2 MW钍基熔盐堆覆盖气净化系统失效事件下的辐射剂量分析

Radiation dose analysis of the cover gas purge system failure incident of 2 MW TMSR-LF1

覆盖气净化系统失效事件是2 MW液态燃料钍基熔盐实验堆(Thorium Molten Salt experimental ReactorLiquid Fueled,TMSR-LF1)可能导致放射性释放的典型假想事件之一。本文根据事件的释放模式和源项,在保守假设的情况下,使用ARCON96计算事件发生后厂房各边界处的大气弥散因子,估算事件发生后假设的烟囱下风向各厂房边界处的工作人员的个人有效剂量,然后分析事件发生后反应堆厂房内的可居留性。经过计算可以得出,覆盖气净化系统失效事件发生后,产生的有效剂量主要来源于浸没外照射途径。厂房边界处最大24 h全身累积剂量为3.04 mSv,低于国家核安全导则规定的场区应急行动水平,事件发生后TMSR-LF1将进入厂房应急状态,无需场外应急。

[Background] The cover gas purge system failure incident is one of the typical incidents of 2 MW liquid-fueled thorium molten salt experimental reactor - liquid fueled （TMSR-LF1）, which could result in radiation releasing. [Purpose] This paper attempts to analyze the habitability for operations in the powerhouse under the cover gas removal system failure incidental condition, and provide data for nuclear emergency for TMSR-LF1. [Methods] Based on source items and emission pattern, we did conservative evaluations of atmospheric dispersion factors of powerhouse boundaries by using ARCON96 and 24 h individual effective dose for occupational workers locate at powerhouse boundaries. [Results] For this incident, the highest 24 h individual cumulative dose is 3.04 mSv and it appears on the powerhouse boundary nearest to the reactor core. [Conclusion] Compared the results with the national standards, it is not up to site-area emergency action level so that the reactor would enter in alert emergency classification,