反应堆冷中子源中子物理学计算

Neutronics calculation of a reactor cold neutron source

用MCNP软件计算反应堆冷中子源，慢化剂室内平均中子注量率为6．69×10^13／cm^-2·s^-1，波长为0．411113和0．6nm的冷中子增益因子-16和32。冷源慢化剂中正仲氢比例对输出的冷中子能谱有较大影响，而在3K范围内慢化剂温度变化对冷中子能谱的影响很小。计算结果表明，冷中子源性能达到基本设计要求。

The construction of a reactor cold neutron source （CNS） will be completed in the near future. To evaluate performance of the CNS, a neutronics calculation using MCNP4C code has been carried out. The results show that the average neutron flux in the moderator is 6.69× 10^13/cm^2·s, and the cold neutron gain factors corresponding to 4-A and 6-A wavelengths are 16 and 32, respectively. The results also indicate that different ratios ofortho-Hz/para-H2 have an obvious impact on cold neutron spectrum in the moderator, but within 3 K of the moderator temperature changes, the spectrum varies slightly.