It is well known that the cost of a technology drops as it is deployed and becomes more widely used. We have all noticed that we pay less for using a telephone, computer or airplane than our parents did, simply because the cost of these goods has been substantially reduced since the first products rolled off factory production lines. Economic theory cites two causes to explain this phenomenon: the scale effect and the learning effect. The first one is both familiar and intuitive. The bigger the factory, the less each unit costs to produce. In other words, the unit cost of large production runs is lower than for smaller volumes. At the start of a technology cycle the capacity of each production unit is relatively small, in particular because demand is still limited. Subsequently the size of factories gradually increases, stabilizing when diseconomies of scale start to appear (due, for instance, to time spent moving from one workshop to another). The learning effect in manufacturing is linked to the know-how which accumulates over time. The most intuitive example to illustrate this point is the repetition of a single task. You may spend more than ten minutes folding your first paper hen, but barely a minute after making a thousand or so. Manufacturing an airliner, steam turbine or solar panel is much the same. The learning effect is generally measured by the learning rate which corresponds to the reduction in cost when cumulative production doubles. The cost per kWh of wind power, for example, drops by about 10 per cent each time installed capacity doubles.

Nuclear technology displays the opposite trend. The per-kW construction cost of the most recent reactors, in constant (inflation-adjusted) euros or dollars, is higher than that of the first reactors. A technology with rising costs is a very strange beast, which requires closer study, particularly as this feature distinguishes it from several competing technologies, such as wind or solar. If nuclear engineering firms fail to find a solution in the near future, the cost of nuclear power will continue to rise, undermining its competitiveness.