The need for specifications, fabrication and testing requirements for nuclear components

Every CANDU power plant contains literally thousands of individual components, each of which must be designed for a minimum thirty year lifetime with a minimum of maintenance. This stringent requirement is necessary since the failure of many components may cause a forced shutdown or an extended outage with the resultant expense of replacement energy costs. One way of minimizing the risk of a plant shutdown is to install duplicate systems. However, the high capital cost of the additional equipment and the fact that maintenance during operation increases the radiation exposure to the plant workers discourages this approach. The approach taken by Ontario Hydro and Atomic Energy of Canada in the design of CANDU plants is to ensure that the integrity and operability of every component is as high as possible. This is achieved by the proper specification, fabrication and testing of individual components. The fact that CANDU plants have dominated the top positions in worldwide availability ratings attests to the success of this method. The review provides specific examples of this approach for procuring components and shows the means for providing suppliers with the specifications necessary to ensure minimum maintenance and long life