基于蒙特卡罗方法的新型乏燃料干式贮存容器辐射安全仿真验证

针对自主设计的贮存24组燃耗深度为45 GWD/MTU的乏燃料组件的CHN-24型专用容器临界及辐射屏蔽问题,采用蒙特卡罗程序MCNP,建立CHN-24容器临界及辐射屏蔽计算模型。研究结果表明:正常贮存条件下容器内乏燃料的有效增殖因数(k_(eff))为0.283,发生浸水事故时,k_(eff)随着容器内水位升高逐渐增大,注满水时keff达到最大值0.706;容器表面剂量当量率随浸水量增大而减小;正常贮存条件下,即无水浸入时,容器表面及距表面1 m处的最大剂量当量率值分别为0.42 m Sv·h~(-1)、0.08 m Sv·h~(-1)。以上均符合国际原子能机构规定的临界及剂量安全标准,同时表明蒙特卡罗方法可应用于乏燃料容器的临界及辐射屏蔽安全验证。该研究为我国研发具有自主知识产权的核电乏燃料贮存专用容器提供了一定的参考依据。

Monte Carlo-based simulation on radiation shielding verification for a dry spent fuel storage model

Background: Radiation shielding performance and criticality safety play important roles in the safety performance of dry fuel container.Purpose: The purpose is to develop a type of dry spent fuel storage CHN-24 container, which can contain burn-up 45 GWD/MTU spent fuel totaled 24 groups.Methods: Radiation shielding performance and criticality safety were checked and validated using Monte Carlo method to establish a radiation-dose rate-calculation model for the CHN-24 container.Results: The fuel keff in container under normal storage condition was 0.283, which increased gradually with the water level and reached the maximum 0.706 at the highest level. The dose equivalent rates decreased with the increasing flooding, and under normal condition, the dose rates at the surface of the container and at a distance of 1 m from the surface were 0.42 mSv·h?1 and 0.08 mSv·h?1, respectively, which conforms to the radiation safety standards of International Atomic Energy Agency (IAEA).Conclusion: The results showed that Monte Carlo method can be applied to verify the critical security and radiation shielding performance of dry spent fuel container.