Neutronic analysis of critical configurations in geologic repositories. 1: Weapons-grade plutonium

Journal Article · Sat Nov 01 04:00:00 EST 1997 · Nuclear Science and Engineering

OSTI ID:556638

Greenspan, E; Vujic, J; Burch, J ^[1]

---

1. Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering

Neutronic characteristics of critical configurations, which may be formed if large enough quantities of weapons-grade plutonium that might be stored in a geologic repository are released, transported, and deposited below the repository on rock surfaces in fractures, are investigated. Three neutronic characteristics of the plutonium-rock-water systems are examined: multiplication factor k, time eigenvalue {alpha}. Three processes are identified that have the potential for a large positive reactivity feedback: (a) water removal, (b) spectrum hardening, and (c) homogenization. The higher the initial water concentration, the more absorbing the medium, the more heterogeneous the plutonium deposition, and the larger the core volume, the larger the magnitude of positive reactivity feedback can be. Critical configurations were identified in which all but one (i.e., core expansion) of the reactivity feedback mechanisms are positive. Scenarios are described in which natural phenomena could drive slightly subcritical configurations to develop an autocatalytic prompt supercritical chain reaction.

• Sponsoring Organization: Los Alamos National Lab., NM (United States)
• OSTI ID: 556638
• Journal Information: Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Journal Issue: 3 Vol. 127; ISSN NSENAO; ISSN 0029-5639
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
CRITICALITY
PARAMETRIC ANALYSIS
PLUTONIUM
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE FACILITIES
RADIONUCLIDE MIGRATION
SAFETY ANALYSIS