Sun in a Bottle - Charles Seife [102]
At first glance, it is not obvious how it would contribute at all. Most of the problems with aging weapons involve the decay of the plutonium “pits” that start the reaction going. Will the pits work? Are they safe? Can you remanufacture old pits or must you rebuild them from scratch? These issues are relevant only to a bomb’s primary stage, the stage powered by fission, not fusion (except for the slight boost given by the injection of a little fusion fuel at the center of the bomb). The fusion happens in the bomb’s secondary stage, and there doesn’t seem to be nearly as much concern about aging problems with a bomb’s secondary. If the primary is where most of the problems are, what good does it do to study fusion reactions at NIF? NIF’s results would seem to apply mostly to the secondary, not the primary.
Since so much about weapons work is classified, it is hard to see precisely what problems NIF is intended to solve. But some of the people in the know say that NIF has a point. The “JASONs,” for example, argue that NIF does help maintain the stockpile—but not right away. NIF will contribute to science-based stockpile stewardship, the panel wrote in 1996, “but its contribution is almost exclusively to the long-term tasks, not to immediate needs associated with short-term tasks.” That is, NIF will help eventually, but it is not terribly useful in the short term.
What are those long-term tasks? Two years earlier, the JASON panel was a little more explicit. NIF would help a bit with understanding what happens when tritium in a primary’s booster decays. (However, since tritium has a half-life of only twelve years, it stands to reason that weapons designers periodically must replace old tritium in weapons with fresh tritium. This is probably routine by now.) NIF will also help scientists understand the underlying physics and “benchmark” the computer codes—like LASNEX—that simulate imploding and fusing plasma. (But why is this important if you are not designing new weapons? The ones in the stockpile already presumably work just fine, so you presumably don’t need a finer understanding of plasma physics to maintain them.) The JASON members have access to classified information, but even so, their justifications for NIF seem a little thin—at first. And then JASON lists one more contribution that NIF makes to stockpile stewardship: “NIF will contribute to training and retaining expertise in weapons science and engineering, thereby permitting responsible stewardship without further underground tests.” That’s the main reason for NIF.
With the moratorium in place, nuclear tests are at an end. New scientists entering the program will never have a chance to design a bomb and test it. They will never have a chance to study a live nuclear explosion. All they have left are computer simulations and experiments that mimic one part of a nuclear explosion. NIF would be the only facility that mimics the explosion of a secondary; it would give young scientists a chance to study secondary physics without ever seeing a nuclear test. And that’s the point of NIF. NIF is essentially a training ground for weapons scientists. As old ones retire and new ones grow up without ever having seen a nuclear test, NIF is a way to give them some level of experience so that America doesn’t lose its nuclear expertise.
NIF isn’t truly about energy. It is not about keeping our stockpile safe, at least not directly. It is about keeping the United States