2018 High Power Targetry Workshop

Target system maintenance experience in hot cell at J-PARC

7 Jun 2018, 16:40

20m

1200 FRIB Bldg

Oral 7-Operation of Targets and Beam Dumps Session 7-Operation of Targets and Beam Dumps

Speaker

Dr Takashi Naoe (Japan Atomic Energy Agency)

Description

At the Japan Proton Accelerator Research Complex (J-PARC), a mercury target system has been in operation as a neutron production target of the spallation neutron source driven by 3-GeV protons. It is loaded on a big target trolley that has a dimension of 12.2 m in length, 2.6 m in width and 4 m in height and moves horizontally on a rail in a hot cell. The volume of the hot cell is as large as L43 $\times$ W12 $\times$ H15 m. Half area of the hot cell is used for the maintenance of the mercury target system and the floor is covered by a stainless lining considering a leak of liquid mercury. The other half area is used for the replacement of the proton beam window and moderators. Target vessel replacement is performed with full-remote handling devices such as a 6-axis power manipulator, 3 pairs of master/slave manipulators, an in-cell overhead 20 t crane and radiation resistant cameras. Since a large amount of radioactive gaseous nuclides are generated in mercury via the spallation reactions, they should be transferred from the surge tank of the mercury circulation system to an off-gas processing system before removing the used target vessel. The off-gas processing system is installed in a room nearby the hot cell. It is also operated during target replacement work to suppress the release of tritium in the mercury target system to open air . The used target vessel is contained in a stainless steel container and moved to a storage room on the basement floor with the overhead crane. More detailed design of hot cell and experiences on the target system maintenance will be presented.

Presentation materials

Slides

66-Target_system_maintenance_experieence_experience_in_hot_cell_at_J-PARC.pdf