使用MCNP5对启动物理实验中一次中子源(PNS)在堆外源量程探测器(SRD)响应进行模拟计算,分析堆芯有效倍增因子effk、带源有效倍增因子sk和探测器计数C之间的关系。通过对SRD响应系数a的预测,得到优于传统的1/C外推预测临界法的a’/C外推预测临界法,使硼稀释过程中的外推曲线线性度更好。计算结果表明,接近临界时a’/C值与eff1?k线更加吻合。 Using MCNP5 to simulate the response of a primary neutron source (PNS) to the reactor’s extrinsic range detector (SRD) during the start-up physics experiment, the core effective multiplication factor effk, the effective source effective multiplication factor sk and the detector count C are analyzed Relationship. By predicting the SRD response coefficient a, the a ’/ C extrapolation predictive threshold method which is superior to the traditional 1 / C extrapolation prediction critical method is obtained, which makes the extrapolation curve linearity better in the boron dilution process. The calculated results show that the value of a ’/ C approximates the eff1? K line closer to the critical point.