Part 1 of 2 Parts
      When a nuclear reactor melts down, a substance is formed called corium which is composed of nuclear fuel, fission products, control rods, structural materials and other components forms. The corium proceeds to melt through the reactor vessel and continues melting through the soil and rock below the reactor building.
    The Sandia National Laboratory researches all aspects of nuclear energy. This extends from uranium production, fuel rod manufacture, transportation, reactor design, and disposal of spent nuclear fuel. One of their goals is to be sure that all of these activities can be carried out as safely as possible. MELCOR software was developed as part of Scandia’s mission. It allows the modeling of nuclear accidents and the spread of corium. Scandia seeks to model catastrophic accidents to identify the causes and to study how changes to the scenarios might result in different outcomes.
      During a three-year Laboratory Directed Research and Development project at the Scandia National Laboratory, a team of researchers discovered and patented a new process for creating a special sand-like mixture of minerals that can be injected into the core of a nuclear reactor during an accident. The result is that the spread of corium is slowed considerably, and the meltdown will be less severe.
     The researchers on the project created computer models with software called MELCOR mentioned above that tracks the formation and spread of corium during a meltdown. David Louie is a nuclear engineer at Scandia. He said, “During a severe reactor accident, the vessel that contained the fuel melts and ruptures, and then all that stuff falls out on the containment floor and starts spreading.” He went on to say that although nuclear accidents are very rare, the consequences can be very extreme for people and the environment. In addition, there is a very negative impact on the public trust in nuclear safety.
    When corium spreads during a meltdown, it increases the release of radioactive materials. Corium melts through the reactor building floor and seeps into the soil. It chemically reacts with any materials that it comes into contact with. One example is what happens when corium comes into contact with concrete. The chemical reaction releases hydrogen gas which could lead to a serious explosions.
    During actual nuclear reactor meltdowns and in computer modeling of accidents, the usual procedure is to inject water into the reactor to try to cool the corium. Unfortunately, this procedure does not cool the corium fast enough to prevent the radioactive contamination from spreading beyond the reactor core. Louie said, “Eventually corium stops spreading because water will cool it down. But you don’t want the accident to get worse and worse while you’re working to bring water in. The water also provides a source of explosive hydrogen.”
    Louie, Yifeng Wang, Jessica Kruichak and other members of the Scandia team researched and tested natural carbonate minerals such as calcite and dolomite. Their research was aimed at determining whether any of the tested minerals could help contain the corium and slow or eliminate the progress of it spreading.
Please read Part 2