Simultaneous Measurement of<sup>235</sup>U Fission and Capture Cross Sections From 0.01 eV to 3 keV Using a Gamma Multiplicity Detector

Danon, Y.; Williams, D.; Bahran, Rian; Blain, E.; McDermott, B.; Barry, D. P.; Leinweber, G.; Block, Robert C.; Rapp, M. J.

doi:10.1080/00295639.2017.1312937

Cited by 14 publications

(16 citation statements)

References 14 publications

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“…As seen on Figure 1, the trends were a -27 to -33 % decrease at 1-2 keV (end of RRR) which is in agreement with Danon measurements (2017) 13 and a +8 to +10% increase in the 10-100keV region (URR) which is in agreement with Jandel measurements (2012) 14 . Uncertainties are significantly reduced.…”

Section: Trends For 235 U Capturesupporting

confidence: 88%

Trends on Major Actinides from an Integral Data Assimilation

2019

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Nuclear data evaluations on major actinides can be improved by integral data assimilation. Appropriate integral measurements with reliable experimental techniques have been selected such as ICSBEP, IRPhE and MASURCA critical masses, PROFIL irradiation experiments and the FCAIX experimental programme (critical masses and spectral indices). Highly reliable analyses are possible with the use of as-built geometries calculated with the TRIPOLI4 Monte Carlo code. The C/E values have been used in an integral data assimilation solving the Bayes equation. The trends on the JEFF3.1.1 235U capture cross section are quite consistent with recent differential measurements. Assimilation results suggest up to a 2.5% decrease for 238U capture from 3 keV to 60 keV, and a 4-5% decrease for 238U inelastic in the plateau region. For this energy range, uncertainties are respectively reduced from 3-4 to 1-2% and from 6-9% to 2-2.5% for 238U capture and 238U inelastic. Results on 239Pu fission cross sections are included in posterior uncertainties. The increase trends on 239Pu capture cross-section is of around 3% in the [2 keV-100 keV] energy range. For 240Pu capture cross section, the increase is of around 4% in the [3 keV-100 keV] energy range and goes in the same direction as a recent evaluation.

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Section: Trends For 235 U Capturesupporting

confidence: 88%

Trends on Major Actinides from an Integral Data Assimilation

2019

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“…Focusing on the end of the resolved resonances range (RRR) from 1 to 2.25 keV, we compared our assimilation trends in this energy range with recent differential measurements made at RPI. Figure 6 displays results of these measurements as published in reference [14] (as they are not currently available in the EXFOR database) with a comparison to ENDF/B-VII and JENDL-4.0. One has to note that for 235 U capture cross section, JEFF-3.1.1 and ENDF/B-VII.1 evaluations are identical.…”

Section: Masurca 1bmentioning

confidence: 99%

Use of integral data assimilation and differential measurements as a contribution to improve ²³⁵U and ²³⁸U cross sections evaluations in the fast and epithermal energy range

Huy

Noguère

Rimpault

2018

EPJ Nuclear Sci. Technol.

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Critical mass calculations of various HEU-fueled fast reactors result in large discrepancies in C/E values, depending on the nuclear data library used and the configuration modeled. Thus, it seems relevant to use integral experiments to try to reassess cross sections that might be responsible for such a dispersion in critical mass results. This work makes use of the Generalized Least Square method to solve Bayes equation, as implemented in the CONRAD code. Experimental database used includes ICSBEP Uranium based critical experiments and benefits from recent re-analyses of MASURCA and FCA-IX criticality experiments (with Monte-Carlo calculations) and of PROFIL irradiation experiments. These last ones provide very specific information on 235 U and 238 U capture cross sections. Due to high experimental uncertainties associated to fission spectra, we chose to consider either fitting these data or set them to JEFF-3.1.1 evaluations. The work focused on JEFF-3.1.1 235 U and 238 U evaluations and results presented in this paper for 235 U capture and 238 U capture, and inelastic cross sections are compared to recent differential experiment or recent evaluations. Our integral experiment assimilation work notably suggests a 30% decrease for 235 U capture around 1-2.25 keV, a 10% increase in the unresolved resonance range when using JEFF-3.1.1 as "a priori" data. These results are in agreement with recent microscopic measurements from Danon et al. [Nucl. Sci. Eng. 187, 291 (2017)] and Jandel et al. [Phys. Rev. Lett. 109, 202506 (2012)]. For 238 U cross sections, results are highly dependent on fission spectra. *

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“…Recently, two measurements using such methods were published [17,18]. In reference [17] a fission chamber was used to measure the fraction of fission gammas in the total gammas measured.…”

Section: Simultaneous Neutron Capture and Fission Measurementsmentioning

confidence: 99%

“…This fraction was later used to correct the measurement. In reference [18] the fission yield was first obtained from events with E dep > E b . The fission yield was then subtracted from the total yield measured with events E dep < E b by normalization to two known capture yields (resonance integrals or the thermal capture cross section).…”

Section: Simultaneous Neutron Capture and Fission Measurementsmentioning

confidence: 99%

“…The fission yield was then subtracted from the total yield measured with events E dep < E b by normalization to two known capture yields (resonance integrals or the thermal capture cross section). The grouped results from reference [18] are shown in Figure 5 and were used to help resolve the difference between the evaluations of 235 U in the energy range from 500 to 3000 eV. The agreement between the evaluation and the measure fission yield is very good, but there are differences in the capture yield that were tabulated in reference [18].…”

Section: Simultaneous Neutron Capture and Fission Measurementsmentioning

confidence: 99%

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Innovative experiments for reduction of nuclear data uncertainty

Danon

2018

EPJ Nuclear Sci. Technol.

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Due to the complexity of nuclear reaction models, current nuclear data evaluations must rely on experimental observations to constrain models and provide the accuracy needed for applications. For criticality applications, the accuracy of nuclear data needed is higher than what is currently possible from differential experiments alone, and integral measurements are often used for data adjustment within the uncertainties of differential experiments. This approach does not necessarily result in physically correct cross sections or other adjusted quantities because compensation between different materials is hard to avoid. One of the objectives of the recent CIELO project [M. Chadwick et al., Nucl. Data Sheets 118, 1 (2014)] was simultaneous evaluation of important materials in an attempt to minimize the effects of compensation. Improvement to the evaluation process depends on obtaining new experimental data with high accuracy and lower uncertainty that will help constrain the evaluations for certain important reactions. Improved experiments are accomplished by careful design with the objective of achieving high accuracy and lower uncertainty, and by designing new innovative experiments. New and unconventional experiments do not necessarily provide differential data but instead nuclear data that evaluators will find useful to constrain the evaluation and reduce the uncertainty. This also means that closer information exchange and collaboration between experimentalists and evaluators is important. For conventional experiments such as neutron transmission or capture measurements, it is important to understand the sources of uncertainty and address them in the experiment design. Such a process can also lead to the design of innovative methods. For example, the filtered beam method minimizes uncertainties due to background, and the Quasi-Differential Neutron Scattering method simplifies the experiment and data analysis and results in lower experimental uncertainty. A review of the sources of uncertainty in various experiments and examples of experimental techniques that help reduce experimental and evaluation uncertainty and increase accuracy will be discussed.

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Simultaneous Measurement of²³⁵U Fission and Capture Cross Sections From 0.01 eV to 3 keV Using a Gamma Multiplicity Detector

Cited by 14 publications

References 14 publications

Trends on Major Actinides from an Integral Data Assimilation

Trends on Major Actinides from an Integral Data Assimilation

Use of integral data assimilation and differential measurements as a contribution to improve ²³⁵U and ²³⁸U cross sections evaluations in the fast and epithermal energy range

Innovative experiments for reduction of nuclear data uncertainty

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Simultaneous Measurement of235U Fission and Capture Cross Sections From 0.01 eV to 3 keV Using a Gamma Multiplicity Detector

Cited by 14 publications

References 14 publications

Trends on Major Actinides from an Integral Data Assimilation

Trends on Major Actinides from an Integral Data Assimilation

Use of integral data assimilation and differential measurements as a contribution to improve 235U and 238U cross sections evaluations in the fast and epithermal energy range

Innovative experiments for reduction of nuclear data uncertainty

Contact Info

Product

Resources

About

Simultaneous Measurement of²³⁵U Fission and Capture Cross Sections From 0.01 eV to 3 keV Using a Gamma Multiplicity Detector

Use of integral data assimilation and differential measurements as a contribution to improve ²³⁵U and ²³⁸U cross sections evaluations in the fast and epithermal energy range