. Louis. Of the K-65 residues in Silo 2, some were produced by Mallinckrodt, and some by processing at the FEMP site. Silos 1 and 2 at the FEMP site contain 3,770 Ci of 226Ra and 685 Ci of 230Th. A very different approach has been adopted for managing the FEMP residues from that proposed by DOE for managing the NFSS residues. The fact that the FEMP residues are still in the silos and can be more readily removed by slurrying than the NFSS residues, which have been interred in an underground storage facility, is a significant difference between the sites and cannot be ignored when comparing and contrasting the disposal approaches (National Research Council, 1992, p. 7).
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 10. Radium-226 Activity in the NFSS Waste Containment Structure After Removal of Selected Residues in Year 1
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK FIGURE 11. Thorium-230 Activity in the NFSS Waste Containment Structure After Removal of Selected Residues in Year 1
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK TABLE 3. Comparison of K-65 Residues at NFSS and Fernald Environmental Management Project (FEMP) (U.S. Department of Energy Fernald Site Office, 1994) Facility Location Residue/Waste Origin Total Volume m3 (yd3) Total Mass (dry) 1 (MT) Ra-226 Inventory 1 Mean (Ci) Th-230 Inventory 1 Mean (Ci) NFSS-WCS Bldg. 411 K-65 MCW 2 3,000 (3,925) 3,450 1,881 195 FEMP Silo 1 Silo 2 K-65 MCW 2 K-65 MCW 2 & FEMP 3,280 (4,290) 2,840 (3,715) 6,724 5,822 2,630 1,140 403 282 FEMP Silo 3 cold metal oxides (from FEMP raffinate waste streams) 3,900 (5,101) 8,841 26.3 453 1 Based on a volume of 3,000 m3 and any dry mass density of 1,050 g/cm3 for Bldg. 411, a volume of 3,280 m3 and a dry mass density of 2.050 g/cm3 for Silos 1, a volume of 2,840 m3 and a dry mass density of 2.050 g/cm3 for Silos 2, and a volume of 3,900 m3 and a dry mass density of 2.267 g/cm3 for Silos 3. 2 Mallinckrodt Chemical Works,St. Louis, MO.
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SAFETY OF THE HIGH-LEVEL URANIUM ORE RESIDUES AT THE NIAGARA FALLS STORAGE SITE, LEWISTON, NEW YORK The disposal approach adopted by the FEMP site is to sluice the residues out of the silos with water and to vitrify them by adding sufficient glass frit to make a waste disposal form that meets disposal site acceptance criteria. The vitrified residues, probably in the form of small glass spheres (marbles) would then be shipped off-site. A pilot plant is being built at the FEMP site to demonstrate the vitrification step, and initial operation is expected in 1996. The performance criteria and acceptability of the final waste form have not yet been established. DEFENSE SITE vs NON-DEFENSE SITE Because FEMP is designated as a DOE “defense” site, the vitrified residues can be shipped to the Nevada Test Site (NTS) for disposal (U.S. Department of Energy Office of Environmental Management, 1995, p. OH 14 to OH 15). This is not true of the residues at the NFSS because NFSS is not a designated defense site, but rather is classified as a Formerly Utilized Site [Manhattan Engineer District/Atomic Energy Commission] Remedial Action Program (FUSRAP) site. While there may be merit in such a distinction in the context of managing and funding DOE's vast waste management complex, the Committee sees little technical reason for maintaining the distinction in the case of managing NFSS and the FEMP residues which are very similar in origin and content.
Representative terms from entire chapter: