Reactor activation-burnup calculation is a crucial component of reactor analysis, involving an iterative process that combines criticality programs with point burnup programs.

This study aims to design and develop a novel lightweight, general-purpose activation-burnup program, named LightAB (Light Activation and Burnup) for activation-burnup calculation.

Burnup databases on the basis of ORIGEN-2 and ORIGEN-S were utilized and the Chebyshev rational approximation (CRAM) algorithm was implemented in LightAB for accurate burnup systems. Point burnup calculations in decay mode, constant flux mode, and constant power mode were supported by LightAB with well-structured program architecture, consisting of a solver module, an I/O module, and a burnup chain module. In the meanwhile, nuclide was used as the fundamental unit of storage, and physical quantities such as burnup database path and sub-burnup step division were specified as the input module of LightAB. Thereafter, the decay of ²³⁷Np and the irradiation of Zr under fixed-flux conditions were calculated using LightAB for accuracy validation, and various reactor burnup models, including pressurized water reactor (PWR) cell, PWR assembly, and Organisation for Economic Co-operation and Development/Nuclear Energy Agency (OECD/NEA) fast reactor models, were calculated by coupling LightAB with RMC programs. Finally, LightAB was applied to the irradiation production of transplutonium isotope with comparison to RMC.

Results of LightAB are consistent with that of ORIGEN 2.1 for the calculation of ²³⁷Np's decay and Zr's irradiation. Calculation results of LightAB coupling with RMS programs are consistent with RMC calculations. The errors between LightAB and RMC for production calculation of transplutonium isotope in three cases are within 5%.

LightAB has shown promising application prospects in the irradiation production of transplutonium isotopes compared with RMC simulation calculations.