Numerical Study And Preliminary Application Of Activation Method Based On CRAM

Nuclear reactors will produce a large number of neutrons when the plant is in operation. These neutrons have very strong activation effect on in-core materials and corrosion products, which will cause radiation harmful effects on staff who are responsible for work such as operations, maintenance and decommission. So the calculation of material neutron activation has a very important implication for the reactor design and safety. This paper studied activation calculation of nuclear reactor structural materials (mainly light nuclei and medium mass nuclei), conducted investigation and research on methods and codes, developed an activation calculation codes CEACT based on Chebyshev rational approximation method (CRAM) and Euler exponential method with a preliminary test and application.Activation which is a special form of burnup focuses on absorption reaction of light nuclei and medium mass nuclide. This paper focuses on the method of activation calculation based on the burnup theory. Therefore, the method which is suitable for burnup calculation, also applies to activation calculation. There are two categories of methods for solving the burnup equations, namely analytical method and numerical method. After comparison of the advantages and disadvantages of different methods, traditional Euler exponential method and CRAM were selected for solving the burnup equations respectively. Euler exponential method of is a traditional and simple numerical method. It improves the time item based on the Euler exponential method with simple implementation process. But for short life nuclei, this method needs equalization treatment according to the calculation time. Compared with traditional burnup method, CRAM has higher accuracy and efficiency, can deal with the stiffness problem for short life nuclide burnup system. The EAF-2007 database was adopted for the codes CEACT with Euler exponential Method and CRAM respectively.Finally, this paper used CEACT activation codes and a European general activation codes FISPACT to study the activation of cladding material in PWR reactor and first wall material in fusion reactor. The results show that the CEACT codes can achieve high accuracy and can provide technical support for shielding design and safety analysis for both fission reactor and fusion reactor domestically.