Strict controls on farming and food would play a central role in minimising the potential impact of hypothetical severe nuclear incidents at Sellafield, the Environmental Protection Agency (EPA) reported on Thursday.

The EPA examined the potential impact of four “very rare severe incidents”.

The study incorporated worst case weather scenarios for Ireland – easterly winds and rain over the east coast of Ireland. During these weather conditions, a radioactive plume arising from Sellafield would travel across Ireland depositing radioactive material along its path.

While leafy vegetables, such as salad leaves, could be immediately contaminated by radionuclides, other slower growing plant foods, such as fruits and potatoes, would have lower levels of radioactivity due to their later harvesting, the EPA noted.

Silage and hay made from contaminated grass could be replaced with other uncontaminated feedstuffs

Cattle and sheep farmers could change their feeding regimes for beef cattle and sheep to reduce the concentrations of caesium-137 in beef and lamb, according to the organisation.

Silage and hay made from contaminated grass could be replaced with other uncontaminated feedstuffs in order to substantially reduce or avoid peak radioactivity levels in meat.

Dairy farmers too could play a role in avoiding or reducing the transfer of radioactivity from grass into milk by switching to alternative feedstuffs and feed additives for their cows.

The EPA noted that while such protective actions by farmers “could be very effective, there are significant economic and resource costs.”

Sellafield and potential incidents

The 600ha nuclear site at Sellafield in the northwest of England is only approximately 180km (112 miles) from the northeast coast of Ireland.

One of two nuclear fuel reprocessing sites in Europe, it is the largest nuclear site in Europe with over 1,000 nuclear facilities that process and store used nuclear fuel and other radioactive materials.

The four hypothetical “very rare severe incidents” the EPA examined were:

Scenario A – An unspecified severe event resulting in a continuous aerial release over two hours with a 50 kW heat input to the plume.

Scenario B – An unspecified severe event resulting in a continuous aerial release over two hours with a 500kW heat input to the plume.

Scenario C – Meteorite impact resulting in a continuous release over five minutes.

Scenario D – Impact of a large aircraft resulting in a continuous release over 30 minutes.

The EPA stressed that for almost 90% of the time, the prevalent meteorological conditions in Ireland would result in any radioactive plume from Sellafield travelling in an easterly direction, away from Ireland.

National emergency plan

Ireland has a National Emergency Plan for Nuclear Accidents (NEPNA) in place to provide a coordinated emergency response to a situation where there is widespread radioactive contamination in Ireland.

The NEPNA includes guidance on protective actions such as sheltering and food controls to reduce the radiation dose received by the population.

According to the EPA, while these controls have been shown to be very effective in controlling radioactivity levels in foods for sale, and hence radiation doses to people, they do have significant socio-economic implications and costs.

“This includes the loss of tourism and markets for Irish seafood and farm products because of consumer concerns regarding the levels of artificial radioactivity,” Thursday's report read.