RESEARCHES FOR THE CANDU NUCLEAR REACTOR FUEL CHANNELS DECOMMISSIONING. PART 1 - DECOMMISSIONING DEVICE AND FUEL CHANNEL DISMANTLING PRESENTATION

Abstract

The objective of this paper is to present a possible method for horizontal fuel channels dismantling from calandria vessel, based on the knowledge referring to assembly the fuel channel into calandria, and a solution for a device designing for the decommissioning of the horizontal fuel channels in the CANDU 6 nuclear reactor. In the final phase of the nuclear reactor dismantling, the most important operation is the decommissioning of fuel channels. The nuclear reactor fuel channels decommissioning consists in a planning phase and the implementation of all dismantling procedures and operations. The dismantling operation stages of the fuel channel components should be repeated for each of all 380 channels of the reactor, starting from the front of calandria side and continuing with the rear side. The device shall be designed according to the radiation protection procedures. The fuel channel decommissioning device is an autonomous device designed for dismantling and extraction of the channel closure plug and shield plug, extraction of the end fitting, cutting and extraction of the pressure tube. The fuel channel decommissioning device consists of following major components: coupling and locking fuel channel module, assembly valve for access to the fuel channel, storage tubes assembly for extracted components, handling elements assembly, cutting and extraction device and housing device. The decommissioning device assembly of the fuel channel components is composed of the device itself and moving platform support for coupling of the selected channel to be dismantled and is achieved according to the particular features of the fuel channel components to be dismantled. The radiological safety analyses should be made by certified experts for protection assessment to radiation exposure of workers in time of fuel channel dismantling.