New York Times: A US Department of Energy plan to bury a 50-year-old stockpile of uranium-233 in the Nevada National Security Site is drawing criticism from former DOE adviser Robert Alvarez of the Institute for Policy Studies. Made by irradiating thorium-232 with neutrons, the ²³³U was produced for use in reactors and nuclear weapons at a time when the US government thought naturally occurring uranium supplies were limited. When more sources were discovered, the ²³³U, which is harder to work with than the naturally occurring isotopes, was placed into storage in Oak Ridge, Tennessee. Because ²³³U is the basic fuel needed to build a nuclear weapon and has a half-life of 159 200 years, Alvarez says that the department’s plan for shallow burial of the material is not secure enough. However, department officials say that making the uranium weapons-ready would require an industrial capacity that most nations don’t possess. They also say that removing it from the secret burial site would require heavy machinery, so it couldn’t be easily taken.