Some EU nuclear power plants have been curtailed two summers in a row due to heat waves. While this gets LOTS of press, I haven't seen analysis on the actual impacts, and if the situation can be fixed. So, short report for @Energy4Humanity: bit.ly/323ZPIv [THREAD]
The total impact of heat-wave curtailment since 2000 have meant loosing on the order of ~0.1% of European nuclear output (in France ~0.15%). Figures are approximate, particularly outside of France, but gives a sense scale of the problem on an annual output basis. 
The lost capacity due to curtailment during heat waves, (much more important than annual output reduction!), is relatively modest. In France (which is by far "hardest hit"), it is hard to discern the impact of heat-wave curtailment in actual production & availability data.
The overall problem could be mitigated by rescheduling outages for refuelling (so they are less likely to occur during heatwaves) or to install cooling towers at plants that use direct cooling from rivers. However, is there currently enough economic incentive to do so?
The main reason for curtailed output is that river sited plants have restrictions on the temperature at which water can be returned to the river. Loosing a few days of output every few years does typically not provide sufficient incentive to invest to avoid the situation.
But does this, as many news reports have emphasised, make nuclear power unreliable, and particularly ill-suited in a warming climate in comparison to other low-carbon electricity? See FR 2018 summer duration curves and a comparison to wind-power output (scaled) to get a feeling.
