Fuel Processing Flow Sheets

Cladding Zircaloy Zircaloy Stainless Stainless None 

Circulating Coolant and moderator Coolant Coolant Fuel 

The simplest flow sheet, Fig. 1.10, is applicable to heavy-water reactors fueled with natural uranium containing 0.711 w/o Feed preparation for this type of reactor consists of 

As the efficiency of conversion of heat to electricity in a heavy-water nuclear power plant is about 30 percent, the rate at which a 1000-MW plant would have to be supplied with natural uranium is 

In commercial transactions uranium concentrates are measured in short tons (2000 lb) of UjOg. In this unit, the annual uranium consumption of this reactor would be 

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Figure 5. Fuel processing flow sheets for (A) HTGR and (B) Molten salt breeder reactor. (After Ref. 8.)...

The fuel processing operations to be used in conjunction with a nuclear power reactor and the amount of nuclear fuel that must be provided depend on the type of reactor and on the extent to which fissile and fertile constituents in spent fuel discharged from the reactor are to be recovered for reuse. Figures 1.10 and 1.11 outline representative fuel processing flow sheets for uranium-fueled thermal reactors generating 1000 MW of electricity, at a capacity factor of 80 percent. 

Figure 1.10 Fuel processing flow sheet for 1000-MWe heavy-water reactor. Basis 1 year, 80 percent capacity factor.

Figure 1.11 shows three possible fuel processing flow sheets for reactors cooled and moderated by light water. The specific example shown is for a pressurized-water reactor. Fuel for this type of reactor consists of UOj enriched to around 3.3 w/o in U. The expected performance of this type of reactor is described in some detail in Chap. 3, Sec. 7. After... 

Once a decision has been made to recover materials and/or energy, process flow sheets must be developed for the removal of the desired components, subject to predetermined materials specifications. A typical flow sheet for the recovery of specific components and the preparation of combustible materials for use as a fuel source is presented in Fig. 25-63. The light combustible materials are often identified as refuse-derived fuel (RDF). 

Np, and fission products. The Thorex solvent extraction process is generally used to reprocess spent Th-based fuels. As in the Purex process, the solvent is TBP diluted in an appropriate mixture of aliphatic hydrocarbons. Figure 12.9 shows the Thorex process flow sheet used by Kuchler et al. [41] for reprocessing high-burn-up thorium fuel. 

Many of these drawbacks were circumvented in a process developed at Chalmers University, which was successfully demonstrated in continuous operation using the old high-level raffinate concentrate from Purex processing of low burn-up fuel. Although operation was very easy and stable, the process flow sheet was complicated using bromoacetic acid, HDEHP, TBP, and lactic acid [57-59]. 

The Fischer-Tropsch process converts synthesis gas into hydrocarbon products. It was extensively used by Germany in the Second World War and developed in South Africa during the Apartheid years. It is now subject to extensive research and development for the conversion of coal into liquid fuels as an alternative to crude oil. The general process flow-sheet is shown in Figure 11.4. 

At the end of irradiation in such reactors, fuel consists of a mixture of thorium, uranium containing fissile isotopes, and fission products. Figure 3.33 showed a fuel-cycle flow sheet for an HTGR. The Thorex process has been developed for recovering the uranium and thorium from such fuel cycles, freeing them from fission products and separating them from each other. The Thorex process will be described in this section. When the fuel being irradiated contains appreciable the plutonium thus formed requires that a combination of the Thorex and Purex processes be used. 

Kiichler and associates [K6, K7] of Farbwerke Hoechst have investigated the modifications necessary in the acid Thorex process to enable it to handle (I) the high concentration of fission products present in fuel with the burnups of up to 100,000 MWd/MT expected in fuel from the HTGR, AVR, and THTR, and (2) uranium concentrations of up to 20 percent in thorium, which may be used in these reactors when fissile uranium is diluted with U to deter its use as a nuclear explosive. They found two difficulties with the acid Thorex process flow sheets previously used at Oak Ridge [B14] and Hanford [Jl] ... 

Figure 10.29 shows the principal steps in applying the Purex process to irradiated LMFBR fuel, step 7 of Fig. 10.28. The flow scheme and the compositions and locations of solvent, scrubbing, and stripping streams have been taken from the process flow sheet of a 1978 Oak Ridge report [Oil] describing a planned experimental reprocessing facility designed for 0.5 MT of uranium-plutonium fuel or 0.2 MT of uranium-plutonium-thoiium fuel per day. As that report gave process flow rates only for the uranium-plutonium-thorium fuel. Fig. 10.29 does not give flow rates for the uranium-plutonium fuel of present interest. This flow sheet shows the codecontamination step, in which flssion products are separated from uranium and plutonium the partitioning step, which produces an aqueous stream of partially decontaminated...

Figure 11.19 shows the process flow sheet for a pilot-scale fluidized bed gasifier, capable of processing some 20 kg/h of biomass feed, coupled with a thermal cracker and reformer reactor. The reformer is loaded with fluidizable nickel-based reforming catalyst and fitted with gas analysis ports at its inlet and outlet. The system has been used to evaluate catalyst activity and the decay of hydrocarbon conversion with time from a slip stream sample of the raw fuel gas. In this way, it is possible to quantify the frequently reported phenomenon of commercial catalyst deactivation, sometimes quite rapid, from high activity of fresh samples to lower residual activity brought about by various factors, including the presence of poisons (sulphur, chlorine) and coke formation. 

A possible process flow sheet for an SOFC power plant [43] is shown in Figure 32.10. On the fuel side, water is injected into the methane supply line in front of a boiler which is heated by the hot off-gas. The amount of water is derived... 

MCFC combined with a turbine technology has been considered since the mid-1990s. Figure 12.20 shows the process flow sheet, where natural gas is fed to an external reformer and then to the anode. The anode exhaust is then oxidized in a catalytic burner that is mixed with air from the compressor and fed to the cathode side of the fuel cell. The now heated cathode exhaust is used to turn a turbine to produce power in a bottoming cycle. Such configuration has been found to have a steady-state electrical efficiency of 54.8%. 

Utilities These include steam, cooling water, process water, electricity, fuel, compressed air, and refrigeration. The consumption of utilities can be estimated from the material and energy balances for the process, together with the equipment flow sheet. 

Zabunoglu, O.H. Ozdemir, L. Purex co-processing of spent LWR fuels Flow sheet, Ann. Nucl. Energy 32 (2005) 151-162. 

C. 2008. Towards an optimized flow-sheet for a SANEX demonstration process using centrifugal contactors. ATALANTE 2008 Nuclear Fuel Cycles for a Sustainable Future, May, Montpellier, France. 

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