Environmental tritium contamination from a gaseous tritium light device maintenance facility

A series of radiological characterization, decontamination works and validation assessments have been conducted for a Gaseous Tritium Light Device (GTLD) maintenance facility in Brisbane, Australia in 2003 and more recently in 2007. The initial survey utilised soil pore water tritium concentration as an indicator of the extent of contamination. Tritium, existing as tritiated water or HTO, is environmentally mobile and tends to behave as non-radioactive water would, i.e. will permeate through soil under normal hydraulic conditions. A more useful measure, and that exploited in this work, for the purposes of dealing with contaminated land is the 'non-aqueous tritium' concentration present in the soil. In addition to tritium existing as HTO, organically bound tritium (OBT), a result of fixation by biological and chemical processes, or tritium diffused into various matrices may be present and represent the non-aqueous component. Quantification of all these variants allows assessment of the reservoir of tritium that may become available in environmental processes. Screening soil contamination levels for non-aqueous tritium concentration of 8.5 Bq.g^-1 and 16 Bq.g^-1 for residential and industrial/commercial land uses respectively were applied. Comparison of non-aqueous tritium and soil pore water tritium and elemental zinc concentration in soil were made and tritium concentrations in groundwater wells surrounding the facility were determined (tk)