Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source

Conference · Mon Sep 20 00:00:00 EDT 1999

OSTI ID:761233

Hollas, Charles L. ^[1]; Goulding, Charles A. ^[1]; Myers, William L. ^[1]

---

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

A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using ³He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MCNP K-Code calculations.

• Research Organization: Los Alamos National Lab. (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: 761233
• Report Number(s): LA-UR-99-2192; TRN: US0100592
• Resource Relation: Conference: ICNC '99: 6. International Conference on Nuclear Criticality Safety, Palais des Congres, Versailles (France), 20-24 Sep 1999; Other Information: PBD: 20 Sep 1999
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COUNTING RATES
CRITICALITY
DELAYED NEUTRONS
ENRICHED URANIUM
HIGHLY ENRICHED URANIUM
NEUTRON DETECTION
NEUTRON DETECTORS
NEUTRON SOURCES
NEUTRONS
SAFETY
Nuclear Criticality Safety Program (NCSP)
Highly Enriched Uranium (HEU) Systems
Neutron Detector
Multiplication Factor
MCNP K-Code Calculations
Hage-Cifarelli Formalism
Feynman Reduced Variance Method