Determination and Inter-Comparison of 238U and 232Th in Zircon Sand Using Gamma Spectrometry

Abstract

An inter-comparison exercise is a quality control tool to standardize a laboratory and was performed between HPU lab at Nuclear Fuel Complex and RPS (NF) lab at Bhabha Atomic Research Centre to determine and compare the concentration of primordial radionuclides in a zircon sample received from Health Physics Unit (HPU), Indian Rare Earth Limited Manavalakurichi weighing 470 g. RPS (NF) lab is annually participating in international inter-comparison exercise conducted by IAEA and is a nodal laboratory for the in-house inter-laboratory comparison exercise. Thus, its values are considered true values. The measured concentrations for ²³⁸U and ²³²Th in zircon sample do not vary considerably as 0.37% variation is observed in true value and measured value of ²³⁸U and 0.32% variation is observed in true value and measured value of ²³²Th. U score is also calculated from the results obtained where it is found to be 0.124 for ²³⁸U and 0.195 for ²³²Th. Trueness and precision tests are also performed, and the laboratory results are found to be “acceptable”. It represents that the laboratory performance is evaluated as satisfactory and does not significantly differ from the expected values as per the statistical tools. This ensures that the analytical measurement results of the laboratory are reliable and traceable to reference standard laboratory.