Nuclear Neighbors

    It’s perversely easy to miss interesting things that are happening right next door. Take our immediate neighbors to the north, for example. On the south side of Genessee is the UCSD campus, although it’s mostly trees at that point. But many students are unaware of what lies on the other side of the street — one of the leaders in nuclear reactor research, General Atomics, as well as a few nuclear reactors.

    Arash Keshmirian/Guardian

    The decommissioned TRIGA research reactors are the primary draw to the site for visitors, but General Atomics’ DIII-D Research Program has eclipsed them in research potential. This site is not dedicated to the typical fission reactors most are familiar with, but with a different animal entirely: fusion.

    For those who are not nuclear physicists, the process is a bit mind-boggling. But essentially, the goal of a fusion reactor is to create a working model of the sun, heating hydrogen isotopes to an extreme temperature (around 250 million degrees Celsius) until they combine together in a superheated cloud of ionized gas called plasma. This is the primary difference between the DIII-D Reactor and other typical reactors. Instead of dividing atoms, they are combining them.

    The novel feature of the process is how much safer it is when compared to traditional reactors. The only byproducts of a fusion reaction are helium gas and neutrons. Although these neutrons can produce radioactivity, the difference in radioactivity compared to a fission reactor is large. There is no radioactive waste of the type that needs to be kept in swimming pools long after the reactor has been decommissioned, and there is little chance of a Chernobyl-type disaster. According to General Atomics, “Any malfunction will produce a rapid elimination of the conditions necessary to sustain the fusion reaction and, as a result, a complete and safe shutdown of the fusion process is assured.””

    With an ever-increasing population and usage of energy and fossil fuels unfortunately increasing at a steady rate, even the most optimistic agree that new energy sources will become necessary in the near future. If one assumes a limited fossil fuel supply, that leaves two alternatives: renewables — hydropower, solar, wind, geothermal and biomass — and nuclear energy. If fusion reactors could be created on a global scale, they would offer a fairly clean, renewable energy source that is desperately needed.

    But it’s far from easy. Fusion research is pushing the boundaries of modern technology. The major challenge is containing and controlling superheated plasma long enough for the ions to fuse. There is literally no material on earth that can withstand contact with heated plasma, which means that the plasma has to be kept in place by alternate methods — namely magnetic and electric fields. To simply reach this point, the DIII-D reactor requires the development of superconducting magnet technology, plasma heating techniques (microwaves and neutral beams), large-scale high-vacuum technology and several advanced materials. The DIII-D is simply a research reactor, only running for approximately five-second intervals, called shots, and only about a quarter of the size expected to be necessary for full-scale fusion reactors.

    General Atomics is not alone in its search for a reliable fusion reactor. Since declassification of fusion research, this search has been a global one, involving more than 40 major countries. There are several DIII-D-sized or larger reactors in other parts of the world — with the goal of a full-scale reactor by 2013, and the hope that self-sustained nuclear fusion could be achieved by 2017. The name for this project is the International Thermonuclear Experimental Reactor, or ITER, and is on track to be built in France, a world leader in nuclear power technology.

    Because of this multinational project, what was perhaps the most interesting part of the General Atomics facility was not the reactor itself, but rather its environment. DIII-D’s 130-plus crew is not limited to just nuclear physicists, but also includes researchers from many disciplines, including mechanical engineering, computer science, high-voltage and low-voltage specialties and electronics.

    “That’s the nice thing about working at this facility; essentially, you have everything,”” Assistant Director Peter Petersen said, who added that he’s never encountered a wider variety of people in his 30 years of working in the field. “We have people from Europe come here to do experiments, [and] we have people from UCSD [as well].””

    Such a wide array of employees makes the workplace interesting. Personal touches are all around the facility, from “Wizard of Oz”” posters and a machine affectionately named Toto, to a Froot Loops box labeled, “IN CASE OF HERESY BREAK CARDBOARD.””

    Unfortunately, the experiments only run for about 12 weeks per year, with the first usually beginning around February. The preceding months are used to clean the machine and calibrate over 60 diagnostics that collect data during a shot. During a typical shot, these diagnostics collect over three gigabytes of data, which is later analyzed by the scientists organizing the experiment.

    General Atomics, which receives most of its funding from the federal government, hopes to obtain enough money to run for 27 weeks per year, but expects an uphill battle. Clean, efficient nuclear energy reactors may be some time away from being reality, but the prospect is enticing enough to ensure that federally-funded corporations will continue to strive for it.

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