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

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 peakmore » 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.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ; ;  [4] ;  [4]
  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)
Publication Date:
OSTI Identifier:
1236370
Report Number(s):
LBNL--184622
ir:184622; TRN: US1600261
Resource Type:
Technical Report
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
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