Safeguards: Modelling of the Detection and Characterization of Nuclear Materials
Doktorsavhandling, 2010

Nuclear safeguards is a collective term for the tools and methods needed to ensure nonproliferation and safety in connection to utilization of nuclear materials. It encompasses a variety of concepts from legislation to measurement equipment. The objective of this thesis is to present a number of research results related to nuclear materials control and accountability, especially the area of nondestructive assay. Physical aspects of nuclear materials are often the same as for materials encountered in everyday life. One special aspect though is that nuclear materials also emit radiation allowing them to be qualitatively and quantitatively measured without direct interaction with the material. For the successful assay of the material, the particle generation and detection needs to be well understood, and verified with measurements, simulations and models. Four topics of research are included in the thesis. First the generation and multiplication of neutrons and gamma rays in a fissile multiplying sample is treated. The formalism used enables investigation of the number of generated, absorbed and detected particles, offering understanding of the different processes involved. Secondly, the issue of relating the coincident detector signals, generated by both neutrons and gamma rays, to sample parameters is dealt with. Fission rate depends directly on the sample mass, while parameters such as neutron generation by alpha decay and neutron leakage multiplication are parameters that depend on the size, composition and geometry of the sample. Artificial neural networks are utilized to solve the inverse problem of finding sample characteristics from the measured rates of particle multiples. In the third part the interactions between neutrons and organic scintillation detectors are treated. The detector material consists of hydrogen and carbon, on which the neutrons scatter and transfer energy. The problem shares many characteristics with the area of neutron moderation found in reactor physics. Finally the last part of the thesis consists of measurement systems. Measuring coincident neutrons and gamma rays using fast scintillation detectors and data acquisition systems, can enable development of new types of methods for interpreting material signatures.

scintillation detectors

number distribution

nuclear safeguards

cross correlations

light pulse distribution

master equations

multiplicities

¯ssile material

FB
Opponent: John K. Mattingly

Författare

Andreas Enqvist

Chalmers, Teknisk fysik, Nukleär teknik

A note on the multiplicity expressions in nuclear safeguards.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 603(2009)p. 541-544

Artikel i vetenskaplig tidskrift

Sample characterization using both neutron and gamma multiplicities

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 615(2010)p. 62-69

Artikel i vetenskaplig tidskrift

Calculation of the light pulse distributions induced by fast neutrons in organic scintillation detectors

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 618(2010)p. 266-274

Artikel i vetenskaplig tidskrift

Monte Carlo and analytical models of neutron detection with organic scintillation detectors

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 582(2007)p. 629-637

Artikel i vetenskaplig tidskrift

The Detection Statistics of Neutrons and Photons Emitted from a Fissile Sample.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 607(2009)p. 451-457

Artikel i vetenskaplig tidskrift

Measurement and simulation of neutron/gamma-ray cross-correlation functions from spontaneous fission

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 595(2008)p. 426-430

Artikel i vetenskaplig tidskrift

Unfolding sample parameters from neutron and gamma multiplicities using artificial neural networks.

ESARDA Bulletin,; (2009)p. 21-29

Artikel i vetenskaplig tidskrift

The number distribution of neutrons and gamma photons generated in a multiplying sample

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 566(2006)p. 598-608

Artikel i vetenskaplig tidskrift

Initial Evaluation for a Combined Neutron and Gamma 1 Ray Multiplicity Counter

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,; Vol. 621(2010)p. 493-497

Artikel i vetenskaplig tidskrift

Ämneskategorier

Subatomär fysik

Annan teknik

ISBN

978-91-7385-356-9

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3037

CTH-NT - Chalmers University of Technology, Nuclear Engineering

FB

Opponent: John K. Mattingly