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Current Progress in Standardization of Shielding Concrete Composition for Japanese Facility Design

Yoshihiro Hirao, Koichi Okuno, Ken-ichi Kimura, Mikihiro Nakata, Tomohiro Ogata, Yukio Sakamoto, Ken-ichi Tanaka, Koji Oishi, Satoshi Ishikawa, Masahiro Yoshida, Toshio Amano, Kazuaki Kosako, Toshinobu Maenaka

Nuclear Science and Engineering / Volume 198 / Number 2 / February 2024 / Pages 185-192

Research Article / dx.doi.org/10.1080/00295639.2023.2177077

Received:November 28, 2022
Accepted:February 2, 2023
Published:January 10, 2024

The working group on shielding materials under the Standards Committee of the Atomic Energy Society of Japan has been studying the standard composition of shielding concrete that has a clear basis for use in the design of Japanese facilities. The policy for determining the composition, the procedure of study, the results obtained to date, and future tasks are described. Concrete is broadly classified into silicon type and calcium type depending on the aggregate. The reference mix design and composition were selected from the Japanese recommendation, and minor elements in the composition were replaced with silicon and calcium while preserving their weight in order to reduce regional differences. However, the penetration dose calculation for 235U thermal fission neutrons indicated that iron and carbon should be retained. The penetration dose calculations for photons from 235U prompt fission and radioisotopes showed that the attenuation ratios of silicon-type and calcium-type concretes differ in the energy region where electron pair production becomes dominant. The water content of concrete was found to vary with thickness as a result of moisture migration analysis over time. Finally, a draft composition of silicon-type concrete by thickness was determined using the residual water content at 60 years after placement. A method for correcting the elemental content under different mix conditions was also proposed.