Deep Geologic Repository
A deep geologic repository stores high-level nuclear waste in stable underground formations at 300-1,000m depth. Engineered barriers prevent radionuclide migration for millennia.
Sites target low-permeability rock like granite, salt, or clay; Finland's Onkalo is first operational (2025 start). US Yucca Mountain designed for 70,000 MTHM but stalled. Repositories must isolate waste for 10,000+ years per regulations. Multi-barrier system: wasteform, canister, backfill, geosphere.
Why it matters now
Deep repositories are critical for spent fuel disposal as US pools fill and SMRs proliferate in 2025-2026. Delays block restarts; private ventures like Deep Isolation gain traction for investors.