A New Approach to Military Nuclear Waste The United States has many pressing nuclear waste problems, but the worst may be the leftovers from the manufacturing of nuclear weapons. Unlike the wastes from civilian reactors, the military wastes are liquids and sludges stored in underground tanks in environmentally sensitive areas. Scores of tanks have leaked some of the material into the dirt. And there is no debate about how the wastes might be repurposed; they have already been scavenged for useful materials like uranium and plutonium. So for decades, the goal has been to solidify them by mixing them with glass, a process called vitrification, so the material can eventually be buried in a repository. With great difficulty and delay, the Energy Department opened a factory to do just that in 1996 at its Savannah River nuclear reservation near Aiken, S.C. In 1989, the Energy Department signed an agreement with the Environmental Protection Agency and Washington State to start work on solidification at the Hanford nuclear reservation on the Columbia River. The process was to begin by 1999, but the pact has repeatedly been rewritten as deadlines were missed. Savannah River had been built and operated by DuPont, a chemical company, and its wastes were simpler and easier to handle there. Hanford had been run by many different contractors, and its wastes had many components that had to be removed before the remainder could go to the glass factory. The federal government has drafted plans for a new glass plant at Hanford several times but dropped them because of technical problems. A plant under construction now, described as being more than 60 percent complete, was originally supposed to cost $5.6 billion but its price tag is now put at over $12 billion, not counting operating costs. It is supposed to run for decades, with the start date now estimated at 2019. But given the extraordinary delays and cost increases, a start-up, Kurion of Irvine, Calif., sees an opening. Kurion has already done nuclear work at Fukushima Daiichi in Japan, where it built a system to filter cesium out of contaminated water at the plant's stricken reactors. So far it has not thus far convinced the Energy Department to hire it at Hanford, however. In the vitrification process, the wastes and glass are typically heated to melting temperature by giant electrodes submerged in the mixture. But the electrodes will eventually wear out -- a problem if the plant has to run for decades and is so radioactive that the maintenance work has to be done by remote control, noted Richard Keenan, Kurion's vice president for engineering. So Kurion uses inductive heating, in which an object that can conduct electricity is put in a chamber surrounded by coils. This create a fluctuating magnetic field that generates heat without physical contact. "If there is no contact with electrodes, there are no corrosivity concerns," Mr. Keenan said.The technique could be used for tank wastes and for soil contaminated by tank leaks. Another twist is meant to address the nature of the tanks at Hanford. They accepted waste that was strongly acidic, but the tanks are made of ordinary carbon steel, which could not tolerate the acidity. So workers added a neutralizing agent that led the wastes to divide: a heavy sludge falls out of the mixture and lines the bottom, and a liquid fills the top. Kurion is trying to convince the Energy Department that the liquid should be filtered with materials like the ones it used at Fukushima because when those have captured much of the radioactive materials, they are easy to melt into glass. The company is also suggesting glass mixtures that are tailored to the waste. The goal is to make glass that will not leach its radioactive contents in millenniums to come. With careful attention to glass chemistry, Mr. Keenan said, technicians can get more radioactive material into each batch without spoiling the glass. So far, the Energy Department seems resolved to complete the main vitrification plant. But a spokeswoman, Lori M. Gamache, said, "At the appropriate time we will evaluate whether their technologies represent cost-effective methods of vitrifying waste." She said the department planned to submit a report on bulk vitrification, the technology for handling contaminated dirt, in two years. At the end of the vitrification process, the molten glass cools in stainless steel containers that are then welded shut. What happens to those is still an open question. At one point they were supposed to go to Yucca Mountain, a proposed national waste repository in Nevada, but the Obama administration shelved that plan. The federal government has not proposed an alternative site and has no method in place to select one.