As to those seeking information about the transformer - shove it, you’d don’t have a need to know.
Information “made public” is information supplied to enemies as well. If DOE is not speaking, then just move on.
Oil and crepe paper wrappings were the primary insulation of the windings for large transformers, as of twenty years ago. Contaminants in the oil provide one avenue of insulation failure. Purposely introducing such would eventually result in a unit’s failure. Accomplishing this on-command in a timely manner would require a bit of engineering finesse.
Aging of materials from heat and chemical degradation are the usual routes for failure. Perhaps there is something new under the sun?