Kr36 is Krypton

Krypton's name is based on the Greek "crypt-hidden" because it is difficult to isolate.  It is a rare, basically inert noble gas.  It glows with white light; used to detect Pakistani and North Korean early nuclear facilities.  No, Krypton is not a planet (a la Superman) and there is no such thing as Kryptonite.

The somewhat dark painting features layers of multi-colored transparent K's and R's.