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The CAPRA plutonium burner has been designed along the guidelines of advanced fast reactor plants. Besides the classical accident preventing systems a third shutdown level has been installed which by inherent and passive systems prevent any core melt accident. Nevertheless also the impact of severe accident scenarios has been investigated and possible measures for mitigation have been studied. Within this framework measures for preventing and mitigating recriticalities as additional lines of defence have been integrated into the safety strategy.

Possibilities for controlled material relocation (CMR)

Pin level:

Removal pathway through hollow pellets

Subassembly level:

Removal pathway through a special hollow structure with movable
absorber balls/pellets above and below the core (left)
Removal pathways through expanded annular gaps (right)

Core level:

Removal pathway through diluent bundles with movable absorber
balls above the core (right)

The idea of the controlled material relocation (CMR) is the assurance of an early and permanent removal of any molten fuel from the core during an accident. By this the nuclear chain reaction is stopped and the reactor made deeply subcritical. Any recriticality should be prevented by reactor design. The ideas for CMR are now investigated also experimentally in the Japanese EAGLE project. Within this project a recriticality free reactor design should be developed.

For details please visit the EAGLE web pages (under construction).

Controlled Material Relocation (CMR) on Core Level

Simulation of the fuel/steel pool discharge process through a central diluent subsassembly (core level) with the SIMMER-III code. The different materials in their different phases (solid, liquid, particulate) are distinguished by different colors.