Radiological implications of NORM in the production of rare-earth compounds

Abstract
The composite rare earth chloride produced from monazite contain low levels of natural radionuclides and is being used as the input material for the production of individual rare earth compounds which have wide applications. Gross alpha, beta and ²²⁸Ra activity concentrations in composite rare earth chloride and individual rare earth compounds such as oxides of Ce, Nd, Pr, Sm, Gd etc are presented. The significant radionuclide of environmental concern is identified as ²²⁸Ra and the activity level varied between 0.1 and 7.8 Bq.g^-1 in different compounds. Sporadic ²²⁸Ra levels up to 16 Bq.g^-1 was observed in Lanthanum oxide. The external gamma exposure rates and airborne activity due to thorium and thoron progeny in the process locations are studied. The activity levels in liquid effluent and potential exposure scenarios are indicated.