Research Of Thermal Feedback For The Whole Core High-Fidelity Neutron Transport Calculation

The core of neutron physical numerical simulation in a numerical nuclear reactor lies in the development of a "one-step method" fine and efficient neutron transport calculation program and the establishment of a fully three-dimensional fine calculation model.In the process of neutron physical calculation,core physics and thermal parameters influence and restrict each other,among which thermal feedback effect is the basis of core physics analysis,and thermal feedback calculation is also an important part of neutron physics calculation of the reactor.The main purpose of thermal feedback calculation is to predict how the temperatures of fuel and moderator inside the reactor core change over time,and by temperature feedback to the reactor core physics to analyze the influence of temperature on power distribution and reactivity control.To some extent,it can also simulate physical processes in the real reactor,which has certain positive significance to the reactor core physical calculation.In this paper,the existing high-fidelity neutron transport calculation codes and their thermal feedback calculation methods are investigated.After summarizing and analyzing the advantages and disadvantages of each various models and taking the requirements of the program to be coupled into account,the single-channel model is selected to study the thermal feedback calculation method and to develop the thermal feedback code.The single-channel model has the advantages of its simplicity and high computational efficiency,and it can provide enough accuracy for the current code.In this paper,the thermal feedback calculation method is studied under steady and transient states based on the single-channel model,and the calculation method of temperature of moderator has been improved,and the independent thermal feedback solver under steady and transient states has been developed based on the C programming language.The reliability of the method is confirmed by calculating a single rod.According to the developed thermal feedback solver,the thermal feedback module is successfully coupled to HNET under steady state,and the coupled code is verified and analyzed under different calculation conditions.Compared with other high-fidelity neutron transport calculation codes,the eigenvalues calculated by HNET under different boron concentrations and power levels are in the same range.The axial power distributions and axial termperature distributions are almost the same.All results show that HNET coupling with thermal feedback is able to solve the problems which need thermal feedback under steady state,and it shows well accuracy and efficiency,which is practical for research of reactor physical calculation.