Thorium for fission power
|Auteur||J.W.Storm van Leeuwen|
|Classificatie||6.01.2.70/04 (THORIUM CYCLUS)|
Uit de publicatie:
Thorium for fission power Jan Willem Storm van Leeuwen, MSc Independent consultant member of the Nuclear Consulting Group firstname.lastname@example.org www.stormsmith.nl May 2016 1 Thorium as nuclear fuel Thorium Thorium is a radioactive metal, 3-4 times more abundant in the Earth’s crust than uranium. Thorium has a characteristic terrestrial isotopic composition, consisting for nearly 100% of Th-232, and traces of other isotopes, for example Th-228 and Th-230. Thorium is a highly reactive metal. At standard temperature and pressure, thorium is slowly attacked by water, but does not readily dissolve in most common acids, the exception being hydrochloric acid. It dissolves in concentrated nitric acid containing a small amount of catalytic fluoride or fluorosilicate ions; if these are not present, passivation can occur. At high temperatures, it is easily attacked by oxygen, hydrogen, nitrogen, the halogens, and sulfur. It can also form binary compounds with carbon and phosphorus. Finely divided thorium metal presents a fire hazard due to its pyrophoricity and must therefore be handled carefully. When heated in air, thorium turnings ignite and burn brilliantly with a white light to produce the dioxide. In bulk, the reaction of pure thorium with air is slow, although corrosion may eventually occur after several months; most thorium samples are however contaminated with varying degrees of the dioxide, which greatly accelerates corrosion. Such samples slowly tarnish in air, becoming gray and finally black. None of the thorium isotopes is fissile. The concept of thorium as nuclear fuel is based on the conversion by neutron capture of non-fissile thorium-232 into uranium-233, which is as fissile as plutonium-239. Consequently the application of thorium as fuel for nuclear power requires a special nuclear system. We will return to this issue below.