Evaluation of the use of magnetic sector secondary ion mass spectrometry to investigate C-14 distribution in Magnox reactor core graphite

摘要

Large quantities of irradiated graphite will arise from the decommissioning of the UK's Magnox power stations. Irradiated graphite contains C-14 as well as other longer lived radionuclides (e.g. Cl-36). The potential use of magnetic sector secondary ion mass spectrometry (MS-SIMS) to examine the distribution of the 14C within trepanned graphite samples from a Magnox nuclear power station has been investigated. This work indicates that the methodology proposed has the potential to be used to analyse irradiated graphite samples with preliminary results highlighting a possible C-14 enrichment in the carbonaceous deposit found on a channel wall sample. C-14 concentrations in samples without this deposit were below the limits of detection of the instrument. The methodology used for these determinations ensured that possible mass interferences between C-14 species and oxygen-bearing or nitrogen-bearing species were eliminated from the analysis. Future work will utilize the methodology proposed in this work on a larger number of samples.