Nuclear chemistry transmutation

Dubois, I., Ekberg, C., Englund, S. et al. 2007. Partitioning and transmutation Annual report 2006. Nuclear Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology. 

Nuclear chemistry (radiochemistry) has now become a large and very important branch of science. Over four hundred radioactive isotopes have been made in the laboratory, whereas only about three hundred stable isotopes have been detected in nature. Three elements —technetium (43), astatine (85), and promethium (61), as well as some trans-uranium elements, seem not to occur in nature, and are available only as products of artificial transmutation. The use of radioactive isotopes as tracers has become a valuable technique in scientific and medical research. The controlled release of nuclear energy promises to lead us into a new world, in which the achievement of man is no longer limited by the supply of energy available to him. 

With the development of nuclear reactors and charged particle accelerators (commonly referred to as atom smashers ) over the second half of the twentieth century, the transmutation of one element into another has become commonplace. In fact some two dozen synthetic elements with atomic numbers higher than naturally occurring uranium have been produced by nuclear transmutation reactions. Thus, in principle, it is possible to achieve the alchemist s dream of transmuting lead into gold, but the cost of production via nuclear transmutation reactions would far exceed the value of the gold. SEE ALSO Alchemy Nuclear Chemistry Nuclear Fission Radioactivity Transactinides. 

Nuclear chemistry is the study of changes in atomic nuclei. Such changes are termed nuclear reactions. Radioactive decay and nuclear transmutation are nuclear reactions. 

Today, physical chemistry has accomplished its great task of elucidating the microcosmos. The existence, properties and combinatory rules for atoms have been firmly established. The problem now is to work out where they came from. Their source clearly lies outside the Earth, for spontaneous (cold) fusion does not occur on our planet, whereas radioactive transmutation (breakup or decay), e.g. the decay of uranium to lead, is well known to nuclear geologists. The task of nuclear astrophysics is to determine where and how each species of atomic nucleus (or isotope) is produced beyond the confines of the Earth. 

However, the secret of transmutation did not lie in chemistry and the peripheral electrons that determine the chemical properties of the atom. Instead, the solution to this mystery had to be sought in the nucleus of the atom and the strong and weak nuclear interactions which organise and stracture it. 

Chemistry is the art of combining atoms. Nuclear physics is the science of the transmutation of the elements. Bombarding atomic nuclei by other atomic nuclei can produce transmutation of both target and projectile. Alchemy is thus nuclear, not atomic. 

JOLIOT-CURIE. IRENE 11897-195ft. A French nuclear scientist who won the Nohel prize for chemistry with her husband Frederick Joliet-Curie. Their joint work involved production of artiliciul radioactive elements by using t/-rays to bombard boron. They discovered that hydrogen-containing material when exposed to what they considered p rays would emit protons. Tliev were involved in many firsts they gave Ihe first chemical proof of aitillcial transmutation and of capture of alpha particles, and were the firsi to prepare positron emitter. Her career started with a Sc.D. at the Univ ersity of Paris, and included scores of honors and awards. 

The first indication of the modern concept of an element is to be found as early as Boyle (1627-1691), who was, however, far in advance of his time. Lavoisier (1743-1794) gives the purely empirical definition of an element, still valid in chemistry, as a substance which cannot be divided by any means or by any conversion. We must make an exception at present only for nuclear processes in which, both in natural radioactivity and in artificial processes brought about by neutrons, protons, etc., transmutation of the elements can take place. 

Research in nuclear and radiochemistry comprises Study of radioactive matter in nature, investigation of radioactive transmutations and of nuclear reactions by chemical methods, hot atom chemistry (chemical effects of nuclear reactions) and influence of chemical bonding on nuclear properties, production of radionuclides and labelled compounds, and the chemistry of radioelements - which represent more than a quarter of all chemical elements. 

In the Middle Ages, many early chemists tried to change, or transmute, ordinary metals into gold. Although they made many discoveries that contributed to the development of modern chemistry, their attempts to transmute metals were doomed from the start. These early chemists did not realize that a transmutation, whereby one element changes into another, is a nuclear reaction. It changes the nucleus of an atom and therefore cannot be achieved by ordinary chemical means. 

Rutherford s work has made him known as the father of nuclear physics with his research on radioactivity (alpha and beta particles and protons, which he named), and he was the first to describe the concepts of half-life and decay constant. He showed that elements such as uranium transmute (become different elements) through radioactive decay, and he was the first to observe nuclear reactions (split the atom in 1917). In 1908 he received the Nobel Prize in chemistry for his investigations into the disintegration of the elements, and the chemistry of radioactive substances. He was president of the Royal Society (1926-30) and of the Institute of Physics (1931-33) and was decorated with the Order of Merit (1925). He became Lord Rutherford in 1931. 

The investigation of safety and more particularly of severe accident conditions is important for accelerator driven systems (ADS). Subcritical ADS could be of particular interest for the actinide transmutation from the safety point of view, because fast reactors with Neptunium, Americium and Curium have a much smaller fraction of delayed neutron emitters (compared to the common fuels and U), a small Doppler effect and possibly a positive coolant void coefficient. This poses a particular problem of control since the fraction of delayed neutrons is essential for the operation of a nuclear reactor in the critical state. In addition, the IRC presented in the past a review of accelerator-driven sub-critical systems with emphasis on safety related power transients followed by a survey of thorium specific problems of chemistry, metallurgy, fuel fabrication and proliferation resistance. 

---