Lead-cooled fast reactor is one of the fourth-generation nuclear energy systems, which has great development potential due to good neutronic, thermal-hydraulic characteristics and inherent safety. The lead and bismuth eutectic alloy (LBE) cooled fast reactor BLESS-D (Breeding Lead-Based Economical Safe System) is a small fast reactor developed by the State Power Investment Corporation Research Institute (SPICRI). It is designed as a multi-purpose integrated small reactor system with the characteristics of small power, compact size and inherent safety. In the future, it could be used for electricity consumption for remote areas, polar expedition, island development and etc.
The conceptual design of BLESS-D is described in this paper, including the design criteria, safety features, main parameters and main components. The thermal power of BLESS-D is 300 MW. It is a pool-style reactor with LBE as the coolant, equipped with 8 helical tube steam generators and 4 primary pumps. The safety system consists of passive Decay Heat Removal System (DHR) and RVACS (Reactor Vessel Air Cooling System) outside the reactor vessel. For the preliminary transient analysis, the primary system and secondary boundary of BLESS-D is modeled with SNAP/TRACE. And the steady state simulation results are compared with the design values which shows good agreement. After that, the transient accidents under different conditions are studied to evaluate the feasibility and safety of the current design. In this paper, the results of Unprotected Transient Over Power (UTOP), Unprotected Loss Of Flow (ULOF), and Unprotected Loss Of Heat Sink (ULOHS) are discussed which shows that the current safety system design is sufficient to ensure the reactor safety although some optimizations are still needed.