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Utility Working Conference and Vendor Technology Expo
August 8–11, 2021
Marco Island, FL|JW Marriott Marco Island
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Nuclear Science and Engineering
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Bumpy roads lead to beautiful places
Per Nuclear News tradition, this month’s issue is dedicated to highlighting our nuclear technology supply chain. U.S. nuclear suppliers have certainly seen their share of challenges in the last decade or so. The widely anticipated “Nuclear Renaissance” of the early 2000s gave way to Fukushima, then a wavelet of plant closures that ANS President Steve Nesbit addresses in his column on page 15 of the August 2021 issue of Nuclear News.
However, the nuclear narrative has taken on a more positive tone of late. Significant federal investments in advanced nuclear energy systems, coupled with a broader recognition of the need to decarbonize, has stoked excitement for a new generation of U.S. technology on the verge of scaled commercial deployment by the end of the decade. Hopefully, in the words of Washington Nationals manager Davey Martinez, whose team went from a 19–32 record to World Series champs in 2019, “Bumpy roads lead to beautiful places.”
Jesse M. Brown, R. C. Block, A. Youmans, H. Choun, A. Ney, E. Blain, D. P. Barry, M. J. Rapp, Y. Danon
Nuclear Science and Engineering | Volume 194 | Number 3 | March 2020 | Pages 221-231
Technical Paper | dx.doi.org/10.1080/00295639.2019.1688087
Articles are hosted by Taylor and Francis Online.
Often discrepancies can be found in the corresponding cross sections of different evaluated nuclear data libraries. Traditional integral benchmarks that are used to validate such libraries are sensitive to cross-section values across many different energies. This means an erroneously low cross section at one energy may compensate for an erroneously high cross section at another energy, and the integral benchmark value may still be met. While the evaluated cross section may agree with that single benchmark, it could affect other systems differently. To reduce the potential for this error, an energy differential validation method is proposed herein for continuous energy Monte Carlo neutron transport models in the resolved resonance region and the unresolved resonance region (URR). The proposed method exposes the underlying physics of the URR and validates both the average cross section and resonance self-shielding effect driven by the fluctuations in that cross section. This is done by measuring the neutron transmission of a thick sample that, by its nature, exaggerates the resonance self-shielding effect. This validation method is shown to be very sensitive to the cross-section model used (resolved versus unresolved) and the fluctuation correction employed, allowing it to probe the validity of the previously mentioned cross-section evaluations. Tantalum-181 is used as an example to demonstrate the impact of different resonance evaluations. It was found that the JEFF-3.3 and JENDL-4.0u evaluations made reasonable choices for cross-section models of 181Ta; none of the current evaluations, however, can be used to properly model the validation transmission over all energies. It was also found that updating resonance parameters in the URR provided better agreement with the validation transmission.