a recent European Commission report points out that Europe is going through worst drought in the last 500 years. Its effects are perfectly visible through the drastic decrease in the flows of some of the main European rivers.
But in addition to its significant ecological impacts, the current drought reveals something else: the great dependency of nuclear power plants on water. This summer, France had to activate a drought plan for some nuclear power plants and these saw their production reduced.
Why a flow of Water insufficient can prevent the correct operation of nuclear power plants?
The question of refrigeration
nuclear power plants use large volumes of watermainly as a cooling medium. This type of power plant operates on the same principle as conventional thermal power plants, that is, those powered by coal, natural gas or fuel oil, but they differ in the way they heat water.
While conventional thermal plants boil water to obtain steam from the burning of fossil fuels, nuclear power plants do so from nuclear reactions. The steam obtained is used to turn turbines that subsequently produce electricity through an alternator.
Finally, the steam that has passed through the turbine is cooled in water before it can be reused to produce more electricity. Precisely, refrigeration is the process involving the largest uses of water in nuclear power plants.
Without water there is no electricity
A large part of the currently operating reactors in Europe are cooled with fresh water from rivers and lakes. The low flow of the rivers as a result of the drought forces to reduce the generation of electricity in nuclear power plants. This situation can even force facilities to shut down due to water availability problems, such as already happened in the past.
In this context, water used for electricity generation highlights two concepts: water extraction and water consumption. The first refers to the total volume of water extracted from a body of surface water for use. The second represents the part of the water initially extracted that evaporates during the cooling process of the nuclear power plants and, therefore, is immediately removed from the aquatic environment.
This distinction is crucial in order to understand how drought can affect nuclear energy production: regardless of the water that evaporates and is therefore consumed during the electricity generation process, significant volumes of starting water are necessary to make operate a nuclear power plant. If these volumes are not initially available in the rivers, power plants cannot function properly.
The effects of heat waves
In addition to the low flows, the increase in the temperature of the rivers due to heat waves also affects the cooling capacity of nuclear power plants. These types of plants use fresh water to cool and reduce the temperature of their systems. Once the cooling process has finished, many plants return a large part of the initially captured liquid back to the original body of water, but at a higher temperature.
When the water from the rivers is already very hot, it is not possible to discharge the water from a nuclear power plant, respecting the temperature limits set by legislation to avoid damage to aquatic ecosystems. Because of this, many nuclear power plants have had to reduce their output.
Despite the existence of ecological limitations on the heating of rivers, recently, the French Government has allowed some of its nuclear power plants to cross these thermal boundaries as a temporary measure. In this sense, the commitment to cooling technologies that are less sensitive to changes in flow rates and water temperature, such as cooling towers, would ensure that the water discharged into rivers does not exceed temperature limits.
The drought has created unprecedented tension in the river flows. Very likely, the situation will continue at least until November of this year throughout the European Mediterranean. Faced with this situation, nuclear power plants struggle to stay cool. Droughts affecting nuclear power production are another reminder of water’s impact on things we don’t necessarily associate it with. Something that we must not overlook in the future.
Diego Sesma MartinProfessor and researcher at the Department of Economics and Business at the University of La Rioja, University of La Rioja.
This article was originally published on The Conversation. read the original.
