Berkelium production

The einsteinium and berkelium product fractions are usually decontaminated from 252Cf by factors of 103-104 and 102-103, respectively and the californium product fractions are usually decontaminated from 2 3Es by a factor of 102. The maximum concentrations of 232Cf, 249Bk, and 253Es in the respective product fractions are typically about 0.4 g/L, about 50 mg/L, and about 3 mg/L, respectively. 

Americium, californium, and einsteinium oxides have been reduced by lanthanum metal, whereas thorium has been used as the reductant metal to prepare actinium, plutonium, and curium metals from their respective oxides. Berkelimn metal could also be prepared by Th reduction of Bk02 or Bk203, but the quantity of berkelium oxide available for reduction at one time has not been large enough to produce other than thin foils by this technique. Such a form of product metal can be very difficult to handle in subsequent experimentation. The rate and yield of Am from the reduction at 1525 K of americium dioxide with lanthanum metal are given in Fig. 2. 

Some properties of berkelium metal have been reported. Thus, its melting point is 986 + 25 °C and its volatility, relative to its congeners, is in the order Cm < Bk < Am < Cf. Its chemical behaviour is described as somewhat similar to Sm, and it does not correspond, as a metal, to Tb or Lu. It reacts with hydrogen at 225 °C to give BkH2, which is isomorphous with other lanthanide and actinide hydrides of the type MH2+ (x < 1). BkO may be formed as an impurity in the production of metallic Bk. 

An innovative procedure for the rapid separation of berkelium from other actinides, lanthanides, and fission products has been reported... 

The possible existence of divalent berkelium was studied by polarog-raphy in acetonitrile solution. Because of high background currents (caused by radiolysis products) obscuring the polarographic wave, evidence for Bk(II) was not obtained (182). Divalent berkelium has been reported to exist in mixed lanthanide chloride-strontium chloride melts. The claim is based on the results of the distribution of trace... 

This collection of the state-of-the-art papers emphasizes the continuing importance of industrial-scale production, separation, and recovery of transplutonium elements. Americium (At. No. 95) and curium (At. No. 96) were first isolated in weighable amounts during and immediately after World War II. Berkelium and californium were isolated in 1958 and einsteinium in 1961. These five man-made elements, in each case, subsequently became available in increasing quantities. 

The berkelium, californium, einsteinium, and fermium products are then packaged and transferred from the main cell bank to other facilities in which they are purified further. 

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. 

Because of its promise, the pressurized ion exchange approach was applied immediately to transcurium element production at TRU, and Fig. 2 indicates the sort of separation that was obtained. This shows the relative alpha count rate given by an in-line detector, and it demonstrates good separation of Fm, Es, Cf, and Cm. Berkelium is also well separated, appearing between Cf and Cm, but it is not shown because it is not an alpha-emitter. 

In 2000, chemists synthesized atoms of Bh (ti 17 s), using the reaction Ne 4n) Bh. Atoms recoiling from the back of the berkelium target were absorbed onto carbon particles suspended in a flow of helium gas and transported to a quartz wool trap in an oven at 1000 °C. There the carbon and the nuclear reaction products were reacted with a mixture of HCl and O2 gases. Some six atoms of bohrium were detected as a volatile oxychloride, believed to be BhOsCl, by analogy with Tc and Re. 

Many of the actinoids are also separated by exploiting their redox behavior. Thorium is exclusively tetravalent and berkelium is chemically similar to cerium, so iodate precipitation of Th and extraction of Bk(IV) with bis(2-ethylhexyl)orthophos-phoric acid (HDEHP) are used to isolated these elements. The differing stabilities of the (III), (IV), (V), and (VI) states of U, Np, and Pu have be exploited in precipitation and solvent extraction separations of these elements from each other and from fission product and other impurities with which they are found. Because of its technical importance, the process chemistry to separate U and Pu in nuclear materials has been highly developed. Extraction of Bk(IV) with HDEHP is used to separate Bk from neighbouring elements. 

Gas-phase reactions of the bare monopositive berkelium ion, Bk+, with several reagents including cycloocta-tetraene have been examined by a mass spectrometric technique adapted for the highly radioactive transuranium actinides. The products included 7r-bonded organoberkelium ions such as BkCOT+, presumably, the berkelium-cyclooctatetraenyl half-sandwich complex ion.22... 

After the discovery of uranium radioactivity by Henri Becquerel in 1896, uranium ores were used primarily as a source of radioactive decay products such as Ra. With the discovery of nuclear fission by Otto Hahn and Fritz Strassman in 1938, uranium became extremely important as a source of nuclear energy. Hahn and Strassman made the experimental discovery Lise Meitner and Otto Frisch provided the theoretical explanation. Enrichment of the spontaneous fissioning isotope U in uranium targets led to the development of the atomic bomb, and subsequently to the production of nuclear-generated electrical power. There are considerable amounts of uranium in nuclear waste throughout the world, see also Actinium Berkelium Einsteinium Fermium Lawrencium Mendelevium Neptunium Nobelium Plutonium Protactinium Rutherfordium Thorium. 

The first synthetic actinide element, neptunium, was discovered in 1040. The last element of the actinide series, lawrencium, was created for the first time in 1061. These and the nine other intervening elements have added a new dimension to science, technology, industry, medicine, and politics in an e aordinarily short period of time. Each synthetic actinide element from atomic number 03 to atomic number 98 (with the exception of berkelium, atomic number 07) can now be manufactured in essentially any desired quantity, a truly remarkable achievement. The high points of the history of the actinide elements are traced, production methods are described, and a forecast is given of the manufacturing levels to be expected during the next decade. An analysis is presented of the current and near-term implications the various isotopes of the actinide elements. 

In a study of the berkelium oxygen system (Turcotte 1980) it was concluded that the growth of the Cf daughter in berkelium oxides gave different effects, depending upon the amount of Cf. For a Cf content up to 25 mol %, the Cf in the matrix was apparently oxidized to a dioxide when the value reached 64 mol%, the Cf content controlled the Bk oxidation and the stoichiometry of the mixed cation product was limited to the stoichiometry of An70i2- The behavior of the mixed oxides is in accord with the behaviors known for the two pure oxide systems. 

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