The Department of Energy considers the cocktail of uranium isotopes contained in 403 welded, steel canisters destined for the Nevada National Security Site as low-level nuclear waste.
Yes, its main ingredient, uranium-235, is the atom-splitting material used in the first U.S. nuclear bomb and has a half-life of nearly 704 million years. And a second key ingredient, uranium-233, is also nuclear bomb material and will be around at least 159,200 years before half of its radioactive punch decays to safer levels.
But that’s not the biggest problem, according to Nevada officials, who are coaxing their counterparts at the Department of Energy to take utmost precautions when hauling and disposing the stuff here. They insist tight security is required because it contains an impurity that in the hands of terrorists could be turned into a so-called “dirty bomb.”
The impurity is a different isotope, uranium-232. Though it has a much shorter half-life, roughly 70 years, waste containing it requires heavy shielding and must be handled using remote-control cranes.
And as it decays, 232 creates a new menace: thallium-208. That offspring emits short-lived but intense, deadly gamma rays that are, in a nutshell, “radiotoxic” — or biologically harmful to the human environment.
The waste product reached its maximum gamma radiation dose in 1980, or about 10 years after the nuclear fuel that created it was irradiated in a commercial power reactor at Indian Point, N.Y.
Bob Halstead, executive director of the Nevada Nuclear Projects Agency, expects to meet soon with DOE officials to discuss the need for high-security truck transport of the waste from Tennessee to the Nevada site, 65 miles northwest of Las Vegas.
The federal government’s transportation cost will be between $2 million and $3 million, on par with what DOE would spend for hauling bomb-grade, special nuclear material nearly 2,000 miles.
“I hope DOE does what they say they are going to do,” Halstead said last week. “My concern is the security issue. This is a very strange waste form.”
The waste includes remnants of New York’s commercial nuclear power and reprocessing operations from a half-century ago.
The 403 steel canisters have been stored in a building at Oak Ridge National Laboratory in Tennessee, where parts of the nation’s first atomic bombs were developed. The historic building is being cleaned up, and disposing the canisters in Nevada would save the federal government $600 million in remediation costs over 10 years.
The waste itself isn’t nuclear bomb-grade material because it was mixed with cadmium compounds to stop neutrons from triggering an atom-splitting, chain reaction.
But the intense, gamma-ray producing thallium-208 has the potential to be dirty bomb material, even though the amount of the uranium-232 impurity is very small, approximately 120 parts per million. For comparison, 120 parts per million is about the same as dumping most of a 20-pound sack of salt pellets into an average backyard swimming pool.
The waste is not considered high-level, like the 77,000 tons of used reactor fuel pellets in steel-tube assemblies that had been destined for deep geologic disposal in a repository at Yucca Mountain. DOE’s plans for entombing highly radioactive spent fuel in Yucca Mountain, 100 miles northwest of Las Vegas, were quashed by the Obama administration last year.
Nor is this uranium-tainted waste considered transuranic since its elements don’t have more than 92 protons, such as plutonium and other heavier radioactive metals that require disposal in the Waste Isolation Pilot Plant in New Mexico.
Instead, it is an orphaned type of low-level radioactive waste awaiting a new home in a relatively shallow, 40-foot-deep landfill at the Nevada National Nuclear Security Site.
DOE considers it simply “low-level,” but according to the Nuclear Regulatory Commission, the waste is similar to “not greater than Class C” low-level. That means it requires special handling and safeguards and is more potent in terms of its dose-rate than Class A or B low-level waste.
The waste, from a research program called the Consolidated Edison Uranium Solidification Project, is the end-product of thorium nuclear fuel that was irradiated at the Indian Point 1 reactor in New York from 1962 to 1965 and reprocessed at the commercial plant in West Valley, N.Y., to extract plutonium, thorium and uranium for recycling. In addition to 600,000 gallons of high-level radioactive solution that were transformed into glass logs, the extraction process left 8,000 gallons of uranium nitrate solution that eventually was shipped to Oak Ridge.
In the mid-1980s, it was converted to a ceramic form with neutron-absorbing materials to prevent sustained nuclear chain reactions. It was baked together inside 403 welded steel canisters and stored in the vintage World War II building at Oak Ridge.
One government scientist familiar with the project, who asked not to be identified, said the material meets low-level standards based on measurements taken as the liquid was converted to a solid material in 1986. Calculations were made to extrapolate its radioactive content into the future.
Robert Alvarez, a senior scholar for the Institute for Policy Studies and a former DOE senior adviser, said the disposal strategy for the 403 canisters is flawed and “moves the goalposts for even more material like this to be disposed in shallow landfills.”
As impurities decay, the atom-splitting uranium isotopes become more pure. Eventually, “somebody could make unauthorized nuclear weapons,” Alvarez said. “It really sets a bad precedent for both nonproliferation, and environment, safety and health. I think it should be sent to WIPP (the Waste Isolation Pilot Plant) because of its radiotoxic properties.”
Yucca Mountain Project scientists envisioned ways to keep intruders from stumbling onto a tomb of high-level radioactive materials stored in a maze of tunnels for 10,000 years.
They settled on positioning indicators above the nuclear cache based on how people express danger. Project officials imagined etching on 25-ton granite monoliths distraught faces patterned after artist Edvard Munch’s 1893 painting, “The Scream.” They had hoped the images would remain intact over the millennia to illustrate the horror of what could happen if someone retrieved metal containers holding the decaying nuclear fuel pellets.
To complement the artwork, they had planned to write in at least six languages — English, French, Arabic, Chinese, Spanish, and Russian — words that express the phrase, “Caution: Biohazardous waste buried here.” A similar plan was crafted for the Waste Isolation Pilot Plant near Carlsbad, N.M., where the nation’s plutonium-tainted nuclear waste is kept inside caverns in a 2,000-foot-thick salt formation.
Department of Energy officials have not said what, if any, markers they plan to install at the Nevada National Security Site to warn intruders about retrieving the 403 canisters of uranium-tainted waste they plan to bury in Area 5.
Contact reporter Keith Rogers at krogers @reviewjournal.com or 702-383-0308.