Uranium

Crystallographic Data. 177. Uranium Mononitride

Crystal structure of uranium nitride, UN. The structure is face-centered cubic with a lattice constant of 4889 ± 0.001 Å at 26°C and sodium chloride type. The theoretical density is 14315 kg m–3, and the U—N bond distance for coordination number 6 is 2.4449 Å.

Crystallographic Data. 177. Uranium Mononitride, Kempter, Charles, McGuire Joseph, and Nadler M. , Analytical Chemistry, 01/1959, Volume 31, Issue 1, p.156 - 157, (1959)

Synthesis and decay properties of superheavy elements

Abstract: A fundamental outcome of modern nuclear theory is the prediction of the "island of stability" in the region of hypothetical superheavy elements. A significant enhancement in nuclear stability at approaching the closed shells with Z = 114 (possibly 120 and 122) and N = 184 is expected for the nuclei with large neutron excess. For this reason, for the synthesis of nuclei with Z = 112-116 and 118, we chose the reactions 238U, 242,244Pu, 243Am, 245,248Cm, and 249Cf + 48Ca, which are characterized by fusion products with a maximal neutron excess. The formation and decay properties of the heaviest nuclei were registered with the use of a gas-filled recoil separator installed at a 48Ca-beam of the heavy-ion cyclotron. The new nuclides mainly undergo sequential α-decay, which ends with spontaneous fission (SF). The total time of decay ranges from 0.5 ms to ~1 d, depending on the proton and neutron numbers in the synthesized nuclei. The atomic number of the new elements 115 and 113 was confirmed also by an independent radiochemical experiment based on the identification of the neutron-rich isotope 268Db (TSF ~ 30 h), the final product in the chain of α-decays of the odd-odd parent nucleus 288115. The comparison of the decay properties of 29 new nuclides with Z = 104-118 and N = 162-177 gives evidence of the decisive influence of the structure of superheavy elements on their stability with respect to different modes of radioactive decay. The investigations connected with the search for superheavy elements in Nature are also presented.

Synthesis and decay properties of superheavy elements, Oganessian, Yuri , Pure and Applied Chemistry, 2006, Volume 78, Issue 5, p.889 - 904, (2006)

IAEA Analysis of Uranium Supply to 2050

The IAEA is the world's centre of cooperation in the nuclear field. It was set up as the world's "Atoms for Peace" organization in 1957 within the United Nations family. The Agency works with its Member States and multiple partners worldwide to promote safe, secure and peaceful nuclear technologies.

The IAEA has published "Analysis of Uranium Supply to 2050". The document's foreword comments "It has been nearly a decade since the IAEA prepared its forecast of uranium supply to 2035. Since the preparation of that study uranium supply has become more complex, and the uranium mining and milling industry has changed dramatically. The importance of the secondary, or non-production, supply has increased, while becoming more diversified. Therefore it was essential that a new analysis be completed to provide the information required for making strategic decisions related to nuclear power and its fuel supply. This study should be useful for government and industry planners, policy and decision makers, and project managers. Potential users include both consumers and producers of nuclear fuel."

Nuclear Power Expansion in the USA

Dr. Thomas Neff, a research affiliate at the MIT (Massachussetts Institute of Technology) Center for International Studies states that limited supplies of uranium fuel for nuclear power plants may thwart the renewed and growing interest in nuclear energy in the United States and other nations.

Over the past 20 years, safety concerns and politics dampened all aspects of development of nuclear energy. No new reactors were ordered and there was investment neither in new uranium mines nor in building facilities to produce fuel for existing reactors. Instead, the nuclear industry lived off commercial and government inventories which are now nearly gone. It is stated that worldwide uranium production meets only about 65% of current reactor requirements.

A few years ago uranium inventories were being sold at US$ 10 per pound; the current price is US$ 85 per pound.

Much of the uranium used by the United States comes from mines in Australia, Canada, Namibia, and, Kazakhstan. Small amounts are mined in the western United States, but the United States is largely reliant on overseas supplies. The United States also relies for half its fuel on Russia under a “swords to ploughshares” 1991 deal. This deal is converting about 20,000 Russian nuclear weapons to fuel for U.S. nuclear power plants, but it ends in 2013, leaving a substantial supply gap for the United States.

Further, China, India, and even Russia have plans for massive deployments of nuclear power and are trying to lock up supplies from countries on which the United States has traditionally relied. As a result, the United States could be the “last one to buy, and it could pay the highest prices, if it can get uranium at all,” Neff said. “The take-home message is that if we're going to increase use of nuclear power, we need massive new investments in capacity to mine uranium and facilities to process it.”

Mined uranium comes in several forms, or isotopes. For starting a nuclear chain reaction in a reactor, the only important isotope is uranium-235, which accounts for only 7 out of 1000 atoms in the mined product. To fuel a nuclear reactor, the concentration of uranium-235 must be 40 to 50 out of 1000 atoms. This is done by separating isotopes in an enrichment plant to achieve the higher concentration, but there is not enough processing capacity worldwide to enrich all the uranium required.

Illegal uranium mining?

The BBC are reporting possible illegal mining of uranium at a mine in the Democratic Republic of Congo. The government states the mine was shut but a BBC correspondent cliams 6,000 illegal miners work the Shinkolobwe mine. The International Atomic Energy Agency is said to be very concerned. The BBC state the uranium is processed nearby and delivered illegally to the world market via Zambia.

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Copyright 1993-2011 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.