The research groups of Nagaoka University of Technology, Kansai Gakuin University, Utsunomiya University, Daihatsu Industries, Advantage, Japan Atomic Energy Agency, etc. have been working on radioactive waste such as fuel debris (Note) associated with the decommissioning of the Fukushima Daiichi Nuclear Power Station. In order to ensure the long-term hydrogen safety of the storage container and improve the hydrogen safety technology, we aimed to develop a technology to reduce the concentration of hydrogen accumulated in the storage container.
In this project, we have developed two high-performance hydrogen recombination catalyst (PAR) manufacturing technologies.One is a highly practical "honeycomb type hydrogen safety catalyst" that applies an automobile catalyst.As a result, the generated hydrogen and oxygen can be returned to safe water in the container without external power supply.
The other is a spherical catalyst in which fine particles of alumina carrying platinum precious metal are coated on the surface of a spherical alumina base material.This has a higher hydrogen processing capacity per unit volume than conventional catalysts, it is easy to adjust the hydrogen processing capacity by the number of catalysts, and it can be used efficiently according to the load amount of fuel debris etc. in the container. become.
In addition, in order to establish hydrogen treatment technology using PAR, it is necessary to install PAR in the fuel debris storage container and evaluate the hydrogen behavior experimentally.For this reason, we were able to manufacture a simulated container and conduct a series of experiments to clarify various factors that affect PAR performance and to establish hydrogen treatment technology.
Furthermore, a model was constructed to simulate the heat and mass transfer phenomena due to natural convection in the fuel debris storage container.In addition, in order to elucidate the reduction behavior of hydrogen concentration due to the hydrogen recombination reaction in the container, we constructed a natural convection model necessary for predicting and evaluating the unsteady concentration behavior of hydrogen and a catalytic reaction model for predicting the bonding reaction between hydrogen and oxygen. And developed the simulation method.
Note: Fuel that has melted due to a nuclear accident has cooled and solidified.
