Transient Safety Analysis for Accelerator Driven System with Gas-lift Pump

摘要

Accelerator driven system (ADS), which combines a sub-critical reactor, a high energy proton accelerator, a spallation target and gas-lift pump, has a remarkable potential for transmutation of the long-lived nuclear waste. For the design of ADS, a major part is about safety investigations for transient behaviors under conditions leading to severe accidents. In this study, using Gear algorithm, TASAR (Transient analysis of Simplified ADS Reactor) code has been developed to evaluate the transient analysis of a simplified accelerator driven system with gas-lift pump, so as to describe the XADS(eXperimental ADS) specifics such as subcritical core, strong external neutron source and lead-bismuth-eutectic (LBE) coolant. Point reactor neutron kinetics model with six groups of delayed neutron is adopted for the solution of reactor power. All possible flow and heat transfer conditions are considered and the corresponding optional models are supplied in the theoretical calculations. As transient scenarios, the following cases are analyzed: Spurious beam trip (BT), unprotected beam overpower (UBOP), unprotected transient overpower (UTOP), unprotected loss of flow (ULOF). Meanwhile, the calculation results by TASAR code show good agreement with experiment results of NACIE facility. The results reveal that, the accelerator and gas-lift pump influence the loop mass flow rate and core temperatures of research system in this paper greatly. Besides, the present simulation consequences represent that the simplified accelerator driven system with gas-lift pump has a very good safety performance, and further design and safety optimizations are under consideration.