[andreasley]

A more likely explanation: "The French IRSN has put forth the hypothesis in Jan-2018 that a possible reason for the release of Ru-106 radioactivity at Mayak-PA might be an unsuccessful attempt to extract the short-lived reactor-generated-isotope cerium-144 for the European/Italian nuetrino-detecton-project Borexino. Mayak-PA had agreed to deliver cerium-144 in early 2018, but canceled the contract in December 2017. Mayak PA was the only facility contractually-willing to attempt the extraction of cerium-144 from "fresh" spent nuclear fuel, 2–3 years old." [1]

[1] https://en.wikipedia.org/wiki/Airborne_radioactivity_increas...