中文摘要：

利用FDS团队（Fission＆Fusion Design Study）开发的中子学与热工水力学耦合安全分析软件,对一种加速器驱动铅铋自然循环次临界反应堆的束流中断及束流超功率事故进行了模拟分析。计算结果表明：加速器驱动次临界洁净核能系统（Accelerator Driven Sub-critical System,ADS）次临界堆的功率对束流瞬变的响应几乎是瞬时的;事故工况下,自然循环会根据堆芯功率自动调整至重新达到稳定;失束时间越长,材料温度降得越低,功率瞬间恢复值越低,束流恢复后,材料温度回升的速度越快;束流200%超功率事故发生后堆芯功率最终稳定在初始功率值的192.2%,燃料温度增幅最大,为286 K,燃料和包壳不会发生损坏和熔化,冷却剂不会发生沸腾。

英文摘要：

Background： Beam interruption and beam overpower are two typical transient accidents for accelerator-driven system. Purpose： To investigate the safety characteristics of the lead-bismuth cooled Accelerator Driven Sub-critical System （ADS） under beam transient accident, the steady state, beam trip and beam overpower accident of lead-bismuth cooled accelerator-driven system were simulated by using NTC-2D. Methods： NTC-2D is a two-dimensional version of neutronics and thermo-hydraulics coupled simulation program NTC developed by FDS team. Results： As for the beam interruptions, the temperature variations of cladding and fuel pellet at different time （1 s, 3 s, 6 s, 12 s） were given. The longer the beam interruptions, the lower temperature of cladding and fuel. After beam overpower occurred, core power finally stabilized at 192.2% of the initial power value. The temperatures of the fuel, cladding and coolant were all smaller than the safety limits. The fuel and cladding would not melt and the coolant would not boil. Conclusion： The reactor was safe under two accidents. The transient response of the power for ADS under beam transient accidents is instantaneous. Delayed neutron has less effect on neutron generation time. Natural circulation can reach new steady under two accidents.