▁" for ▁many ▁years ". ▁In ▁December ▁ 2 0 1 7 , ▁however , ▁senior ▁May ak ▁executive ▁Y uri ▁M ork ov ▁admitted ▁that ▁r uth enium - 1 0 6 ▁is ▁rout in ely ▁released ▁as ▁part ▁of ▁the ▁plant ' s ▁processing ▁of ▁spent ▁nuclear ▁fuel . ▁M ork ov ▁character ized ▁the ▁amount ▁released ▁as ▁" ins ign ific ant " ▁and ▁denied ▁May ak ▁was ▁the ▁source ▁of ▁the ▁radiation ▁sp ike . ▁ ▁Dom estic ▁investigation ▁within ▁Russia ▁is ▁ham per ed ▁by ▁the ▁problem ▁that ▁May ak ▁is ▁in ▁the ▁w alled - off ▁closed ▁city ▁of ▁O zy or sk , ▁which ▁non - res ident ▁Rus si ans ▁are ▁bar red ▁from ▁visit ing ▁without ▁special ▁permission , ▁and ▁by ▁government ▁har ass ment ▁of ▁nuclear ▁critics . ▁In ▁Russia ▁prominent ▁nuclear ▁critics ▁experience ▁government ▁ra ids , ▁are ▁accused ▁on ▁state ▁TV ▁of ▁" exp lo iting ▁the ▁nuclear ▁issue ▁to ▁f oment ▁revolution ", ▁and ▁risk ▁criminal ▁pro sec ution ▁on ▁charges ▁of ▁inc itement ▁of ▁hat red ▁against ▁nuclear ▁energy ▁employees . ▁ ▁The ▁Russian ▁Academy ▁of ▁Sciences ' s ▁N uc lear ▁Saf ety ▁Institute ▁set ▁up ▁an ▁international ▁committee ▁to ▁investigate ▁the ▁incident . ▁The ▁French ▁Institute ▁of ▁Rad iop rote ction ▁and ▁N uc lear ▁Security ▁( IR SN ) ▁provided ▁a ▁report ▁to ▁the ▁committee ▁in ▁January ▁ 2 0 1 8 . ▁The ▁report ▁concluded ▁that ▁the ▁most ▁likely ▁source ▁of ▁the ▁poll ution ▁is