STUDY ON EXTERNAL EXPOSURE CHARACTERIZATION OF MONAZITE

  • U.K. Jayaram et al.

Abstract

It is perceived that one gram of monazite contains 0.09 gram of ThO2, 0.08  gram of thorium element and activity of 232Th is found to be 3252.5Bq with all the daughter products in secular equilibrium where the specific activity of thorium is 4.07kBq g-1. It is verified that a total of 1724 keV photon energy is emitted per unit disintegration of 232Th. Gamma energies under the spectrum were divided into three bands Viz. 100-500keV, 500-1000keV and 1000-3000keV and corresponding yield contribution from thorium series gammas were studied. Total energy per disintegration and total energy per gram of monazite have been estimated for the three energy bands.  Variation in KERMA (kinetic energy released in material), at various energy bands with a small monazite source and different scattering conditions of NHBRA (Natural High background Radiation Area) are studied and discussed here. Dose rate due to stack of monazite arranged in various shapes were measured and compared with theoretically predicted values. Measured dose rate at different shapes of monazite sources were matched with theoretically predicted values. Natural background dose rate and concentration of radon isotopes were measured at high background area dwellings at Manavalakurichy and UNSCEAR 2000 formula for dose rate calculation was substantiated.

Published
2019-11-15
Section
Articles