The raindeers was radioactiv long before Chernobyl. Sovjet did extensive bomb testing during the cold war up north and the northern part of Norway got plenty of radioactive fallout from that. The following as one of the more insane ones: <a href="https://en.wikipedia.org/wiki/Tsar_Bomba" rel="nofollow">https://en.wikipedia.org/wiki/Tsar_Bomba</a>