MIT team finds that the ratio of component atoms is vital to performance.
The massive task of cleaning up radioactive residue from the country's nuclear weapons manufacturing operation is far from over, and in many cases there is no feasible way to safely dispose of the dangerous material, Dr. Henry Kendall said in a physics colloquium last Thursday.
In his talk entitled "Radioactive Waste: Science, Technology and Politics," Dr. Kendall outlined present conditions at national weapons laboratories including Hanford in Washington state and Rocky Flats outside Denver. He and other members of a task force appointed by the US Secretary of Energy have been studying the labs' future for the past year and made their report in February. Dr. Kendall is the Julius A. Stratton Professor of Physics. He shared the Nobel prize for physics in 1990 and is a founding member and chairman of the Union of Concerned Scientists.
Since the advent of increased environmental legislation beginning in the 1960s, the government has closed contaminated facilities and appropriated money to clean up sites, but despite these efforts, the problem is virtually intractable in some cases, Dr. Kendall said. At Hanford, for example, there are more than a billion tons of contaminated soil and groundwater that will cost an estimated $35 billion to clean. "And this certainly must be an underestimate," he said. "It certainly looks to me, and a number of other people agree, that some of this stuff is simply beyond reach. You could not clean it up no matter how much money you put into it."
There are 160 tanks of high-level waste at Hanford, and 67 are assumed to have leaked about a million gallons into the underlying soil, Dr. Kendall said. Running alongside the complex is the Columbia River. By the 1960s, Hanford (which at one time included the largest nuclear reactor in the world) was dumping more than 15,000 curies of radioactive material into the river each day, and ocean fish up to 150 miles from the river's mouth have been found to be radioactive.
"The records have either been lost or are incomplete; they're still finding sites up there," he said. "Those sites are simply dripping radioactivity into the river and they will continue to do so for a very long time."
Complicating the problem is a method once used to conserve storage space. Ferrocyanide was added to some of the tanks to precipitate out some cesium and strontium nuclides so the liquid could be drained into leaching fields, Dr. Kendall said. The resulting compounds in the tanks are explosive as a result. There was an explosion of this type in the Soviet Union in 1967, resulting in radioactive contamination of three provinces.
"That place is sodden with plutonium-you have no idea," Dr. Kendall said of Hanford. "I thought I knew something about radioactivity, but I never saw anything until I went there."
At Rocky Flats, where plutonium was made into the fissionable portion of nuclear weapons, tiny particles of plutonium emit alpha particles (posing a threat to human health in even the tiniest quantities) and can also ignite on contact with air. There were two serious fires there during the Cold War as a result, he said. The closed plant contains hundreds of miles of contaminated piping and ductwork serving the gloveboxes used by workers. There are almost 13 metric tons of plutonium on site, some of it "in forms not safe for long-term storage," he said.
The plant was closed by the Department of Energy so abruptly that bottles of plutonium nitrate are still resting in those gloveboxes. "This is hot stuff if you walk out on it, and for the most part, it is still there," Dr. Kendall said. Some of that material could go critical, resulting in greatly increased releases of radioactivity, he added. Residents near many US facilities have taken action to force the government to deal with the contamination, "but Rocky Flats has the most angry and upset constituency of any element of the DoD weapons complex."
A third site, the Idaho National Engineering Lab, sits over the second-largest aquifer in the United States. That aquifer has been injected with cesium, strontium, petroleum sludge and sewage, Dr. Kendall said. Solid radioactive waste was put in uncovered trenches; during spring floods, "this stuff just sort of floated around," he said. There are also barrels of material that are "unapproachable" because of the intense radioactivity they emit, "and they have no idea how to deal with that at present."
The cost to the government of cleaning up all the country's nuclear weapons facilities is about $5,800 per cubic meter for low-level waste and $6 million per cubic meter for high-level waste and the total bill could be $1 trillion, Dr. Kendall said. Passage and enforcement of environmental regulations affecting the weapons facilities represented "a tremendous sea change. [but] many of them mandated things that were physically impossible," such as a requirement that Hanford be completely decontaminated by 2018. The safest places to store radioactive waste permanently are deep, geologically stable areas of the ocean, but a study of that idea was shelved in 1985, he said.
The Congressional Budget Office has determined that the bureaucracy of the clean-up effort is such that at least 40 percent of program funds have been spent on administrative and support activities, Dr. Kendall said. Furthermore, no priorities have been set on the various contamination problems; "that's one of the big lacks our study focused on," he added.
All the money and legislation that have been directed toward the problem are not going to solve it any time soon because "a lot of the required technology simply does not exist," he said. "The system is not in a stable state, and a lot of these goals technologically at the moment seem unachievable."
A version of this article appeared in MIT Tech Talk on March 15, 1995.