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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 73 records · Page 4

Data Assimilation using Non-invasive Monte Carlo Sensitivity Analysis of Reactor Kinetics Parameters [Slides]

Sensitivity coefficients of prompt neutron decay constant (α) and effective delayed neutron fraction (β eff ) to Pu-239 nuclear data were calculated using a newly available tool (ACEtk). Uncertainty calculations showed the following trends: (1) The prompt neutron decay constant can be used to reduce nuclear data-induced uncertainty in Pu-239(n,f) and (2) the effective delayed neutron fraction can be used to effectively reduce nuclear data-induced uncertainty in Pu-239 total fission $\tilde{v}$. Sensitivity/uncertainty analysis can be used to determine optimal experiment/detector setup to identify compensating errors in nuclear data. Upcoming work includes investigating other nuclide-reaction pairs and response sensitivities, such as Δ$\rho$, neutron leakage spectra, and reaction rate measurements to constrain nuclear data of interest.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Expanding Benchmarks for Nuclear Data Validation [Slides]

The presentation discusses benchmarking in comparison to experimental truth, the integral experiments that were performed, and that benchmarks are evaluated experiments. It also discusses validation testing, and that the ultimate goal of the validation end product is to improve evaluated nuclear data for applications It does state that validation highlights errors in the Nuclear Data Pipeline that affect applications, for example: Missing Cd Capture Gammas in ENDF/B-VII.1. It acknowledges that additional types of experiments are needed to test data used in applications, and that validation experiments do not have to be complicated and expensive. The presentation also discusses different types of measurements including activation foil and fission chamber measurements, reactor kinetics measurements, and subcritical measurements. The presentation concludes with an experiment summary and states that all applications need validation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

International Intercomparison for Nuclear Accident Dosimetry Using Godiva-IV

During the week of August 22, 2022, Integral Experiment Request (IER) 538, an international blind intercomparison for nuclear accident dosimetry (NAD) exercise, was completed using the Godiva-IV critical assembly at the National Criticality Experiments Research Center (NCERC) located in the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS). This exercise builds upon a series of experiments that include the characterization the radiation fields around Godiva (IER-147) and Flattop (IER-252) and follow up intercomparisons of dosimetry around both Godiva IV and Flattop (IER-148 and IER-253, respectively). The participants consisted of seven Department of Energy laboratories and one laboratory each from the US Navy, United Kingdom, and France. The participants of the exercise were Lawrence Livermore National Laboratory (LLNL); Los Alamos National Laboratory (LANL); Sandia National Laboratory (SNL); Savannah River Site (SRS); Hanford Site, Missions Support and Test Services (MSTS); Y-12 National Security Complex (Y-12); Naval Dosimetry Center (NDC); Atomic Weapons Establishment (AWE); and Institut de Radioprotection et de Sûreté Nucléaire (IRSN). MSTS dosimeters were included in the irradiations but not reported for evaluation. This report primarily discusses the performance of the 24 hour results submitted by participants, though available final results are briefly discussed. Information for each irradiation performed is provided for participating laboratories to produce their own final report which will be incorporated into the CED-4a report.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Neutron Pulsed Die-Away Experiments at LLNL [Slides]

This presentation discusses why PNDA is ideal for TSL validations as it does not require fissile material, it has very simple target shapes and compositions, it is only sensitive to absorption and scattering of target medium, and that well conducted experiments have uncertainties of 0.1% - 0.5%. The presentation concludes by examining PNDA’s advantages and its role in nuclear data validations as it offers a cost-effective experiment for an integral benchmark, it provides the ability to focus on specific cross section data validation including thermal neutron absorption and thermal scattering laws, and the low experimental uncertainty makes it an excellent benchmark candidate. Additionally, it is easily tunable and can facilitate temperature dependent cross section validation by cooling or heating up targets.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

IER 441: Experiments to Measure the Effect of Tantalum on Critical Systems (SNL/ORNL) [Slides]

This presentation provides information on the experiments to measure the effect of Tantalum (Ta) on critical systems. This talk presents details on the Sandia Critical Experiments Program with the Seven Percent Critical Experiment (7uPCX) and the Burnup Credit Critical Experiment (BUCCX). The presentation highlights motivations, experiment design, and evaluations and publications.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

IER-523: Design of a UO 2 -BeO Critical Experiment at Sandia [Slides]

This lecture is on the design of a Uranium Dioxide-Beryllium Oxide UO 2 -BeO Critical Experiment at Sandia. This presentation provides background info on the Annular Core Research Reactor (ACRR). Additionally, this presentation shows experimental and alternative designs and concludes with a sensitivity analysis.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

IER305: Molybdenum Sleeve Experiments in the Sandia Critical Experiments Facility [Slides]

This presentation is on the Molybdenum (Mo) sleeve experiments at the Sandia Critical Experiments Facility. The Institut de Radioprotection et de Sûreté Nucléaire (IRSN) performed the preliminary design of the experiment. IRSN performed the final nuclear design of the experiment. Sandia performed the detailed design of the experiment to make it work in the critical assembly and Sandia also oversaw the fabrication and installation of the hardware. The slides include cutaway and overall views and a look into the results.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Preliminary Design of Critical Experiments Involving Commercially Available B 4 C Neutron Absorber Plates with Low-Enriched UO 2 Fuel [Slides]

Conclusions of this presentation conclude that the experiment is feasible with at least 10 critical configurations, and low expected benchmark uncertainty. Potential high impact for the understanding of commercially used neutron absorber plates. Next steps are to think about other configurations: rod pitch, other rods – Finalize plate support, uncertainty study. Additionally, the potential use of IER-441 central test region to safely place the plate in the core. Next steps include the Determination of the neutron absorber plate characterization path and the Potential SINBAD benchmark of neutron transmission measurements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Design of UO 2 -BeO Critical Experiment at Sandia [Poster]

The purpose of this proposal is to design a new integral critical experiment to investigate the effects of beryllium oxide and high assay low-enriched uranium fuels. this proposal considers using several existing resources at Sandia: (1) the Critical Experiments (SCX) facility and water tank, (2) spare UO 2 -BeO fuel for the Annular Core Research Reactor (ACRR), and 7uPCX fuel rods from previous benchmark experiments.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

IER-479/547: Low-Temperature TEX Final Design and Surrogate Measurements [Slides]

This presentation covers the final design, and measurements of the Low-Temperature TEX. Visual Diagrams of the apparatus and detailed part explanations are included. Neutronic calculations for Low-Temperature TEX was performed. Six configurations were proposed. Thermal analysis for the boundary cases was performed. Thermal testing with surrogate materials has been underway and testing will resume shortly.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Neutron Absorber Plate Characterization Plan for Criticality Experiments Design [Slides]

The goal of this presentation is to show the feasibility of performing a critical experiment with a B 4 C/Aluminum alloy neutron absorber plate. The motivation of this experiment is to provide integral data on modern neutron absorber product “Boralcan” by Rio Tinto. In 2020, used in about 20% of spent fuel pools in the US, and in casks for storage and transportation in the US and in Europe. The added value of this experiment: Neutron absorber plate modeling method verification: homogeneous or not, a lot of potential savings by relaxing boron loading credit limits. No available critical benchmark involving Boralcan, other boron-related experiments are relatively old. Nuclear data validation for B, C, and Al in the form of B 4 C in Al matrix.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Godiva IV Shielding Benchmark Overview [Slides]

This presentation shows that Integral experiments increase the level of realism from that of data measurements. Further, Godiva IV is capable of intensities to activate foils. IER 498 uses a relative measurement to provide an intermediate level of realism. With reproducibility and room return management are key components. The test matrix put forward in CED-2 enables numerous cross-comparisons. IER 498 facilitates various additional works using a room return shield to isolate the source. IER 557 demonstrated burst reproducibility sufficient for IER 498.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗