Access Control System Developed for LHD Controlled Area

Abstract

An access-control system has been developed for the safety operation of the large helical device (LHD) at the National Institute for Fusion Science.The central part of the control system consists of a main computer, a manual-operation box and a sequencer-control system. The system monitors five turnstiles, eight shielding doors and other points of entry and directly supplies the interlock signals to the LHD control system. The sequencer-control system, which provides independent access control of each gate, is effective to control simultaneously all of the entry according to the status of the LHD and to permit the access of radiation workers belonging to a specific work group according to the situation of LHD plasma experiment. The safety management of LHD experiments has been performed without any serious troubles by this access control system including the interlock system since 1998.