ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
Standards Program
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!
Latest Magazine Issues
Dec 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
December 2025
Nuclear Technology
Fusion Science and Technology
November 2025
Latest News
INL makes first fuel for Molten Chloride Reactor Experiment
Idaho National Laboratory has announced the creation of the first batch of enriched uranium chloride fuel salt for the Molten Chloride Reactor Experiment (MCRE). INL said that its fuel production team delivered the first fuel salt batch at the end of September, and it intends to produce four additional batches by March 2026. MCRE will require a total of 72–75 batches of fuel salt for the reactor to go critical.
F. H. Fröhner
Nuclear Science and Engineering | Volume 106 | Number 3 | November 1990 | Pages 345-352
Technical Paper | doi.org/10.13182/NSE89-177
Articles are hosted by Taylor and Francis Online.
Recent measurements define the prompt fission neutron spectrum of 252Cf from 25 keV to 20 MeV with sufficient accuracy to show that the standard representation by a Maxwell spectrum with the temperature parameter TM = 1.42 MeV is not adequate. The next simplest macroscopic representation, a Watt spectrum with the two parameters Tw = 1.18 MeV and Ew = 0.36 MeV, fits the recent data surprisingly well, at least as well as the best currently available microscopic models of fission neutron emission. The resulting chi-square does not indicate any need for a more sophisticated description, nor is the fit improved by refinements such as superposition of two Watt distributions (for a representative fragment pair), or relativistic corrections.
