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Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Latest News
Investment bill would provide funding options for energy projects
Coons
Moran
The bipartisan Financing Our Futures Act, which expands certain financing tools to all types of energy resources and infrastructure projects, was reintroduced to the U.S. Senate on February 20 by Sens. Jerry Moran (R., Kan.) and Chris Coons (D., Del.).
Via amendment to the Internal Revenue Code, the legislation would allow advanced nuclear energy projects to form as master limited partnerships (MLPs), a tax structure currently available only to traditional energy projects.
An MLP is a business structure that is taxed as a partnership but the ownership interests of which are traded like corporate stock on a market. Until the Internal Revenue Code is amended, MLPs will continue to be available only to investors in energy portfolios for oil, natural gas, coal extraction, and pipeline projects that derive at least 90 percent of their income from these sources. This change would take effect on January 1, 2026.
H. A. Morewitz
Nuclear Technology | Volume 53 | Number 2 | May 1981 | Pages 120-134
Technical Paper | Realistic Estimates of the Consequences of Nuclear Accident / Nuclear Safety | doi.org/10.13182/NT81-A32616
Articles are hosted by Taylor and Francis Online.
A review of reactor accidents and destructive tests shows that when water was present, only a very small fraction of the volatile fission product inventory (other than noble gases) was released to the environment. In addition, the iodine component was released over a period of days. However, in those situations where there was no water and the containment was poor, the release of volatile fission products was large and rapid. The role of water in both limiting and delaying the release of iodine can be explained by the fact that the chemical form of iodine in intact fuel rods was cesium iodide (Csl). It is one of the most stable compounds of iodine, but it easily dissolves in water. The only ways to obtain gaseous forms of iodine from a water solution of Csl are by the slow processes of either contacting the solution surface with air or by reacting the solution with hydrocarbon materials (paint, etc.). Of the other volatile fission products, most dissolve in water. Rubidium, strontium, barium, cesium, and their oxides dissolve in water after first reacting to form their respective hydroxides. Arsenic and selenium oxides are directly soluble in water. However, tellurium and its compounds (except the alkali metal tellurides, the acid, and the hydride) are largely insoluble in water. In reactor accidents and destruction tests where water was absent, up to 45% of the tellurium was released to the atmosphere in the form of fine particles (<1 µm in diameter), yet in all cases when water was present, no tellurium was released. This result may be related to the fallout of the fine particles due to growth caused by condensation of water vapor or to the solubility of Cs2Te, since there is some evidence for this compound in intact fuel Vaporized fission product compounds form aerosol particles as they condense. Analysis has shown that the aerodynamic sizes of agglomerated aerosols should increase as the aerosol concentration is increased, and this has been confirmed by a large number of experiments that indicate a size dependence with the cube root of concentration. Above ∼30 g/m3 concentration, the experiments show an even stronger dependence of aerosol size on the concentration leading to the rapid formation of very large agglomerates. In addition, when aerosols are released into a saturated steam atmosphere, the steam condenses on them and causes them to grow to still larger sizes. The large aerosols fall out in a short time so that the aerosol mass available for leakage is reduced. Furthermore, in saturated steam atmospheres, leak paths are rapidly plugged with water so that the leakage of aerosols to the environment is dramatically restricted. Due to the solubility of the volatile fission product compounds and the aerosol behavior mechanisms, the off-site dispersion of radioactive materials (other than gases) following a major light water reactor accident will be small.
