Conceptual Study for a Demonstration High Temperature Gas-Cooled Reactor (HTGR)

The core nuclear design was performed for a demonstration High Temperature Gas-Cooled Reactor (HTR-F) with 260MW thermal power with the aim of starting operation in the late 2030s.The design policy of the HTR-F is to use existing technology that does not require new demonstration tests, enabling operation in the late 2030s.Therefore, the core nuclear design of the HTR-F was based on the proven technologies of the High Temperature Engineering Test Reactor (HTTR) and the Small-sized HTGR System (HTR50S), which was conceptually designed by improving HTTR technology.In the core design of the HTR-F, to achieve higher output than HTTR and HTR50S, the number of fuel block layers was increased and the fuel regions expanded by making the annular core, and the nuclear characteristics of the new core were investigated through whole-core burnup calculations.Additionally, the placement and size adjustment of burnable poisons (BP) were used to further suppress the effective multiplication factor.As a result, the core became an annular core with 12layers of fuel blocks, the effective multiplication factor was suppressed to 1.05 or less throughout the burn period, and a burnup of 45GWd/t was achieved.