NANODOT2: NANOMATERIALS FOR THE RADIOMETRIC DETECTION OF TRITIUM

该项目NANODOT2（用于放射性检测氚的纳米材料）旨在利用纳米材料制造的最新进展，开发一种新型原型仪器，用于分析和表征运行核设施和退役核设施周围陆地和海洋环境中的放射性氚。NANODOT2完全属于NERC的职权范围，是一个为期12个月的后续项目，来自早期NERC资助的博士学位，是兰开斯特大学和混合仪器公司（一家专门从事先进辐射测量仪器制造和营销的中小企业）之间的合作。氚(T)是氢的一种放射性同位素，在核反应堆的日常运行中产生。这可能会在水中产生氚，特别是在乏燃料（SF）冷却池和SF处理和废物处理设施中-所有潜在的泄漏源到地面和更远的地方。水性T最常以氚化水（HTO）的形式存在于地下水中。由于T是H的同位素，HTO的行为与H2O难以区分，因此在环境中具有很高的流动性，由于HTO/H2O的等效性，其迁移速率与地下水的流速相同。这也使得HTO在人体组织中高度流动，带来相关的健康风险——世卫组织对饮用水中T的限制是<10 kBq/L。此外，尽管由于人为活动，氚的含量往往极低，而且容易分散，但它对许多工业来说是一个问题，例如，海洋渔业往往需要进行大量清理，即使其含量低于可接受的法定限度。因此，在核设施周围的陆地和海洋环境以及核设施运行/退役产生的废物中，对T进行快速、准确和精确的分析，存在着迫切的健康、安全和经济需求。兰开斯特和混合动力公司已经合作了40年，以满足这些需求。氚以软发射衰变，使得在野外进行快速辐射检测非常困难。然而，在兰开斯特大学进行的一项非常成功的NERC/RSC ACTF博士研究（奖励NE/H025650/1，以下简称NANODOT1）的数据提供了原理证明，通过电解，T可以被HTO的纳米多孔钯（Pd）层选择性和可逆地隔离，然后通过液体闪烁计数很容易检测到预浓缩的T。随后，由Lancaster & Hybrid公司资助的InnovateUK/核退役管理局资助的可行性研究（131756，TRIBECA，电化学辅助辐射测量法检测氚）再次证明了将纳米多孔Pd层直接耦合到固体闪烁体的可能性。这提供了一种方法，通过该方法可以在基于pmt的固体闪烁计数分析之前将T预先浓缩在闪烁体表面，从而有可能产生一种用于T检测的新型辐射仪器，提供快速，无干扰，原位检测和监测。TRIBECA还展示了这种氚传感器及其基础技术的市场，并获得了英国专利申请GB2523732“氚测量”。NANODOT1将该技术提升至TRL3（可行性），而TRIBECA进一步将其提升至TRL5（组件开发）。NANODOT2的目标是将该技术带入TRL6（演示）。具体来说，我们的目标是建立一个原型仪器，该仪器基于一种新型的Pd纳米材料修饰的固体闪烁体用于β辐射检测，提供：-比现有技术更便宜，更快，更敏感和更可靠的T检测；快速，准确和精确测量水性T用于环境分析和核废料/过程/流出流表征。关键词：氚检测；环境放射性;分析科学;环境监测;纳米材料利益相关者：兰开斯特大学，混合仪器

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; NanomaterialsStakeholders: Lancaster University, Hybrid Instruments