Benchmarking PHITS for radiation dose assessment from fly ash-blended concrete using MCNP6 and ResRad-Build
Lam Duy Nhat, Le Huu Loi, Le Quang Vuong, Vu Tuan Minh, Ho Van Doanh, Phan Long Ho, Tran Thien Thanh, Hoang Duc Tam
Applied Radiation and Isotopes, vol. 234, p. 112658, Apr. 2026
Abstract
In this study, the PHITS Monte Carlo code is applied for the first time to evaluate indoor radiation exposure associated with fly ash–blended concrete, and its performance is systematically benchmarked against the widely used ResRad-Build program and MCNP6 code. A reference room conforming to RP-112 dimensions (5 m × 4 m × 2.8 m) was modeled, and eight concrete mixtures containing 0–50% fly ash were investigated. The activity concentrations of 226Ra, 232Th, and 40K, along with material composition ratios and densities, were used as input parameters for simulations with PHITS, ResRad-Build, and MCNP6. The annual effective doses calculated using PHITS ranged from 0.378 to 0.489 mSv.y−1. The maximum relative deviations between PHITS and MCNP6 and between PHITS and ResRad-Build were 5.9% and 7.9%, respectively. PHITS exhibited the closest agreement with the reference dose estimate derived from measured activity concentrations, with a maximum relative deviation of 3.6%. These findings clearly demonstrate that PHITS is a highly reliable and effective tool for assessing indoor radiation exposure from building materials.
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