Advanced SFR concept design studies at KAERI

Full text: Advanced SFR design concepts have been proposed and evaluated against the design requirements to satisfy the Gen IV technology goals. Two types of conceptual core designs, Breakeven and TRU burner cores were developed. Breakeven core is 1,200 MWe and does not have blankets to enhance the proliferation resistance. According to the current study, TRU burning rate increases linearly with the rated core powers from 600 MWe to 1,200 MWe. Considering 1) the realistic size of an SFR demonstration reactor for the long-term R and D plan with the goal of a demonstration SFR construction by 2028, and 2) the availability of a KALIMER-600 reactor system design that was developed in the last R and D phase, a TRU burner of 600 MWe was selected. The heat transport system of Advanced SFR was designed to be a pool type to enhance system safety through slow system transients, where primary sodium is contained in a reactor vessel. The heat transport system is composed of Primary Heat Transport System (PHTS), Intermediate Heat Transport System (IHTS), Steam Generating System (SGS) and Residual Heat Removal System (RHRS). The heat transport system was established through trade studies in order to enhance the safety and to improve the economics and performance of the KALIMER-600 design. Trade studies were performed for the number of IHTS loops, the number of PHTS pumps, Steam Generator (SG) design concepts, energy conversion system concepts, cover gas operation methods, and an improved concept of safety-graded passive decay heat removal system. From the study, the heat transport system of Advanced SFR has design features such as two IHTS loops, a Rankine cycle energy conversion system, two double-wall straight tube type SGs, and a passive decay heat removal system. In order to secure the economic competitiveness of an SFR, several concepts were implemented in the mechanical structural design without losing the reactor safety level. The material of reactor vessel and internal structure is a Type 316 stainless steel. The outer diameter of the reactor vessel is 14.5m, which is a very compact size compared to the other designs. Various R and D activities have been performed in order to support the development of Advanced SFR design concepts and to update computational tools. These activities include validating neutronics analysis codes, PDRC experiment, the conceptual design of supercritical carbon dioxide (S-CO2) Brayton cycle system, Na-CO2 interaction test, under-sodium viewing technique, computerization of structural integrity evaluation, sodium technologies, and metal fuel technology. (author)