Present status of JRR-3 neutron guide tubes

JRR-3 reactor is a research reactor of 20 MW, and its main use is neutron beam experiments. Aiming at effective and efficient utilization, neutron guide tubes were introduced in 1990. Neutron guide tubes consist of 2 tubes for hot neutrons and 3 tubes for cold neutrons, and they are laid up to the beam hall adjacent to the reactor building. This allows the installation of about 20 experimental devices, and a wide variety of researches are carried out using these devices. To achieve higher performance of these neutron guide tubes, the updating to supermirror with high neutron transport efficiency is under way. As for the hot neutron guide tubes, hot neutron intensity has become approximately 6 times until now, which realized a large extent of efficiency. On the other hand, the soundness of the equipment has become a major issue after the Great East Japan Earthquake. This paper reports the confirmation of the soundness of neutron guide tubes, contents of restoration work, and current situation after the restoration work. (A.O.)