<p style="margin: 0mm">The high temperature gas-cooled reactors (HTGRs) are the next-generation reactors with high safety, because the cores of HTGRs would not melt. The coolant of the HTGRs is He. But it is important to improve the oxidation resistance of the fuel for the huge oxygen ingress into the core to improve the safety of HTGRs, because almost volume of the cores of the HTGRs consist of graphite. The coated fuel particle (CFP), of which diameter is around 1 mm, is used in HTGRs. A small sphere containing fissile materials is sealed up with ceramics coating layers to form a CFP. Mixture of CFPs and starting materials of binding material (matrix) is sintered to form fuel compact. The matrix is graphite now. Then the binding material can finally vanish completely if the huge oxygen ingress into the core. In this study, the development of oxidation resistant fuel compact, of which matrix is mixture of SiC and graphite, has been carried out. Simulated CFPs (alumina particles) and starting materials of matrix (Si powder, graphite powder and resin) were molded and hot-pressed into simulated fuel compacts. In order to maintain the structural integrity of fuel elements for HTGR under accident conditions, not only oxidation-resistant but also high-strength fuel compacts should be developed further. Hot press conditions such as pressure, temperature and duration time would be one of the factors affecting the strength of the HTGR fuel elements. In order to identify the optimal hot press conditions for preparing the high-strength fuel elements, the effect of the hot press conditions on the mechanical strength properties of the HTGR fuel elements should be evaluated quantitatively by modeling. In the present study, the response surface model, which represents the relationship between the hot press conditions and the mechanical strength properties, has been constructed by introducing statistical design of experiments (DOE) approaches, and the optimal hot press conditions for producing the high-strength fuel elements were estimated by the model. The validity of the model was discussed by comparing the model prediction with the experimental observation.</p>

A Statistical Approach for Modeling the Effect of Hot Press Conditions on the Mechanical Strength Properties of Htgr Fuel Elements

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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