Development of an Assessment Method for Building Materials Under Euratom Scope.

In 2013, the European Commission published its basic safety standards for protection against the dangers arising from exposure to ionizing radiation (Council Directive 2013/59/Euratom)-also known as EU-BSS. As a result, the use of raw materials with potentially elevated activity concentrations such as fly ash, phosphogypsum, and slags will now fall under EU-BSS scope when applied in building materials. In light of this new policy, a variety of tools are available to assess compliance with the 1-mSv y reference level for building materials. At the heart of these tools is a gamma-spectrometric determination of the naturally occurring radionuclides Ra, Th, and K in the material of concern. As a large number of construction products contain a certain amount of the raw material that falls under the scope of the EU regulation, this policy will lead to substantial measurement of building materials that pose little radiation risk. For this reason, a method is developed to enable assessment against the 1-mSv value not on the basis of gamma-spectrometric analysis but rather based on the product's material composition. The proposed method prescribes a maximum permitted content of raw materials with potentially elevated activity concentrations in terms of a weight percentage of the end product, where the raw materials of concern are defined as those listed in Annex XIII of the EU-BSS. The permitted content is a function of the product's surface density. Therefore, a product with a low surface density of up to 25 kg m can consist of nearly 100% raw materials with potentially elevated activity concentrations, and this percentage drops to around 15% for products with a surface density of around 500 kg m. Building materials that comply with these requirements on product composition are exempt from testing, while products that do not comply must perform regular gamma-spectrometric analysis. A full validation and testing of the method is provided. In addition, the paper discusses issues relevant for regulatory implementation.