Reprocessing spent nuclear fuel recovers approx. 95% of reusable uranium and plutonium, and separates out the remaining approx. 5% of high-level radioactive waste.
This means reprocessing of spent fuel can greatly reduce the amount of HLW.
HLW is mixed with melted glass and poured into durable stainless canisters (this is termed vitrified) at the reprocessing plant and then stored at HLW storage facilities for 30-50 years to allow cooling.