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At least 1,441 records · Page 80
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Experiments with HEU (93.14 wt.%) metal annuli with internal graphite cylinder

A variety of critical experiments were constructed of enriched uranium metal (oralloy ) during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, only three experimental configurations are described here. They are internal graphite reflected metal uranium assemblies with three different diameter HEU annuli (15-9 inches, 15-7 inches and 13-7 inches). These experiments can be found in Reference 1 and in their associated logbook

36 MATERIALS SCIENCE↗
DOE OSTI2017

Final Report: Archiving Data to Support Data Synthesis of DOE Sponsored Elevated CO 2 Experiments

Over the last three decades DOE made a large investment in field-scale experiments in order to understand the role of terrestrial ecosystems in the global carbon cycle, and forecast how carbon cycling will change over the next century. The Smithsonian Environmental Research Center received one of the first awards in this program and managed two long-term studies (25 years and 10 years) with a total of approximately $10 million of support from DOE, and many more millions leveraged from the Smithsonian Institution and agencies such as NSF. The present DOE grant was based on the premise that such a large investment demands a proper synthesis effort so that the full potential of these experiments are realized through data analysis and modeling. The goal of the this grant was to archive legacy data from two major elevated carbon dioxide experiments in DOE databases, and to engage in synthesis activities using these data. Both goals were met. All datasets deemed a high priority for data synthesis and modeling were prepared for archiving and analysis. Many of these datasets were deposited in DOE’s CDIAC, while others are being held at the Oak Ridge National Lab and the Smithsonian Institution until they can be received by DOE’s new ESS-DIVE system at Berkeley Lab. Most of the effort was invested in researching and re-constituting high-quality data sets from a 30-year elevated CO 2 experiment. Using these data, the grant produced products that are already benefiting climate change science, including the publication of new coastal wetland allometry equations based on 9,771 observations, public posting of dozens of datasets, metadata and supporting codes from long-term experiments at the Global Change Research Wetland, and publication of two synthetic data papers on scrub oak forest responses to elevated CO 2 . In addition, three papers are in review or nearing submission reporting unexpected long-term patterns in ecosystem responses to elevated CO 2 and nitrogen in a coastal wetland.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Experiments on Material Differentiation

In the initial LCP proposal it was expected that experiments on material differentiation would be performed as one of the tasks in FY14. Due to funding being lower than projected, these experiments were put on hold for FY14 but initial planning for future experiments was performed. In parallel with this task, Task 3 continued work on improving the capabilities for correlating muons with secondary particles such as gammas or neutrons. Potential facilities for future experiments were identified and ROM costs were determined. By establishing communications early, this will facilitate a more efficient movement into experimental facilities in the future. The primary component of the planning was to identify possible locations for the experiments along with ROM estimates for use of these facilities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Determination of the Kinematics of the Qweak Experiment and Investigation of an Atomic Hydrogen Moller Polarimeter

The Q weak experiment has tested the Standard Model through making a precise measurement of the weak charge of the proton ($Q^p_W$). This was done through measuring the parity-violating asymmetry for polarized electrons scattering off of unpolarized protons. The parity-violating asymmetry measured is directly proportional to the four-momentum transfer ($Q^2$) from the electron to the proton. The extraction of $Q^p_W$ from the measured asymmetry requires a precise $Q^2$ determination. The Q weak experiment had a $Q^2$ = 24.8 ± 0.1 m(GeV 2 ) which achieved the goal of an uncertainty of <= 0.5%. From the measured asymmetry and $Q^2$, $Q^p_W$ was determined to be 0.0719 ± 0.0045, which is in good agreement with the Standard Model prediction. This puts a 7.5 TeV lower limit on possible "new physics". This dissertation describes the analysis of Q^2 for the Q weak experiment. Future parity-violating electron scattering experiments similar to the Q weak experiment will measure asymmetries to high precision in order to test the Standard Model. These measurements will require the beam polarization to be measured to sub-0.5% precision. Presently the electron beam polarization is measured through Moller scattering off of a ferromagnetic foil or through using Compton scattering, both of which can have issues reaching this precision. A novel Atomic Hydrogen Moller Polarimeter has been proposed as a non-invasive way to measure the polarization of an electron beam via Moller scattering off of polarized monatomic hydrogen gas. This dissertation describes the development and initial analysis of a Monte Carlo simulation of an Atomic Hydrogen Moller Polarimeter.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Simulations of Two Heavily Confined PBX 9502 Cook-off Experiments.

Finite element models of two cook-off experiments were constructed using the Aria code.These experiments provided thermocouple measurements that were used as boundary conditions to carry out finite element (FE) simulations and comparisons of the FE thermal response with internal temperature measurements in the PBX 9502. These FE models contain a pressure dependent PBX 9502 thermal decomposition model developed by Hobbs’ et al.. Comparisons of the FE results and the experiments are presented. These comparisons assess the predictive capabilities of Hobbs’ model under the experimental conditions. Limiting cases of the PBX 9502 decomposition model are considered. Two parameterizations associated with the pressure dependency of the PBX 9502 decomposition model were carried out to fit the experiments using internal temperature measurements. Two inverse heat conduction problems were implemented to estimate temperatures as functions of time at locations on the outer surface of the PBX 9502. Thermocouple conduction error studies were carried out to assess the comparisons of the FE model thermal response with the experiments.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2016

Long Baseline Neutrino Experiment (LBNE) Target Material Radiation Damage from Energetic Protons of the Brookhaven Linear Isotope Production (BLIP) Facility

In search of a low-Z pion production target for the Long Baseline Neutrino Facility (LBNF) of the Deep Underground Neutrino Experiment (DUNE) various grades of graphite were irradiated with 140-180 MeV protons to fluence up to ~6 10 20 cm -2 and irradiation temperatures in the range of 100-200oC. The objective of the irradiation experiment was to assess the radiation induced changes in the graphite onset by its interaction with energetic protons and deduce some measure of performance and survivability under the design conditions of LBNF. A multi-faceted post-irradiation evaluation was conducted to both qualify and quantify the induced material property changes. These studies included dimensional stability and thermal expansion, damage annealing via thermal cycling, high temperature post-irradiation annealing to mimic irradiation at elevated temperatures, stress-strain behavior, oxidation contribution to the postirradiation analysis, potential influence of the argon atmosphere under which irradiation took place, and lattice evolution. Dilatometry-based techniques were coupled with ultrasound-based annealing methodologies as well as DSC and TGA analyses. X-ray diffraction experiments assessed the lattice parameter changes and SEM analyses were used to study the different graphite grade structures. The multi-faceted post-irradiation evaluation, in conjunction with off-beam analyses, revealed some important facts regarding the choice of a graphite grade. Specifically, it was observed that the microstructure of a grade plays an important role in its dimensional stability. X-ray diffraction data indicated variability in basal plane spacing prior to irradiation with POCO d 002 =3.3833 Å, IG-430 d 002 =3.36814 Å and R7650 d 002 =3.37944 Å. Isotropic graphite grades such as POCO and IG-430 are confirmed to undergo microstructural shrinking under irradiation. All four irradiated graphite grades experience irradiation-induced creep leading to increased Young’s modulus with changes as high as 50% that varies with microstructure. X-ray diffraction on irradiated graphite confirmed previously made observations where under both energetic protons as well as fast neutrons of fluence > 5 10 20 cm -2 and at temperatures around 200°C acceleration of the effects on both the micro-and macrostructure is observed. Amongst the irradiated grades POCO graphite showed tendency to increase crystallinity order but also shows turbostratic state resulting from the interaction of its lattice with protons. This report presents and discusses the details of the irradiation experiment and the results of the postirradiation evaluation with main objective the assessment of the applicability and survivability of the selected four graphite grades as high-power accelerators pion production targets where the structural integrity, density reduction, dimensional and physical property stability are of paramount importance.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Current Loss in 0.1 - 100 Terawatt Vacuum Transmission Lines: Experiments and Simulations

Current loss in magnetically insulated transmission lines (MITLs) was investigated using data from experiments conducted on Z and Mykonos. Data from experiments conducted on Z were used to optimize an ion diode current loss model that has been implemented into the transmission line circuit model of Z. Details on the current loss model and comparisons to data from Z experiments have been previously published in a peer-reviewed journal [Hutsel, et al., Phys. Rev. Accel. Beams 21, 030401]. Dedicated power flow experiments conducted on Mykonos investigated current loss in a millimeter-scale anode-cathode gap MITL operated at lineal current densities greater than 410 kA/cm and with electric field stresses in excess of 240 kV/cm where it is expected that both anode and cathode plasmas are formed. The experiment MITLs were exposed to varying vacuum conditions; including vacuum pressure at shot time, time under vacuum, and vacuum storage protocols. The results indicate that the vacuum conditions have an effect on current loss in high lineal current density MITLs.

42 ENGINEERING↗
DOE OSTI2018

IER 489: Critical Unresolved Region Integral Experiment (CURIE) CEDT Phase-2 Final Design

The final design for the CURIE integral benchmark experiment is presented in this report. Measurements will be performed on the Comet vertical assembly machine and include various critical configurations consisting of High Enriched Uranium (HEU) metal plates and Teflon moderator plates surrounded by a thick copper reflector. The various configurations with different Teflon plate thickness planned allow for complimentary measurements with differing nuclear data sensitivity in the Unresolved Resonance Region (URR). Similar to previously performed Zeus experiments, the proposed work will serve to validate vital nuclear data quantities and uncertainties and identify deficiencies in current radiation transport codes. Additionally, it will assess the applicability of optimization approaches to nuclear critical experiment design. The final experiment design is detailed in this report and includes design, optimization, uncertainty and continuous-energy nuclear data sensitivity analysis for the final experimental configurations that will provide the basis for a future benchmark evaluation intended for submission to the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook [1]. This document discusses the method, approach, considerations and final design chosen with conclusions. It also includes cost and schedule. The basis and principles of this document come from the preliminary design report [2]. Section 2 discusses the content and potential impact; section 3 gives an overview of the nuclear data and unresolved resonance region; section 4 gives a summary of the work done during the preliminary design; section 5 discusses the machine learning method and principles used for final design; section 6 summaries the results from final design; section 7 provides conclusions and the range of configurations chosen to carry forward to experiment execution; and section 8 includes a summary of costs.

42 ENGINEERING↗
DOE OSTI2018

Search for Dark Matter with the LZ Experiment

Overwhelming evidence from astrophysical observations indicates that only 20% of the matter in the universe consists of ordinary matter, while the remaining 80% is made of some form of matter called "dark matter''. Although these indirect astrophysical observations convince us that dark matter exists, dark matter has not yet been directly observed. The standard model of particle physics, which has been very successful in explaining the properties of ordinary matter, can neither explain dark matter's presence nor its properties. The discovery and identification of dark matter would have a profound impact on cosmology, astronomy, and particle physics. A leading dark matter candidate consistent with all astrophysical data is a weakly interacting massive particle (WIMP). WIMPs could be detected through their interactions with atomic nuclei in specially designed detectors. Since the collision rates are expected to be very small (a few collisions per year for a 1-ton detector), large detectors with low backgrounds and excellent detection capability for rare collisions are needed to gain knowledge of the nature of dark matter. With dark matter experiments such as the LZ experiment, we are in a position to detect and study this dark matter through sensitive terrestrial direct detection experiments. If no discovery is made with LZ, it will be very difficult to reconcile the sensitivity limit of this experiment with most conventional WIMP scenarios, and alternate paradigms will have to be strongly considered for dark matter. The main focus of the U-M dark matter group over the past two years was on design validation and fabrication for the LZ project, followed by commissioning and operation of the LZ dark matter experiment, and the analysis of the science data during the following funding cycle. The U-M dark matter group had identified two key areas to contribute to the LZ project: the design and fabrication of a radon removal element for the xenon circulation system, and the execution and coordination of prototyping and design validation performed by the small xenon chamber group.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Progress and Improvements on Temperature Measurements for Dynamic and Advanced Certification Materials Experiments on Z

Temperature measurements are very important in shock and ramp type dynamic materials experiments. In particular, accurate temperature measurements can provide stringent additional constraints on determining the equation of state for materials at high pressure. The key to providing these constraints is to develop diagnostic techniques that can determine the temperature with sufficient accuracy. To enable such measurements, we are working to improve our diagnostic capability with three separate techniques, each of which has specific applicability in a particular temperature range. To improve our capability at low temperatures (< 1 eV) we are working on a technique that takes advantage of the change in reflectivity of Au as the temperature is increased. This is most applicable to ramp type experiments. In the intermediate range (~1 eV < T< 5-10 eV) we are improving our optical pyrometry diagnostic by adding the capability of doing an absolute calibration as part of the diagnostic procedure for the shock or shock ramp dynamic materials experiment. This will enable more accurate temperature measurements for shock and shock ramp type experiments. For higher temperatures that occur in very high-pressure shock experiments, above 10 eV, we are developing the capability of doing x-ray Thomson scattering measurements. Such measurements will enable us to characterize strongly shocked or warm dense matter materials. Work on these diagnostic approaches is summarized in this report.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The FIFE Project: Supporting Non-LHC Experiments at Fermilab [PowerPoint]

FabrIc for Frontier Experiments (FIFE) standardizes computing framework for non-LHC FNAL experiments and offers a robust, shared, and modular set of tools for experiments. The FIFE project provides a valuable service for FNAL non-LHC experiments and makes life much easier for those on multiple experiments. Plans include increasing containerization and transition to other. Following existing approaches saves time and effort and enables easy international cooperation. We are eagerly seeking common approaches as widely as possible in future projects (Rucio, HPC, IRIS_HEP, etc.).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Shortening the Design and Certification Cycle for Additively Manufactured Materials by Improved Mesoscale Simulations and Validation Experiments: Fiscal Year 2019 Status Report.

This report outlines the fiscal year (FY) 2019 status of an ongoing multi-year effort to develop a general, microstructurally-aware, continuum-level model for representing the dynamic response of material with complex microstructures. This work has focused on accurately representing the response of both conventionally wrought processed and additively manufactured (AM) 304L stainless steel (SS) as a test case. Additive manufacturing, or 3D printing, is an emerging technology capable of enabling shortened design and certification cycles for stockpile components through rapid prototyping. However, there is not an understanding of how the complex and unique microstructures of AM materials affect their mechanical response at high strain rates. To achieve our project goal, an upscaling technique was developed to bridge the gap between the microstructural and continuum scales to represent AM microstructures on a Finite Element (FE) mesh. This process involves the simulations of the additive process using the Sandia developed kinetic Monte Carlo (KMC) code SPPARKS. These SPPARKS microstructures are characterized using clustering algorithms from machine learning and used to populate the quadrature points of a FE mesh. Additionally, a spall kinetic model (SKM) was developed to more accurately represent the dynamic failure of AM materials. Validation experiments were performed using both pulsed power machines and projectile launchers. These experiments have provided equation of state (EOS) and flow strength measurements of both wrought and AM 304L SS to above Mbar pressures. In some experiments, multi-point interferometry was used to quantify the variation is observed material response of the AM 304L SS. Analysis of these experiments is ongoing, but preliminary comparisons of our upscaling technique and SKM to experimental data were performed as a validation exercise. Moving forward, this project will advance and further validate our computational framework, using advanced theory and additional high-fidelity experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Baseline Postirradiation Examination of the FUTURIX-FTA Experiments

Postirradiation Examination (PIE) results from the baseline examination of the FUTURIX-FTA irradiation experiment are presented in this report. The FUTURIX-FTA irradiation was designed to study the fuel performance of candidate transmutation fuels. The FUTURIX-FTA experiment was conducted in the true fast neutron spectrum conditions of the Phénix sodium fast test reactor in France. FUTURIX-FTA contained several compositions that were also irradiated as part of the AFC-1 test in cadmium filtered positions in the Idaho National Laboratory (INL) Advanced Test Reactor (ATR) that approximate the neutron spectrum of a fast reactor. This experiment was a joint collaboration between the Department of Energy (DOE) in the U.S. and the Commissariat á l'Energie Atomique et aux Energies Alternatives (CEA) in France. A joint agreement between DOE and CEA was established in 2004 to conduct an irradiation experiment of metallic and nitride fuels in the Phénix reactor at CEA. Both the FUTURIX-FTA tests and the AFC-1 tests were conducted for the DOE Advanced Fuels Campaign (AFC) that is part of Fuel Cycle Research & Development (FCRD) program. These programs seek to develop and demonstrate the technologies needed to transmute long-lived transuranic actinide isotopes contained in spent nuclear fuel via fast reactor technology. The long term goal of this work is to reduce the radiotoxicity of future high level waste repositories. Post-irradiation examination of irradiated fuels experiments provides data related to in reactor fuel performance and input into future fuel design choices. The compositions of the FUTURIX-FTA pins were designed to test if minor actinides could be incorporated into the fuel of a fast reactor without significantly changing fuel performance observed for previously well studied fuels. The fuel performance of metallic fuel in fast reactors has been well documented. Likewise the irradiation performance of nitride fuels in fast reactors has also been documented. However the existing database for nitride fuels is much smaller than the database for metal fuels.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

CISME report on experiments with HMX powder, PBX 9501 prills, and heated PBX 9501

The ability to predict post-ignition explosive response is relevant to explosives safety, particularly weapons assembly/disassembly operations that must operate under a sufficiently conservative safety basis to meet risk mitigation criteria for inadvertent nuclear detonation (IND). In particular, hazard determinations hinge on whether the PBX 9501 main charge can ultimately attain detonation from an initial, non-shock, ignition stimulus. The CISME experiment uses a spherical explosive charge, which is thermally ignited in the center using a fiber-delivered infrared laser pulse. This ignition mechanism - i.e. a localized thermal hotspot - is representative of the ignition-causing insults typical in accident scenarios, including low-velocity impact, drop, skid, and punch events. In fiscal year 2018 CISME experiments were conducted with pristine PBX 9501 spheres, confined and unconfined. Sub-detonative, low-violence reactions were observed. Here we report experiments conducted since 2018. The explosive charge was varied: experiments were conducted with room temperature pour-density HMX powder and prills of PBX 9501, and heated, thermally damaged PBX 9501. Experiments were conducted in a confined configuration, with two 4 mm-thick stainless-steel hemispherical shells bolted around the sphere. Detonation, via DDT (deflagration-to-detonation transition) was observed in the 3-inch diameter powdered HMX and the 6-inch diameter heated and thermally-damaged PBX 9501 tests. No transition to DDT was observed in smaller diameters for those configurations, and no DDT was observed for pour-density prills of PBX 9501 of any diameter. The original test series demonstrated that the response of pristine, undamaged PBX 9501 to a central ignition is relatively benign. This new test series shows that increased porosity, lack of polymer binders and thermal damage can greatly increase the violence of the post-ignition response, up to and including detonation. These results bridge the explosive response of PBX 9501 from sub-detonative through detonation as a function of diameter and provide valuable test cases for modeling efforts that strive to capture the DDT threshold. By exploring explosive response in a more representative 3D geometry, we can also benchmark these new results to more plentiful DDT datasets generated from testing in 1D tube confinement (the historical test configuration)–the configuration upon which almost all DDT models were developed.

42 ENGINEERING↗
DOE OSTI2020

Long-baseline Sterile Neutrino Searches in the NOvA Experiment

Experimental high energy physics constitutes the experimental investigation of the fundamental building blocks of matter and radiation and their interactions. These fundamental building blocks are classified as bosons and fermions. Neutrinos are fermions that come under the lepton category. According to the Standard Model of particle physics, they are massless, neutral particles that interacts with matter only through weak force and comes in three different flavors. Neutrinos exhibit a characteristic property, known as the neutrino oscillation. Neutrino oscillation is the the change of neutrino from one flavor to another flavor as they propagates in space. This phenomenon is only possible if the neutrinos are massive. The reported anomalous result from LSND and MiniBooNE experiments demanded the existence of a fourth kind of neutrino, at the same time, LEP experimental result confirms that only three active neutrino can exist. So if they exists, this fourth kind of neutrino can’t interact through weak force or they can be called as sterile neutrino. Some of the experiments favored the existence of sterile neutrinos, at the same time, there are some other experiments that disfavors their existence. So the search for the sterile neutrinos is very active in the field of experimental neutrino physics. NOvA is a long-baseline experiment with two functionally identical detectors, a Near Detector (ND) at Fermilab and a Far Detector at Ash River, Minnesota which is 810 km far away from the ND. They are offaxis detectors that lie 14.6 mrad off from the beam axis. This enables the detector to receive a neutrino beam with energy peak at 2 GeV. The NOvA experiment is designed to run with both the neutrino beam and antineutrino beam and NOvA has the potential to search for the existence of sterile neutrinos. This thesis is based on the sterile neutrino search by looking at the depletion of the neutral-current (NC) energy spectrum of neutrinos at the FD. Since NC events are not sensitive to three flavor oscillation, any depletion of NC events at the FD indicates the existence of sterile neutrinos.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Laser Network US Experiments at the University of Texas at Austin

Under Subcontract B638654, The University of Texas at Austin (UT Austin) Center for High Energy Density Science supported three Laser Network US experiments and conducted upgrade planning for the Texas Petawatt Laser Facility. For the experiment “Investigation of the physics of MeV X-ray and particle generation using Compound Parabolic Concentrators” led by Dr. Andrew Mackinnon of Lawrence Livermore National Laboratory, UT Austin provided postdoctoral associate support in the person of Dr. Ganesh Tiwari. For the experiments “Megatesla magnetic fields and enhanced gamma-ray beam generation” led by Hans Rinderknecht of LLE, University of Rochester (experiment) and Alexey Arefiev of UC San Diego (theory) and “High resolution imaging of resonately accelerated electrons under tight focusing” led by Deepak Kumar of ELI-Beamlines, Czech Republic, UT Austin provided the Texas Petawatt Laser staff and a prorated share of the materials and supplies approximately equal to the average of those required for one 5-week experimental campaign. Summaries of these three experiments are provided in this report. Two staff members were hired—Dr. Sandra Bruce at 40% and Dr. Erhard Gaul at 50% time—to support Texas Petawatt Laser maintenance and operations and to plan for the Texas Relativistic Intensity Ultrafast Multi-beam Plasma Facility (TRIUMPF).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Real-time data reduction at 100 Tbps: Challenge and opportunity for AI-based data reduction for next-generation large-scale nuclear physics collider experiment

The modern large-scale nuclear physics (NP) experiments in high-energy particle colliders utilize streaming-readout electronics to digitize detector response at O(100) Tbps bandwidth. Prominent examples at Brookhaven National Lab (BNL) include the sPHENIX experiment at Relativistic Heavy Ion Collider (RHIC), which is under construction, and the experiments proposed for the Electron-Ion Collider (EIC), planned for the 2030s . One of the main challenges for these streaming readout systems is to manage the data rate with sufficient data reduction in real time so the end-data fit persistent storage for offline analysis, which is typically at O(1000) times smaller and O(100) Gbps. Such data reduction traditionally is achieved via real-time high level triggers, which select and save a small subset of collisions of interest. Although triggering is applicable to high energy collider experiments such as those at the Large Hardron Collider at CERN, it is insufficient for these nuclear physics experiments which study diverse collision topologies. And traditional triggering approach is inefficient to preserve the max information harvested from the operation of colliders that costs O(100)M per year to DOE. Meanwhile, in recent years, ML-based high-throughput data reduction has emerged as a promising approach to efficiently preserve max information for a given space of persistent storage, e.g. via AI data compression, feature extraction, and noise filtering.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Uranium–Molybdenum Alloy Critical Experiments for the Design of the Health Physics Research Reactor

Clean critical experiments with a uranium-molybdenum alloy (average of 10.1616 wt. % Mo with a density of 17.08 g/cm 3 ) were performed at the Oak Ridge Critical Experiments Facility in 1961 to support the design of the Health Physics Research Reactor (HPRR). The HPRR was similar to the Godiva burst reactor at Los Alamos National Laboratory and was designed to produce 50 microseconds burst of 10 17 fission pulses of radiation for dosimetry measurements, initially in support of the determination of the doses from the nuclear detonations in Japan during World War II. These experiments reported here were used to verify the calculational methods used to design the HPRR. These delayed critical measurements were:1) a solid unreflected and unmoderated 8-in.-dimeter U-Mo cylinder, 2) an unmoderated and unreflected annulus with 8-in.-outside diameter, 2-in.-inside diameter cylinder with a central void, 3) an unmoderated and unreflected annulus with 8-in.-outside diameter, 2-in.-inside diameter cylinder with a central void filled with stainless steel, 4) Same as 3) but with 3-in-thick Plexiglas reflector on top with and without cadmium between the reflector and the U-Mo alloy assembly with steel in the center, and 5) an unmoderated and unreflected annulus which was a modification of the second but with the lower 5 inches of the central hole enlarged to 3.5 in. with various reflector conditions. The reflector conditions were: 1-in.-thick Plexiglas on all outer surfaces-void in the center; 1-in.-thick Plexiglas on all outer surfaces-Plexiglas in the center; 2-in.- thick Plexiglas on radial surface-void in the center; 6-in.-thick Plexiglas on the bottom only-Plexiglas in the center; and 6-in.-thick Plexiglas on bottom, 1-in.-thick on top and on the lower 8.25-cm.-section of the radial surface-void in the center. For some of these reflector conditions 0.025-cm.thick cadmium was located between the reflector and the U-Mo alloy. The uranium contained 93.17 wt. % 235 U. Reflection was a safety concern for this unmoderated and unreflected reactor and reduction of reflection effects was also investigated by insertion of neutron absorber around the U-Mo alloy. The stainless steel 304 contained 18% nickel and 8% chromium and the rest iron. The reflector material was a methacrylate plastic (Plexiglas) containing 5.8 x 10 22 atoms/cm 3 of hydrogen and 3.6 x 10 22 atoms/cm 3 of carbon with a density of 1.20 g/cm 3 . The purpose of this report is to document the experimental information for the measurements performed so that at a later date researchers could perform the required uncertainty and calculational analyses and documentation to use these data for an International Nuclear Criticality Safety Benchmark Program (ICSBEP) or a EURATON Nuclear Energy Agency (NEA) benchmark. The data from the experiments described should be acceptable for use as criticality safety benchmark experiments for the ICSBEP and the NEA nuclear criticality safety benchmark program, once the uncertainty analysis is completed. Based on previous ICSBEP benchmarks with this enriched uranium metal at ORCEF, the uncertainties in k eff could be as low as ±0.0002 for some configurations.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗