Predicting products of nuclear decay

Beta Decay Gamma Production Predicting Products of Nuclear Decay... 

A nuclear equation represents a nuclear process such as radioactive decay. The total of the mass numbers on each side of the reaction arrow must be identical, and the sum of the atomic numbers of the reactants must equal the sum of the atomic numbers of the products. Nuclear equations can be used to predict products of nuclear reactions. 

The ANS-5.1 standard for decay heat generation in NPPs provides a simplified mean of estimating nuclear fuel cooling requirements that can be readily programmed into computer codes used to predict plant performance. The ANS-5.1 standard models the energy release from the fission products of and Pu using a summation of exponential... 

Attempts have been made to use the a-decay properties of the " Ca-induced reaction products to benchmark the nuclear mass evaluations arising from the various model calculations and to determine the location of the closed proton shell in transhassium space. Globally, the decay properties most closely match the predictions of the macroscopic-microscopic model, which predicts a spherical shell closure at Z = 114 [52, 58, 371-373]. However, the resiliency of theory is such that the a-decay Q values are also adequately reproduced by other models that predict a higher Z closed shell. Discrimination among the model calculations will only come about through the measurements of the decay properties of nuclides with higher Z and/or N than are currently known [8, 66]. 

Fig. 14.1 Nuclear reaction sequence for production of transplutonium elements by intensive slow-neutron irradiation. The principal path is shown by heavy arrows (horizontal, neutron capture vertical, beta decay). The sequence above is a prediction.

The discovery of technetium in 1937 by the Italian scientists Carlo Perrier and Emilio Segre was an important affirmation of the configuration of the Periodic Table. The table had predicted the existence of an element with 43 protons in its nucleus, but no such element had ever been found. (In fact, technetium does not occur naturally on Earth, as all of its known isotopes are radioactive and decay to other elements on a timescale that is relatively small when compared with the age of the earth.) Perrier and Segre were able to observe technetium from molybdenum that had been bombarded with deuterons. They named the element technetium, from the Greek word technetos, meaning artificial. Technetium is produced in relatively large quantities during nuclear fission, so there is currently an ample supply of the element from nuclear reactors and nuclear weapons production. 

Radioactive wastes come directly from nuclear-reactor-fuel reprocessing plants and from industries employing radioactivity for processing work. The dominating elements from nuclear reactor fuels are cesium 137 and strontium 90, with the latter th,e controlling isotope owing to low permissible concentration values (Table 10-2). Rodger cites an example to illustrate the severity of the problem. In the year a.d. 2000 the installed reactor capacity on a world-wide basis is predicted to be 2.2 X 10 Mw. If this system is operated for 50 years, the Sr steady-state level (rate of production = rate of decay) would be 8.6 X 10 curies, which would require 5 per cent of the entire world ocean volume to dilute to the maxi-... 

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