Proliferation resistance and safeguardability of very high temperature reactor

超高温ガス炉の核拡散抵抗性と保障措置適用性

芝 知宙  ; 富川 裕文; 堀 雅人

Shiba, Tomooki; Tomikawa, Hirofumi; Hori, Masato

In this study, we evaluate the proliferation resistance (PR) of VHTR in order to analyse diversion/acquisition paths and we reflect the outcome in the design of a safeguards approach, using an estimation method recently developed in JAEA for the -rays emitted from spent fuel. For this purpose, we firstly evaluated the intrinsic PR of plutonium (Pu) material against various burnups using some PR evaluation methods. In addition, we assessed the safeguardability of the pebble bed type VHTR (PBR). The PBR loads new fuel online, in the form of spheres, at the top of the reactor and discharges spent fuel spheres with high burnup from the base of the reactor. Given such an online refueling, it is not possible to implement item-based safeguards. As the safeguardability was assessed, we revealed the necessity for a new type of burnup monitoring technology, to measure the burnup level of fuel spheres just after discharge, taking into consideration the threat of diversion/weaponization scenarios particularly with spent fuel at lower burnup. Therefore, we developed an advanced burnup monitoring method.