Practical in-situ measurement approaches for NORM and building materials

Abstract

Background: The implementation of the new Basic Safety Standards (BSS) implies the requirement of activity concentration determination in the various types of NORM bearing materials and residues. The new BSS introduces the Activity Concentration Index (ACI) as a screening tool for building materials applied in dwellings. Therefore, measurement solutions that are useful in an industrial context will be required for NORM residues and building materials.

Materials & methods: Geometry corrected on-site measurements with LaBr3(Ce) and NaI(Tl) probes are performed on materials in industrial processes. These results are compared with standard analytical procedure, done by a certified laboratory. The indoor radon concentrations are measured by a Sun Nuclear 1029 Continuous Radon monitor or a Sarad Radon Scout PMT during three days in Winter 2011-‘12. Simultaneously, integrating passive radon detectors are exposed for three months.

Results & conclusions: (1) A new user-friendly method for the determination of the activity concentration was developed via measurements at the port of Antwerp and at selected companies. The activity concentrations of shipped goods and several building materials are determined with several detectors and the results are compared to the BSS limits. (2) NuTeC has developed and validated an alternative, in-situ ACI determination method (B-NORM method). The B-NORM method is applied to analyze numerous building materials available on the Belgian market. Interesting conclusions can be made and all materials are classified as A1 or A2 materials, indicating that no precautions or further material or dosimetric studies are required. (3) The relation between radon and building materials applied, the airtightness and the progress in the construction works are studied. Several radon measurements are performed in the winter of 2011- ‘12; in consecutive construction stages of new dwellings. Our study considers a case study of a set of several side by side located residential units under construction, all with well specified building materials. In this way differences due to geological background were excluded. The differences in the ventilation regime in the studied dwellings were determined by airtightness measurements. A relation between air tightness and construction stage could be determined.