Delayed Gamma-Ray Spectroscopy for Non-Destructive Assay of Nuclear Materials

Technical Report · Mon Jun 01 00:00:00 EDT 2015

DOI:https://doi.org/10.2172/1236370· OSTI ID:1236370

Ludewigt, Bernhard ^[1]; Mozin, Vladimir ^[1]; Campbell, Luke ^[2]; Favalli, Andrea ^[3]; Reedy, Edward T.E. ^[4]; Seipel, Heather ^[4]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Idaho National Lab. (INL), Idaho Falls, ID (United States)

High-­energy, beta-delayed gamma-­ray spectroscopy is a potential, non-­destructive assay techniques for the independent verification of declared quantities of special nuclear materials at key stages of the fuel cycle and for directly assaying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Other potential applications include determination of MOX fuel composition, characterization of nuclear waste packages, and challenges in homeland security and arms control verification. Experimental measurements were performed to evaluate fission fragment yields, to test methods for determining isotopic fractions, and to benchmark the modeling code package. Experimental measurement campaigns were carried out at the IAC using a photo-­neutron source and at OSU using a thermal neutron beam from the TRIGA reactor to characterize the emission of high-­energy delayed gamma rays from ²³⁵U, ²³⁹Pu, and ²⁴¹Pu targets following neutron induced fission. Data were collected for pure and combined targets for several irradiation/spectroscopy cycle times ranging from 10/10 seconds to 15/30 minutes.The delayed gamma-ray signature of ²⁴¹Pu, a significant fissile constituent in spent fuel, was measured and compared to ²³⁹Pu. The ²⁴¹Pu/²³⁹Pu ratios varied between 0.5 and 1.2 for ten prominent lines in the 2700-­3600 keV energy range. Such significant differences in relative peak intensities make it possible to determine relative fractions of these isotopes in a mixed sample. A method for determining fission product yields by fitting the energy and time dependence of the delayed gamma-­ray emission was developed and demonstrated on a limited ²³⁵U data set. De-­convolution methods for determining fissile fractions were developed and tested on the experimental data. The use of high count-­rate LaBr₃ detectors was investigated as a potential alternative to HPGe detectors. Modeling capabilities were added to an existing framework and codes were adapted as needed for analyzing experiments and assessing application-­specific assay concepts. A de-­convolution analysis of the delayed gamma-­ray response spectra modeled for spent fuel assemblies was performed using the same method that was applied to the experimental spectra.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• OSTI ID: 1236370
• Report Number(s): LBNL-184622; ir:184622; TRN: US1600261
• Country of Publication: United States
• Language: English

Related Subjects

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
SPENT FUELS
MIXED OXIDE FUELS
FISSION PRODUCTS
RADIOACTIVE WASTES
THERMAL NEUTRONS
PHOTOFISSION
NEUTRON REACTIONS
GAMMA SPECTROSCOPY
PLUTONIUM 241 TARGET
DELAYED GAMMA RADIATION
PLUTONIUM 239 TARGET
URANIUM 235 TARGET
HIGH-PURITY GE DETECTORS
LANTHANUM BROMIDES
RADIOACTIVE WASTE STORAGE
COMPARATIVE EVALUATIONS
FISSION FRAGMENTS
FISSION
REPROCESSING
COMPUTERIZED SIMULATION
COMPUTER CODES
GAMMA SPECTRA
VERIFICATION
YIELDS
ARMS CONTROL
ENERGY DEPENDENCE
TIME DEPENDENCE
BENCHMARKS
INVENTORIES
NATIONAL SECURITY
SPENT FUEL STORAGE
RADIOACTIVE WASTE DISPOSAL
CHEMICAL COMPOSITION
ISOTOPE RATIO
SPECTRA UNFOLDING