CONTRIBUTIONS FOR THE DECOMMISSIONING OF THE HORIZONTAL FUEL CHANNELS IN THE CANDU 6 NUCLEAR REACTOR. PART 1 - MAIN STEPS OF THE FUEL CHANNEL DECOMMISSIONING

Abstract

The purpose of this study is to achieve a possible method for decommissioning of the horizontal fuel channels of calandria vessel, based on the knowledge referring to assembly the fuel channel into calandria of CANDU 6 nuclear reactor. Nuclear reactor decommissioning consists in a planning phase and the implementation of all procedures and operations. The decommissioning of fuel channels represents one of the last operation which is performed in the nuclear power decommissioning and it is the most important operation in the nuclear reactor dismantling. The decommissioning of fuel channels, one of the most important operation in the nuclear reactor dismantling, represents the final phase of nuclear facility decommissioning and refers to the technical operations taken to extract the components from inside of the nuclear reactor channel. The decommissioning is a complex process and requires activities such as disassembly decommissioning device, locking/unlocking the channel closure and the shield plug, pressure tube cutting, extracting of each component from the channel, as well as radioactive waste management. 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 radiological safety analyses should be made by certified experts for protection assessment to radiation exposure of workers in time of fuel channel dismantling.