基于蒙卡-点核积分耦合的核电厂退役辐射场计算

Calculation of radiation field during nuclear power plant decommissioning based on the coupling of MC and point kernel integration

针对核电厂退役现场中复杂和简单几何区域并存的问题,以及退役过程对辐射场计算提出的快速、准确的要求,提出了蒙卡和点核积分耦合计算方法,并开发了耦合计算程序。对于单体源模型,由于模型简单,耦合方法、点核方法与蒙卡方法的计算结果均较接近,相对偏差小于10%,但耦合方法的计算速度比蒙卡方法提高了3.5倍;采用耦合方法和蒙卡方法分别计算了多体源模型的辐射场,结果表明耦合方法的计算准确度较高,相对蒙卡方法偏差小于40%,计算时间约为蒙卡方法的1/5。以秦山一期退役辐射场为例开展了计算分析,结果显示,耦合方法与蒙卡方法的计算结果相差不超过1个数量级,但前者计算速度比后者提高了约3倍,说明耦合方法可以满足核电厂退役辐射场计算需要。

In view of the coexistence of complex and simple geometrical areas in the decommissioning site of nuclear power plants,and the requirements of speediness and accuracy for the radiation field calculation during decommissioning process,a coupling calculation method of Monte Carlo and point kernel integration is proposed.Besides,a coupling calculation program is developed.For the single source model,due to the simpleness of this model,the results of the coupling method,the point kernel integration method and the Monte Carlo method are all close,and the relative deviations are less than 10%;but the calculation speed of the coupling method is 3.5 times as fast as that of the Monte Carlo method.Then the radiation field of the multi-body source model is calculated by the coupling method and the Monte Carlo method.The results show that the calculation accuracy of the coupling method is relatively high,the deviations are less than 40%,and the calculation time is shortened to 1/5 compared with the Monte Carlo method.The decommissioning radiation field of Qinshan phase I is calculated.The results demonstrate that the calculation results of the coupling method and the Monte Carlo method differ by no more than one order of magnitude,and the calculation speed of the former increases by 3 times than the latter,indicating that the coupling method can meet the needs of decommissioning radiation field calculation of nuclear power plants.