Editing Thorium Reactor Waste and Proliferation (section)

== The Waste Problem with Conventional Reactors ==

Conventional uranium light water reactors (LWRs) use only approximately 2–3% of the uranium fuel that enters them. The remaining 97–98% exits as spent nuclear fuel — a mixture of:

* Unused uranium-238 (the dominant component)
* Unused uranium-235 (small quantity)
* Plutonium (various isotopes, ~1% of spent fuel mass)
* Minor actinides (neptunium, americium, curium — small quantities but extremely long-lived)
* Fission products (shorter-lived isotopes)

The minor actinides and some of the plutonium are the primary drivers of the long-term radiological hazard of spent nuclear fuel. They have half-lives of thousands to hundreds of thousands of years, requiring secure geological storage for periods that exceed all of recorded human history. The proposed Yucca Mountain nuclear waste repository in the United States was designed specifically to manage this material over a 10,000-year regulatory compliance period.

A single 1,000 MW conventional LWR produces approximately 30 tonnes of spent nuclear fuel per year.