Actinides alpha emission

With the commercial development of nuclear reactors, the actinides have become important industrial elements. A major concern of the nuclear industry is the biological hazard associated with nuclear fuels and their wastes 2). In addition to their chemical toxicity, the high specific activity of alpha emission exhibited by the common isotopes of the transuranium elements make these elements potent carcinogens (3, b 9 5, 7). Unlike organic... 

Actinide Content and Alpha Emission Rates for Various Components of an Epoxide Resin Moulding Compound ... 

There are three common ways by which nuclei can approach the region of stability (1) loss of alpha particles (a-decay) (2) loss of beta particles (/3-decay) (3) capture of an orbital electron. We have already encountered the first type of radioactivity, a-decay, in equation (/0). Emission of a helium nucleus, or alpha particle, is a common form of radioactivity among nuclei with charge greater than 82, since it provides a mechanism by which these nuclei can be converted to new nuclei of lower charge and mass which lie in the belt of stability. The actinides, in particular, are very likely to decay in this way. 

Uranium is the fourth metal in the actinide series. It looks much like other actinide metallic elements with a silvery luster. It is comparatively heavy, yet malleable and ductile. It reacts with air to form an oxide of uranium. It is one of the few naturally radioactive elements that is fissionable, meaning that as it absorbs more neutrons, it splits into a series of other lighter elements (lower atomic weights) through a process of alpha decay and beta emission that is known as the uranium decay series, as follows U-238—> Th-234—>Pa-234—>U-234—> Th-230 Ra-226 Rn-222 Po-218 Pb-2l4 At-218 Bi-2l4 Rn-218 Po-2l4 Ti-210—>Pb-210—>Bi-210 Ti-206—>Pb-206 (stable isotope of lead,... 

Decay by SF has been observed in the elements heavier than thorium (Z = 90). At californium (Z = 98), SFbegins to compete favorably with alpha-particle emission as a mode of decay, and becomes the primary decay mode for many of the higher atomic number actinides and the transactinides. As with all fission, SF releases neutrons. Unlike the induced fission process described in Section 2.3.2, SF takes place without addition of energy. Radioisotopes for which SF is an important decay mode may be used as neutron sources. 

FIGURE 1.28 (a) Schematic representation of alpha particle emission and (b) alpha spectrum of uranium (with a spike) after separation from other actinides in a soil sample (also... 

Low alpha particle emission ingredients may need to be pure with respect to actinide elements, to avoid alpha particle emissions that can cause soft errors in dynamic random access memories of 64K capacity and upwards. 

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