The Post-Disposal Behaviour of C-14 and Irradiated Graphite

石墨是核反应堆退役后产生的一种主要废物形式，如英国的Magnox和AGR核电站。这种石墨含有一系列在反应堆堆芯中产生的放射性污染物。这种石墨的安全处置取决于对这些污染物在处置场所的行为的理解。与反应堆石墨相关的最重要的污染物之一是碳-14，一种在环境中自然存在的碳的放射性变体。从风险的角度来看，碳-14很重要，因为它持续存在于环境中，并可以通过与植物或微生物的相互作用而被纳入食物中。目前，核反应堆退役后产生的石墨要进行深层地质处理，这需要将其深埋地下，成本非常高。该项目的目的是为了更好地了解碳-14是如何与石墨结合的，它将如何在深层地质条件下从石墨中释放出来，以及碳-14的化学和微生物学如何影响其从处置地点运输出来并最终与人接触。人们希望，这种认识的提高可能会导致一些石墨被安全地处置到近地面设施，并且可以对与石墨处置相关的风险做出更现实的估计。

Graphite is a key waste form arising from the decommissioning of nuclear reactors such as the UK's Magnox and AGR nuclear power stations. This graphite contains a range of radioactive contaminants generated during its time in the reactor core. The safe disposal of this graphite is dependent on an understanding of how these contaminants behave in a disposal site. One of the most important contaminant associated with reactor graphite is carbon-14, a radioactive variant of the carbon naturally found in the environment. Carbon-14 is important from a risk point of view since it persists in the environment and can become incorporated into food through interaction with plants of microorganisms. Graphite arising from the decommissioning of nuclear reactors is currently destined for deep geological disposal, which involves burying deep underground which is very expensive. The aim of this project is to get a better understanding of how carbon-14 is incorporated into graphite, how it will be released from graphite under deep geological conditions and how the chemistry and microbiology of carbon-14 influence its transport out of a disposal site and its ultimate contact with people. It is hoped that this improved understanding may result in some graphite being disposed of safely to near-surface facilities and that more realistic estimates of the risks associated with graphite disposal can be made.