Benchmarking PHITS for radiation dose assessment from fly ash-blended concrete using MCNP6 and ResRad-Build

Area of Science:

• Radiation physics and shielding
• Nuclear engineering
• Environmental science

Background:

• Fly ash utilization in concrete can impact indoor radiation exposure.
• Accurate dosimetry is crucial for public health and safety.
• Benchmarking simulation tools is essential for reliable assessments.

Purpose of the Study:

• To evaluate indoor radiation exposure from fly ash-blended concrete using the PHITS Monte Carlo code.
• To benchmark PHITS performance against established codes (ResRad-Build, MCNP6).
• To validate PHITS for assessing radiation from building materials.

Main Methods:

• Modeling a reference room (RP-112 dimensions) with varying fly ash content (0-50%).
• Simulating radiation exposure using PHITS, ResRad-Build, and MCNP6 with input parameters including ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations.
• Systematic comparison of annual effective doses calculated by the different codes.

Main Results:

• PHITS calculated annual effective doses ranging from 0.378 to 0.489 mSv/y.
• Maximum relative deviations were 5.9% (vs. MCNP6) and 7.9% (vs. ResRad-Build).
• PHITS showed excellent agreement with reference dose estimates (max deviation 3.6%).

Conclusions:

• PHITS is a highly reliable and effective tool for indoor radiation exposure assessment.
• The code accurately simulates radiation from fly ash-blended concrete.
• PHITS provides a validated method for evaluating radiation safety of building materials.