A New Method for Generating Probability Tables in the Unresolved Resonance Region

Journal Article · Tue Apr 18 04:00:00 UTC 2017 · Nuclear Science and Engineering

DOI: https://doi.org/10.1080/00295639.2016.1273632 · OSTI ID:1361302

Holcomb, Andrew M. ^[1]; Leal, Luiz C. ^[2]; Rahnema, Farzad ^[3]; Wiarda, Dorothea ^[4]

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1. Georgia Inst. of Technology, Atlanta, GA (United States). Dept. of Nuclear and Radiological Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division
2. Intitute for Radiological Protection (IRSN), Paris (France)
3. Georgia Inst. of Technology, Atlanta, GA (United States). Dept. of Nuclear and Radiological Engineering
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division

One new method for constructing probability tables in the unresolved resonance region (URR) has been developed. This new methodology is an extensive modification of the single-level Breit-Wigner (SLBW) pseudo-resonance pair sequence method commonly used to generate probability tables in the URR. The new method uses a Monte Carlo process to generate many pseudo-resonance sequences by first sampling the average resonance parameter data in the URR and then converting the sampled resonance parameters to the more robust R-matrix limited (RML) format. Furthermore, for each sampled set of pseudo-resonance sequences, the temperature-dependent cross sections are reconstructed on a small grid around the energy of reference using the Reich-Moore formalism and the Leal-Hwang Doppler broadening methodology. We then use the effective cross sections calculated at the energies of reference to construct probability tables in the URR. The RML cross-section reconstruction algorithm has been rigorously tested for a variety of isotopes, including ¹⁶O, ¹⁹F, ³⁵Cl, ⁵⁶Fe, ⁶³Cu, and ⁶⁵Cu. The new URR method also produced normalized cross-section factor probability tables for ²³⁸U that were found to be in agreement with current standards. The modified ²³⁸U probability tables were shown to produce results in excellent agreement with several standard benchmarks, including the IEU-MET-FAST-007 (BIG TEN), IEU-MET-FAST-003, and IEU-COMP-FAST-004 benchmarks.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1361302
• Journal Information: Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Journal Issue: 2 Vol. 186; ISSN 0029-5639
• Publisher: American Nuclear Society - Taylor & FrancisCopyright Statement
• Country of Publication: United States
• Language: English