启明星Ⅱ次临界非稳态热中子注量率测量

中子注量率及分布是反应堆的重要参数，本工作通过核数守恒在非稳态情况下的推导和求解，从理论上论证了次临界反应堆非稳态情况下中子注量率测量的可行性。将活化法和固体径迹法有机结合，利用固体径迹探测器标定活化片的测量数据，测量了启明星Ⅱ零功率装置的He-3管实验孔道内及反应堆外壁的中子注量率的分布，并与模拟计算结果进行了比较，利用MCNPX程序得到的模拟计算结果与实验结果的趋势一致，证明了该测量方法可以测量低通量的中子注量率，可实现反应堆不同时刻、不同位置的中子注量率测量，为CiADS技术的研发提供了实验数据与技术支撑。Neutron flux measurements were carried out at VENUS-Ⅱ lead-based zero power reactor by neutron activation method combined with solid-state nuclear track detectors (SSNTD). This experimental method was proposed based on the principle of nuclear number conservation when a foil was irradiated in an unsteady-state neutron field. By this method, thermal neutron flux distributions inside the He-3 duct were measured when VENUS-Ⅱ was operated under unsteady-state. The neutron flux distributions were also calculated with MCNPX code and were consistent with the experimental data. In addition, the neutron fluxes in the outer layer of VENUSⅡ were measured under steady-state. These results would benefit the further study of experimental methods for neutron flux measurement and provide important support for the design of CiADS.