Robotics in the Nuclear Environment: Inspection and Repairs Inside the Primary Coolant System

EDF is the French national power generating utility. It has built and operates 58 pressurized water reactor (PWR) nuclear power plants on 19 sites. Of these, thirty-four are 900 megawatt units (the first of which, the Fessenheim NPP, came on line in 1977), twenty are 1300 MW units, and four are 1450 MW units, the latest of which, at the Civaux plant, came on line in 1998. The average age of these nuclear power plants is thus 20 years. They produce close to 85% of the power EDF generates in France. Renewal of the nuclear plants is under study, as are other means of power generation. For the moment, EDF is requesting approval to run its nuclear plants for up to 40 years. Moreover, it has started a major project on the lifetime of PWR reactors, the main objective of which is to extend the authorized lifetime to 60 years. Major requirements for maintaining the current performance of the French nuclear generating facility and reducing the cost per kWh generated include optimization of expenses and reduction of fuel costs. These factors enabled the cost per kWh to be reduced by 13% in 2001. One way to reduce costs involves optimization of maintenance programs and methods. However, increasing the operating lifetime of plants, and the concomitant ageing of equipment and materials, is likely to result in increasing maintenance requirements. For this reason it is important to establish new, more cost-effective maintenance methods in order to keep costs down. Some of these methods make use of robotics. They make it possible for work to be carried out from the inside of circuits, for inspections and even for repair if defects are detected. The results presented here are those of work carried out by the EDF R&D division on behalf of the Nuclear Power Plant Operations (NPPO) division.