Assessment of TFWT and OBT in terrestrial plants at Tarapur, a tropical NPP Site in India, and a comparative analysis with model-computed concentrations

Abstract

Tritium, a key radionuclide from pressurized heavy water reactors, disperses rapidly and is absorbed by organisms as Tissue-Free Water Tritium (TFWT) and Organically Bound Tritium (OBT). This study examines the measured TFWT and OBT concentrations in terrestrial plants around Nuclear Power Plant (NPP) site at Tarapur, India, from 2016 to 2018 and compared with the computed concentrations. A Gaussian Plume Model (GPM) was used to compute air tritium concentrations, incorporating meteorological data and site-specific model parameters. The key parameters include fractional water content (WCp), water equivalent factor (WEQp), and the OBT-to-TFWT ratio (Rp). Results show higher concentrations near the NPP, with measured values exceeding computed estimates may be due to GPM limitations and environmental variability. A statistical evaluations (mean fractional bias: − 0.095) of computed to measured air tritium (2014 to 2018) confirmed systematic underestimation by computation, highlighting the need for field measurements and site-specific parameterization in tritium transport modelling.