Thorium in general, or just liquid fluoride thorium reactors? We know that thorium can work as fuel. We've used thorium as fuel in the past. It can run in Canadian CANDU reactors, or be incorporated into the fuel mix in conventional light water reactors to get drastically improved fuel efficiency, or you can run pebble bed reactors entirely on thorium fuel if you're clever in your ball handling. It's just that uranium is so cheap now that there's not much demand for the increased fuel efficiency that thorium would give -- at least, not until someone does the engineering legwork to get thorium fuel working in existing reactors.