The most dangerous parts of spent fuel is the actinides which are the elements heavier than uranium all of them are radioactive some for millions of years and every one of them is fuel in a epithermal or fast neutron spectrum being burnt to fission products. Only two fission products have half lives long enough to worry about on geological time scales Tc and Sr both have 100k half lives you have a choice with reprocessing separate them and turn them into borasilica glass which is chemically inert and not leachable by meteoric or ground waters. In that form you still a borehole into.granite or shake and put them in stable rocks. Or you make target pins with them and put them into a hard fast neutron spectrum and transmute them into short half life isotopes. Fast spectrum reactors can make fuel and burn long lived fission products at the same time in the same core.
As a professional geologist I can name four places in Texas also that have geologically stable rocks in place for 500 million to 1.3 billion years and will be stable for at least that length in the future Texas is not near any active tectonic margins. You only need a million years of isolation for the long lived fission products and less than 1000 for all the others that is a blink in geologic time. Drill a bore hole 1000 meters into granite fill the bottom 500 with reprocessing separate fission products in borosilica glass and the other 500 with cement same for scales still down then go horizontal just like a shale gas well for 2000+ meters then place the wastes at the time of the well fill the vertical with cement. There is a reason the.natural gas under tens of thousands of psi of pressure is still in the shale after tens to.hundreds of.millions of years it’s gas and water tight and stable over those times scales. No need to use gas shales for waste management there are plenty of dry shales in the Geological settings to.use for waste management.
Oh how I loathe auto correct. Especially when you can’t turn it off.
Still= drill
Shake = shales