SMR, 3D source term simulation for exact shielding design based on genetic algorithm

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One of the most important issue in the safe design of a small modular nuclear power reactor (SMR) is utilizing an efficient, compact, and lightweight radiation shielding capable of meeting the principal requirements of radiation protection. The radiation shielding design is a complicated multi-objective problem considering the current limitations. In this study, the three-dimensional and accurate modeling of the source term considering the real conditions of the reactor core has been performed and uses the genetic algorithm (GA) to improve the reactor radiation protection shielding system of SMR power reactors. The method upgraded in this research aims to reach an efficient design for the radiation shielding of the SMR power reactors regarding the present requirements and limitations. The thickness of different layers against the mixed-radiation fields of neutrons and gamma emitted from a nuclear reactor has been optimized to obtain a compact and lightweight shield design. The genetic algorithm coupled with the Monte Carlo Nth-Particle (MCNP) has been used for optimization. The shielding of a small modular reactor has been considered as a practical example and the reference for the calculations to evaluate and validate the developed technique and the thickness of different layers of radiation shielding has been optimized using the developed intelligent method. The shielding materials are identical to the original design, and optimization merely involves layer thickness values. Finally, considering the requirements and limitations, our design has been proposed, with a weight and volume comparison to the original design.The calculations indicate that the overall thickness of the shielding is suggested as 128.6 cm, compared to 153.7 cm the thickness of the reference to obtain the total dose of neutrons and Gamma less than 10µSv/h. The results imply a 20.9% reduction in volume and 19.35% in weight of the radiation shielding compared to the reference reactor design. It should be noted that unlike previous research, the present study used an optimization based on Monte Carlo calculations considering the real 3-D geometry of the reactor and its shield.