ADS中液态铅铋靶流动管道屏蔽计算

Shielding calculation of LBE target flow pipeline in ADS

对于具有独立回路冷却液态铅铋(Liquid Lead-bismuth Eutectic,LBE)散裂靶的加速器驱动的次临界系统(Accelerator Driven Sub-critical System,ADS),高能质子束流辐照靶体产生的散裂产物进入管道后,会持续释放光子,会对靠近流动管道的工作人员造成辐射损伤。本文利用高能粒子输运程序Fluka计算散裂靶的散裂产物累积产额,然后利用放射性衰变计算程序Origen2计算散裂产物释放的光子强度及分群能谱,最后利用Fluka进行流动管道内光子源项的屏蔽计算。对一种典型的Y型LBE有窗靶进行的流动管道屏蔽计算结果表明,参照GB18871-2002职业性放射性工作人员年剂量当量限值20 m Sv的标准,若使用铅作为屏蔽材料,流动管道的管壁应该加厚20 cm。本文工作可为ADS系统LBE有窗靶的回路屏蔽设计提供参考。

[Background] Accelerator driven sub-critical system（ADS） devices use independent loops to cool liquid lead-bismuth eutectic（LBE） spallation targets, spallations produced by the high-energy proton beam irradiating target will continue releasing photons after entering the flow pipe, which may cause radiation damage to the workers nearby the flow pipe. [Purpose] This study aims to obtain the radiation dose equivalent produced by the photons and select the appropriate shielding scheme. [Methods] Accumulative yield of spallation products of a typical Y-type LBE with window target was calculated using the high-energy particle transport program Fluka. The radioactive decay calculation program Origen2 was employed to calculate the photon intensity and population energy spectrum of the spallation product. Then the shielding of flow pipe was assessed by Fluka. [Results] The flow pipe wall should be thickened by 20 cm using lead as the shielding materials according to the GB18871-2002 national standard which requires occupational radioactive workers’ annual dose equivalent limit of 20 m Sv. [Conclusion] This work provides reference for shielding design of loop of LBE windowed target of ADS.