Dose Measurements through the Concrete and Iron Shields under the 100 to 400 MeV Quasi-Monoenergetic Neutron Field (at RCNP, Osaka Univ.)

Yoshibumi Nakane ,Yosuke Iwamoto,Daiki Satoh,Masayuki Hagiwara,Takashi Nakamura,Hiroshi Yashima,Hiroshi Iwase,Tomoya Nunomiya,Tatsuhiko Sato,Akihiko Masuda,Hiroshi Nakashima,A Tamii ,Tadao Matsumoto ,T Shima ,K Hatanaka

doi:10.1051/epjconf/201715308022

Abstract

Shielding benchmark experiments are useful to verify the accuracy of calculation methods for the radiation shielding designs of high-energy accelerator facilities. In the present work, the benchmark experiments were carried out for 244- and 387-MeV quasi-monoenergetic neutron field at RCNP of Osaka University. Neutron dose rates through the test shields, 100-300 cm thick concrete and 40-100 cm thick iron, were measured by four kinds of neutron dose equivalent monitors, three kinds of wide-energy range monitors applied to high-energy neutron fields above 20 MeV and a conventional type rem monitor for neutrons up to 20 MeV, placed behind the test shields. Measured dose rates were compared one another. Measured results with the wide-energy range monitors were in agreement one another for both the concrete and the iron shields. For the conventional type rem monitor, measured results are smaller than those with the wide-energy range monitors for the concrete shields, while that are in agreements for the iron shields. The attenuation lengths were obtained from the measurements. The lengths from all the monitors are in agreement on the whole, though some differences are shown. These results are almost same as those from others measured at several hundred MeV neutron fields.

Highlights

In the radiation shielding designs and safety analyses, calculation methods were used(1) for high-energy and high-intensity proton accelerator facilities
Neutron dose rates through the concrete and the iron test shields were measured by four kinds of neutron dose equivalent monitors for 244- and 387-MeV quasi-monoenergetic neutrons generated from the 7Li(p,n) reactions at the Research Center of Nuclear Physics (RCNP) ring cyclotron of Osaka University(2)
The attenuation lengths were obtained from the measurements for the concrete and the iron shields, and compared

Summary

Introduction

In the radiation shielding designs and safety analyses, calculation methods were used(1) for high-energy and high-intensity proton accelerator facilities. In order to verify the accuracy of calculation methods for the dose estimations of shielding designs, shielding benchmark experiments for several hundred MeV neutrons are useful, especially for those performed at the fields that the intensity and the energy spectrum of source are well known. Neutron dose rates through the concrete and the iron test shields were measured by four kinds of neutron dose equivalent monitors for 244- and 387-MeV quasi-monoenergetic neutrons generated from the 7Li(p,n) reactions at the Research Center of Nuclear Physics (RCNP) ring cyclotron of Osaka University(2). The test shields, 100-, 200- and 300-cm thick concrete and 40-, 70and 100-cm thick iron, were placed on the neutron beam at the position of 17.66 m from the Li target. Neutron dose rates were measured with four kinds of neutron monitors placed behind the test shields

Hydrogen Oxygen Sodium Magnesium Aluminum Silicon P o t assium Calcium

Results and discussions

JAEA Wide Range D A RW IN

Conclusion