Plutonium processing waste

Am-Cm Recovery from Plutonium Process Waste. Trans. Amer. Nucl. Soc. 

Hanford, Washington, 1973, plutonium processing waste pond ... 

WATER, VARIOUS LOCATIONS Hanford, Washington plutonium processing waste ponds ... 

The wastes from uranium and plutonium processing of the reactor fuel usually contain the neptunium. Precipitation, solvent extraction, ion exchange, and volatihty procedures (see Diffusion separation methods) can be used to isolate and purify the neptunium. 

Nuclear Waste Reprocessing. Liquid waste remaining from processing of spent reactor fuel for military plutonium production is typically acidic and contains substantial transuranic residues. The cleanup of such waste in 1996 is a higher priority than military plutonium processing. Cleanup requires removal of long-Hved actinides from nitric or hydrochloric acid solutions. The transuranium extraction (Tmex) process has been developed for... 

An overview is given of plutonium process chemistry used at the U. S. Department of Energy Hanford, Los Alamos National Laboratory, Rocky Flats, and Savannah River sites, with particular emphasis on solution chemistry involved in recovery, purification, and waste treatment operations. By extrapolating from the present system of processes, this paper also attempts to chart the future direction of plutonium process development and operation. Areas where a better understanding of basic plutonium chemistry will contribute to development of improved processing are indicated. 

Figure 3 shows a flowsheet for plutonium processing at Rocky Flats. Impure plutonium metal is sent through a molten salt extraction (MSE) process to remove americium. The purified plutonium metal is sent to the foundry. Plutonium metal that does not meet foundry requirements is processed further, either through an aqueous or electrorefining process. The waste chloride salt from MSE is dissolved then the actinides are precipitated with carbonate and redissolved in 7f1 HN03 and finally, the plutonium is recovered by an anion exchange process. 

Waste Handling for Unirradiated Plutonium Processing. Higher capacity, better-performing, and more radiation-resistant separation materials such as new ion exchange resins(21) and solvent extractants, similar to dihexyl-N,N-di ethyl carbamoyl methylphosphonate,(22) are needed to selectively recover actinides from acidic wastes. The application of membranes and other new techniques should be explored. 

An overview is presented of plutonium process chemistry at Rocky Flats and of research in progress to improve plutonium processing operations or to develop new processes. Both pyrochemical and aqueous methods are used to process plutonium metal scrap, oxide, and other residues. The pyrochemical processes currently in production include electrorefining, fluorination, hydriding, molten salt extraction, calcination, and reduction operations. Aqueous processing and waste treatment methods involve nitric acid dissolution, ion exchange, solvent extraction, and precipitation techniques. 

Both preformed and in situ ferrite lowered plutonium concentrations in simulated process waste from 10-4 g/1 to 10-8 g/1 in one treatment step. Two or three flocculant precipitations, as currently used for waste processing, were required to achieve the same result. Ferrite waste treatment produced 4.1 g/1 solids, while production waste processing during the past year, using the flocculant process, produced 7.9 g/1 solids. 

Brammond, W. Armantrout, G. 1998. Ceramic process equipment for the immobilization of plutonium. In Waste Managenent 98 Conference. Laser Options, Inc., Tucson, Rep. 65-05, CD-ROM. 

Plutonium-contaminated waste, principally from weapons materials processing. There are two classes of plutonium wastes the transuranic, containing mostly plutonium and other transuranics, and the high-level wastes that contain significant heat-generating products, strontium, and cesium. 

Like microflltration, ultraflltration process can also be used in conjunction with chemical precipitation techniques to improve decontamination factors. Ultrafiltration processes could be useful for decontaminating alpha wastes from laundry and washing water streams of plutonium-processing plant on a large scale [15,16]. 

Siddall investigated the ability of these compounds to extract Am(III), Ce(III), Pm(III), and HN03 from 0.1 to 12M HN03 solutions. His favorable results led him to suggest such bidentate extractants could be used to remove trivalent actinides from high-level TBP extraction process waste. This idea was later patented (5). Schulz demonstrated in 1973 that DHDECMP was an effective extractant for americium and plutonium from radioactive Hanford generated wastes (6). 

Although incineration is used widely for volume reduction of industrial and household combustible waste, the incineration process for plutonium-contaminated waste has required very special development to ensure protection of the operators, efficient ofiF-gas cleaning to protect the environment, and the avoidance of criticality owing to the concentration of plutonium in the ash. An incinerator for this duty now has been operated successfully in the United Kingdom on a pilot-plant scale and it... 

Alpha-particle counting is the most commonly used method for determining plutonium concentrations at low levels in biological samples, as well as in process waste streams, and in soil, water, and air filter samples (Brouns 1980). This method does not distinguish between the different alpha-particle emitters of plutonium (plutonium-236, plutonium-238, plutonium-239, plutonium-240, plutonium- 242), nor does it detect plutonium-241, a beta-particle emitter. 

AR477 3.10 Liquid waste treatment system design guide for plutonium processing and fuel fabrication... 

A few ppm of Cm will lead to a significant overestimation of the result. However, Cm is an important tagging nuclide that could be used for neutron measurements in combination with known concentration ratios of curium, plutonium and uranium (Rinard and Menlove 1997). This technique can be applied only if chemical processes do not change the element ratio, i.e., there is no separation. This is the case for determining plutonium and uranium composition in selected process wastes, e.g., the leaching process of spent fuel or vitrification process. 

The waste drum assay system (WDAS) measures the residual small plutonium amounts of in-process wastes in 200 liter drums. The system uses a modified neutron coincidence counter with a counter comprising 60 He tubes ( 20% efficiency) with low background. WDAS applies the add-a-source correction technique that corrects for the effects of the waste matrix on neutrons (Menlove et al. 1993, Menlove 1995). A small Cf source is placed in various positions near the external surface of the sample drum. The changes in the Cf coincidence counting rate provide a matrix correction for the plutonium inside the drum. 

There are a number of situations where the existence of dilute plutonium with low H/Pu ratios might have to be considered to effectively control criticality. Among these are the dispersion of plutonium in soil, the accumulation of plutonium in fuel processing wastes, and the accumulation in filter materials. These systems may not only have finite critical masses at plutonium concentrations <7 g/liter, but may also contain added scatterers which can reduce the critical masses of the systems to several times less than those of pure plutonium-water systems. 

Isotopes of curium are also found in waste streams from plutonium-239 production, but in amounts smaller than those of americium. Curium is produced by the beta decay of Am and Am formed by neutron capture in Am and Am. The amount of curium-244 accumulated in process wastes and in unprocessed irradiated fuel elements as of 1985 is estimated at more than 100 kg [5]. Separation and purification of curium and americium is best carried out by the ion-exchange procedures described below (see Section 14.3.5). 

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