A safeguards benchmark for how much material matters: 8 kg of plutonium, 25 kg of uranium-235 contained in high enriched uranium, or 8 kg of uranium-233, with larger amounts for low enriched and natural uranium. Inspection goals and the detection probability required at each facility are set in terms of significant quantities, so a facility's annual throughput in SQs drives how intensively it is inspected.
Plant's throughput is dozens of significant quantities of plutonium in spent fuel, so the cameras never come down.
Also heard as
- SQ
Related terms
Safeguards
The verification system that checks nuclear material is not diverted from peaceful use to weapons.
Criticality safety
The discipline of preventing an accidental chain reaction wherever fissile material is handled outside a reactor.
Spent fuel pool
A deep, water-filled pool at a reactor where used fuel is stored to cool and to shield its radiation.