Prompt Neutron Decay Constants and Subcritical Measurements for Material Control and Accountability in SHEBA

Conference · Mon Oct 05 04:00:00 EDT 1998

OSTI ID:674733

Sanchez, Rene G. ^[1]; Jaegers, Peter J. ^[1]

---

1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Rossi-Alpha measurements were performed on the SHEBA assembly to determine the prompt neutron decay constants. These prompt neutron decay constants represent an eigenvalue characteristic of this particular assembly, which can be used to infer the amount of fissile material in the assembly. In addition, subcritical measurements using Rossi-Alpha and the source-jerk techniques were also performed on the SHEBA assembly. These measurements were compared against TWODANT calculations and agreed quite well. The subcritical measurements were also used to obtain a unique signature that represented the amount of material associated with the degree of subcriticality of the SHEBA assembly. Finally, the Feynman variance-to-mean technique in conjunction with TWODANT, were used to determine the effective delayed neutron fraction for the SHEBA assembly.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 674733
• Report Number(s): LA-UR--98-336; CONF-981003--; ON: DE98007218
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COMPARATIVE EVALUATIONS
CRITICALITY
Critical Assembly Vessel (CAV)
DELAYED NEUTRON FRACTION
EIGENVALUES
FISSILE MATERIALS
Feynman Variance-To-Mean Method
NUCLEAR MATERIALS MANAGEMENT
Nuclear Criticality Safety Program (NCSP)
PROMPT NEUTRONS
Prompt Neutron Decay
ROSSI ALPHA METHOD
Rossi-Alpha Measurements
SHEBA Assembly
Source-Jerk Technique
TWODANT Calculations
ZERO POWER REACTORS