NORM-BMI: Investigation of naturally occurring radioactive material (NORM) in building materials in Ireland.

The NORM-BMI project is an Environmental Protection Agency (EPA) funded study designed to (i) investigate activity concentrations of naturally occurring radionuclides in key building-material categories used in Ireland, and (ii) develop recommendations on how Ireland should adopt the EU Basic Safety Standards (EU-BSS, 2013/59/Euratom) for building materials.  

A three-batch sampling strategy was adopted. Batch 1 covered common bulk materials (concrete, cement, aggregates, gypsum products, plaster and tiles) to enable comparison with recent European datasets. Batch 2 targeted aggregates, construction sands and demolition materials, extending the sample range to legacy and recycled products. Batch 3 included aggregates from different geological locations (influenced by Tellus data), industrial by-products and imported tiles.  

The radiological assessment is based on the activity concentration Gamma Index (Iγ) defined in the EU-BSS, a screening quantity derived solely from the activity concentrations of Ra-226, Th-232 and K-40, with Iγ = 1 corresponding to the reference level of 1 mSv·y⁻¹ for bulk building materials. Samples are measured by high-resolution HPGe gamma spectrometry in three laboratories: the EPA Laboratory (Dublin), University College Dublin (UCD) and the University of Cantabria (Spain). EPA and UCD employ closely harmonised procedures, including identical container geometries, whereas the Spanish laboratory (the only one of the three accredited for building-material measurements) uses different sealing protocols, count times and geometries, providing a realistic interlaboratory comparison under non-identical but operationally relevant conditions.  

Preliminary results show that all bulk construction materials investigated (concretes, cements, aggregates and sands) exhibit Iγ values below the EU-BSS screening level of 1, while some tiles yield indices slightly above 1 but within the higher limit applicable to superficial materials. Together with a review of regulatory practice in other EU Member States, these results underpin practical recommendations for how Ireland could phase in EU-BSS compliant control of NORM in construction materials and design a scalable national monitoring programme.