Estimation of 231Pa in uranium and thorium process samples using high resolution gamma spectrometry

Protactinium 231 is a radionuclide occurring naturally as a member of 235U decay series. It is a long-lived by-product actinide which is also produced in the thorium fuel cycle. 231Pa is required to be separated for radiological, chemical and spectroscopic studies. 231Pa occurs at ppb levels in uranium and thorium ores being processed by Jaduguda and IRE plants respectively. Assay of 231Pa in various sample streams of these plants is to be done to identify the source of protactinium for preconcentration and extraction. High resolution gamma ray spectrometry has been used for this study. The main task is the estimation of 231Pa activity in ppb levels using gamma energies of very small yields under strong interference from uranium and thorium daughter products. This paper describes the detection and analysis of 231Pa in samples taken from uranium and thorium process streams