Resonance Calculation Method for Non-Rod-Type Fuel in NECP-X Based on Global-Local Coupling Method

Based on the global-local coupling resonance calculation method that has been developed in the NECP-X program, this paper studies the resonance calculation method for non-rod-type fuels. Firstly, the Dancoff correction factor of the real problem is calculated by the neutron current method to deal with the global spatial effect. Then, the pitch of the moderator around small-scale problem is obtained based on the equivalent Dancoff correction factor. Finally, for the calculation of the effective self-shielding cross-sections of the small-scale problem, the resonance pseudo-nuclides subgroup method is used. The method is applied to the numerical calculation of non-rod-type fuel. Numerical results show that when compared with the Monte Carlo results, the maximum microscopic absorption cross-section deviation is less than 1.8%, and the k_inf deviations do not exceed 110 pcm when the method deals with the resonance of non-rod-type fuel pins. These results show that the method has high calculation accuracy; in the calculation of large-scale problem, the deviation of keff of the JRR-3M which is based on plate fuels is about 300 pcm during its burnup life, and the maximum assembly power deviation is less than 0.62%. Therefore, the resonance calculation method proposed in this paper has a high accuracy and precision.