Improvements in Remote Removal Techniques for Active Components during Large-Scale Retubing of CANDU Reactors

Abstract

This paper describes the evolution of the "On Face" tooling and the techniques used for the remote removal of the radioactive pressure tubes and end fittings from CANDU reactors. Starting with a brief description of Pickering units 1 and 2 techniques, the improvements for units 3 and 4 are discussed together with a forward look at the techniques being developed for the Bruce A reactors. The "P1/P2" tooling design was done on a crash basis with little development time available for sophisticated tooling. The resultant tooling was adequate but did not allow for techniques that could reduce cycle time and manrem reduction. The greater lead time afforded for the P3/P4 work enabled more effective tooling to be developed. Two tools, the End Fitting Removal Tool and the Pressure Tube Push Tool along with their operation are described. These new tools and procedures enabled significant gains in productivity and manrem reduction to be made. The improved statistics are reviewed in the paper. The Bruce reactor channel is different to that at Pickering but similar tooling can be used. The main difference is that emphasis has been placed on increasing the amount of remote working that can take place before local manual intervention is required for further setup work. This is achieved by the use of remotely controlled shield plug handling machines and the ability to handle multiple end fitting removal work stations. This equipment is briefly described.