高温剪断式触发吸收球非能动停堆装置可行性分析

Feasibility analysis on passive shutdown device with high temperature shearing trigger absorber ball

非能动停堆系统是事故工况下核能系统的重要安全保障。为保证和增强钍基熔盐堆核能系统的安全性,通过对比分析现有的非能动停堆装置,本文提出了钍基熔盐堆高温剪断式触发吸收球非能动停堆装置。利用Inconel 625合金在650-700°C力学特性发生陡降的特点,对高温剪断式触发结构——薄壁挡板进行设计,并通过Abaqus软件对其二维结构在事故工况下不同温度时的响应状态进行稳态、瞬态断裂模拟。模拟结果表明,当设定温度超过650°C且持续升高时,薄壁挡板会在4-10 s内发生断裂;在非事故工况下,若温度异常升高到670°C后随即降低时,薄壁挡板不会发生断裂。因此,在紧急事故工况时,设计的高温剪断式触发结构能够可靠剪断,确保第二停堆系统非能动触发,进一步提高钍基熔盐堆的安全性。

Background： The passive shutdown system is an important safety guarantee for the nuclear energy system in case of accidents. Purpose： This study aims to analyze the feasibility of the passive shutdown device with high temperature shearing trigger absorber ball to ensure and enhance the safety of thorium-based molten salt reactor （TMSR） nuclear energy system. Methods： Based on the mechanical properties steep drop from 650 ℃ to 700 ℃ of inconel 625 alloy, a thin-wall baffle made of this alloy is designed as the high temperature shearing trigger structure. The steady state and transient fault fracture simulation of the two dimensional structure are carried out by Abaqus software at different temperatures under accident conditions. Results： The simulation results show that the thin-wall baffle cracks within 4-10 s when the preset temperature exceeds 650 ℃ and continues rising. While it will not fracture under the non-accident condition when the temperature rises to 670 ℃ and then reduces immediately. Conclusion： The high temperature shearing trigger structure can reliably fracture to trigger the passive shutdown system under the emergency condition, and further enhance the safety of thorium-based molten salt reactor.