To explore the Monte-Carlo definition of multiplication factor and the impact from specific reactions, a compact Monte Carlo method is established, which obtains k_∞ simply based on neutron balance, without concerning geometry or time; the neutron transport is merely of one dimension, the kinetic energy; the neutron-multiplying reactions (n, xn), which are significant in a fast spectrum, are treated as fission. This paper tries to demonstrate the accuracy of such a method in k_∞ calculation. Based on continuous-energy ACE data format, a Monte Carlo code is developed and validated with intermediate-spectrum benchmarks and pseudo fast-spectrum materials; the state-of-the-art Monte Carlo code RMC is used to make comparative calculations. It is found that the code gives satisfactory predictions on benchmark values and the relative differences with RMC are within 100 pcm for all materials and reactivity levels. In fast spectra a tendency of difference of k_∞ between the two codes is found and well explained by a quantitative study of different treatments of the (n, xn) reactions.

为了探索乘法因子的蒙特卡洛定义和特定反应的影响，建立了一种紧凑的蒙特卡洛方法，该方法仅基于中子平衡即可获得_k∞，而无需考虑几何形状或时间。中子传输只是一维动能。在快速光谱中很重要的中子倍增反应（n，xn）被视为裂变。本文试图证明这种方法在_k∞中的准确性。计算。基于连续能量ACE数据格式，开发了蒙特卡洛代码，并使用中谱基准和伪快谱材料进行了验证；最新的蒙特卡罗代码RMC用于进行比较计算。发现该代码对基准值给出了令人满意的预测，并且对于所有材料和反应性水平，与RMC的相对差异均在100 pcm之内。在快速光谱k的差的倾向_∞两个码之间没有发现由第（n，xn）映射反应的不同处理的定量研究很好地解释。