A new radioactive liquid waste cementation facility was under commissioning recently in the Institute of Nuclear and New Energy Technology of Tsinghua University, which is designed to simultaneously process multiple intermediate-level radioactive waste drums. Therefore, the multiple volume sources and the scattering effect becomes a key issue in its radiation protection. For this purpose, the Monte Carlo program FLUKA code and experimental measurement were both adopted. In the FLUKA simulation, five different scenarios were considered, i.e., one drum, two drums, four drums, six drums, and eight drums. For the multiple volume sources, the source subroutine code of FLUKA was rewritten to realize the sampling. The complex shielding also leads to a deep penetration problem; hence, the optimization algorithm and variance reduction techniques were adopted. During the measurement, two scenarios, outdoor and indoor, were carried out separately representing the dose field when only one drum is considered and when the scattering effect is considered. A comparison between the experiments and calculations shows very good agreement. From both of the Monte Carlo simulation and the experimental measurement, it can be drawn that, in the horizontal direction, with the increase of the drum number, the dose rate increases very little, while in the vertical direction, the increase of the dose rate is very obvious with the increase of the drum number. The complicated source term sampling methods, the optimization algorithm and variance reduction techniques, and the experimental verification can provide valuable references for the similar scattering problem in radiation protection and shielding design.

中文翻译：

---

放射性液体废物固结设施的多重复杂源项和深度渗透的辐射防护的蒙特卡罗模拟和实验验证

清华大学核能与新能源技术研究所最近正在建设一个新的放射性废液胶结设施，该设施旨在同时处理多个中级放射性废料桶。因此，多个体积源和散射效应成为其辐射防护中的关键问题。为此，采用了蒙特卡洛程序FLUKA代码和实验测量。在FLUKA模拟中，考虑了五个不同的场景，即一个鼓，两个鼓，四个鼓，六个鼓和八个鼓。对于多个体积源，重写了FLUKA的源子例程代码以实现采样。复杂的屏蔽层还导致了深度渗透问题。因此，采用了优化算法和方差减少技术。在测量过程中，分别考虑了一个鼓和考虑了散射效果时，分别执行了室外和室内两种场景，分别代表剂量场。实验和计算之间的比较显示出很好的一致性。从蒙特卡罗模拟和实验测量都可以得出，在水平方向上，随着转鼓数量的增加，剂量率几乎没有增加，而在垂直方向上，剂量率却增加了随着鼓数的增加非常明显。复杂的源项采样方法，优化算法和方差减少技术，