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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Fission Product Chain Yield Measurements [Slides]

Fission product chain yields were historically determined by chemical separation and beta counting of fissile samples irradiated in carefully controlled fission chamber experiments. These measurements provided the means to extract absolute fission product yields (yield per fission, or Y $\mathcal{i}$ /$\mathcal{f}$ for the $\mathcal{i}$ $\mathcal{th}$ fission product) that are included in the international nuclear data libraries, and ultimately used to model and characterize multiplying systems. However, reevaluations conducted at Los Alamos National Lab and Lawrence Livermore National Lab in 2005-2009 for neutron-induced fission of 235 U and 239 Pu highlighted disagreement among many of the measurements. This led to several new, targeted experimental programs to resolve these disagreements. In this presentation we will highlight recent efforts to address these discrepancies using energy-integral measurements at the National Criticality Experiments Research Center (NCERC) and outline our plans to complete the work over the next several years.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Status of the n+ 35 Cl Cross Sections [Slides]

In the recently released ENDF/B-VIII.0 library, the 35 Cl(n,p) cross section above 100 keV significantly differs from the ENDF/B-VII.0 library. This resulted in large differences in the predicted reactivity in nuclear reactor simulations. The lack of experimental data for incident neutron energies above 100 keV does not allow a precise evaluation of the 35 Cl(n,p) reaction channel. Evaluation of 35 Cl(n,p) cross section was included as one of the highest priorities in recent DOE calls for proposals within the Nuclear Data Interagency Working Group / Research Program.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Thermal Neutron Scattering Evaluation Methods Development at ORNL [Slides]

The goal of the project was to develop a procedure to generate covariance matrix for S( α,β ) data that incorporated both computational simulations and experimental data. Experimental data and computer simulation fit is achieved using the Unified Monte Carlo (UMC) method. The framework is material & simulation method independent, and this is demonstrated using light water. A methodology was developed for generalized generation of covariances for thermal scattering files. The framework was subsequently tested on light water by generating covariance of pDOS with encouraging results. Preliminary results suggest temperature effects of polyethylene may warrant further investigation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Current Status of AMPX [Slides]

This presentation discussed the added additional GNDS functionality to AMPX which we intend to share with SAMMY. Additionally, this presentation discusses how new ENDF/B-VIII.0 libraries were generated for SCALE. The presentation also discusses the AMPX training that was prepared and presented in Oak Ridge and at NRC headquarters.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

TNSL support in GNDS 2.0 and beyond [Slides]

This presentation begins by discussing the TNSL format options that went through a major overhaul in GNDS-2.0 and it examines the changes in 2.0. Additionally, it discusses three issues with further changes that should be considered. The first issue is that the project needs some guidance on what to expect when evaluations are performed with coherent inelastic. The second issue is that GNDS-2.0 does not provide a way to clearly specify in the evaluation how to switch to ‘standard’ incident neutron evaluations for energies or temperatures outside the TNSL domain. The third issue is that when GNDS-2.0 was designed, it was assumed that S(α,β) would always be given on a uniform interpolation grid. The presentation concludes by discussing how New JENDL-5 TNSL evaluations have some complications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Neural Thermal Scattering (NeTS) Modules for Graphite & Beryllium [Slides]

This presentation discusses the motivations behind the project, which include facilitating compact formulation for TSL data, extending AI knowledge, and providing advanced reactor simulation framework. It also discusses how the project accounts for beryllium and graphite complexity, including atomistic, dynamical, and neural. Additionally, new material-informed neural thermal scattering (NeTS) Modules are examined. The implications, conclusions, and plan future work for the project are also discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

TSL Nuclear Fuel Evaluations and Capabilities at NC State University [Slides]

This presentation discusses the purpose of this project which is to provide thermal scattering law (TSL) and cross section data to support advanced reactor modeling and criticality safety. The presentation also examines modeling and simulations, evaluation updates, and benchmark applications in connection with the project. In summation, new and updated uranium fuel evaluations have been submitted to the ENDF/B libraries. These include vital fuel materials U-metal, UC, UN, and UO 2 .

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Implementation of TSL Evaluations Beyond the Incoherent Approximation [Slides]

This presentation discusses the motivation behind the project, which is to facilitate the production of TSL libraries that contain high fidelity physics including coherent inelastic effects, such as graphite and beryllium. High fidelity TSL libraries are of interest in various applications, for example in relation to neutron scattering instrument response analysis and directional biases (reflection) in neutronic analysis. In summation, the removal of typical approximations, in terms of incoherent, cubic, and atom site are examined. The application of generalized equations to crystalline graphite and beryllium TSL evaluations and the validation of data and data formats is also discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Updated Gadolinium Validation in SCALE 6.3.0 using ENDF/B-VIII.0 Data [Slides]

This presentation provides a brief recap of the ANS Summer meeting in 2018 with a discussion of the results. The presentation also provides an overview of new models and states that all new models have been checked but have not yet been added to the VALID library. It also states that the models were originally created as part of a master's thesis or summer internships. Additionally, all models have been rerun in SCALE 6.3.0 using CE ENDF/B-VIII.0 library. In conclusion, this project has facilitated a significant expansion of validation set containing gadolinium, including 13 cases previously in VALID plus 99 new cases. The completion of IPPE HST experiments confirm no clear trend as a function of concentration or spectrum. Solid absorber cases also show no clear trends and LANL HMT experiments have significant discrepancies in Gd alloy cases. While almost half of the total gadolinium-bearing cases from the ICSBEP Handbook are considered here, the presentation recognizes that there is more work to be done.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Proposed Methodology for Evaluating and Validating TSLs [Slides]

This presentation begins by providing an overview of the research and discusses recent efforts in validating thermal neutron scattering cross sections, including differential cross section measurements at ORNL for evaluation and validation, total cross section measurements at RPI, pulsed-neutron die-away experiments at LLNL, and integral criticality experiments by LLNL. The presentation also proposes a methodology not only for validating thermal scattering files that utilizes all available experimental data, but also for evaluating new libraries as demonstrated on polystyrene. In conclusion, polystyrene evaluation was conducted using multiple experiments, including differential and integral. The proposed methodology has been shown to improve neutron transport and files have been submitted to NNDC for inclusion in ENDF/B-VIII.1 release. MCT-012 & PCM-002 has been relatively insensitive to changes in $\mathcal{S}(α,β)$. The research found that differences in differential results don’t always propagate to differences in integral results, hence why evaluation of differential data important. Future work on the project is also discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗