Improvement of Detection Limit in 14MeV Neutron Direct Interrogation Method by Decreasing Background
Improvement of Detection Limit in 14MeV Neutron Direct Interrogation Method by Decreasing Background
复制标题
降低本底提高14MeV中子直接询问法探测限
DOI：
10.1080/18811248.2008.9711452
复制
发表时间：
2008
影响因子：
1.2
通讯作者：
H. Tobita
中科院分区：
文献类型：
--
作者：
M. Haruyama;M. Takase;H. Tobita
为了提高14 MeV中子直接探询法的探测限，采用连续能量蒙特卡罗输运程序（MVP）进行了模拟计算。结果表明，采用SUS-304（铁基合金）不锈钢反射体代替传统探测系统中的石墨慢化体，可大大减少核裂变中子计数区的本底中子。这种改进的检测系统的本底水平变为传统系统和方法的本底水平的1/10，000。也就是说，通过采用不锈钢SUS-304检测系统，使用直接询问法，测量时间为10分钟，可以将常规方法的石墨检测系统中的背景计数5，000减少到0.5。至于检测限，可以提高到使用常规检测系统和方法的检测限的1/1000。用不锈钢探测系统对受天然铀污染的胶结废物的探测极限为0.000122 Bq/g。对于纤维素废物，其为0.000451 Bq/g，对于金属废物，其为0.000702 Bq/g。这些测量可以在10分钟内完成。
For the improvement of the detection limit in the 14MeV neutron direct interrogation method, the simulation calculation using the continuous-energy Monte Carlo transportation code (MVP) was carried out. From the results, it was clarified that the background neutrons appearing in the nuclear-fission neutron counting area can be greatly decreased by adopting a stainless steel SUS-304 (an iron-based alloy) reflector in place of a graphite moderator in the conventional detection system. The background level of this modified detection system becomes 1/10,000 of that with the conventional system and method. Namely, the background counting of 5,000 in the graphite detection system by the conventional method can be decreased to 0.5 by adopting the stainless steel SUS-304 detection system using the direct interrogation method for a measurement time of 10 min. As for the detection limit, it can be improved to 1/1000 of that using the conventional detection system and method. The detection limit for the cementation waste that is contaminated with natural uranium is 0.000122 Bq/g using the stainless steel detection system. For the cellulose waste, it is 0.000451 Bq/g, and for the metallic waste, 0.000702 Bq/g. These measurements could be performed in 10 min.