There are a few theories floating around, discussed here: https://www.thedrive.com/the-war-zone/29326/what-we-know-about-a-reported-radiation-leak-in-russia-aft

There are a few theories floating around, discussed here: https://www.thedrive.com/the-war-zone/29326/what-we-know-about-a-reported-radiation-leak-in-russia-after-a-missile-engine-exploded https://www.thedrive.com/the-war-zone/29326/what-we-know-abo...