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  Institute for Reactor Safety and Reactor Technology (Univ.-Prof. Dr. rer. nat. Hans-Josef Allelein)

Investigations on the use of ceramic materials in innovative Light Water Reactor Designs

The use of SiC-capsules in fuel elements to improve decay heat removal in incidents.

The main aim of the innovative reactor concept is keeping control in case of extreme incidents. In order to achieve this aim, it is also necessary to ensure that, after a complete loss of all cooling systems, no damage to the fission product barrier can take place and thereby any possibility of environmental contamination is excluded.

Objective:

Investigations on the feasibility of a water-cooled (H2O) core with rod lattices with no possibility of meltdown (after the failure of all active systems and total loss of coolant).

Concept:

The project should give information on the effects of a ceramic capsulating of the fuel element pellets in failure situations. Previous works on the use of ceramic components in light-water reactors have shown that there are no difficulties as far as neutron-physics and thermohydraulics are concerned. The safety properties, in particular those in the early accident phase, can be significantly improved. An extension of the waiting period takes place, after which damages, caused by excessive temperatures, can also occur in the reactor of plants with low core power density. To avoid the meltdown of the nuclear structure in the reactor pressure vessel (RPV), possible methods to increase the self-acting heat transport from the RPV are being sought for, excluding any damage to the nuclear structure and the fission product barrier. The produced decay heat can be removed from the surface of the RPV into the water pond of the RPV-cavern. The remaining heat transport out of the safety shield into the environment could take place by means of both active and passive systems.

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