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

石墨是英国Magnox和AGR核电站等核反应堆退役时产生的一种主要废物形式。这种石墨含有一系列在其运行期间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了解。与反应堆石墨有关的最重要的污染物之一是碳-14，这是环境中自然存在的碳的一种放射性变体。从风险的角度来看，碳-14很重要，因为它在环境中持续存在，并可以通过与微生物植物的相互作用而并入食品中。核反应堆退役产生的石墨目前被用于深层地质处理，这涉及到深埋在地下，这是非常昂贵的。该项目的目的是更好地了解碳-14是如何融入到石墨中的，在深部地质条件下它将如何从石墨中释放出来，以及碳-14的化学和微生物如何影响其从处置地点运输出去以及最终与人接触。希望这种更好的理解可能导致将一些石墨安全地处置到近地表设施，并能够对与处置石墨有关的风险作出更现实的估计。

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.