EDF looks for ways how to reduce water consumption in its nuclear power plants

After a major heatwave of 2003, the EDF launched an initiative develop solutions addressing the impacts of climate change on nuclear installations. Referred to as the "high heat programme", the project is designed to help the company to cope with extreme weather events on its existing and future nuclear fleet. Considerable effort was made to improve the performance of the cooling systems, in addition to the electronics in the reactor buildings which were reinforced to be able to withstand temperatures above 50°C.  

EDF relies on several innovations to reduce its water consumption of its nuclear powerplants, such as the capture of the water vapor from cooling towers, new cooling sources on the EPR2, and larger effluent reservoir storage. The group is also studying how to adapt environmental standards, which will need to be reevaluated to take into account the impacts of climate change. 

The energy company assured at a press conference in May this year, that it wants to do everything possible to comply with the government's water plan and the water savings requested. "Our approach to climate took a turn with the 2003 heat wave, which saw the implementation of a water and climate hazard management plan," recalls Alexandre Marty, head of the climate and natural resources division at EDF. "The climate risk has been integrated as a major risk of the group since 2018." 

The rise in temperatures has so far not threatened the smooth and safe operation of the power plants over the world, which have not been affected by the repeated heatwaves of recent summers. But as conditions evolve, the hot climate of the Middle East that hosts fossil power plants could provide insight on solutions to limit electricity production losses due to excess heat. The innovations currently under testing will benefit EDF’s existing nuclear fleet, but also new EPR and EPR1200 reactors the company is planning on delivering in France and in Europe.  

To comply with the government's water plan, presented last March, EDF plans to save on the consumption of its power plants, especially the thirty reactors located near a watercourse and cooled by cooling towers. "We are trying to recover the water vapor from the plume to recondense it and recover part of it," explains Cécile Laugier, EDF's environmental director. An experimental installation to test different models of cold sources, which are the heat exchangers of the cooling towers, is already in place at the Bugey power plant. 

As for the EPR2, the design studies for the cold source of the new reactors plan to draw about 10m3/s of water from the river, of which 8 m3/s are returned. Normally 70% of the water is returned to the river, the increase is achieved mainly by the use of modern cooling towers. (In the case of shore-side plants without cooling towers, all the water is returned as part of a closed circuit.) 

EDF is also considering increasing the storage capacities of the effluent reservoirs of its power plants, a project that until now concerned only the Civaux  power plant. These measures are in addition to those already taken since the 2003 heat wave plan, including a reduction in the water consumption of cooling towers, the addition of cooling units, and an increase in ventilation rates.  

The energy company is also designing solutions to compensate for electricity production losses for environmental reasons. The programme has expanded to take into account a variety of extreme weather events (heatwaves, droughts, floods, storms) and to integrate long-term climate changes into the design of new facilities.  In case of high heat, some reactors may have to limit their power to avoid overheating rivers. Since 2000, production adjustments have represented 0.3% of the annual production of the nuclear fleet and could rise up to 1.5% by 2050. The criteria of the Nuclear Safety Authority and the Environment Code indeed provide for exceptions in case of "exceptional situation", such as a high demand for electricity, but EDF wants to go further.