A national programme OMEGA started in 1988 for R&D in new technologies for the partitioning and transmutation of high level waste (Takizuka, 1997). The OMEGA programme consists of two areas of research, the separation of elements from high-level waste based on their physical and chemical properties and the transmutation of MAs and LLFPs into short lived or stable nuclides. A conceptual design programme has been put

together including code systems (Nakahara and Tsutsui, 1982; Nishida et al., 1990) and integral experiments (Takada et al., 1992) to investigate two concepts, a solid system and a molten salt system.

For the solid system, the design is based on a sodium-cooled fast reactor. The accelerator injects a 1.5 GeV proton beam onto a tungsten target, surrounded by a sub­critical blanket of actinide alloy fuel. The target blanket is at a total thermal power of 820 MW cooled by downward flowing sodium. The remainder of the heat transfer cycle is based on a tertiary cycle system (Figure 13.2).

The other design study is based on a molten salt target/blanket system, generating 800 MWt. The molten salt acts as a fuel and target and also as a coolant. The beam is

1.5 GeV. The latter concept is based on future generation reactor technology.