Defense waste

Classification of wastes may be according to purpose, distinguishing between defense waste related to military appHcations, and commercial waste related to civiUan appHcations. Classification may also be by the type of waste, ie, mill tailings, high level radioactive waste (HLW), spent fuel, low level radioactive waste (LLW), or transuranic waste (TRU). Alternatively, the radionucHdes and the degree of radioactivity can define the waste. Surveys of nuclear waste management (1,2) and more technical information (3—5) are available. 

The Waste Isolation Pilot Plant (WIPP) is in an excavated salt cavern in southern New Mexico, twenty-seven miles from Carlsbad. The WIPP site is 2,000 yards underground, and defense waste is being placed. There are plans to place there about 6 million cubic feet of material there containing fewer than five million curies of radio activity. 

Okemgbo A.A., Hill H.H., Metcalf S.G., and Bachelor M., Metal ion interferences in reverse polarity capillary zone electrophoretic analysis of Hanford Defense Waste for ethylenediaminetetraacetic acid (EDTA) and N-hydroxy-ethylethylenediaminetriacetic acid (HEDTA), Anal. Chim. Acta, 396,105,1999. 

Over 5001 of HLW have been vitrified in France and Germany. In the USA, the HLW at the Nuclear Fuel Services plant in West Valley Plant, New York, have been vitrified (300 two-ton canisters) and vitrification is ongoing at the Defense Waste Processing Facility (DWPF) at Savannah River, South Carolina 1600 canisters by February 2004). A vitrification plant is under construction at Hanford, Washington. Vitrification of all of the HLW in the USA will generate approximately 20 000 canisters, which are destined for disposal at the geological repository at Yucca Mountain. 

Baer, D. R., Pederson, L. R. McVay, G. L. 1984. Glass reactivity in aqueous solutions. Journal of Vacuum Science Technology, A 2 (2), 738-743. Barkatt, A., Gibson, B. C. et al. 1986. Mechanisms of defense waste glass dissolution. Nuclear Technology, 73, 140-164. 

The work on hi level waste solidification has led to applications of the same materials to other areas of waste management. These include decontamination of defense wastes currently in tank storage at Richland, WA, selective separation of Cs for beneficial uses, and development of a process flowsheet for conversion of Zircaloy fuel cladding hulls to sodium zirconate for use in waste stabilization. Each is briefly described below. 

Sodium titanate has been found to be very effective in removing Sr from defense waste typified by a 6m NaNO - 0.6m NaOH solution also containing the sodium salts of aluminate, nitrite, phosphate, carbonate, sulfate, and chromate in the range of O.lU to 0.007 N and Sr in the analytical concentration range of O.OU to O.U ppm ( ). Sodium titanate columns have provided a Sr decontamination factor of greater than io3 for 2500 column volumes of the waste at flow rates of 2 to 6 column volumes per hour. The material has also been shown to remove residual actinide contamination from the same and similar waste streams ( ). 

Dosch, R.G., "The Use of Titanates in Decontamination of Defense Waste," SAND78-O7IO, June (1978). 

High-level radioactive defense waste solutions, originating from plutonium recovery and waste processing operations at the U.S. Department of Energy s Hanford Site, currently are stored in mild steel-lined concrete tanks located in thick sedimentary beds of sand and gravel. Statistically designed experiments were used to identify the effects of 12 major chemical components of Hanford waste solution on radionuclide solubility and sorption. 

Packaging of defense wastes started in early 1990s. 

W.L. Ebert, S.F. Wolf, and J.K. Bates, The release of technetium from defense waste processing facility glasses, Mater. Res. Soc. Symp. Proc., 412 (1996) 221-227. 

In normal operation, the PRF generates about 120 m3 of salt waste solution per month. Currently, this waste solution is made alkaline and routed to underground storage tanks where it mixes with other Hanford defense waste liquors. An alternative waste treatment scheme is desirable to avoid converting large volumes of non-actinide waste to retrievable actinide waste (>10 nCi alpha activity/g) and also to help make the PRF independent of future tank farm management operations. 

SNF constitutes about half of the HLW in the United States. The other half comes from the construction and existence of nuclear weapons. All HLW is a federal responsibility. About 90% of the radioactivity in nuclear waste is from HLW. The largest volume of nuclear waste is low-level waste (LLW) and that is mostly the responsibihty of the state (or group of states) in which it is generated. LLW is rather awkwardly defined, being everything that is neither HLW nor defense waste and consists of wastes from hospitals pharmaceutical labs research labs and the moon suits, tools, and the like from nuclear power plants. In the eastern United States, most of the LLW is in the form of the plastic beads that make up the ion-exchange resins used in nuclear power plants to clean various loops of water used in power production. 

Research has focused on Yucca Mountain, Nevada, at the western edge of the National Test Site, for its suitability as a nuclear waste repository for SNF and some defense waste. Many political leaders of Nevada strongly oppose this plan, and they seriously question that nuclear waste can be safely kept out of the human environment for 10,000 years, as is required under the federal Nuclear Waste Policy Act. 

High-level radioactive waste (HLW) will be converted from an alkaline slurry to a durable borosilicate glass in the Defense Waste Processing Facility (DWPF) at the Savannah River Plant (SRP) in South Carolina [17]. This waste is the residue from thirty years of reprocessing of irradiated nuclear fuels for national defense purposes and is currently stored in large carbon-steel tanks. 

Defense Waste Processing Facility (DWPF) Process Description Overview of DWPF Process, DPSOP 257-8, Pan 2, Item 100, Rev. 5, pp. 1-6 (1989). 

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