cool '' does not begin to describe it . First , Brian Cracciola showed us around Livermore 's High Explosives Applications Facility , where he is the operations manager . At HEAF , scientists conduct up to 1,000 explosions a year and heat up explosives to react to thermal changes . He walked us into a tank that can blow up 22 pounds of explosives . `` When and if the president ever has to push that button , we need to know that the weapons will work , '' Cracciola said . `` And as we scale down the nuclear weapons , we are working to make them much safer and much more reliable . '' Bruce Goodwin , who runs the weapons program at Livermore , explained that high-explosive molecule testing is even more extensive than the traditional testing done before 1992 , when a nuclear test involved blowing up a nuclear weapon . `` There are hundreds of ways a nuclear device can fail , '' Goodwin told us `` We catalogue those and we test against them in a non-nuclear fashion . And , more importantly , we can do complete three-dimensional simulations of things that
Livermore , California -LRB- CNN -RRB- -- The new START arms control agreement with Russia calls for the United States to significantly reduce its nuclear stockpile , but critics are rightly asking whether this will leave the U.S. safe . They say the U.S. must maintain a healthy nuclear deterrent , even as it works toward President Obama 's goal of a world free of nuclear weapons . That leaves questions about the quality of the nuclear weapons the U.S. will keep in its arsenal , which are aging . Are they safe ? Are they reliable ? And , given that the United States stopped testing nuclear weapons by blowing them up -- both above and below ground -- 18 years ago , how will we know ? Those are some of the questions that CNN 's Foreign Affairs Correspondent Jill Dougherty and I sought to answer when we flew to Northern California for an exclusive tour of the Lawrence Livermore National Laboratory . At Livermore , it is all about virtual testing . Scientists actually generate the conditions of a nuclear weapon to analyze the nuclear stockpiles to make sure they are functioning correctly . The word ``