U.S. Energy Secretary Steven Chu speaks at the general conference of the International Atomic Energy Agency in Vienna, Austria, on Monday, Sept. 19, 2011. (AP Photo/Ronald Zak)

Photo by: Ronald Zak

U.S. Energy Secretary Steven Chu speaks at the general conference of the International Atomic Energy Agency in Vienna, Austria, on Monday, Sept. 19, 2011. (AP Photo/Ronald Zak)