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Division Spotlight
Radiation Protection & Shielding
The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
Meeting Spotlight
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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!
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Latest News
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
Rajesh Mohan, Feroz Ahmed, L. S. Kothari
Nuclear Science and Engineering | Volume 81 | Number 4 | August 1982 | Pages 532-539
Technical Paper | doi.org/10.13182/NSE82-A21443
Articles are hosted by Taylor and Francis Online.
The multigroup diffusion equation is solved for the pulsed problem and the time-dependent energy spectra are obtained using the eigenfunction expansion method. It is shown that complete spectral equilibrium can be obtained beyond 2000 ns in a 40-cm cube (B2 ∼ 0.015 cm-2) of natural uranium. This time is found to increase with increasing assembly size. The earlier exponential decays observed in a pulsed uranium system are traced to the establishment of the pseudo-equilibrium condition due to the trapping of neutrons in certain energy groups. It is shown that such a pseudo-decay corresponds to the establishment of the first higher mode of decay and the time range in which it is established is a function of B2.
