Background The Monte Carlo (MC) particle transport methodology incorporates stochastic principles derived from probability theory and mathematical statistics to establish computational frameworks. This approach facilitates the numerical resolution of complex particle transport phenomena in nuclear systems. Over the course of seven decades of development, Monte Carlo (MC) particle transport theory and algorithms have reached a high level of technical maturity. This has resulted in the development of several specialized software packages, which are widely applied in fields such as nuclear radiation shielding, reactor core criticality safety analysis, nuclear detection, and radiation medicine.

Purpose JMCT is a 3D Monte Carlo particle transport software that supports neutrons, photons, electrons, and their coupling. It features visual modeling tools, general transport algorithms with variance reduction techniques, comprehensive tallying capabilities, and ultra-large-scale parallel computing power. JMCT has been successfully applied to the simulation of reactor models such as the Ningde Nuclear Power Plant, CAP1400, CFR600, and Hualong One. Additionally, it has been introduced and procured by multiple institutions in the nuclear energy sector, including the CGN Research Institute, Shanghai Nuclear Engineering Research and Design Institute (SNERDI), and the China Institute of Atomic Energy (CIAE).The JMCT software faces issues such as functional development, code maintenance, and user source code protection.

Methods Expandable points in the Monte Carlo particle transport simulation was identified by analyzing Monte Carlo particle transport equation. A highly expandable Monte Carlo transport software architecture was designed, enabling functional component modules to becomes highly cohesive and loosely coupled. This architecture significantly simplified development and maintenance while protecting user-developed functional component source code. Based on this architecture, the Monte Carlo Particle Transport solver library MCPT was developed.

Results MCPT provides seven categories of secondary development interfaces, substantially meeting users' customized development and source code protection requirements. It also offers various mature functional component modules that can reduce users' coding workload. Preliminary evaluations indicate that developing personalized Monte Carlo particle transport simulation software using MCPT can save 30%-95% of coding efforts.

Conclusions JMCT has been reconstructed using MCPT. This transformation has significantly improved both expandability and maintainability.