Comparative Assessment of Radioactive Contamination in APR 1400 Reactor During SBO and TMI Accidents

Abstract

An alternative approach to estimate the tissue phantom ratio (TPR) at depths of 20 cm and 10 cm (TPR₂₀,₁₀) under non-reference conditions is required to address situations where a 10 × 10 cm² field size is not achievable on a specific linear accelerator (LINAC) during a beam quality test. This study aims to estimate the TPR20,10 under non-reference conditions using a geometric sequence approach, and to compare it with the TPR₂₀,₁₀ under non-reference conditions estimated using the Sauer method, the Palmas method, a linear fit approach, as well as with the TPR₂₀,₁₀ under reference conditions calculated using the TRS-398 protocol. The first step in this study was measuring the percentage depth dose (PDD), D20cm, and D10cm with field size variations from 4 × 4 cm² to 10 × 10 cm² for both 6 MV and 10 MV X-ray beams. The PDD were used to estimate the TPR₂₀,₁₀ using a geometric sequence approach, the Sauer method, the Palmans method, and a linear fit approach, and to calculate the TPR₂₀,₁₀ using the TRS-398 protocol. The D20 cm and D10 cm were also used to calculate the TPR₂₀,₁₀ using the TRS-398 protocol. The TPR₂₀,₁₀ for 6 MV and 10 MV X-ray beams estimated using the geometric sequence approach were 0.683 ± 0.004 and 0.742 ± 0.005, respectively. The level of precision that could be reached by the geometric sequence approach is potentially equivalent to the TRS-398 protocol, the Sauer method, the Palmans method, and the linear fit approach. The TPR₂₀,₁₀ for 6 MV and 10 MV X-ray beams estimated using the geometric sequence method did not show a significant difference compared with the TPR₂₀,₁₀ calculated using the TRS-398 protocol. However, the TPR₂₀,₁₀ for 6 MV and 10 MV X-ray beams estimated using the geometric sequence approach showed a significant difference compared with those TPR₂₀,₁₀ estimated using the Sauer method and the Palmans method.