NANODOT2: NANOMATERIALS FOR THE RADIOMETRIC DETECTION OF TRITIUM

This project, NANODOT2 (NANOmaterials for the radiometric Detection Of TriTium) aims to exploit recent advances in nanomaterials fabrication to develop a novel, prototype instrument for the analysis and characterisation of radioactive tritium in the terrestrial and marine environments around both operational nuclear facilities and those in decommissioning. Falling squarely within NERC's remit, NANODOT2 is a 12 month follow project from an earlier NERC-funded PhD and is a collaboration between Lancaster University and Hybrid Instruments, an SME specialising in the manufacture and marketing of advanced radiometric instrumentation.

Tritium (T) is a radioactive isotope of hydrogen made during the routine operation of nuclear reactors. This can give rise to waterborne tritium in, inter alia, spent fuel (SF) cooling ponds and SF processing & waste treatment facilities - all potential sources of leakage to ground and beyond. Waterborne T is most commonly present in groundwater in the form of tritiated water, HTO. As T is an isotope of H, HTO behaves indistinguishably from H2O and so is highly mobile in the environment, its migration rate being identical to the velocity of groundwater due to the HTO/H2O equivalency. This also makes HTO highly mobile in human tissue, with associated health risks - the WHO limit for T in drinking water is <10 kBq/L. Additionally, despite often being present in extremely low quantity as a result of anthropogenic activities and easily dispersed, tritium is a concern to many industries i.e. sea fisheries often commanding extensive clean-up even where it is present at less than accepted statutory limits.

Thus there are pressing health & safety and economic needs for fast, accurate & precise analysis of T in the terrestrial and marine environments around nuclear sites and in the wastes arising from their operation/decommissioning. Lancaster and Hybrid have been working in collaboration for >4 years to address these needs.

Tritium decays with a soft beta emission making rapid radiometric detection in the field very difficult. However, data from a very successful NERC/RSC ACTF PhD studentship (award NE/H025650/1, hereafter NANODOT1) conducted at Lancaster with Hybrid, provide PROOF OF PRINCIPLE that, by electrolysis, T can be selectively & reversibly sequestered by nanoporous palladium (Pd) layers from HTO, the pre-concentrated T then being easily detected by liquid scintillation counting.

A subsequent InnovateUK/Nuclear Decommissioning Authority funded feasibility study (award 131756, TRIBECA, TRItium detection By Electro-Chemically Assisted radiometrics), again conducted by Lancaster & Hybrid, demonstrated the possibility of coupling nanoporous Pd layers directly to solid scintillators. This provided a means by which T could be pre-concentrated at a scintillator surface prior to analysis by PMT-based solid scintillation counting, potentially yielding a novel radiometric instrument for T detection offering fast, interference free, in situ detection & monitoring. TRIBECA also demonstrated the market for such a tritium sensor and its underpinning technology, and led to a UK patent application GB2523732 "Tritium Measurement".

NANODOT1 took this technology to (Technology Readiness Level) TRL3 (feasibility) whilst TRIBECA further advanced it to TRL5 (component development). NANODOT2 aims to take the technology to TRL6 (demonstration).
Specifically, we aim to build a prototype instrument that, based on a novel Pd nanomaterial-modified solid scintillator for beta radiation detection, offers:
-cheaper, faster, more sensitive & more reliable T detection than current technology; and
-fast, accurate & precise measurement of waterborne T for environmental analysis and nuclear waste/process/effluent stream characterisation.

Keywords: Tritium Detection; Environmental Radioactivity; Analytical Science; Environmental Monitoring; Nanomaterials
Stakeholders: Lancaster University, Hybrid Instruments

Impact will be in four key domains:

KNOWLEDGE: through the creation of new fundamental understanding and technology related to tritium separation and monitoring, leading to economic, social, environmental, safety, health and security benefits associated with improved radioactive waste management and disposal practice.

ECONOMY: through knowledge transfer (KT) and commercialisation of new tritium detection technology, leading to uptake or implementation of research in the areas of environmental monitoring and waste characterisation, to reduce the cost of nuclear decommissioning, waste management, site restoration and land quality management by bringing a new product and processes to market.

PEOPLE: through provision of highly skilled employees (researcher and technician) to the nuclear (and allied) sectors in support of the national Nuclear Skills Pipeline, trained through excellent research.

SOCIETY: through knowledge exchange (KE) with key stakeholders to enhance, from safety and environmental perspectives, the legitimacy of radioactive waste management policy & regulation, and improve public confidence.


These impacts will benefit the three groups of stakeholders described in the Beneficiaries section as follows.

Industry will benefit directly from the knowledge & technologies generated by the research, allowing them to meet the requirements of regulators in a manner that is faster, safer and more cost effective. As well, it will benefit from the training of a potential employee with direct appreciation of the challenges and needs of three targeted markets - environmental sensing & monitoring technologies; nuclear decommissioning; and the radiation detector market.

Regulators regard below ground contamination of land as a potential issue for a number of nuclear sites in the UK and overseas (see above ) and so, in service to public safety, provide requirements for groundwater monitoring to those sites. As well, the regulators have economic responsibility with the Environment Agency in particular being obliged (under EU Directive 96/61/EC) to maintain a watching brief for the Best Available Technology Not Entailing Excessive Economical Costs (BATNEEC) for tritium detection. Current monitoring of all isotopes of interest involves ex situ sample analysis that is slow and expensive (especially in terms of analyst time and experimental consumables). Used in conjunction with appropriate microfluidic based sampling & sample pre-treatment systems (to be developed in subsequent round of funding), NANODOT2 may obviate all of the above technical / analytical difficulties as well as address regulators statutory, BATNEEC-derived economic imperatives. Thus the regulators, on behalf of the public and as required by statute, will benefit from a new technology providing a faster, safer, more easily deployable (potentially in situ) and cost effective method for environmental monitoring and characterisation of nuclear waste / process streams.

The reduced financial cost of such monitoring programmes and resultant diminished burden on the UK taxpayer will also be of benefit to the public - as well as providing potential for societal impacts through better monitoring of legacy contaminants in groundwater, early detection of future accidental release and thus greater public confidence.

Finally, as well as the three non academic groups of stakeholders identified above, academia will benefit from new scientific discoveries through dissemination in peer-reviewed journals and at national and international conferences.