There was a concept a long time ago that you would do a different type of reactor called a "fast reactor," that would make a bunch of another element called plutonium, and then you would pull that out, and then you would burn that. That's called "breeding" in a fast reactor. That is bad because plutonium is nuclear weapons material. It's messy. The processing you have to get through is not only environmentally difficultly, it's extremely expensive.

Computers and games don't waste time - people do.

Security is, I would say, our top priority because for all the exciting things you will be able to do with computers - organizing your lives, staying in touch with people, being creative - if we don't solve these security problems, then people will hold back.

I spend a lot of time reading.

I'm not big on to-do lists. Instead, I use e-mail and desktop folders and my online calendar. So when I walk up to my desk, I can focus on the e-mails I've flagged and check the folders that are monitoring particular projects and particular blogs.

Energy is very primal stuff and there are a lot of leads that are promising, still at a fairly risky stage, but over the next decade some of these breakthrough approaches are going to pay out, and U.S. research and U.S. leadership on this should be part of how it gets solved.

I like my job because it involves learning. I like being around smart people who are trying to figure out new things. I like the fact that if people really try they can figure out how to invent things that actually have an impact.