Up to my knowledge, spent Fuel and plutonium are first sent for recycling in France and not burry as such.
Spent fuel is currently sent to La Hague, where afaik they store almost all of it in warehouses surrounded by barbed wire, just like everybody else. It'll take decades to move all of it to Bure, or wherever else they decide to put it.
[1] https://www.base.bund.de/DE/themen/soa/endlager-weltweit/fra...
To my understanding, the tag "research project" has been mainly used to avoid a crowd of NIMBYs from day one. There is already nuclear waste in the tunnels and not in small quantities. It does work and is used for what it has been designed.
Budget is hardly surprising when we talk about a facility supposed to store the garbage of a country that has been running full nuclear for 40 years.
> Spent fuel is currently sent to La Hague, where afaik they store almost all of it in warehouses
Part of it is there are to be recycle in Mox. An other part is to be re-enriched. The rest will very likely be buried underground since the Fast Neutron reactor plans are unlikely to happen any time soon due to short term politics.
1- Select a not-so-random place in middle of the desert with stable geological ground
2- Make a tunnel 600m underground.
3- Put the dumps here
4- Congratulations: your nuclear waste problem is not a problem anymore.
You solved it in the scientifically recommended way. And the same way than France, Sweden, Finland and China did it.