News of the Week affect the rate of the reaction. If the activated complex is larger than the ground state, then pressure slows the reaction and vice versa. This is important in explosives, Rogers says, because explosives are detonated with a pressure pulse. If an explosive molecule must expand to reach its activated, metastable state, then the detonating force—the pressure pulse—actually is slowing the rate of activation. Such an explosive would be very stable, or insensitive. "What we have found is that we can use the kinetic isotope effect to determine the sign of the volume of activation," Rogers says. Rogers and Janney conducted thermal initiation experiments using a differential scanning calorimeter on completely deuterated TATB. TATB is an extremely insensitive explosive. It requires a very large pressure pulse— around 200 kilobars—to detonate it. "We found that we could specify what the elementary process was," Rogers says, "measure the kinetics, observe them in an explosive test, and make a predictive model on the basis of the kinetics of the kinetic isotope effect in explosives initiation." TATB is insensitive because it expands upon activation. Other, sensitive explosives apparently have a negative volume of activation, Rogers says. According to Rogers, the technique he and Janney have developed will allow researchers to predict the properties of potential explosives. •
Radioactive waste disposal project begun The Department of Energy's West Valley, N.Y., project to demonstrate the feasibility of converting liquid high-level radioactive wastes into a durable solid that can be disposed of safely is now under way. It formally began with the state of New York turning over to DOE its reprocessing site at West Valley, 30 miles southeast of Buffalo. The West Valley facility, which in the late 1960s separated plutonium and unused uranium from nuclear power plant waste material, has been shut down since 1972. Nearly 600,000 gal of high-level radioactive wastes from power plants are stored there, awaiting further processing and permanent disposal. DOE plans to design and construct a facility at West Valley to solidify these wastes and will safely decontaminate and decommission the fa8
C&EN March 8, 1982
cility when the wastes have been treated and transported to a permanent disposal site. Westinghouse Electric Corp. will run the project for DOE through a newly formed subsidiary called West Valley Nuclear Services. Principal contractor on the project is Dames & Moore, a San Francisco engineering firm. Among the first major projects at the facility will be selection of the solid form into which the liquid wastes will be converted and the process that will be used for the conversion. The most likely candidate, according to a West Valley Nuclear representative, is production of borosilicate glass pellets by a slurry-fed ceramic melter process. This technique, being developed by DOE's Savannah River and Battelle Pacific Northwest laboratories, is the best developed of the dozen or so solidification techniques under study at national laboratories and universities. Other methods, though, including those that make concrete-type solids, coated ceramics, or ceramics trapped in metal matrices, also will be considered for the demonstration. Two additional activities that will begin this summer at West Valley are photographic and ultrasonic inspection of the large underground tank where the liquid radioactive wastes now are being stored, and the drilling of monitoring wells around the perimeter of the waste burial ground to gather both geological and hydrological data on the site. Once a process is selected, the reprocessing facility will be designed and constructed. Old reprocessing machinery will be removed to make room for the new equipment. Actual solidification of the wastes is not expected to begin until near the end of the decade. Once begun, it will take about three years to solidify all of the wastes stored at West Valley, Westinghouse says. •
Group proposes system to ensure food safety The Food Safety Council, a private industry/consumer group, has issued its final report containing what it calls a major innovative and practical approach for regulatory agencies to make food safety decisions. The council was formed six years ago at a time when the debate over food safety and how best to obtain it was particularly acrimonious. It is supported by 28 dues-paying corpo-
rations. But its board of trustees, which accepted the report, is composed of equal numbers of representatives from the public (academia, government, and public and consumer interest groups) and industry. The report addresses itself to four issues: how scientifically to assess risk in the food supply, how to determine socially acceptable levels of risks, how to manage food risks, and how to involve all affected interests in the decision-making process. For assessing a substance's risk, the council proposes use of systematic sequence of testing, in the form of a decision tree. The tree is designed to provide the maximum quality of toxicological information at the least possible cost, but because the science of toxicology is still evolving, the council says it would not be appropriate to require, either by legislation or by regulation, the precise sequence and type of testing it describes. If when all chronic studies have been completed, all the data taken together establish a dose below which there is adequate reason to believe there will be no significant adverse effect, the council recommends use of a safety factor to determine the maximum dose considered acceptable for human exposure—a course now followed by most federal agencies. If, however, some questions remain about a substance's safety, the council recommends the use of quantitative risk assessment, involving the use of mathematical models, riskbenefit, and risk-risk assessment as outlined in a decision tree. The tree provides for different treatment of substances that are avoidable in food than for those that are environmental contaminants or trace residues. The council, however, specifically rejects the use of cost-benefit analysis in making food safety decisions on the grounds that human health or even life cannot be translated meaningfully into economic costs. And it says that under no circumstances should a food or color additive or an animal drug whose residues in food are detectable be approved if the substance can cause cancer by a genotoxic mechanism. The council specifically says it is not recommending any legislative or regulatory changes in food safety laws. However, the report comes at a time when Congress is actively considering changes in the food laws. Copies of the final report will be available in April from 1725 K St., N.W., Washington, D.C. 20006. •
