To incinerate fissile plutonium effectively from the viewpoint of reduction of nuclear proliferation risk, we have proposed and developed a design concept named "Clean-burn HTGR". The characteristic is employing inert matrix of fuel composed of Yttria Stabilized Zirconia (YSZ) to prevent plutonium generation and enhance proliferation resistance.
For Coated Fuel Particles (CFPs) in conventional HTGRs, an increase in the internal pressure, which is caused by the generation of free-oxygen and Fission Product (FP) gases with burnup, is considered a major cause of the fuel failure occurring during operation. Therefore, JAEA has proposed a safety-enhanced Pu-burner HTGR by introducing CFPs with fuel kernels coated by Zirconium Carbide (ZrC), which acts as an oxygen getter. A study on the safety-enhanced Pu-burner HTGR has been conducted by the University of Tokyo, the Japan Atomic Energy Agency (JAEA), Fuji Electric Co., Ltd., and Nuclear Fuel Industries, Ltd. to establish the basic technologies necessary. JAEA has conducted the fuel design, the reactor core design and an experiment with ZrC coating. In the fuel-design study, an existing code for calculating the internal gas pressure in UO2-kerneled CFP was modified to analyze that in the PuO2-kerneled one with consideration of the depression effect due to ZrC coating. The fuel design has been performed with consideration of the depression effect due to ZrC coating using the code. In the design study of the reactor core, the nuclear burnup calculations with the whole core model has been performed by the SRAC/COREBN code. In addition, the ZrC-coating experiment has been conducted to obtain material properties such as stoichiometry, density, and microscopic structure of the ZrC, and then the correlation to coating conditions, such as temperature and gas-flow rate, has been examined based on the obtained material-characteristic data.
Appearance of ZrC coated YSZ particles
- Reference
- Y. Fukaya et al., Proposal of a plutonium burner system based on HTGR with high proliferation resistance, J. Nucl. Sci. Technol, 51(6), pp.818-831 (2014).
- M. Goto et al., Study on Pu-burner High Temperature Gas-cooled Reactor in Japan 2. Design Study of Fuel and Reactor Core, Proceedings of HTR2018 (2018).
- S. Ueta et al., Study on Pu-burner High Temperature Gas-cooled Reactor in Japan 5. Test and characterization for ZrC coating, Proceedings of HTR2018 (2018).
- Y. Fukaya, et al., Study on Pu-burner High Temperature Gas-cooled Reactor in Japan 6. Introduction scenario, Proceedings of HTR2018 (2018).