基于堆外中子能谱测量的堆芯中子场 反演方法

[Background] The self-powered detectors (SPD) are widely used in commercial reactor for the real-time measurement of neutron flux distribution, but neutron spectrum cannot be obtained by SPD. Meanwhile, due to the extreme condition of advanced reactor systems, the existing in-core measurement systems cannot meet the requirement of real-time measurement of neutron field in the core of advanced reactor. [Purpose] This study aim to develop an inversion method of in-core neutron field based on ex-core neutron spectrum measurement. [Methods] First of all, Monte Carlo calculation method was employed to obtain the spectrum response matrix between adjacent truncated planes in the core by forward neutron transport calculation. Then, the in-core neutron field could be inversed. Finally, two simplified reactor models were used for method verification and validation. [Results] For the neutron field in the pressure vessel, the average relative deviation between the inversion result and the Monte Carlo transport computation result was about 14%, and for the neutron field in the external fuel region, the average relative deviation was about 11%. [Conclusion] The inversion method of in-core neutron field proposed in this paper preliminarily demonstrated the feasibility of the method for neutron spectrum monitoring in the reactor core.