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Why are there so many nuclear power plants located on the coast?

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Like several other breakthrough inventions, nuclear power has amazing potential, yet devastating impacts, in case of accidents. On the one hand, we may harness it to generate a terrific amount of energy without increasing carbon emissions. On the other, it brings to mind ominous scenes, some of which are recent enough to be vividly impressed on our memory.

It comes as no surprise that the public debate on nuclear power is as vigorous and polarised as ever, with good arguments on both sides. In this blog we focus on geospatial information (from GIS) about nuclear power plants and wider human activity in the ocean.

If you’ve ever cast your eyes over a map of nuclear power plants, you might have noticed that a lot of them are situated along a river or on the coast. Like any other thermoelectric power plants, nuclear plants turn heat into mechanical energy, and finally into electrical energy. The amount of heat produced can be gigantic and not all of it can be converted into electricity. To cut a long story short, power plants need cooling systems; seawater is abundant, cold, and – above all – free.

Nuclear is the “thirstiest” power source, as it tends to be less efficient than coal or other sources of thermoelectric power. There are essentially three ways to cool down a reactor:

  1. Direct cooling: if the plant is situated next to a large waterbody, water is run through the condensers and then discharged back a few degrees warmer.
  2. Indirect cooling: when no seas, rivers or lake are around, cooling may be done by passing the steam through the condenser and then using a cooling tower, which creates a directional air flow and maximises air contact with the falling water droplets. An on-site pond or canal may be sufficient for cooling the water.
  3. Dry cooling: some power plants can be cooled by air alone.

Price suggests that power plants situated on the coast are preferable because seawater can dilute and dissipate the heat of the discharge more easily.

So, at EMODnet Human Activities we have decided to make available a new dataset showing the location of nuclear power plants in Europe situated on the coast or near a large waterbody. Plants are broken down by status (operational, shut down, planned, under construction) and information is available on construction year, criticalities, fuel type, capacity, number of reactors, operator, water source, etc.

At this point you might be wondering: does discharging warm water into the ocean have an impact on the marine environment? Well, beyond some minor chlorination, the water itself is never in contact with the radioactive material and so it is not polluted. But there’s more to it than meets the eye. The discharge from nuclear power stations can also contain heavy metals and salts that can harm aquatic life. In addition, some organisms might inadvertently enter the cooling water system due to poor swimming ability (entrapment), fish and crustaceans might be entrapped by intake screens used to prevent debris entering into the system (impingement), and zooplankton might penetrate the screens through the cooling system, before being discharged back to the ocean (entrainment)[1].

In Europe low water temperature is an important criterion for power plant location. For a planned Turkish nuclear plant, there is a 1%-gain in output if a plant is sited on the Black Sea coast with cooler water than on the Mediterranean coast.[2]

While nuclear power does not contribute to global warming, rising sea temperature has an effect on power plants. When during the summer months water reaches unusually high temperatures, the cooling capacity of the reactor system is reduced. At some point the cooling capacity drops enough to match the decay heat that would be produced should a shutdown occur. At this point, the reactor power must be reduced accordingly[3].

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The information and views set out in this blog are those of the author and do not necessarily reflect the official opinion of the European Commission. Neither the European Commission nor any person acting on the European Commission's behalf may be held responsible for the use which may be made of the information therein.

July 18th, 2019 | Written by

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