Status of GNDS support in AMPX/SAMMY and future outlook [Slides]
Abstract not provided.
97 MATHEMATICS AND COMPUTING↗
SEARCH · Engineering Papers
Results for “analytical methods”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Bayesian Monte-Carlo Evaluation Framework for Imperfect Data [Slides]
BMC evaluation is a tool to address imperfect data & models, non-linear models, and non-normal PDFs. New posterior PDFs may need new storage formats to allow storage of non-normal PDFs. Storing posterior sets allows for: variance, covariance, skewness, etc.
97 MATHEMATICS AND COMPUTING↗
Validation of KENO Delayed Neutron Fraction (β eff ) Capabilities [Slides]
Not provided.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Nuclear Data Activities Supporting MCNP [Slides]
Nuclear Data Team at LANL is working to improve nuclear data availability. These efforts include an updated, modernized, and improved website and a new, dynamic tool for examining what ACE data is on your machine.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Update on Covariance Data Testing Strategy at LANL [Slides]
LANL is working towards an ENDF/B-VIII.0-based Covariance Library, with several key goals and work processes outlined. This includes processing through NJOY’s ERRORR module, identifying and correcting mathematical and physical deficiencies, communicating across pipeline from evaluator to end user, understanding use cases and interpreting results, and releasing to customers. Their testing approach includes interaction, processing, checks (mathematical properties, constraints, and physical bounds), and error propagation.
97 MATHEMATICS AND COMPUTING↗
NJOY work in FY21 [Slides]
LANL lists several NJOY priorities for the future, including the maintenance of NJOY2016 for the foreseeable future, as well as the delivery of usable NJOY21 components.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Nuclear Data Adjustment with Whisper for Criticality Safety Applications [Slides]
Nuclear data adjustment is used by Whisper to compute residual nuclear data uncertainties within a full suite of benchmarks; in order to do so, a complete set of nuclear data covariances, benchmarks and k-effective sensitivity profiles (for both benchmarks and applications) is required. For applications that are similar to the full benchmark suite, the residual uncertainties add a small margin to the overall USL calculation. For applications that are dissimilar to the full benchmark suite, the residual uncertainties add a reasonable margin to the overall USL calculation (more conservative). This methodology helps to overcome any issues in the released covariance libraries where nuclear data uncertainties appear to be too large.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Study Involving IRSN, LANL, & PRNL Sensitivity/Uncertainty Tools to Support Validation [Slides]
Abstract not provided.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Investigating Fission Reaction Rate Ratio Sensitivities [Slides]
One EUCLID project goal is to create a NEW capability in the MCNP6 code. This is being tested on reaction rate sensitivities and compared with SENSMG results. Reaction rate ratio sensitivities were added to EUCLID sensitivity library and investigated to determine value toward designing optimized experiments aimed at reducing compensating errors in nuclear data. The use of adjustment using multiple responses (and underlying/required capabilities) may benefit many applications. These include a tool for adjustment using multiple integral responses (ND adjustment and validation community); sensitivities of additional responses (ND adjustment and validation community); sensitivity capabilities (users in many application areas including safeguards/nonproliferation, criticality safety, etc.); and experiment optimization capability (applications which can benefit from integral experiments). Team is working to build and test future tools and to understand compensating errors
235U↗
Verification of MCNP Critical Benchmark Model of U233-COMP-THERM-004 [Slides]
The verification of U233-COMP-THERM-004 contributed to the LANL centralized repository that’s currently under development. Revisions made to the MCNP model were statistically significant. Magnitude of bias is relatively small in comparison to other uranium benchmark biases and thus will likely have not a significant effect on the USL.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Impacts of LEU+ and ATF on Fresh Fuel Storage Criticality Safety [Slides]
Racks in the New Fuel Vault (NFV) and Spent Fuel Pool (SFP) and accompanying fuel handling procedures are currently designed with a maximum enrichment of 5.0 wt. %. Publicly available source documents were used to develop baseline models of fresh fuel storage configurations.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Polaris Depletion Calculations: Selected Best Practices [Slides]
Abstract not provided.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Sensitivity/Uncertainty Analysis for Nuclear Criticality Safety Validation [Slides]
Sensitivity coefficients predict the expected change in a response ($\kappa$) due to a change in some input parameter ($\Sigma$). These responses can be k eff (or ratios of reaction rates). These input parameters are typically nuclear data. The coefficients are dimensionless ratios. What would happen to the system k eff if some piece of data were changed by some amount? The coefficient is calculated without making the change.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Calculation of Spent Fuel Pool Time-to-Boil using Polaris/ORIGAMI [Slides]
The goal of this experiment was to calculate time-to-boil (TTB) for a Spent Fuel Pool (SFP). TTB is important for SFP management that represents the amount of time available to address loss of forced cooling. Researchers calculated and compared TTB for two cases using SCALE: SFP containing representative LEU fuel (≤ 5 wt %) and SFP containing representative LEU+ fuel (5 – 8 wt %). There were approximately 2300 fuel assemblies in the SFP for each case. Researchers concluded that the impact of LEU+ core on time-to-boil is very small. At such low cooling times, the impact of increased decay heat is not significant. Decay heat of SFP assemblies is small compared to discharge core decay heat.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Illustration of Neutronic Decoupling in Fresh Fuel Storage Environments [Slides]
Operations beyond static storage of fuel assemblies occur in SFPs (moving around the pool, inspection, etc.). These assemblies are assumed suitably distanced at 30 cm. When assemblies are separated by enough water, the neutrons from one cannot cause fission in another, which results in neutronic decoupling. This assumption was investigated for PWR and BWR assemblies as part of ORNL-TM/2021/2330.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Criticality and Radiation Shielding Impacts of ENDF/B-VIII.0 [Slides]
Several impacts of ENDF/B-VIII.0 on Radiation Shielding Applications were observed by researchers. Most reaction rates, attenuation ratios, and dose rates are similar for ENDF/B-VII.1 and ENDF/B-VIII.0. A significant reduction in reactor dosimetry results was noted. Investigation continues to reveal underlying data for discrepancies.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
SCALE Sensitivity Tutorial [Slides]
In sensitivity analysis, we seek to quantify the degree to which fundamental data (i.e., nuclear data) influence a system’s response. In uncertainty analysis, we seek to quantify the degree to which uncertainty in fundamental data contributes to uncertainty in a system’s response. In SCALE, the TSUNAMI suite provides tools for sensitivity and uncertainty analysis, similarity analysis, and nuclear data and covariance adjustment.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗