CDA analysis of lead-cooled fast reactor

Tobita, Yoshiharu; not registered; Fujita, Satoshi

The feasibility study for the commercialization of fast reactors is underway in Japan Nuclear Cycle Development Institute, aiming at the achievement of the economic competitiveness, making full use of the natural resources, reduction of the environmental impact and the assurance of the nuclear non-proliferation and safety. This report shows the results of the analysis of the core-disruptive accident in lead-cooled reactor, which was performed to clarify the safety aspects of the heavy metal cooled fast reactors. The analysis showed that the high boiling point and density of lead made the event progression in the core-disruptive accident genuine and mild and prohibited the energetic re-criticality. Therefore, the dedicated designs to avoid the energetic recriticality, such as the fuel sub-assembly with inner duct and/or the fuel sub-assembly with partial removal of axial blanket pellet are not necessary in the lead-cooled fast reactor. On the other hand, the importance of the integrity of the primary boundary, structures in the reactor vessel, and decay heat removal system against the high temperature lead was pointed out from the viewpoint of the in-vessel retention of the accident.