用蒙特卡罗方法计算点通量和面通量时,都存在着估计量无界问题。由于估计量无界直接影响蒙特卡罗方法的计算效果,有时还直接影响收敛速度,因此,作为蒙特卡罗方法的一个问题受到了普遍重视。作为点通量计算中的估计量无界问题,从1963年开始直到现在仍然不断地有人在进行研究,并取得了不少可喜的成果。然而,作为面通量计算中的估计量无界问题,直 When Monte Carlo method is used to calculate the point flux and the surface flux, there is an unbounded estimator. As the unbounded estimation directly affects the computational effect of the Monte Carlo method and sometimes directly affects the convergence rate, a problem as a Monte Carlo method has received universal attention. As an unbounded estimator in the calculation of point fluxes, there have been ongoing studies from 1963 till now and many promising achievements have been made. However, as an unbounded problem in the estimation of surface flux, straight