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"Nuclear Archaeologists" Find
World War II Plutonium
A plutonium sample recently found at a U.S. waste dump is leftover from a batch used by the Manhattan Project, which produced the world's first nuclear bomb test, a team of chemists has announced. A nuclear waste cleanup team unearthed the 0.01 ounces (400 milligrams) sample in a waste pit at the Hanford Nuclear Reservation in Washington, where it was sealed in a glass jar and enclosed in a safe. The discovery highlights new techniques in the emerging field of nuclear archaeology that could become key factors in nuclear deterrence. Although the mysterious material was unearthed in 2004, its origins were unknown until the researchers used state-of-the art methods to identify its age and history. The clues led the team to the X-10 reactor at Oak Ridge, Tennessee, which was once part of the Manhattan Project. The spent sample was sent to Hansford for reprocessing—or removing bomb-grade plutonium from nuclear waste products. "This kind of nuclear archaeology is unclassified, so it gives the public a rare glimpse at what can be done to potentially identify the origin of these types of materials," said nuclear chemist and team member Jon Schwantes, of the Pacific Northwest National Laboratory in Richland, Washington. (Related: "Archaeologists Explore Cold War Nuclear Test Site".) Finding "Fingerprints" The work, described in the journal Analytical Chemistry, highlights experts' growing ability to pinpoint the origins of dangerous nuclear materials. Because plutonium is rare in nature, weapons-grade reactors must process uranium into the right version, or isotope, of plutonium. To find a plutonium sample's age, scientists chart the element's rate of decay back into uranium. The levels of different plutonium isotopes then provide a unique fingerprint that can reveal the reactor of origin. "Each reactor that's producing this material has a slightly different makeup to it," Schwantes explained. "It may be burning a different type of fuel or [running at] higher or lower burnup levels," resulting in different isotope ratios in the finished product. More clues come from levels of reactive agents, such as iron, added during processing and reprocessing. For the Hansford sample, the team could tell that the plutonium was reprocessed using the bismuth-phosphate method, the only industrial-scale technique used in the U.S. in the 1940s. Nuclear Forensics Harold Smith, of the Goldman School of Public Policy at the University of California, Berkeley, noted that "nuclear forensics" efforts actually began in 1949. That year, the U.S. used airplanes near the Chinese coast to monitor airborne debris and determined that the Soviet Union had detonated its first nuclear weapon. Today, if plutonium is captured in transit or terrorists detonate a device, tracking techniques like those Schwantes used could help determine the material's origins. But that requires comparing the stolen material, or the debris from an explosion, to data banks held by makers of nuclear material, Smith said. Such information is not universally available. "You can have hundreds of fingerprints at a crime scene, but it won't do you much good unless you have a data bank of prints to compare it to. That data bank is going to be a pressing issue in the decade ahead." Access to information on reactors and nuclear production is a sensitive national security issue. But Smith said that collaboration among nations is improving, and agencies such as the International Atomic Energy Agency have the beginnings of data banks. Such a system could give pause to those who would acquire nuclear materials illegally. "If Russia and the U.S. were willing to say they will be able to hold accountable anyone who supplies fissile material to terrorists, it could have a significant deterrent effect," Smith said. © 1996-2008 National Geographic Society. All rights
reserved.
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In 1940 a team of scientists
at the University of California, Berkeley, used a sixty-inch cyclotron
to discover and create plutonium, a radioactive element that provides the
explosive component for nuclear weapons and fuel for nuclear reactors.
A sample of the plutonium isotope Pu-239, produced in 1941, was preserved
in a cigar box and stored at the university for many years. In 1966 Glenn
T. Seaborg and Emilio Segré, Nobel Prize-winning physicists who
had participated in the discovery, presented the sample to the Museum of
History and Technology. Curators of the museum's new Hall of Nuclear Energy
praised plutonium as promising "unlimited electrical power for an energy-hungry
world." Source: Smithsonian
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Archaeologists Explore Cold War
Nuclear Test Site
Bright yellow radiation suits are not standard-issue attire for archaeologists. Nor is a Geiger counter. But these precautions are sometimes required for the researchers exploring the eerie A-bomb rubble and ghost towns left over from Cold War blasts at the Nevada Test Site, formerly the Nevada Proving Grounds, on 1,375 square miles of desert 65 miles northwest of Las Vegas. From 1951 until a test moratorium in 1992, 928 nuclear devices were exploded at the Nevada site. Aboveground tests were allowed until 1963, and night explosions were visible all the way to Las Vegas. Cold War Hot Zone Worth Preserving "The Nevada Test Site was one of the battlefields of the Cold War," said Troy Wade, who spent 31 years with the program, starting as an explosives engineer and retiring as an assistant secretary of Energy for Defense Programs at the United States Department of Energy (DOE). "Just as artifacts from a World War II battlefield are worth preserving, so are these." "I'm one of the diminishing number of people who saw atmospheric tests," Wade added. "It's hard to describe the feeling of awe, when you see blinding light, feel the intense heat, and brace against the shock wave—it was very intense and very scary." The unnatural Dr. Strangelove-era desert landscape is littered with mock towns, bridges, bomb shelters, bank vaults, underground parking structures, empty animal pens, and railroads, which were exposed to atomic blasts to determine what could survive a nuclear attack. To Wade, the twisted relics at NTS represent "a snapshot of the destructive power of these weapons." Wade is chairman of the NTS Historical Foundation, which is planning a research center and museum in partnership with the DOE and the Desert Research Institute (DRI), a nonprofit environmental institute in Las Vegas that's affiliated with the Nevada state university system. The museum will house historic films and photos as well as artifacts from NTS. The DOE and DRI have sponsored an archaeological mission to survey and discover structures that are worthy of preservation. To date seven sites have received this "historic place" status, with many more pending. Though one might expect the government to have extensive documentation of this site, the only way to find what lies here is to look, said Colleen Beck, an archaeologist at DRI. "There are many things that exist in the plans but were never built and vice versa," said Beck. For example, archaeological surveys reveal crumpled aluminum shelters and animal pens that were not included in original plans. Twisted Relics Aboveground testing was confined to three areas—Frenchmen Flat, Yucca Flat, and Pahute and Rainier Mesas, where the archaeologists do most of their work. When determining whether something is worthy of being deemed an historic site, the more destruction that occurred, the better, said Bill Johnson, an archaeological team leader from DRI. "The more damage, the greater its integrity—it actually looks as though it was subjected to a nuclear weapon." At Yucca Flat, a 700-foot (213-meter) tower that once stood at Ground Zero holding a bomb is now a gnarled, twisted mass of huge I beams and steel cables covered in glass formed from molten sand. The parched lakebed of Frenchman Flat was exposed to 14 explosions. Here, a few hundred structures have been found. One survivor 1,150 feet (350 meters) from the blast site is a battered but intact Mosler bank vault—all the documents inside at the time were unharmed. "These structures convey fear—frightening times, terrifying power," said Johnson. "There is a mystique to the Atomic Age, and Bill's work creates a link between the mythology and the physical remains," said historian Mandy Whorton, formerly of DOE, now with the environmental research firm Harding ESE, in Golden, Colorado, who has studied early radar sites in the Arctic Circle, Greenland, and Alaska. Ghost Towns, X-Files, and Lunar Landscape Johnson's colleague Beck ventured into a huge structure known as the Reactor Maintenance Assembly and Disassembly building, where scientists worked to develop nuclear rocket engines. "The building was filled with water and there was no electricity—it was my most 'X-files'-like moment," Beck said. Wrapped in bright yellow suits and armed with flashlights and Geiger counters, "we walked through mini hot cells and tracks that had been used to move radioactive material around." At Yucca Flat, Johnson has explored an Atomic Age ghost town—the disintegrating skeletal remains of a Japanese village. The village was never subjected to a nuclear explosion; instead a bare nuclear reactor spewed radiation into these houses to help determine the exposure levels of Hiroshima and Nagasaki survivors. Scientists used the dosage information for medical studies and treatment regimens. When the testing moved underground in 1963, the program became more secretive, said Beck. But the results of the subterranean program could not be completely hidden. An aerial view of the Site reveals a cratered surface caused by underground explosions. The landscape is so moonlike that one crater, the Schooner Crater, was actually used to train Apollo astronauts for moon walks. A-bomb Mannequins One of the more bizarre artifacts yet to be discovered is a family bomb shelter equipped as if for a "Leave It to Beaver" family, with fully dressed mannequins, TVs, furniture, and a kitchen full of canned goods. "It would be like opening King Tut's tomb" to find that 1950s time-capsule shelter, Johnson said. He's already tracking one set of mannequins. The strongest clue is that they were dressed in clothes from J.C. Penney. In 1955, J.C. Penney stores in Nevada displayed the mannequins before and after an A-blast, a store manager at the time has told Johnson. "You just know those mannequins are sitting in a J.C. Penney basement somewhere," Johnson said. National Geographic Today, at 7 pm. ET/PT in the United States, is a daily news journal available only on the National Geographic Channel. Click here to learn more about it. Go>> © 1996-2008 National Geographic Society. All rights
reserved.
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