Core physical conceptual design of small reactor for unmanned underwater vehicle

In order to improve the endurance of unmanned underwater vehicle (UUV) and meet the needs of long-term underwater mission, the conceptual design of the 3.68 MWt long-life small reactor JCZER-20 is carried out in an UUV application scenario with a propulsive power of 850 kW. According to the design content, the concept of active zone partition design is put forward, and a new circulating scheme of coolant in the reactor primary circuit is given. The layout of control body in the reactor and the design of control system are carried out. The control rod structure of JCZER-20 adopts special design to deal with special conditions such as shaking during operation. The reactivity distribution scheme is given, and the reactor physical characteristics are analyzed for the design scheme. This scheme can lengthen coolant channels, effectively improve the total temperature rise of the coolant, but not increase the extra heat load. MCNP-ORIGEN2 simulation results show that the JCZER-20 reactor can operate at full power for more than 30 years without refueling. The reactor core reactivity can be effectively controlled by the control system of reactor. The core design meets preset design requirements.