Northern Ireland - Sub region 1

National Geological Screening for a GDF - Northern Ireland region

There are no plans to site a GDF in Northern Ireland. This screening report is purely a technical exercise. Any future policy decision on geological disposal in Northern Ireland would be a matter for the Executive.


Our work shows that we may find a suitable geological setting for a GDF in much of this subregion.

Northern Ireland - Subregion 1

Rock can be seen at the surface at some places in this subregion such as sea cliffs and in man-made excavations such as quarries or road cuttings. Combined with some deep boreholes and geophysical investigations, this gives us an understanding of the rocks present and their distribution.

There are various types of gaps in our understanding of geology and we deal with these gaps in a number of ways.

There are clay-rich rock layers under most of the subregion including the north around Coleraine, Ballymoney and Ballycastle and south of Carnlough, Ballymena and Magherafelt, in which we may be able to site a GDF. There are also volcanic lavas, slates and similar strong rocks between Ballycastle and Cushendall, and layers of rock salt between Belfast and Larne, in which we may be able to site a facility. We would need to do more work to find out whether these rocks have suitable properties and thicknesses in the depth range of interest for a GDF.

Even where individual clay-rich rock layers are found not to be thick enough to host a GDF they may support the siting of a GDF in deeper rocks as they could act as a barrier to groundwater flow from depth. This is important because movement of groundwater is one of the ways in which radioactive material could be carried back to the surface.

One small area around Coalisland, County Tyrone was mined to depths below 100m for coal resources. In this area the mining is likely to have affected the way in which water moves through the rock. Also possible exploration in the future in this area means that it is more likely that future generations may disturb a facility.

Parts of this area, north of Belfast, have Petroleum Licences to allow companies to explore for oil and gas. This exploration is currently at an early stage and it is not known whether oil or gas in these licence areas will be exploited. RWM will continue to monitor how this exploration programme progresses.

Parts of the subregion which are mined for rock salt, in the south and east of County Antrim, would also need to be taken into account in the siting of a GDF, although the nature of mining in evaporites does not affect the movement of groundwater in the surrounding rocks in the same way as other mining.

For further information, read the report below.

Northern Ireland Subregion 1

We have also produced a summary of the geological attributes of the Northern Ireland Region.

Go to National Geological Screening for a GDF

Go to geological disposal homepage

Published 19 December 2018