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A soft-type neutron-shielding resin has been developed by improving an existing hard-type neutronshielding material using the epoxy-based resin as an additional shielding material. A flexible heat-resistant neutron-shielding material has been developed, which consists of a new polymer-based resin with boron. The neutron shielding performance of the developed flexible heat-resistant resin with the 252 Cf neutron source is almost the same as that of polyethylene. The outgases of H, H 2 , NH 4 , H 2 O, CO, O 2 , C 4 H 10 , and CO 2 from the developed resin have been measured at high temperature (up to 250 C) by thermal desorption spectroscopy methods. The soft-type resin and the newly developed heat-resistant resin will be applied to prevent the effects of neutron streaming and to control the movement of a vibrated pipe as the seal material around the plumbing in the future fast reactor and innovative fission reactor.

Flexible heat-resistant neutron and gamma-ray shielding resins have been successfully developed through the use of a polymer resin. The production process involves a new mixing technique of the resin and materials for neutron absorber/gamma-ray attenuation using a new cold-setting method. The process allows for easy onsite fabrication. The materials are B 4 C powder for neutron shield, Colemanite powder for neutron/gamma-ray shield and FeW powder for gamma-ray shield, respectively. We assessed a basic property and neutron penetration performance of the neutron/gamma-ray shielding resin and carried out a neutron irradiation test of the resin using Japan Research Reactor 3. Gamma-ray shielding performance of the developed resin with FeW powder was performed by using a Monte-Carlo calculation code. The neutron and gamma-ray shielding resins can be used in a high-temperature environment (~200 ºC). These resins will be applied around tokamak fusion devices as an additional shielding: they can reduce neutron and gamma-ray streaming from the device.