SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 2 - January 27, 2006

73 NUCLEAR PHYSICS
Includes nuclear particles; and reactor theory.

For space radiation see 93 Space Radiation.

For atomic and molecular physics see 72 Atomic and Molecular Physics.

For elementary particle physics see 77 Physics of Elementary Particles and Fields.

For nuclear astrophysics see 90 Astrophysics.

20060002849 Argonne National Lab., IL USA

Repository Benefits of AFCI Options

Wigeland, R. A.; Bauer, T. H.; January 2005; 54 pp.; In English Report No.(s): DE2005-842065; ANL-AFCI-129; No Copyright; Avail.: National Technical Information Service (NTIS)

The results described in this report summarize the evaluations of potential benefits to a geologic repository for a variety of AFCI options that were studied during FY04. Many of the options were examined in response to a request by Burton Richter, chair of the Advanced Nuclear Transformation Technology (ANTT) Subcommittee of NERAC, to perform an initial evaluation of the potential benefit to a geologic repository from processing commercial spent nuclear fuel to separate certain chemical elements and to recycle some of these elements in thermal spectrum reactors such as light water reactors. The measure of repository benefit has been defined as the allowable increase in repository drift loading consistent with satisfying all repository thermal design limits, since loading of a geologic repository at Yucca Mountain is currently limited by temperature constraints. Such an increase in drift loading can be used to either reduce the size of a repository of given capacity, or to increase the capacity of a repository of a given size. Any changes in estimated peak dose caused by the resulting alteration in the radionuclide inventory of the repository have not been evaluated, but are the subject of a separate ongoing study. NTIS

Nuclear Fuels; Nuclear Transformations; Spent Fuels

20060002861 Lawrence Livermore National Lab., Livermore, CA USA

Shell Model in a First Principles Approach

Navratil, P.; Jan. 15, 2004; 14 pp.; In English Report No.(s): DE2005-15014004; UCRL-PROC-201765; No Copyright; Avail.: Department of Energy Information Bridge

We develop and apply an ab-initio approach to nuclear structure.

Starting with the NN interaction, that fits two-body scattering and bound state data, and adding a theoretical NNN potential, we evaluate nuclear properties in a no-core approach.

For presently feasible no-core model spaces, we evaluate an effective Hamiltonian in a cluster approach which is guaranteed to provide exact answers for sufficiently large model spaces and/or sufficiently large clusters.

A number of recent applications are surveyed including an initial application to exotic multiquark systems. NTIS

Hamiltonian Functions; Nuclear Reactions

20060002862 Lawrence Livermore National Lab., Livermore, CA USA

Modeling of Fission Neutrons as a Signature for Detection of Highly Enriched Uranium

Wolford, J. K.; Frank, M. I.; Descalle, M. A.; Mar. 2004; 18 pp.; In English Report No.(s): DE2005-15014020; UCRL-CONF-202869; No Copyright; Avail.: National Technical Information Service (NTIS)

We present the results of modeling intended to evaluate the feasibility of using neutrons from induced fission in highly enriched uranium (HEU) as a means of detecting clandestine HEU, even when it is embedded in absorbing surroundings, such as commercial cargo. We characterized radiation from induced fission in HEU, which consisted of delayed neutrons at all energies and prompt neutrons at energies above a threshold. We found that for the candidate detector and for the conditions we considered, a distinctive HEU signature should be detectable, given sufficient detector size, and should be robust over a range of cargo content. In the modeled scenario, an intense neutron source was used to induce fissions in a spherical shell of HEU. To absorb, scatter, and moderate the neutrons, we place one layer of simulated cargo between the source and target and an identical layer between the target and detector. The resulting neutrons and gamma rays are resolved in both time and energy to reveal the portion arising from fission. We predicted the dominant reaction rates within calcium fluoride and liquid organic scintillators. Finally, we assessed the relative effectiveness of two common neutron source energies. NTIS

Fission; Fissionable Materials; Neutrons; Radiation Detectors

Source: NASA