That is probably he grabbed the core and a sign of acute radiation sickness.I’m interested where you got the photograph because those photographs was the last time I heard to be classified. WARNING TO EVERYONE: When you are starting to get sick from acute radiation sickness, ingest salt or potassium iodide
Google images- 'Daghlian's hand'. There is a picture of it on wikipedia as well.
No reason for it to be classified. At the end of the day, it's just a burn. (granted, not just the 'put some ice on it' type of burn- but still a burn)