Polyethylene-reflected plutonium metal sphere : subcritical neutron and gamma measurements.

Technical Report · Sun Nov 01 00:00:00 EDT 2009

DOI:https://doi.org/10.2172/974870· OSTI ID:974870

Mattingly, John K.

Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.

• Research Organization: Sandia National Laboratories
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 974870
• Report Number(s): SAND2009-5804 rev.1
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCURACY
BENCHMARKS
CRITICALITY
Criticality (Nuclear engineering)-Safety measures-Standards
EVALUATION
GAMMA SPECTROMETERS
MANUALS
MULTIPLICITY
NEUTRON TRANSPORT
NEUTRONS
Neutron transport theory-Mathematical models.
Nuclear Criticality Safety Program (NCSP)
PHOTON EMISSION
PHOTON TRANSPORT
PHOTONS
PLUTONIUM
POLYETHYLENES
RADIATION TRANSPORT
SAFETY