Strong<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>M</mml:mi><mml:mn>1</mml:mn><mml:mn /></mml:math>transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Na</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>23</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>below 10 MeV

Vodhanel, R.; Brussel, M.K.; Moreh, R.; Sellyey, W.; Chapuran, T.E.

doi:10.1103/physrevc.29.409

Cited by 23 publications

(11 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Transmission experiments have previously neglected notch refilling because target areal densities were generally significantly smaller than in this experiment [4,9,10]. Thinner target thicknesses are better for measurement of resonant state parameters, but the target thicknesses selected for this experiment were intended to be representative of nuclear fuel assemblies.…”

Section: Notch Refillmentioning

confidence: 99%

See 1 more Smart Citation

Transmission nuclear resonance fluorescence measurements of 238U in thick targets

Quiter

Ludewigt

Mozin

et al. 2011

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

Transmission nuclear resonance fluorescence measurements were made on targets consisting of Pb and depleted U with total areal densities near 86 g/cm 2 . The 238 U content in the targets varied from 0 to 8.5% (atom fraction). The experiment demonstrates the capability of using transmission measurements as a non-destructive technique to identify and quantify the presence of an isotope in samples with thicknesses comparable to the average thickness of a nuclear fuel assembly. The experimental data also appear to demonstrate the process of notch refilling with a predictable intensity. Comparison of measured spectra to previous backscatter 238 U measurements indicates general agreement in observed excited states. Evidence of two new 238 U excited states and possibly a third state have also been observed.

show abstract

Section: Notch Refillmentioning

confidence: 99%

“…NRF signatures are most commonly measured by either a backscatter or a transmission measurement [9,10]. In both measurement techniques, a source photon beam is used to induce nuclear excitations in a target.…”

Section: Introductionmentioning

confidence: 99%

Transmission nuclear resonance fluorescence measurements of 238U in thick targets

Quiter

Ludewigt

Mozin

et al. 2011

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

show abstract

“…Transmission experiments have previously neglected notch refilling because target areal densities were generally significantly smaller [3,42,43]. Thinner target thicknesses are better for measurement of resonant state parameters, but the targets used in this experiment were intended to be representative of nuclear fuel assemblies.…”

Section: A3 Notch Refillmentioning

confidence: 99%

Nuclear Resonance Fluorescence to Measure Plutonium Mass in Spent Nuclear Fuel

Ludewigt¹

2011

View full text Add to dashboard Cite

Executive SummaryThe Next Generation Safeguard Initiative (NGSI) of the U.S. Department of Energy is supporting a multi-lab/university collaboration to quantify the plutonium (Pu) mass in spent nuclear fuel (SNF) assemblies and to detect the diversion of pins with non-destructive assay (NDA) methods. Nuclear Resonance Fluorescence (NRF) has been investigated as one of 14 NDA techniques included in the NGSI study. In contrast to many of the other, older techniques, NRF had not previously been considered for nuclear safeguards or similar applications and basic aspects including nuclear data, modeling and simulation tools, measurement methods, and instrumentation needed to be researched.Nuclear resonance fluorescence is the process by which a nucleus is excited to a specific state by the absorption of a photon, then subsequently de-excites to the ground state by the emission of one or more γ rays. The energies of the γ rays are characteristic of the specific state that underwent NRF and therefore are characteristic of the isotope. The emitted NRF γ rays are detected at backwards angles where the backgrounds from elastically and inelastically scattered photons are lowest. Two distinct assay methods, the backscatter and the transmission methodsare analyzed in this report. In both cases a beam of energetic photons excites nuclear resonances of the isotopes of interest (IOI) within the SNF. In the backscatter assay geometry, the emitted NRF γ rays detected at backwards angles are a measure of the amount of a specific isotope in the SNF. In transmission assay, a detection system down-stream of the SNF measures the excess attenuation of resonant-energy photons due to NRF in the SNF assembly. The detection system consists of a thin sheet composed of the isotope of interest, called the transmission detector (TD), and a detector array that measures the NRF γ rays emanating from the TD. Given the low concentrations of the Pu isotopes in SNF and the relatively small integrated nuclear resonance cross sections, the main challenge for achieving precise and accurate measurements lies in accruing sufficient counting statistics in an acceptable measurement time.The goals of this study were to design and model suitable NRF measurement methods, to quantify capabilities and corresponding instrumentation requirements, to investigate possible implementations, and to evaluate the prospects and potential of the technique for the assay of SNF assemblies, i.e., for the measurement of their Pu isotopic content.Analytical models were developed that enabled calculation of NRF signals for a variety of backscatter and transmission geometries. Extensive simulations were performed using the computer code, Monte Carlo N-particle eXtended (MCNPX) to calculate photon scattering effects, i.e., to determine scattered, non-resonant background and the notch refilling in transmission measurements. We found that MCNPX underestimated the non-resonant elastic scattering at backwards angles by multiple orders of magnitude mainly due to a flawed treatment of ...

show abstract

“…Transmission experiments have previously neglected notch refilling because target areal densities were generally significantly smaller [1,35,36]. Thinner target thicknesses are better for measurement of resonant state parameters, but the targets used in this experiment were intended to be representative of nuclear fuel assemblies.…”

Section: Areal Density Measurementmentioning

confidence: 99%

Nuclear Resonance Fluorescence for Safeguards Applications

Ludewigt¹,

Quiter²,

Ambers³

2011

View full text Add to dashboard Cite

Executive SummaryIn nuclear resonance fluorescence (NRF) measurements, resonances are excited by an external photon beam leading to the emission of gamma rays with specific energies that are characteristic of the emitting isotope. The promise of NRF as a non-destructive analysis technique (NDA) in safeguards applications lies in its potential to directly quantify a specific isotope in an assay target.This report addresses the assessment of NRF-based methods for safeguards applications in the context of related studies at LBNL, LLNL, and BNL. Our FY10 effort was comprised of three tasks: the study of the non-resonant scattering background and its simulation with MCNPX, analysis of our previously performed NRF transmission experiment, and the assessment of NRF for safeguards applications.While the recent correction of the treatment of Rayleigh scattering in MCNPX resulted in much better agreement with some experimental data, the photonuclear processes, which are important contributors to the elastic scattering background at higher energies, are still not included. Our analysis showed that calculations based on ENDF form factors as currently implemented in MCNPX could underestimate the elastic scattering cross section by as much as a factor of ten for a uranium target at photon energies above 2 MeV. Even larger discrepancies, up to several orders of magnitude, are possible for lighter elements such as zirconium. It would be desirable to at least include nuclear Thomson scattering in MCNPX simulations for NRF studies.The transmission experiment, using a bremsstrahlung beam and a target of comparable thickness to a spent nuclear fuel assembly, demonstrated sensitivity to a 238 U content of 1%. However, the precision was count rate limited. The data obtained in this experiment indicated notch refill that could change the measured NRF rates by up to 5% for the worst case. A correction based on MCNPX modeling has been implemented in the analysis.NRF-based methods were assessed for three potential safeguards applications: the isotopic assay of spent nuclear fuel (SNF), the measurement of 235 U enrichment in UF 6 cylinders, and the determination of 239 Pu in mixed oxide (MOX) fuel. Given the small integrated nuclear resonance cross sections, the main challenge in these application, albeit to a varying degree, lies in accruing of sufficient counting statistics in an acceptable measurement times for achieving the desired uncertainties.Pu isotopic masses in SNF could precisely be determined in transmission measurements using bremsstrahlung sources, but such measurements would require up to 100's of hours, a very intense bremsstrahlung source, and a very large array of fast detectors with high energy resolution. Quasimonoenergetic photon sources such as Laser Compton scattering sources could potentially enable greatly improved performance. As an example, assuming a photon source with a 1 keV energy spread, an intensity of 6x10 8 ph/eV/s, and operating continuously or at very high pulse rates, the measurement time would be on ...

show abstract

StrongM1transitions inNa23below 10 MeV

Cited by 23 publications

References 17 publications

Transmission nuclear resonance fluorescence measurements of 238U in thick targets

Transmission nuclear resonance fluorescence measurements of 238U in thick targets

Nuclear Resonance Fluorescence to Measure Plutonium Mass in Spent Nuclear Fuel

Nuclear Resonance Fluorescence for Safeguards Applications

Contact Info

Product

Resources

About