Reprocessing features

An improved solvent extraction process, PUREX, utilizes an organic mixture of tributyl phosphate solvent dissolved in a hydrocarbon diluent, typically dodecane. This was used at Savannah River, Georgia, ca 1955 and Hanford, Washington, ca 1956. Waste volumes were reduced by using recoverable nitric acid as the salting agent. A hybrid REDOX/PUREX process was developed in Idaho Falls, Idaho, ca 1956 to reprocess high bum-up, fuUy enriched (97% u) uranium fuel from naval reactors. Other separations processes have been developed. The desirable features are compared in Table 1. 

One feature of reprocessing plants which poses potential risks of a different nature from those ia a power plant is the need to handle highly radioactive and fissionable material ia Hquid form. This is necessary to carry out the chemical separations process. The Hquid materials and the equipment with which it comes ia contact need to be surrounded by 1.5—1.8-m thick high density concrete shielding and enclosures to protect the workers both from direct radiation exposure and from inhalation of airborne radioisotopes. Rigid controls must also be provided to assure that an iaadvertent criticahty does not occur. 

DuPont carried out and supported research and development by others focused on conceptual design studies for an NRC licensed fuel recycle complex based on its successful reprocessing experience and lessons learned from that experience and the experience of others. The design studies were completed and reports issued in November 1978. Costs for the 3000 ton/ycar integrated fuel reprocessing/fabrication facility were estimated at 3.7 billion (1978 dollars). Special features ofthis facility design include ... 

Although the main incentive of reprocessing is to use uranium resources effectively by recovering and recycling the Pu and U remaining in the SNF, the real feature of the Pu flow in the current world can be described as follows ... 

SOLVENT extraction (liquid-liquid extraction) is the separation and/or concentration of the components of a solution by distribution between two immiscible liquid phases. A particularly valuable feature is its power to separate mixtures into components according to their chemical type. Solvent extraction is widely used in the chemical industry. Its applications range from hydrometallurgy, e.g., reprocessing of spent nuclear fuel, to fertilizer manufacture and from petrochemicals to pharmaceutical products. Important factors in industrial extraction are the selection of an appropriate solvent and the design of equipment most suited to the process requirements. 

In the course of works each of the decommissioning objects can be a source of SNF, SRW, LRW, noxious chemicals or other non-radioactive waste reprocessible and re-usable in industry. Still, the main feature of the complex decommissioning objects is the presence of SNF and generation of RW during work execution. Considering a special importance of SNF, SRW and LRW for the work to be done and for justification of priorities, at some work phase they can be attributed to the category of independent objects of management. This is a quite natural decision because in the course of the... 

Another feature of the thorium fuel cycle which affects reprocessing is the buildup of 232U in the irradiated fuel. 

Electro-reduction and -oxidation processes are easy to operate and control remotely. Unlike the use of redox chemicals, they do not give rise to waste salts. Convenient remote control and operation and avoidance of waste salts are especially attractive features for commercial processing of any type of power reactor fuel. According]y, the electrode reactions were introduced quite early as intermediate steps in reprocessing. The electrochemical decladding of spent fuels was the first process in this field to be advanced up to the technical scale in the USA (J, 2 3, ... 

U.S. plants. The principal U.S. reprocessing plants are listed in Table 10.3, together with their main process features. All use some form of the Purex process. In 1979, the only ones operating were the Savannah River and Idaho plants of the U.S. Department of Energy (DOE). The Hanford plant had been used primarily for recovery of plutonium and uranium from irradiated natural uranium, but was versatile and had been used, for example, for Thorex... 

The Barnwell Nuclear Fuel Plant is the newest U.S. reprocessing plant. In 1979, it was nearly complete, but standing unused because of U.S. government policy unfavorable to reprocessing fuel from power reactors. Its main process features are to be described in Sec. 4.14 as an example of a modem Purex plant. 

Overseas plants. Table 10.4 lists the reprocessing plants outside of the United States and the Soviet Union with capacities greater than 100 kg heavy metal per day and gives their principal process features. In addition to these plants, smaller plants have been operated in Italy, India, and, probably, other countries. 

Distillation units which have been developed for treating high-level liquid waste have a number of special features required for operation with reprocessing wastes ... 

The first two methods require rigid process control except in natural or slightly enriched reprocessing plants before plutonium partitioning. Other features of the layout include a calculated pitch on the process cell floors so that a major spill will not cause the solution depth to exceed criticality. A steam jet and sump pump with alarm devices are located in a geometrically safe sump at the low point in the cell area. To avoid loss of fissionable-fuel material, there should be no gravity connections between the process tanks and the waste storage area. 

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