Measurement and calculation of radon releases from NORM residues: development of new IAEA document

In 1992, the IAEA published Technical Reports Series number 333 (TRS 333), 'Measurement and Calculation of Radon Releases from Uranium Mill Tailings'. Since that time, a number of developments have taken place in measurement techniques for and modelling of radon exhalation, and experience has been gained with practical aspects of various residue repositories. Therefore the IAEA decided to produce a revision of TRS 333, and to expand its scope to include other NORM residues. The new document is at an advanced draft stage and is expected to appear in 2012. The primary focus is the release of 222Rn, although the material presented can also be applied to 22oRn (thoron) with modifications. The report covers methods of prediction, measurement and monitoring of radon emanation from grains into interstitial spaces, transport within the residue and soil profile, and exhalation into the atmosphere from the surface. The related topics of emanation and exhalation from non-residue materials, behaviour of radon in the atmosphere following exhalation, implications for dose assessment, and applications of radon as a tracer of environmental processes are all outside of the scope of the report.