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 ANS Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
Latest Magazine Issues
May 2026
Jan 2026
2026
Latest Journal Issues
Nuclear Science and Engineering
June 2026
Nuclear Technology
Fusion Science and Technology
Latest News
NRC proposes changes to its rules on nuclear materials
In response to Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” the NRC is proposing sweeping changes to its rules governing the use of nuclear materials that are widely used in industry, medicine, and research. The changes would amend NRC regulations for the licensing of nuclear byproduct material, some source material, and some special nuclear material.
As published in the May 18 Federal Register, the NRC is seeking public comment on this proposed rule and draft interim guidance until July 2.
R. T. Santoro, R. G. Alsmiller, Jr., J. M. Barnes, G. T. Chapman
Nuclear Science and Engineering | Volume 78 | Number 3 | July 1981 | Pages 259-272
Technical Paper | doi.org/10.13182/NSE81-A20303
Articles are hosted by Taylor and Francis Online.
Integral experiments that measure the transport of ∼14-MeV deuterium-tritium (D-T) neutrons through laminated slabs of proposed fusion reactor shield materials have been carried out at the Oak Ridge National Laboratory. Measured and calculated neutron and gamma-ray energy spectra are compared as a function of the thickness and composition of Type 304 stainless steel, borated polyethylene (BP), and Hevimet (a tungsten alloy), and as a function of detector position behind these materials. The measured data were obtained by means of an NE-213 liquid scintillator using pulse-shape discrimination methods to resolve neutron and gamma-ray pulse-height data and spectral unfolding methods to convert these data to energy spectra. The calculated data were obtained using two-dimensional discrete-ordinates radiation transport methods in a complex calculational network that takes into account the energy-angle dependence of the D-T neutrons and the nonphysical anomalies of the Sn method. The transport calculations incorporate ENDF/B-IV cross-section data from the VITAMIN C data library. The measured and calculated neutron energy spectra are in good agreement behind slab configurations of Type 304 stainless steel and BP (∼10% for all neutron energies >850 keV). When 5 cm of Hevimet are added to a 45-cm-thick Type 304 stainless steel plus BP slab assembly, the agreement is less favorable. The agreement among the measured and calculated gamma-ray spectra for energies >750 keV ranges from ∼25% to a factor of ∼5 depending on the slab composition.