一种基于^(103)Rh(n,n′)^(103)Rh^m反应的快中子注量监测方法

A fast neutron fluence monitor method based on ^(103)Rh(n,n′)^(103)Rhm reaction

给出了一种基于^(103)Rh(n,n′)^(103)Rh^m反应监测快中子注量的方法。根据干扰核素半衰期不同的特点,选取合适的冷却和测量时间,降低了^(103)Rh(n,n′)^(103)Rh^m活化率测量中干扰核素的影响。根据152Eu标定实验结果,利用遗传算法优化探测器尺寸,建立探测器蒙特卡罗算法模型。利用模型校正^(99)Mo-^(99)Tcm放射源实验效率,解决了探测器效率标定和射线自吸收问题。开展了快中子注量监测,实验结果与铁、硫、镍等快中子监测箔一致性较好,测量不确定度约为13.1%。

Background： Accurate neutron energy spectra and neutron flux parameters are needed to provide the neutron beam service for the reactor users. Purpose： The aim is to accurately measure the fast neutron fluence in Xi＇an pulsed reactor. Methods： A neutron fluence monitor method based on ^103Rh（n,n＇）^103Rh^m reaction was presented. According to the difference of half-life of interference nuclides, cool-down time and measuring time are properly selected to reduce impacts of interference nuclides during the ^103Rh（n,n＇）^103Rh^m activation rate measurements. On the basis of 152Eu calibration experiment results, the Monte Carlo model of detector was established with optimized detector size by genetic algorithm, the problem of detector efficiency calibration and ray self-absorption was solved. Results： A fast neutron fluence monitor experiment based on this method has been performed, the result of which was consistent with Fe, S, and Ni. The uncertainty of measurement is 13.1%. Conclusion： The establishment of this method successfully solved the problem of fast neutron fluence monitoring in Xi＇an pulsed reactor.