Dr. Ciara McMahon:

Since the early 1980s the EPA, and previously the RPII, have monitored sea water sediment, shellfish and fish, looking for artificial radioactivity mainly as a result of discharges from Sellafield. It is not a nuclear power plant. It is a nuclear fuel reprocessing plant and because of the difference in those operations its discharges of radioactivity into the environment are much larger. That is partly why people have difficulty understanding that new nuclear power plants may not lead to large increases in radioactivity going into the environment. It all comes down to whether fuel is reprocessed or not. Reprocessing leads to larger discharges to the environment.

We can measure the radioactivity in the environment as a result of the Sellafield discharges. What we are measuring comes mainly from discharges in the 1970s and 1980s when they were much higher. Much of what was discharged ended up in the seabed sediments just off the coast of Sellafield and there were muddy sediments just off the coast of Louth too. It got trapped in the sediment there but now because the discharges are lower at Sellafield it is starting to come back up into the water.

We measure radioactivity that has been there since the 1970s and 1980s. Even if discharges stopped completely tomorrow we would probably continue to measure around the same levels of radioactive caesium and plutonium in the sea water, sediments and shellfish and so on. The levels are extremely low. If we add what we are exposed to from all sources of radiation in the environment, including radon, medical exposures and so on, what we are actually exposed to from Sellafield, Chernobyl, Fukushima plus nuclear weapons testing, represents less than 1% of our overall radiation dose. That is for an average member of the public. For somebody who has high levels of radon in his or her home or workplace the percentage coming from Sellafield and Chernobyl, etc., will be even smaller.

In response to the question about what normal operations means, when a nuclear power plant is operating there are discharges to the environment. They are much lower than those from a reprocessing plant but there are ongoing discharges to air and water. As five of the plants will possibly be on the Irish Sea coast we assessed the discharges and what the radiation doses would be. These are routine releases from the 60 to 70 year plant life. We worked with Met Éireann to get data on the weather patterns for the past 21 years and used that to model what would happen over the next 60 years of operation of the plants for discharges to air. We also studied average sea currents and worked with the National University of Ireland, Galway, NUIG, which has experts in sea modelling to assess the maximum discharges that could occur at nuclear power plants.

We had to make assumptions because these plants have not been built yet but we had information on what the UK regulators were considering as the maximum amount that could be discharged to air and water. We also had information on what similar, older plants would currently release into the environment in Europe and the world. We used all that data to examine the radiation doses that would occur over 60 to 70 years. The radiation dose we get currently is approximately 4,000 microsieverts per year, this would increase by less than one additional microsievert. We would not be able to measure that above what we get at the moment. That led to the conclusion that for the routine releases, excluding any emergency occurring, the radiological impact would be insignificant.