运动增殖系统内中子引发持续裂变链的概率  

Probability of Persistent Fission Chain Initiated by Neutrons in Moving Multiplying Assembly

作　　者：王喆[1] 洪振英[1] 

机构地区：[1]北京应用物理与计算数学研究所,北京100094

出　　处：《核科学与工程》2015年第1期69-75,共7页Nuclear Science and Engineering

基　　金：中国工程物理研究院科学技术发展基金(批准号:2013B0103017)

摘　　要：针对具有一定速度的流动介质构成的增殖系统,依据概率守恒关系,在相对速度相空间建立中子引发裂变链概率的微分-积分方程,推导考虑流体宏观运动影响的表达式。在一维球对称坐标系下,采用离散纵标(SN)方法计算考虑和不考虑流体情形中子引发裂变链的概率,并分析其随时间演化过程的差异。结果表明,堆体材料沿径向方向向外运动时,近似考虑流体运动中子引发持续裂变链的概率计算结果高于不考虑流体运动的计算结果,在流体最大速度为30cm/μs(接近1keV的中子速度)时,二者的差别约为6%。对运动介质宏观运动影响的考虑,提高了实际物理建模的合理性,对于堆体的不同体元具有膨胀和压缩等复杂运动形态或体元的运动速度较高的情形,近似考虑流体运动影响是非常必要的。For a multiplying assembly made up of moving materials having a certain speed, a time-dependent integro-differential equation, which describes the evolvement process of probability of the fission chain, has to be derived in relative velocity space according to the probability conservation, and an expression for fluid movement is deduced from the above equation. Concerning such cases as not considering and approximately considering of fluid movement, the probability is calculated by the multi- group SN method in spherical symmetry coordinate, and the differences of results are studied. The results demonstrate that when the material moves outwards, the results of probability of the fission chain, approximately taking fluid movement into account, are higher than those of not considering of fluid movement. When the most speed of fluid is 30 cm/μs, reaching the speed of 1 keV neutron, the difference of the above results approaches 6 %. Considering the influence of fluid movement improves the rationality of the real physical model. For multiplying assembly whose different parts have such different moving states as expanding and contracting or whose speed is much higher, it is essential that fluid movement is approximately considered.

关 键 词：随机中子输运 裂变链概率 运动介质 

分 类 号：O571.437[理学—粒子物理与原子核物理] TL329[理学—物理]