Conceptual design for a large-scale Japan sodium-cooled fast reactor, (1) Feasibility of key technologies

The feasibility evaluations on Japan Sodium-cooled Fast Reactor (JSFR) key technologies are summarized. The hot vessel, two-loop cooling system using high chromium steel, integrated intermediate heat exchanger/pump component (IHX/Pump), advanced steam generator, natural convection DHRS (Decay Heat Removal System) and improved in-service inspection and repair capability have been confirmed to be feasible as development items for the next stage. Since the JSFR reactor vessel adopts ring forged 316FR stainless steel instead of 304SS, new structural design standards are going to be developed and a vessel wall cooling system is not necessary while it was in Joyo and Monju. The two-loop cooling system contributes to simple cooling system and compact component arrangement. The integrated IHX/Pump is one of the JSFR key technologies to achieve a compact primary cooling system. It includes a primary pump, IHX and primary reactor auxiliary cooling system (PRACS) heat exchange tubes. JSFR adopts the double-wall tube reliable steam generator for both safety and investment protection. JSFR adopts fully natural convection to achieve reliable DHRS. The JSFR design takes into account accommodation of a comprehensive in-service inspection and repair (ISIR) program at the very conceptual design stage. The JSFR demonstration plant is scheduled to be operated from 2025.