Curium americium

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

Schreckhise RG, Cline JF. 1980. Comparative uptake and distribution of plutonium, americium, curium and neptunium in four plant species. Health Phys 38 817-824. 

Es wird eine Ubersicht iiber die Chemie der Transplutoniumelemente Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium und Lawrencium unter besonderer Beriick-sichtigung praparativer Untersuchungen an wagbaren Mengen gegeben. 

Beim Arbeiten mit Americium, Curium, Berkelium und Californium sind aufs sorgfaltigste alle SicherheitsmaBnahmen zu beachten, die fur das Arbeiten mit stark a-aktivem Material erforderlich sind. Das heiBt alle praparativen Arbeiten mit reinen Verbindungen sind in Gloveboxen auszufiihren. Derartige Gloveboxanlagen sind an verschiedener Stelle beschrieben worden (131), (142), (207), (210), und es wurde zu weit fiihren, auf alle Einzelheiten hier einzugehen. 

Fuger, J. (1958). Ion exchange behavior and dissociation constants of americium, curium and californium complexes with ethylenediaminetetraacetic acid, J. Inorg. Nucl. Chem. 5, 332. 

This article presents a general discussion of actinide metallurgy, including advanced methods such as levitation melting and chemical vapor-phase reactions. A section on purification of actinide metals by a variety of techniques is included. Finally, an element-by-element discussion is given of the most satisfactory metallurgical preparation for each individual element actinium (included for completeness even though not an actinide element), thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium. 

Bernabee RP. 1983. A rapid method for the determination of americium, curium, plutonium and thorium in biological and environmental samples. Health Phys 44 688-692. 

While the lighter isotopes are prepared by alpha particle bombardment, the heavier ones by neutron irradiation of large quantities of americium, curium or plutonium ... 

The higher actinide metals americium, curium, berkelium and californium have - at normal pressure - again the common structure dhcp and are in this respect similar to some of the lanthanide metals. In fact, the theoretical calculations and certain experimental observations show that in these actinide metals, 5 f electrons are localized, as are the 4f electrons in the lanthanide metals. More detailed considerations on the possible correlations between electronic and crystal structure are found in. ... 

Fellinger, A. P., Baich, M. A. et al. 1999. Americium-curium vitrification process development (I). Materials Research Society Symposium Proceedings, 556, 367-374. 

In an analysis of the hazards of the alpha emitters from reactor operations it has been pointed out (25) that the most significant and hazardous species are plutonium, americium, curium, and neptunium. Plutonium is as hazardous as such fission products as ruthenium-106, cesium-137, cerium-144, and promethium-147, depending on the kind of fuel, the power of the reactor, the storage time of the waste, and whether it is released to the atmosphere or to water. If strontium-90 is removed... 

In 1951 along with Edwin McMillan he received the Nobel prize in chemistry for the creation of the first transuranium elements. He created plutonium, americium, curium, berkelium, and californium at Berkeley. 

Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobdium Lawrencium... 

G. T. Seaborg, Americium-Curium Chem. Technol. Pap. Symp., 1985, 3-17. 

ACTINIUM THORIUM PROTACTINIUM URANIUM NEPTUNIUM PLUTONIUM AMERICIUM CURIUM BERKELIUM CALIFORNIUM EINSTEINIUM FERMIUM MENDELEVIUM NOBELIUM... 

An initial experiment involving the treatment of small irradiated Pu/Al targets for the production of americium 243 and curium 244 was carried out in France in 1968 (2). The chemical process was based essentially on the use of a system comparable to the Talspeak system. After plutonium extraction by a 0.08 M trilaurylammonium nitrate solution in dodecane containing 3 vol % 2-octanol, the actinides (americium, curium) were coextracted with a fraction of the lanthanides by a 0.25 M HDEHP -dodecane solvent from an aqueous solution previously neutralized by A1(N0 ) x(0H)x and adjusted to 0.04 M DTPA. The actinides were selectively stripped by placing the organic phase in contact with an aqueous solution of the composition 3 M LiN0 -0.05 M DTPA. While this experiment achieved the recovery of 150 mg of americium 243 and 15 mg of curium 244 with good yields, the process presented a drawback due to the slow extraction of Al(III) which saturates the HDEHP. This process was therefore abandoned. 

The location of berkelium, a beta emitter which cannot be monitored, can be estimated from the position of the californium in the column, as determined by the neutron peak (from 2 2cf), during the time that curium is in the effluent solution. Typical neutron peaks are shown in Fig. 2. By comparison of the relative distribution coeffients of the actinides, the berkelium location is known to be about midway between californium and curium. The last 5-10% of the americium-curium is purposely routed into the transcurium element product tank to minimize the berkelium loss. Subsequently, this americium-curium is recovered in a second-cycle LiCl AIX run. 

Recovery of Americium—Curium From High-Activity Waste Concentrate by In-Canyon-Tank Precipitation as Oxalates... 

The thermal neutron sources are radioactive isotopes which emit neutrons, acclerators, and nuclear reactors. The neutrons from the sources are moderated with materials such as paraffin, graphite, water, heavy water or beryllium. Some of the radioisotopes used as sources of thermal neutrons are antimony, polonium, americium curium and californium. The various sources have different half-lives, ranging from days to years. 

Modifications to this process can be made to effect recovery of neptunium, americium, curium, californium, strontium, cesium, technetium, and other nuclides. The efficient production of specific transuranic products requires consideration of the irradiation cycle in the reactor and separation of intermediate products for further irradiation. 

Cyanex 301 One of the solvent extraction processes, used together with UREX, for separating the components of used nuclear fuel. This process uses a complex phosphinic acid, [bis(2,4,4-trimethylpentyl)dithiophosphinic acid], made by Cytec Industries, Canada. Its purpose is to separate americium, curium, and lanthanide fission products from the other components. 

Thorium Protactiniiun Uraniiun Neptunium Plutoniiun Americium Curium Californium... 

Thorium Protactinium Uranium Nepturtium Plutonium Americium Curium Berkellum Californium Einsteinium Fermium Mendelevium Nobelium lawtenclum... 

Sullivan MF, Ruemmler PS, Ryan JL, et al. 1986. Influence of oxidizing or reducing agents on gastrointestinal absorption of uranium, plutonium, americium, curium, and promethium by rats. Health Phys 50 233-232. 

Plutonium and the four heavier trans-uranium elements whose existence have been reported, americium, curium, berkelium, and californium, were discovered by Professor G. T. Seaborg and his collaborators at the University of California in Berkeley. Americium has been made as the isotope Am by the following reactions ... 

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