Measurement of tributyl phosphate (TBP) in groundwater at a legacy radioactive waste site and its possible role in contaminant mobilisation Brett Rowling a, * , Andrew S. Kinsela a, b , M. Josick Comarmond a , Catherine E. Hughes a , Jennifer J. Harrison a , Mathew P. Johansen a , Timothy E. Payne a a Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia b University of New South Wales, Sydney, NSW 2052, Australia article info Article history: Received 20 December 2016 Received in revised form 16 March 2017 Accepted 26 May 2017 Available online xxx abstract At many legacy radioactive waste sites, organic compounds have been co-disposed, which may be a factor in mobilisation of radionuclides at these sites. Tri-butyl phosphate (TBP) is a component of waste streams from the nuclear fuel cycle, where it has been used in separating actinides during processing of nuclear fuels. Analyses of ground waters from the Little Forest Legacy Site (LFLS) in eastern Australia were undertaken using solid-phase extraction (SPE) followed by gas chromatographic mass spectrom- etry (GCMS). The results indicate the presence of TBP several decades after waste disposal, with TBP only being detected in the immediate vicinity of the main disposal area. TBP is generally considered to degrade in the environment relatively rapidly. Therefore, it is likely that its presence is due to relatively recent releases of TBP, possibly stemming from leakage due to container degradation. The ongoing presence and solubility of TBP has the potential to provide a mechanism for nuclide mobilisation, with implications for long term management of LFLS and similar legacy waste sites. Crown Copyright © 2017 Published by Elsevier Ltd. All rights reserved. 1. Introduction Tri-butyl phosphate (TBP) is an organic compound which has been found at various locations within the environment, particu- larly in the vicinity of waste disposal sites (Fries and Puttmann, 2001, 2003; Reemtsma et al., 2008). TBP has been produced in significant quantities and utilised in diverse industrial applications including plasticisers, de-foamers, paints, fire retardants, herbi- cides, and as an anti-wear additive in hydraulic fluids (Nakamura, 1991). In addition, TBP can also be used as an organic solvent to recover minerals of economic importance from ores. The nuclear industry has also had a long association with TBP, through the use of the PUREX process and similar applications in the nuclear fuel cycle. Briefly, the PUREX process uses TBP as a strong complexing agent to specifically target the extraction of tetravalent plutonium and hexavalent uranium from process liquors. To recover the TBP and its associated chelates of uranium and plutonium, an organic solvent is used and most commonly this has been kerosene (Probasco et al., 2002). During its use in the PUREX process, TBP breaks down over time due to a combination of hydrolysis and radiation damage which results in a loss of extraction efficiency of TBP (Baillie and Cairns, 1958; Bocek et al., 1980; Kuno and Hina, 1992). When this occurred, the liquor including metal chelates was discarded, often into industrial waste disposal sites. Some of these sites include the Low Level Waste Repository (LLWR) in the UK (Taylor and Baker, 2013) and Maxey Flats in the USA (Francis et al., 1980), at which the presence of TBP as well as numerous volatile aromatic com- pounds and organic acids has been documented. The Little Forest Legacy Site (LFLS) was used as a burial ground for low level laboratory wastes between 1960 and 1968 by the then Australian Atomic Energy Commission (AAEC) (Payne, 2012). At the time a research program into the development of nuclear reactors was underway, and this involved a solvent extraction process which employed TBP to recover uranium and thorium (Cairns et al., 1968). At LFLS, wastes were deposited into shallow, unlined trenches following accepted practices of the time (IAEA, 2007). Research undertaken by the successor to the AAEC, the Australian Nuclear Science and Technology Organisation (ANSTO), has shown the * Corresponding author. E-mail address: brett.rowling@ansto.gov.au (B. Rowling). Contents lists available at ScienceDirect Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad http://dx.doi.org/10.1016/j.jenvrad.2017.05.015 0265-931X/Crown Copyright © 2017 Published by Elsevier Ltd. All rights reserved. Journal of Environmental Radioactivity xxx (2017) 1e8 Please cite this article in press as: Rowling, B., et al., Measurement of tributyl phosphate (TBP) in groundwater at a legacy radioactive waste site and its possible role in contaminant mobilisation, Journal of Environmental Radioactivity (2017), http://dx.doi.org/10.1016/j.jenvrad.2017.05.015