A Study of the Oxidation Behaviour of Pile Grade A (PGA) Nuclear Graphite using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT)

Liam Payne, Peter Heard, Tom Scott

Research output: Contribution to journalArticle (Academic Journal)peer-review

8 Citations (Scopus)
363 Downloads (Pure)

Abstract

Pile grade A (PGA) graphite was used as a material for moderating and reflecting
neutrons in the UK's first generation Magnox nuclear power reactors. As all but one of these reactors are now shut down there is a need to understand the residual state of the material prior to decommissioning of the cores, in particular the location and concentration of key radio-contaminants such as 14C. The oxidation behaviour of unirradiated PGA graphite was studied, in the temperature range 600-1050 °C, in air and nitrogen using thermogravimetric analysis, scanning electron microscopy and X-ray tomography to investigate the possibility of using thermal degradation techniques to examine 14C distribution within irradiated material. The thermal decomposition ofPGA graphite was observed to follow the three oxidation regimes historically identified by previous workers with limited, uniform oxidation at temperatures below 600 °C and
substantial, external oxidation at higher temperatures. This work demonstrates that the different oxidation regimes of PGA graphite could be developed into a methodology to characterise the distribution and concentration of 14C in irradiated graphite by thermal treatment.
Original languageEnglish
Article numbere0143041
Number of pages19
JournalPLoS ONE
Volume10
Issue number11
DOIs
Publication statusPublished - 17 Nov 2015

Keywords

  • Graphite
  • Oxidation
  • Tomography
  • SEM

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