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裂变数的测定通常是利用HPGe探测器无损测量的方法,但这种方法难以在高辐射通量情况下获取实时数据。针对上述场景,本文引入了剂量率测定裂变数的方法,并进行了可行性验证。本文利用数值计算方法计算裂变产物衰变链上各核素含量随时间动态变化情况,结合CENDL3.0库及ENDF BVII.1库中的产额数据及核衰变数据,计算了热中子辐照铀靶后距裂变产物约1 m处空气总吸收剂量率随时间的变化规律。在西安脉冲反应堆跑兔装置上辐照铀靶,跟踪了距裂变产物约0.5 m处总吸收剂量率变化曲线,结合理论计算结果获取了裂变数。计算均值与后期高纯锗探测器测量铀靶所得裂变数偏差为7%,这表明利用缓发?射线剂量率测定235U裂变数的方法可行,可用于较强剂量场下快速确定核燃料的裂变数。
The determination of fission numbers is usually a method of nondestructive measurement using HPGe detectors, but it is difficult to obtain real-time data with high radiant flux. In view of the above scenario, this paper introduced the method of dose rate determination fission number, and carried out feasibility verification. In this paper, the dynamic changes of the contents of various nuclides on the decay chain of fission products were calculated by numerical calculation. Combined with the yield data and nuclear decay data of CENDL3.0 library and ENDF BVII.1 library, The change law of total absorbed dose rate of air about 1 m behind fission product with time. The uranium target was irradiated on the rabbit-run-off device of Xi’an pulsed reactor and the total absorbed dose rate curve was tracked at about 0.5 m away from the fission product. The fission number was obtained by theoretical calculation. The calculated deviation from the calculated uranium target fission number of the high purity germanium detector in the later period is 7%, which indicates that the method of using 235R fission number is feasible and can be used to quickly determine the fission number of nuclear fuel in the strong dose field .