Drywall & Radiation

I was messing around with various methods of blocking cosmic background radiation when I discovered a unique interaction with liquids and drywall in relation to radiation shielding.

First we have a tile of 9999kg of water, exposed to the vacuum of space - the high density completely blocks radiation


Beside it is a tile with the same 9999kg of water - but this time with a backing drywall. The water no longer blocks all of the radiation.


It isn't necessarily the issue of backing - this 9999kg tile of water has the natural background of the planetoid, and correctly blocks all radiation.


...and adding the drywall still reduces the effectiveness of the tile of water. It has the same effectiveness as the 1000kg tile to the right of it (which is the same effectiveness as any 1000kg tile of water)


Additionally, even after removing the drywall backing (via the debug DESTROY tool), any water placed in that location will continue to shield only as much as it would with the drywall backing (this is rectified by saving and reloading)

[here, you can see the same setup from before - where I previously had the 9999kg tile and drywall backing, it still only blocks 16 rads, despite no longer having the drywall]