Nuclear properties decay

RADC (Ref. 9) A zero-dimensional, steady-state inventory code for calculating the overall plant mass balance for an abitrary number of radionuclides, including the total core inventory, the circulating inventory, the plateout inventory, and the He Purification System inventory. The current version of RADC contains a 250-nuclide library with the nuclear properties (decay constants, fission yields, etc.) from the 1978 compilation by Meek and Ryder. RADC has been used extensively to calculate the source terms that appear in Section 11.1 of previous HTGR PSARs and of the Standard MHTGR PSID. 

AH of the 15 plutonium isotopes Hsted in Table 3 are synthetic and radioactive (see Radioisotopes). The lighter isotopes decay mainly by K-electron capture, thereby forming neptunium isotopes. With the exception of mass numbers 237 [15411-93-5] 241 [14119-32-5] and 243, the nine intermediate isotopes, ie, 236—244, are transformed into uranium isotopes by a-decay. The heaviest plutonium isotopes tend to undergo P-decay, thereby forming americium. Detailed reviews of the nuclear properties have been pubUshed (18). 

In a description of nuclear properties, the half-life,, is quoted rather than the decay constant. This quantity is the time it takes for one-half of the original nuclei to decay. That is,... 

Potzel et al. [Ill] have established recoil-free nuclear resonance in another ruthenium nuclide, ° Ru. This isotope, however, is much less profitable than Ru for ruthenium chemistry because of the very small resonance effect as a consequence of the high transition energy (127.2 keV) and the much broader line width (about 30 times broader than the Ru line). The relevant nuclear properties of both ruthenium isotopes are listed in Table 7.1 (end of the book). The decay... 

At low temperatures (15 million K), reactions between helium nuclei are inhibited by electrical repulsion. On the other hand, the nuclear properties of lithium, beryllium and boron nuclei (Z = 3,4, 5), and in particular their stability, are such that they are extremely fragile, decaying at temperatures of only 1 million K. For this reason, they are not formed in appreciable quantities in stars and cannot serve to bridge the gap between helium and carbon, species noted for their nuclear stability but which, it should be recalled, occur only in minute amounts in nature. 

Actinides, the chemical elements with atomic numbers ranging from 89 to 103, form the heaviest complete series in the Periodic Table. They are radioelements, either naturally occurring or synthesized by nuclear reactions. Their predominant practical application depends on the nuclear properties of their isotopes decay, spontaneous or induced fission. Their chemical and physical properties reflect a very complex electronic structure, and their study and understanding are a challenge to experimentalists and theoreticians. 

Chart of the nuclides organizing elements by their nuclear properties Radioactive elements and their modes of decay The periodic table organizing elements by their chemistry properties Chemical bonding... 

Nuclear chemistry consists of a four-pronged endeavor made up of (a) studies of the chemical and physical properties of the heaviest elements where detection of radioactive decay is an essential part of the work, (b) studies of nuclear properties such as structure, reactions, and radioactive decay by people trained as chemists, (c) studies of macroscopic phenomena (such as geochronology or astrophysics) where nuclear processes are intimately involved, and (d) the application of measurement techniques based upon nuclear phenomena (such as nuclear medicine, activation analysis or radiotracers) to study scientific problems in a variety of fields. The principal activity or mainstream of nuclear chemistry involves those activities listed under part (b). 

NUBASE Evaluation of Nuclear and Decay Properties, G. Audi, O. Bersillon, J. Blachot, and A.H. Wapstra, Nuclear Physics A729, 3 (2003). 

Due to effects caused by the nuclear decay in the sample, these so-called source experiments may be difficult to perform and interpret. Several papers dealing with these effects can be found (23). In principle, however, the applicability of Mossbauer spectroscopy to catalytic studies can be extended to include both the Mossbauer isotopes and the corresponding parent nuclides. We therefore list below the Mossbauer isotopes and corresponding parent nuclides that may be of greatest use in catalytic studies, as deduced from their nuclear properties. 

Audi, G Bersillon, O., Blachot, J. and Wapstra, A.H. (2003) The NUBASE evaluation of nuclear and decay properties. Nuclear Physics A, 729(1), 3-128. 

In considering such results (34), one should be aware of the great uncertainties associated with the extrapolation of nuclear properties into the unknown region. The calculations are associated with large errors. The total uncertainty for all three decay modes discussed here is as large as 10 ° for the half-lives. 

The majority of the longer-lived transuranic nuclides produced by neutron capture reactions decay primarily by a-emission. Most environmental samples contain radionuclides from the natural uranium and thorium series in concentrations often many times greater than transuranic concentrations. As a result, the chemical problems encountered in these measurements are derived from the requirement that separated trans-uranics should be free of a-emitting natural-series nuclides which would constitute a-spectrometric interferences. Table I lists those transuranic nuclides detected to date in marine environmental samples, together with some relevant nuclear properties. Their relative concentrations (on an activity basis) are indicated although the ratios may be altered by environmental fractionation processes which enrich and deplete the relative concentrations of the various transuranic elements. Alpha spectrometric measurements do not distinguish between 239p Pu, so these are... 

Table 2.15 Nuclear properties for promethium-samarium decay chains...

A closer analysis of (3.9) makes us expect that the last term gives rise to three different isobaric parabola depending on whether the nuclei are odd-A (even-odd or odd-even), odd-odd, or even-even (Fig. 3.6). In the first case, in which the mass number is odd, we find a single parabola (I) whether all beta decay leads to changes from odd-even to even-odd, etc. For even mass numbers one finds a double parabola (II) — (V). Wh i the individual nuclear properties are considered, the difference betwe the curves for the odd-odd and even-even nuclei may lead to alternatives with regard to the numbers of possible stable isobars it is possible to find three stable isobars (case V) although two (case IV) are more common. Although the odd-odd curve always must lie above the even-even curve, still an odd-odd nucleus may become stable, as is shown for case II. 

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