会議発表用資料 Modeling study of thermal excursion of chemical reactions of beryllium/beryllide pebbles with steam and its implication to fusion DEMO safety

中村, 誠  ,  金, 宰煥  ,  中道, 勝  ,  染谷, 洋二  ,  飛田, 健次  ,  坂本, 宜照  ,  日渡, 良爾

2017-09-22
内容記述
Water-cooled pebble-bed (WCPB) blanket, in which beryllium/beryllide in a pebble form is used, is one of blanket concepts based on present or near-term technology for fusion reactor. However, combination use of water, as coolant, and beryllium/beryllide, as neutron multiplier, may pose a critical safety problem, i.e. the chemical reactivity of the beryllium/beryllide pebble and the hazard of the reaction-produced hydrogen. We present a new phenomenological model of the reaction behaviors of the beryllium and beryllide Be12Ti pebbles with the steam. The model consists of the equations of the transients of (i) the radius of the un-reacted part and (ii) the temperature of the pebble. We have developed a code PSYCHE to numerically solve the model equations. It has been found that the amount of the reaction-produced hydrogen obtained by the code simulation agree well with the experimental observations. We also show an application of the code to safety analysis of the thermal excursion of the Be and Be12Ti pebbles in an in-box LOCA, i.e. loss-of-coolant accident in an blanket box. The analysis indicates that use of the Be12Ti pebbles can avoid the risk of the thermal excursion.
13th International Workshop on Beryllium Technology (BeWS-13)

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