Algorithm Research On The Point Reactor Neutron Dynamic Equation And MNSR Simulation

Using the miniature neutron source reactor(MNSR) in Institute of nuclear technology Shenzhen university researchers have achieved a lot of scientific achievements and technology patents. This subject take MNSR as the research object, and use Visual Studio to develop simulation software of MNSR base on point reactor model, use 3DMax software to create 3D model of MNSR.According to nuclear reactor theory the behavior of neutron which in the core can be described by neutron transport equation, and base on this equation we can get the point reactor model through reasonable simplification and approximation. Point reactor model can well describe the neutron flux density change over time under critical state, however it is difficult to calculate the neutron dynamics equation of the point reactor model, this mainly due to the huge difference between the reactor physics parameters and lead to the neutron dynamics equation has strong stiff(Use general numerical algorithm to calculate stiffness equation have instability and great error). In order to use numerical method to calculate the neutron dynamics equations, researchers published a number of different numerical methods, such as the fully implicit Runge-Kutta method, Pade approximation method, Gear method etc.However according to the requirements of the subject we assum e that the reactivity of reactor inserted in the form of step change, and rewrite the neutron dynamics equation which with six group delayed neutron into matrix form, through the analysis of mathematical method, we get that the solution of neutron dynamics equation which with reactivity step change can be determined after accurately calculating the eigenvalues of the coefficient matrix, So this method transfer the difficulty of neutron dynamics equation calculation to solve eigenvalue, and compared with the method given i n the previous literature, this is a new method. In this paper the QR decomposition algorithm be used to calculate matrix eigenvalue, and the error is very small compared with the precision value calculated by specialized mathematical software.Reactivity control is the key to the safe operation of the reactor. This subject based on the design principle of MNSR to establish the reactivity feedback model, and use engineering experience formula to calculate reactivity insertion quantitatively, and combine this feedback model with neutron dynamic equation to build physical model for MNSR simulation program development, this program can simulate change trend of neutron flux density, core power etc. under steady state. This program dos’ t suitable for accurate simulation of parameters change, because of model is not very perfect.MNSR simulation program need to process many data synchronously when it run, However, if write the program in a serial manner there will be much bug when the program running. In order to solve this problem, multithreading technology is used in this program, it can divide data processing into multiple threads. On the whole, two threads in the MNSR simulation program are designed for program interface data show and program background data calculation respectivelyUsing 3DMax to build the three dimensional simulation of MNSR, 3DMax provides with software development toolkits to users, Take advantage of these toolkits, 3d models can be secondary development, by combining with Visual Studio a visual three-dimensional MNSR simulation program can be created.