By Serge Duchêne with AFP

France on Wednesday recorded a shortfall of more than 20% in its nuclear electricity generation capacity, a new record for outages due to "environmental constraints" or "external environment-related causes": drought, extreme heat and a jellyfish invasion.

Nuclear power accounts for around 70% of electricity production in France. This year, output has been disrupted by multiple heatwaves and periods of drought.

According to AFP calculations based on data published by energy group EDF since 2015, 20.4% of generation capacity was unavailable.

Between 9:45 and 10:00, EDF's nuclear fleet hit a new peak of unavailability for reasons described as "environmental constraints" or "external environmental causes", both in terms of the number of reactors shut down or running at reduced power and the amount of generation capacity lost.