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

## Abstract

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 ^{16}O, ^{19}F, ^{35}Cl, ^{56}Fe, ^{63}Cu, and ^{65}Cu. The new URR method also produced normalized cross-section factor probability tables for ^{238}U that were found to be in agreement with current standards. The modified ^{238}U probability tables were shown to produce results in excellent agreement with several standard benchmarks, including the IEU-MET-FAST-007 (BIG TEN),more »

- Authors:

- 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
- Intitute for Radiological Protection (IRSN), Paris (France)
- 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

- Publication Date:

- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)

- OSTI Identifier:
- 1361302

- Grant/Contract Number:
- AC05-00OR22725

- Resource Type:
- Journal Article: Accepted Manuscript

- Journal Name:
- Nuclear Science and Engineering

- Additional Journal Information:
- Journal Volume: 186; Journal Issue: 2; Journal ID: ISSN 0029-5639

- Publisher:
- American Nuclear Society - Taylor & Francis

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 97 MATHEMATICS AND COMPUTING; Unresolved resonance region; nuclear data processing; neutron cross sections

### Citation Formats

```
Holcomb, Andrew M., Leal, Luiz C., Rahnema, Farzad, and Wiarda, Dorothea.
```*A New Method for Generating Probability Tables in the Unresolved Resonance Region*. United States: N. p., 2017.
Web. doi:10.1080/00295639.2016.1273632.

```
Holcomb, Andrew M., Leal, Luiz C., Rahnema, Farzad, & Wiarda, Dorothea.
```*A New Method for Generating Probability Tables in the Unresolved Resonance Region*. United States. doi:10.1080/00295639.2016.1273632.

```
Holcomb, Andrew M., Leal, Luiz C., Rahnema, Farzad, and Wiarda, Dorothea. Tue .
"A New Method for Generating Probability Tables in the Unresolved Resonance Region". United States.
doi:10.1080/00295639.2016.1273632. https://www.osti.gov/servlets/purl/1361302.
```

```
@article{osti_1361302,
```

title = {A New Method for Generating Probability Tables in the Unresolved Resonance Region},

author = {Holcomb, Andrew M. and Leal, Luiz C. and Rahnema, Farzad and Wiarda, Dorothea},

abstractNote = {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.},

doi = {10.1080/00295639.2016.1273632},

journal = {Nuclear Science and Engineering},

number = 2,

volume = 186,

place = {United States},

year = {Tue Apr 18 00:00:00 EDT 2017},

month = {Tue Apr 18 00:00:00 EDT 2017}

}