Application of improved quasi-static method to high temperature gas cooled reactor simulator

Solving neutron time and space kinetics equation is one of the most important parts in the simulation of high temperature gas cooled reactor (HTR). It can provide the real time neutron flux and the power density for the thermal calculation. The simulation requires solving equation quickly. The improved quasi-static method can be used to fit the requirement of simulation. This method split the flux into two parts, the amplitude function and the shape function. This method simplifies the solving of the neutron kinetics equation. The method of the improved quasi-static used in HTR simulator is described in detail. Piecewise polynomial method is used to solving amplitude function. This can decrease the time step of amplitude function without increasing time. Periodic boundary condition will increase the difficulty of the matrix solving in shape function. In this paper, preconditioned orthomin methods are used to solve shape function, which can solving the shape function in the required time with periodic boundary conditions. At last, the result of the method is shown. The calculation time of the kinetics equation in one time step is less than 100 ms which is smaller than the time step. Analysis of this application show the improved quasi-static is good suitable for simulation of high temperature gas cooled reactor.