|
内容記述 |
The International Fusion Materials Irradiation Facility (IFMIF) project aiming at material tests for a future fusion power plant is now in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the Broader Approach Agreement between Japan and EU. As part of the activities the construction of the Linear IFMIF Prototype Accelerator (LIPAc) is in progress at Rokkasho, Japan. For the validation of the accelerator design to provide 40 MeV and 125 mA continuous wave (CW) deuteron beam on the liquid lithium target, the commissioning of LIPAc is conducted in a stepwise approach to achieve the 125-mA, CW beam acceleration through the low energy section of the IFMIF accelerator up to 9 MeV. After having achieved an important project milestone to accelerate the world highest current deuteron beam of 125 mA at 5 MeV with 0.1% duty cycle (1 ms pulse) through the Radio Frequency Quadrupole linac (RFQ) in July 2019, the next objective is set to validate the acceleration of the deuteron beam with the RFQ at higher duty cycle targeting CW. To this end, the MEBT extension line with quadrupole magnets and steering magnets was newly developed and installed instead of the Superconducting RF accelerator. The High Energy Beam Transport (HEBT) section and the high-power beam dump that can dissipate 125-mA, CW deuteron beam were also installed to complete the beam line for the high duty operation. The present paper describes the details of the study devoted for the radiation safety analysis for obtaining the license from Nuclear Regulation Authority of Japan and to operate the RFQ at high duty cycles up to CW. In particular, the details of the radiation source definition for neutrons and photons, the d-D reaction contribution analysis and the shielding analysis will be discussed. |
