Establishing dose constraint for radiation protection during NPP normal operation: A case study of multi-units 100 MWe SMR in West Kalimantan, Indonesia

This study proposes public dose constraints for Small Modular Reactors (SMRs) during normal operation. These constraints, set by Nuclear Power Plant (NPP) authorities, aim to meet As Low As Reasonably Achievable (ALARA) standards, ensuring consistent adherence to safety protocols and early detection of deviations to prevent accidents. A case study involving ten 100 MWe SMRs in West Kalimantan, Indonesia was conducted. Methods included analyzing background radiation measurement, inventory assessment, radioactive release estimation, Gaussian atmospheric dispersion modeling, and radiation dose calculations. Results indicate an average environmental background dose rate of 0.417 ± 0.1807 mSv/year, with the highest effective dose from a single NPP unit being 1.83E-04 mSv at 100–300 m. Indonesia adheres to regulations for implementing dose constraints to fulfill the ALARA principle. With a proposed dose constraint of 0.1 mSv/year, the deployment of 10 SMR units is considered feasible from a radiation protection perspective, without compromising plant operability, since the combined estimated dose from 10 units is only 1.83E-03 mSv/year. Within the monitoring program, any recorded total dose exceeding 0.698 mSv (background radiation plus the proposed dose constraint) would necessitate an internal review of plant procedures and operations. The anticipated margin remains significantly below the regulatory dose limit, providing flexibility to accommodate variations in local data and reactor operation. Therefore, once the NPP is operated, the proposed dose constraint can reasonably be maintained or periodically reassessed as necessary.