New research into treatment of nuclear graphite waste with plasma
New exciting research from our team has been published in the Journal of Nuclear Materials. The research examines how nuclear graphite waste can be treated with our plasma technology. The paper was put together by long standing member of the Tetronics technical team, Daniel Burton and our partners at Costain.
This paper is another example of the ground-breaking work we are doing in collaboration with our long-time partners at Costain. Together we are on the forefront of technology advancements of treating nuclear waste in a clean and efficient way.
Click here to read the paper in full.
This paper introduces a novel approach, developed through an academic and industrial collaboration, to the thermal treatment of nuclear graphite waste arising as a result of reactor decommissioning and oxide fuel assembly dismantling. A crucial part of the process is the thermal oxidation of the graphite via a plasma furnace. Laboratory scale treatment of the graphite found the oxidation rate to increase with temperature, with a significant increase in the CO/CO2 production ratio at T > 1000 °C.
There was also a linear increase of oxidation rate with air flow rate, up to 100 ml/min, after which, the process became less efficient due to oxygen wastage. Effects of graphite particle size, over the range 0.5–10.0 mm, was found to be relatively small and importantly the effect of the graphite provenance on the oxidation rate was also found to be minimal. Treatment of virgin and irradiated graphite analogues, under the same conditions, showed little difference in oxidation behaviour, providing confidence that this process could be scaled up and used effectively in the disposal of reactor cores.
Scale-up of this work was carried out on a “nuclear-ready” full-scale industrial facility, demonstrating graphite feeding, furnace operation and graphite destruction successfully. Experiments showed that comparable conditions between lab scale and pilot-scale showed similar oxidation behaviour, with 71.6 kg (equating to 90%) of graphite gasified in 6 h, giving an oxidation rate of ∼12 kg/h.
Engagement with UK regulators has indicated that it is likely to be desirable to further investigate the possibility that isolation and confinement of graphite-derived 14C (t1/2 = 5730 yrs) in a carbon sequestration scheme may be an improvement on the baseline strategy, which is to store it in its solid form as untreated graphite in a geological repository.