CONTRIBUTIONS FOR THE DECOMMISSIONING OF THE HORIZONTAL FUEL CHANNELS IN THE CANDU 6 NUCLEAR REACTOR. PART 3 - FUNCTIONING OF THE DECOMMISSIONING DEVICE

Abstract

The scope of this paper is to present the device functioning steps for the horizontal fuel channels decommissioning in the CANDU 6 nuclear reactor calandria vessel. The fuel channel decommissioning device is designed for dismantling and extraction of the fuel channel and its components. The device which perform the fuel channel dismantling, shall provide radiation protection during the stages of decommissioning, ensuring radiation protection of the workers. The decommissioning operation consists of following major steps: platform with device positioning to the fuel channel to be dismantled; coupling and locking the device at the fuel channel; unblock, extract and store the channel closure plug; unblock, extract and store the channel shield plug; block and cut the middle and the end of the pressure tube; block, extract and store the end fitting; block, extract and store the half of pressure tube; mounting of the extended closing plug. The operations steps are performed by the Cutting and Extraction Device and by the extraction actuator from the device handling elements assembly. After each step of dismantling is necessary the confirmation its finalization in order to perform the next operation step. The dismantling operation steps of the fuel channel components are repeated for all the 380 channels of the reactor, from the front of calandria side (plane R) as well as the rear side (plane R').