放射線施設の遮へい計算のための数値表の改善―線量率定数および透過率表―

概要

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The numerical tables of dose rate constants and penetration factors of radioisotopes, published in “Manual for shield calculation of radiation facilities, Nuclear Safety Technology Center (2007)”, are widely employed in estimating the effective dose of radiations from radioisotopes. In order to extend the expedient shield calculation method with the tables in the “Manual”, we have prepared new tables of dose rate constants and penetration factors. Main improvements in the present tables are as follows: 1) Number of radioisotopes available for the calculation is increased from 66 to 429 and that of decay chains are increased from 8 to 48. 2) Some incorrectness in the “Manual”, which is related to the estimation for β-ray bremsstrahlungs, are pointed out and discussed: β-ray spectrum, β-ray bremsstrahlung spectrum and bremsstrahlung emission efficiency ratio. 3) Dose rate constants and penetration factors of bremsstrahlungs caused by mono-energetic electrons (internal conversion and Auger electrons) are newly estimated. The incorrectness in the “Manual” is explained in this paper. Notable differences between the present tables and the “Manual” are also discussed.