摘要
为了深入剖析氢化锂慢化剂正温度效应产生的原因,基于空间核热推进(space nuclear thermal propulsion,SNTP)粒子球床堆(particle bed reactor,PBR)的物理模型,使用MCNP程序,从中子热化效应、氢化锂热膨胀效应和极限情况下氢化锂热离解效应3个方面进行慢化剂正温度效应分析。研究表明,在低能区,靶核的热运动、原子之间的化学键及不同中子波之间的干涉效应不能忽略,且随着温度的升高,靶核的激发态更易被激发,此时非弹性散射更易发生、中子更易获得能量,能谱硬化;氢化锂慢化剂正温度效应对PBR堆芯反应性的影响因素中,中子热化效应占主导地位,引入的反应性达到2 000pcm,氢化锂热膨胀效应和热离解效应影响较小,引入的反应性分别约为-130pcm和200pcm。
To study the reason of the positive temperature effect of lithium hydride modera-tor, based on the particle bed reactor （PBR） physical model of the space nuclear thermal pro-pulsion （SNTP） , it was analyzed by three aspects of the neutron thermal Kernel effect, lithi-um hydride thermal expansion effect and the limit lithium hydride thermal dissociation effect by using MCNP code. The results show that the thermal motion of the target nucleus, and the interference effect of the chemical bonds and neutron wave cannot be ignored in the low energy region. When the temperature rises, the excited target nucleus is more easily excited, and the inelastic scattering is more susceptible to takeplace, the neutron energy spectrum be-comes hardening when getting more energy. The neutron thermal kernel effect is dominant, which causes about 2 000 pcm reactivity to the PBR core, and the thermal expansion effect and the thermal dissociation effect of lithium hydride material are less affected than the for-mer, which causes about -130 pcm and 200 pcm reactivity to the PBR core, respectively. The results provide a basilica reference for the future physical analysis of the PBR core safety.
出处
《现代应用物理》
2017年第1期8-13,共6页
Modern Applied Physics
基金
国家自然科学基金资助项目(11275152)
关键词
空间核热推进
粒子球床堆
热化效应
热膨胀效应
热离解效应
space nuclear thermal propulsion
particle bed reactor
thermal kernel effect
thermal expansion effect
thermal dissociation effect
