Transuranic Metals

Tramex [Transuranic metal (or amine) extraction] A process for separating transuranic elements from fission products by solvent extraction from chloride solutions into a tertiary amine solution. Developed at Oak Ridge National Laboratory, TN, for processing irradiated plutonium. 

Development of a one-step electrochemical process to reduce LWR spent fuel (UO2) to metallic form is under development at Argonne National Laboratory The transuranic metals are separated by pyroproces-sing technology. This reduces waste that requires repository disposal. The transuranic metals could be cast into fuel suitable for the Generation IV reactors or transmuted reducing them to fission products. 

In a rare study of ligand substitution on a transuranic metal ion NMR line-broadening data yield k 29S.2 K) = 980 s Ai/ = 46.6 kJ moP and AS = -31J moP for exchange of the four in the equatorial plane of octahedral [Np04(0H)2] with solvent in aqueous 0.5 mol dm NaOH solution. 

The physical properties of the transuranic metals are of considerable interest for a number of reasons. Plutonium in particular is becoming increasingly important in the large-scale production of power and it, as well as neptunium, is interesting as a member of a new series of elements which in some ways appears to resemble that of the rare earth metals. A good deal of the relevant information concerning the physical behavior of these metals has to be obtained by measurement of their low-temperature properties. 

Work with transuranic metals thus involves not only special bryogenic techniques but also the use of elaborate facilities. The work described in the present paper was therefore carried out jointly by G. T. Meaden of the Clarendon Laboratory and J. A. Lee of the Atomic Energy Research Establishment, Harwell. 

Most of the work carried out with the equipment so far is concerned with the electrical resistance of pure transuranic metals and their alloys [3],... 

Gmelin Handbuch derAnorganischen Chemie, Transurane, TeilB1, Metalle, Spriager-Vedag, Berlin, 1976. 

Krebs, Robert E. The history and use of our earth s chemical elements a reference guide. Westport (CT) Greenwood P, 1998. ix, 346p. ISBN 0-313-30123-9 A short history of chemistry — Atomic structure The periodic table of the chemical elements — Alkali metals and alkali earth metals - Transition elements metals to nonmetals — Metallics and metalloids - Metalloids and nonmetals — Halogens and noble gases - Lanthanide series (rare-earth elements) — Actinide, transuranic, and transactinide series... 

AH the isotopes of americium belonging to the transuranic subseries of the actinide series are radioactive and are artificially produced. Americium has similar chemical and physical characteristics and is hofflologous to europium, located just above it in the rare-earth (lanthanide) series on the periodic table. It is a bright-white malleable heavy metal that is somewhat similar to lead. Americiums melting point is 1,176°C, its boiling point is 2,607°C, and its density is 13.68g/cm. ... 

Berkelium is a metallic element located in group 11 (IB) of the transuranic subseries of the actinide series. Berkelium is located just below the rare-earth metal terbium in the lanthanide series of the periodic table. Therefore, it has many chemical and physical properties similar to terbium ( Tb). Its isotopes are very reactive and are not found in nature. Only small amounts have been artificially produced in particle accelerators and by alpha and beta decay. 

Californium is a synthetic radioactive transuranic element of the actinide series. The pure metal form is not found in nature and has not been artificially produced in particle accelerators. However, a few compounds consisting of cahfornium and nonmetals have been formed by nuclear reactions. The most important isotope of cahfornium is Cf-252, which fissions spontaneously while emitting free neutrons. This makes it of some use as a portable neutron source since there are few elements that produce neutrons all by themselves. Most transuranic elements must be placed in a nuclear reactor, must go through a series of decay processes, or must be mixed with other elements in order to give off neutrons. Cf-252 has a half-life of 2.65 years, and just one microgram (0.000001 grams) of the element produces over 170 mhhon neutrons per minute. 

Einsteinium, as an actinide metal, has several compounds similar to other transuranic elements that are formed with some of the nonmetals, as follows einsteinium dioxide (EsO ), einsteinium trioxide (Es O ), einsteinium trichloride (EsCy, einsteinium dibromide (EsBr ), and einsteinium triiodide (EsI ). 

The technology treats polychlorinated biphenyls (PCBs), dioxins, volatile metals (such as mercury), and nonvolatile metals (such as lead or transuranic radioactive elements). 

The first genuine transuranic element was discovered at Berkeley, where Edwin McMillan used Lawrence s cyclotron in 1939 to bombard uranium with slow neutrons. He saw beta decay from what he predicted was element 93, and set about trying to isolate it. McMillan saw that the element sits beneath the transition metal rhenium in the Periodic Table, and so he assumed it should share some of rhenium s chemical properties. But when he and Fermi s one-time collaborator Emilio Segre performed a chemical analysis, they found that eka-rhenium (in Mendeleyev s terminology) behaved instead like a lanthanide, the series of fourteen elements that loops out of the table after lanthanum (see page 152). Disappointed, they figured that all they had found was one of these known elements. 

R. A. Bulman Chemistry of Plutonium and the Transuranics in the Biosphere JWBuckler, WKoldsch, P.D.Smith Cis, Trans, and Metal Effects in Transition Metal Porphyrins... 

Transuranic Waste. Much of DOE s transuranic radioactive waste is classified as hazardous waste under RCRA and is managed as mixed waste (DOE, 1999b). Many transuranic wastes are hazardous due to the presence of toxic heavy metals or organic chemicals introduced into the waste during processing of plutonium. 

Numerous isotopes of rhodium are known, but only ° Rh is stable. The short half-lives of the remainder mean that few radiochemical applications exist. The heavy isotopes of the element feature among the fission products of uranium and the transuranic elements they can also be made by neutron irradiation. Light isotopes result from a-bombardment of the metal, and those of high neutron deficiency from bombardment by very heavy ions. 

On the other hand, liquid metal-cooled fast reactors (LM-FRs), or breeders, have been under development for many years. With breeding capability, fast reactors can extract up to 60 times as much energy from uranium as can thermal reactors. The successful design, construction, and operation of such plants in several countries, notably France and the Russian Federation, has provided more than 200 reactor-years of experience on which to base further improvements. In the future, fast reactors may also be used to burn plutonium and other long-lived transuranic radioisotopes, allowing isolation time for high-level radioactive waste to be reduced. 

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