ASTRID Nuclear Island design: update in French-Japanese joint team development of Decay Heat Removal systems

摘要

ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) has the objective to integrate innovative options with the objective to prepare the 4th generation reactors. In this framework a French-Japanese agreement was signed in 2014 between CEA, framatome (ex AREVA NP). JAEA, MHI/MFBR to jointly perform components design of ASTRID such as Decay Heat Removal Systems (DHRS). In this respect an ambitious close collaboration is set in the framework of the practical elimination objective of Decay Heat Removal (DHR) function loss which is one of the main ASTRID safety objectives. To reach this target, design is driven by deterministic safety criteria, probabilistic safety indicators and proper technical and economic analysis. Safety demonstration aims at identifying common cause failures and imposes to search for proper diversification of decay heat removal systems. In ASTRID. DHRS main diversification is based on final heat sinks types and intermediate coolant fluids. It is also based on spatial segregation of systems which leads to thermal loading diversification during normal operation as well as severe accident exposure. Implication of two different designers bodies framatome and a Japanese team (JAEA, Mitsubishi FBR Systems (MFBR) and MHI) also participate to diversification. This paper is giving an update concerning ASTRID DHR strategy with description of reference architecture evolution and project objectives. In particular, new developments were made for DHR during normal shutdown and role of Ex-Vessel system. A special focus is made on design process of automatic shutter to hydraulically connect Hot Plenum and cold plenum to enhance primaiy vessel natural convection.