Neutron noise measurements for estimating void velocity in a void-containing water flow where spherical bubbles move upward are simulated using a continuous energy Monte Carlo method. The method is newly equipped with a function for handling time-varying locations of void bubbles. In the simulations, time-series data of neutron counts in axially-placed detectors are obtained. The data are subsequently processed to yield the cross-correlation function (CCF), cross-power spectral density (CPSD), and auto power spectral density (APSD). The void velocities are estimated from the maximum CCF, slope of the phase of the CPSD as a function of frequency, and dip frequency of the APSD. These three methods yield a constant void velocity estimation. The simulations demonstrate that the noise techniques are insensitive to a void flow that contains smaller bubbles.

使用连续能量蒙特卡罗方法模拟用于估计含空隙水流中的空隙速度的中子噪声测量，其中球形气泡向上移动。该方法新配备了处理空泡随时间变化的位置的功能。在模拟中，获得了轴向放置的探测器中子计数的时间序列数据。随后处理数据以产生互相关函数 (CCF)、交叉功率谱密度 (CPSD) 和自功率谱密度 (APSD)。空隙速度是根据最大 CCF、CPSD 相位斜率作为频率的函数以及 APSD 的倾角频率来估计的。这三种方法产生恒定的空隙速度估计。