I haven't read the paper, but i am pretty sure i won't understand it. I bolded the sentences that i find interesting.

ORNL has Zenyatta graphite, could they be performing nuclear tests? Possibly, but there is no public evidence that this is occuring or has occurred.

NUCLEAR – Graphite put to the test …

Conclusions drawn from previous oxidation studies for nuclear grade graphite cannot be extrapolated to new versions of the material, which is an integral component of high-temperature gas-cooled reactors. This was a key finding of a study led by Oak Ridge National Laboratory's Cristian Contescu and published in the Journal of Nuclear Materials. Researchers looked specifically at the behavior of nuclear graphite in contact with traces of moisture at the high temperatures associated with gas-cooled reactors. The research showed that differences in raw material, microstructure and purity have a significant effect on the oxidation and slow degradation rates. This information is vital to the industry as new formulations of nuclear grade graphite, a moderator and major structural component in HTGRs, are developed. The paper is available at http://dx/doi.org/10.1016/j.jnucmat.2014.07.009. [Media contact: Ron Walli, (865) 576-0226;wallira@ornl.gov]

Abstract of article in Journal of Nuclear Materials.

http://www.sciencedirect.com/science/article/pii/S0022311514004449