ZrC被覆燃料粒子検査手法の検討; SiC被覆燃料粒子に対する検査手法の適用性評価

Investigation on inspection methods for ZrC-coated fuel particle; Applicability evaluation of inspection methods for SiC-coated fuel particle

高山 智生*; 植田 祥平   ; 相原 純 ; 安田 淳*; 石橋 英春*; 沢 和弘

Takayama, Tomoo*; Ueta, Shohei; Aihara, Jun; Yasuda, Atsushi*; Ishibashi, Hideharu*; Sawa, Kazuhiro

第四世代原子炉の候補の一つである超高温ガス炉(VHTR)の燃料として、既存のSiC被覆燃料粒子とともにZrC被覆燃料粒子が期待されている。ZrCとSiCの材料特性を比較することにより、ZrC被覆燃料粒子の検査方法にSiC被覆燃料粒子の検査方法が適用できるかについて検討した。SiC被覆燃料粒子の断面組織,被覆層厚さ(SiC層),被覆層密度(SiC層及びO-PyC層),露出ウラン率,SiC層破損率の各検査における支配的な因子として、SiCの硬さ,X線吸収係数,密度,耐酸化性,化学的安定性を抽出した。また、上記手法のZrC被覆燃料粒子への適用性を検討し、被覆層密度(ZrC層及びO-PyC層),ZrC層破損率の検査については、SiC被覆燃料粒子の検査方法を適用困難であり、今後解決すべき課題であることを示した。

As the conventional SiC coated fuel particle, the ZrC coated fuel particle is proposed as a fuel for the Very High Temperature Gas-cooled Reactor (VHTR) which is one of Generation IV nuclear reactors. Applicability of inspection methods of SiC-coated fuel particle for ZrC-coated fuel particle has been examined by comparing properties of ZrC with SiC. It was suggested that hardness, absorption X-ray coefficient, density, oxidation-resistant and chemical stability of SiC were dominant properties for conventional inspection methods such as SiC coating layer thicknesses, coating layers densities for both SiC and O-PyC layers, thorough-coatings failure fraction and SiC coating layer failure fraction. With regards to the applicability of the inspection for the SiC-coated particle, some difficulties are revealed on coating layers densities for both ZrC and O-PyC layers and of ZrC failure fraction, and it was suggested that they were major issues to be solved.