At half operation, ignition and sus tained fusion would not occur, he notes, but fundamental physics and weapons work could still be done. The task force did not evaluate NIF's costs, and McTague says the panel awaits other reviews aimed at sorting out spending. Jeff'Johnson polylactide, and the Blair unit's capacity will be sold out by the time it's running. So, as soon as the Blair unit is operational, Cargill Dow will begin building a unit in Europe. The company in tends to open other plants every 18 to 24 The first commercial-scale production months after that. It plans to have a global unit for polylactide—a polymer derived capacity of about 1 billion lb by 2006. completely from annually renewable The Blair unit will extract dextrose feedstocks—has been announced by from about 40,000 bushels of corn each Cargill Dow Polymers, the two day. Under a patented process, Cargill year-old 50-50 joint venture be Dow will ferment the dex tween Minnetonka, Minn.trose, making lactic acid. based Cargill and Dow The lactic acid is convert Chemical. ed into lactide ring inter mediates. Then a metal Cargill Dow is optimis catalyst is employed in tic about the polymer, breaking open the rings to not only because of its form the polylactide poly environmental benefits, mer. Future plants will but also because of its materi be able to use various pri al properties. "It has cost-per mary feedstocks—such as wheat, formance advantages even rice, or agricultural waste—depending though it is derived from carbo hydrates rather than hydrocarbons," says on what is most economical in a given William S. Stavropoulos, Dow's president geographic area. and chief executive officer. Alex Tullo "Until now, no one has been able to make polylactide a viable commercial offering," points out Jim Stoppert, 2 Cargill Dow Polymers' president and CEO, noting that companies have tried to develop plastics out of lactic acid for more than a century. Disproving conventional wisdom, re Cargill Dow is targeting fibers and searchers have shown that Pu0 2 is not packaging applications for polylactide. the most stable binary plutonium oxide. Either blended with other fibers or on A nonstoichiometric compound, Pu02+x, its own, polylactide is suitable for appar which forms slowly as Pu0 2 reacts with el. Carpet makers may find it attractive moist air, turns out to be the thermodybecause both the face fiber and backing namically favored oxide [Science, 2 8 7 , can be made of polylactide, facilitating 285 (2000)]. The study explains several recycling. Primary packaging applica puzzling observations in plutonium tions include films, thermoformed food chemistry and has implications for civil and beverage containers, and coated pa ian and military applications. per and board. The investigation was conducted by a Cargill Dow says it will build a 300 mil- group of staff scientists at Los Alamos Na lion-lb-per-year plant at Cargill's complex tional Laboratory (LANL), Los Alamos, in Blair, Neb. The plant is scheduled to N.M., including John M. Haschke (now a private consultant in Waco, Texas), Thom come onstream toward the end of 2001. With the polylactide unit, Cargill as H. Allen, and Luis A. Morales. Dow Polymers will have invested more "It's careful and thorough work," re than $300 million in the partnership. marks Norman M. Edelstein, a heavyAnd the partnership intends to spend element researcher at Lawrence Berke much more in coming years. Cargill ley National Laboratory, Berkeley, Calif. Dow says customers are lining up to buy Edelstein adds that these latest findings
Plastic found at the end of the maize
Heavyweight Pu0 loses stability title
represent "an important contribution" for a number of reasons. To begin with, the LANL research an swers decades-old questions about funda mental plutonium properties like color and oxidation state. Haschke points out that Pu0 2 is dark yellow. The green color that has been observed previously is due to the higher oxide, he says—not impuri ties, as some have suggested. And contrary to the commonly held view that the oxidation state of plutonium in the stable oxide is exclusively Pu (IV), the present work shows that Pu0 2 can be oxidized as high as Pu0 2 27, suggesting that more than 25% of plutonium atoms are in the Pu (VI) state. The study also provides another mechanistic explanation for the hydro gen production that's been observed during plutonium hydrolysis and oxida tion. Gas evolution in sealed storage containers leads to pressure buildup—a serious concern for long-term storage. 'The new results have great conse quences for underground disposal of nuclear wastes," writes Charles Madic of the Centre CEA de Saclay (part of the French Atomic Energy Commission), Gif-sur-Yvette, France, in a commentary in the same issue of Science. A key factor in favor of burying pluto nium waste is the highly insoluble nature of Pu (IV) compounds. But now the safety of those practices needs to be reconsid ered, Madic comments, in light of the fact that Pu (VI) species are far more soluble and hence more mobile in geological en vironments. Madic adds that these latest findings also call for "new evaluations of industrial operations involving Pu()2." Haschke explains that water mole cules split into hydrogen and oxygen at oms as water vapor adsorbs on solid Pu0 2 . Oxygen (from water) converts the dioxide into a higher oxide: Pu0 2 + χΆ.,0 -> Pu0 2+x + 2xH In an oxygen-free environment, he says, hydrogen atoms form H2 that can desorb from the oxide surface. "But if oxygen is present, hydrogen and oxygen react to form water because it's the thermodynamically favored pro cess," Haschke asserts. That reaction serves to replenish the supply of surface water molecules. The newly formed H20 may then desorb from the surface or disso ciate. If it dissociates, then the oxidation process continues and dioxide is convert ed to higher and higher oxides. Haschke says the group now plans to address envi ronmental plutonium-migration issues. Mitch Jacoby JANUARY 17, 2000 C&KN
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