Improvement of neutron startup source (NS) handling work by developing a new transportation container for the NS of High Temperature Engineering Test Reactor (HTTR)

Shimazaki, Yosuke ; Sawahata, Hiroaki ; Yanagida, Yoshinori; Shinohara, Masanori ; Kawamoto, Taiki; Takada, Shoji

In High Temperature Engineering Test Reactor (HTTR), three neutron holders containing Cf with 3.7 GBq for each are loaded in the graphite blocks and inserted into the reactor core as a neutron startup source (NS) which is changed at the interval of approximately 7 years. These neutron holders containing the neutron sources are transported from the dealer's hot cell to HTTR using the transportation container. The holders loading to the graphite block are carried out in the fuel handling machine maintenance pit of HTTR. Technical issues were recognized for the transportation container in the past two exchange works for the safety handling work of NS holder. On the other hand, it was required that an overhaul of the conventional transportation container or development of a new transportation container because the conventional transportation container was manufactured about twenty years ago. Therefore, the development of a new transportation container for NSs, which can solve these technical issues with low cost, was carried out. Radiation exposure dose of workers was reduced. As the result, it was confirmed that the NS handling work was improved by new transportation container.