Radioactive transuranic elements

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. 

In 1934 Fermi decided to bombard uranium with neutrons in an attempt to produce transuranic elements, that is, elements beyond uranium, which is number 92 in the periodic table. He thought for a while that he had succeeded, since unstable atoms were produced that did not seem to correspond to any known radioactive isotope. I le was wrong in this conjecture, but the research itself would eventually turn out to be of momentous importance both for physics and for world history, and worthy of the 1938 Nobel Pri2e in Physics. 

In 1938 Niels Bohr had brought the astounding news from Europe that the radiochemists Otto Hahn and Fritz Strassmann in Berlin had conclusively demonstrated that one of the products of the bom-bardmeiit of uranium by neutrons was barium, with atomic number 56, in the middle of the periodic table of elements. He also announced that in Stockholm Lise Meitner and her nephew Otto Frisch had proposed a theory to explain what they called nuclear fission, the splitting of a uranium nucleus under neutron bombardment into two pieces, each with a mass roughly equal to half the mass of the uranium nucleus. The products of Fermi s neutron bombardment of uranium back in Rome had therefore not been transuranic elements, but radioactive isotopes of known elements from the middle of the periodic table. 

Air monitoring will be required, e.g., when volatiles are handled in quantity, where use of radioactive isotopes has led to unacceptable workplace contamination, when processing plutonium or other transuranic elements, when handling unsealed sources in hospitals in therapeutic amounts, and in the use of hot cells/reactors and critical facilities. Routine monitoring of skin, notably the hands, may be required. 

Transuranic elements Elements of atomic number >92. All are radioactive and produced artificially all are members of the actinide group. 

Aetinide metah—includes elements with atomic numbers from 89 to 111. Also includes the transuranic elements (e.g., beyond uranium to lojLr]) and the superactinides (elements with atomic numbers 104 to 118 that are artificial, radioactive, and unstable with very short half-lives). 

The radioactive isotopes of most concern in high level waste (HLW) and their estimated toxicities after several decay periods are given in Table I. These data are largely taken from Wallace ( 1) supplemental estimates from calculations based on ORIGEN code information(2) are included. Other isotopes of the transuranic elements 2U5,2it6,2U7cm),... 

Progress in fission research, particularly in the development of higher efficiency reactors, in radioactive waste management, in transmutation studies and transuranic elements have contributed substantially to a renewed interest in the structure and properties of complex many-electron atoms and ions of arbitrary ionization. 

High-level waste that contains highly radioactive material, including fission products, traces of uranium and plutonium, and other transuranic elements resulting from the chemical reprocessing of spent fuel... 

In the Strasbourg laboratory, which cannot handle radioactive substances, trivalent and tetravalent transuranic elements were simulated by lanthanides (generally europium) and thorium, respectively. 

Different radionuclides have different chemistry, so it seems reasonable to include each nuclide in a specific matrix that is most stable for the desired nuclide. It is possible to find stable matrices for incorporation of numerous nuclides with similar chemical properties. The target elements for such incorporation are the long-lived radionuclides (transuranic elements), 90Sr, 137Cs, and Tc. Many extraction processes have been proposed for radionuclide removal from radioactive wastes. Typically, the goal of the processes is to extract one radionuclide or multiple radionuclides... 

After 1933 Fermi turned increasingly to experimental physics. Inspired by recent work in which artificial radioactive substances were produced by a-particle bombardment, Fermi and several collaborators used neutron bombardment to create several transuranic elements heavier than uranium, including plutonium. This work, and his finding that slow neutrons produce nuclear reactions more efficiently than fast ones, earned Fermi wide acclaim and the 1938 Nobel Prize in physics. After accepting the prize in Sweden, Fermi and his Jewish wife immigrated to the United States to escape the Nazis. 

In principle, the applications of ICP-MS resemble those listed for OES. This technique however is required for samples containing sub-part per billion concentrations of elements. Quantitative information of nonmetals such as P, S, I, B, Br can be obtained. Since atomic mass spectra are much simpler and easier to interpret compared to optical emission spectra, ICP-MS affords superior resolution in the determination of rare earth elements. It is widely used for the control of high-purity materials in semiconductor and electronics industries. The applications also cover the analysis of clinical samples, the use of stable isotopes for metabolic studies, and the determination of radioactive and transuranic elements. In addition to outstanding analytical features for one or a few elements, this technique provides quantitative information on more than 70 elements present from low part-per-trillion to part-per-million concentration range in a single run and within less than 3 min (after sample preparation and calibration). Comprehensive reviews on ICP-MS applications in total element determinations are available. " ... 

---