We need something that ABSORBS radiation (like control rods in a nuke reactor), rather than simply reflecting it, and unlike VOID it would ONLY absorb radiation (VOID absorbs EVERYTHING). After placing it, you would use the console (or property tool) to configure it, which would be based on binary flags (sum them together to combine effects). Below are the flag definitions.
tmp=1 absorbs ELEC
tmp=2 absorbs NEUT
tmp=4 absorbs PHOT
tmp=8 gets destroyed over time by collision with particles (a colision with a pixel of a particle it is configured to absorb will destroy one pixel of the absorber)
tmp=16 any particle that it isn't configured to absorb will pass through it (like PHOT through GLAS) instead of reflecting off of it (as reflection would be the default behavior)

In response to other stimuli (fire, heat, pressure etc) it is indestructible, but unlike DMND it can still be destroyed by BOMB and DEST.

When this stuff is placed but BEFORE it is configured by using the console (or property tool), it should behave like DMND in every, except that it can still be destroyed by BOMB and DEST.

It still can't do what my suggested element can do. Mine can be set to reflect or pass through whatever it does NOT absorb. Mine can be set to deteriorate with each absorption. Mine can be set to absorb more than type of radiation (electron, neutron, photon).
Void can ONLY handle 1 type of radiation at a time.
Void can ONLY reflect what it doesn't absorb.
Void CAN'T be set to deteriorate with each absorption.

My element has a primary use as "control rods" in a nuclear reactor. That's what I'm guessing most people will use it for. Other than that it's not very useful, but the use it does have is VERY IMPORTANT! It is something that currently can NOT BE SIMULATED WITH ANY ELEMENT AT ALL, and NOT EVEN WITH A COMBINATION OF ELEMENTS! Mainly, NO CURRENT ELEMENT CAN BE SET TO PASS OR REFLECT OR ABSORB BASED ON ITS TMP VARIABLE (or any other variable).