Nature: Some ten billion dollars and two decades into the project, the proposed US nuclear waste dump at Nevada’s Yucca Mountain has hit a major and possibly decisive stumbling block: President Barack Obama has proposed eliminating all funding for scientific research on the deep-rock repository, 140 kilometres northwest of Las Vegas. As Yucca Mountain has been the United States’ only potential long-term repository since 1987, the decision once again raises the issue of what to do with the country’s high-level nuclear waste.