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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Design and R&D of RICH detectors for EIC experiments

An Electron-Ion Collider (EIC) has been proposed to further explore the strong force and QCD, focusing on the structure and the interaction of gluon-dominated matter. A generic detector R& D program (EIC PID consortium) for the particle identification in EIC experiments was formed to explore technologically advanced solutions in this scope. In this context two Ring Imaging Cherenkov (RICH) counters have been proposed: a modular RICH detector which consists of an aerogel radiator, a Fresnel lens, a mirrored box, and pixelated photon sensor; a dual-radiator RICH, consisting of an aerogel radiator and C 2 F 6 gas in a mirror-focused configuration. We present the simulations of the two detectors and their estimated performance.

electron-ion collider↗
DOE OSTI2019

Energies and transition parameters of fusion interest in Cr-like ions between Hf XLIX and Au LVI

Using fully relativistic multiconfiguration Dirac–Fock (MCDF) wavefunctions in an active space approximation, we perform systematic calculations of the energies, wavelengths, and lifetimes for the lowest 143 levels belonging to the 3p{sup 6}3d{sup 6} and 3p{sup 5}3d{sup 7} configurations of Cr-like ions between Hf XLIX and Au LVI. Additionally, line strengths, oscillator strengths, and radiative rates for the electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among these levels are reported. In the calculations, the contributions from Breit interaction (BI) and quantum electrodynamics (QED) corrections to the wave functions are taken into account (the addition of the BI and QED in CI affects both the wave functions and the level energies). For some excited states, there are no other theoretical and/or experimental data to compare with to illustrate the quality of our results/assess the accuracy. A similar calculation has been performed with the Flexible Atomic Code (FAC), using W LI as an example. The results obtained in this work are compared with the data compiled in the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST) and other available theoretical/experimental information. Satisfactory agreement is found between them. The energies agree within 0.8% with the experimental results, and the M1 transition rates agree within 5% with other theoretical results. The present results are more extensive than those from previous calculations and considerably expand the existing data sets for Cr-like ions. This study should be beneficial for the analysis of experimental spectra and modeling of fusion plasmas.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

SU-E-T-304: Study of Secondary Neutrons From Uniform Scanning Proton Beams

Purpose: Secondary neutrons are unwanted byproducts from proton therapy and exposure from secondary radiation during treatment could increase risk of developing a secondary cancer later in a patient's lifetime. The purpose of this study is to investigate secondary neutrons from uniform scanning proton beams under various beam conditions using both measurements and Monte Carlo simulations. Methods: CR-39 Plastic Track Nuclear Detectors (PNTD) were used for the measurement. CR-39 PNTD has tissue like sensitivity to the secondary neutrons but insensitive to the therapeutic protons. In this study, we devised two experimental conditions: a) hollow-phantom; phantom is bored with a hollow cylinder along the direction of the beam so that the primary proton passes through the phantom without interacting with the phantom material, b) cylindrical-phantom; a solid cylinder of diameter close to the beam diameter is placed along the beam path. CR-39 PNTDs were placed laterally inside a 60X20X35 cm3 phantom (hollow-phantom) and in air (cylindrical-phantom) at various angles with respect to the primary beam axis. We studied for three different proton energies (78 MeV, 162 MeV and 226 MeV), using a 4 cm modulation width and 5cm diameter brass aperture for the entire experiment and simulation. A comparison of the experiment was performed using the Monte Carlo code FLUKA. Results: The measured secondary neutron dose equivalent per therapeutic primary proton dose (H/D) ranges from 2.1 ± 0.2 to 25.42 ± 2.3 mSv/Gy for the hollow phantom study, and 2.7 ± 0.3 to 46.4 ± 3.4 mSv/Gy for the cylindrical phantom study. Monte Carlo simulations predicated neutron dose equivalent from measurements within a factor of 5. Conclusion: The study suggests that the production of external neutrons is significantly higher than the production of internal neutrons.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2012

The effects of temperatures on the pebble flow in a pebble bed high temperature reactor

The core of a pebble bed high temperature reactor (PBHTR) moves during operation, a feature which leads to better fuel economy (online refueling with no burnable poisons) and lower fuel stress. The pebbles are loaded at the top and trickle to the bottom of the core after which the burnup of each is measured. The pebbles that are not fully burned are recirculated through the core until the target burnup is achieved. The flow pattern of the pebbles through the core is of importance for core simulations because it couples the burnup distribution to the core temperature and power profiles, especially in cores with two or more radial burnup 'zones '. The pebble velocity profile is a strong function of the core geometry and the friction between the pebbles and the surrounding structures (other pebbles or graphite reflector blocks). The friction coefficient for graphite in a helium environment is inversely related to the temperature. The Thorium High Temperature Reactor (THTR) operated in Germany between 1983 and 1989. It featured a two-zone core, an inner core (IC) and outer core (OC), with different fuel mixtures loaded in each zone. The rate at which the IC was refueled relative to the OC in THTR was designed to be 0.56. During its operation, however, this ratio was measured to be 0.76, suggesting the pebbles in the inner core traveled faster than expected. It has been postulated that the positive feedback effect between inner core temperature, burnup, and pebble flow was underestimated in THTR. Because of the power shape, the center of the core in a typical cylindrical PBHTR operates at a higher temperature than the region next to the side reflector. The friction between pebbles in the IC is lower than that in the OC, perhaps causing a higher relative flow rate and lower average burnup, which in turn yield a higher local power density. Furthermore, the pebbles in the center region have higher velocities than the pebbles next to the side reflector due to the interaction between the pebbles and the immobile graphite reflector as well as the geometry of the discharge conus near the bottom of the core. In this paper, the coupling between the temperature profile and the pebble flow dynamics was analyzed by using PEBBED/THERMIX and PEBBLES codes by modeling the HTR-10 reactor in China. Two extreme and opposing velocity profiles are used as a starting point for the iterations. The PEBBED/THERMIX code is used to calculate the burnup, power and temperature profiles with one of the velocity profiles as input. The resulting temperature profile is then passed to PEBBLES code to calculate the updated pebble velocity profile taking the new temperature profile into account. If the aforementioned hypothesis is correct, the strong temperature effect upon the friction coefficients would cause the two cases to converge to different final velocity and temperature profiles. The results of this analysis indicates that a single zone pebble bed core is self-stabilizing in terms of the pebble velocity profile and the effect of the temperature profile on the pebble flow is insignificant. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2015

“Plug-and-Play” potentials: Investigating quantum effects in (H{sub 2}){sub 2}–Li{sup +}–benzene

Quantum and anharmonic effects are investigated in (H{sub 2}){sub 2}–Li{sup +}–benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials, using rigid-body diffusion Monte Carlo (RBDMC) simulations. The potential-energy surface (PES) is calculated as a modified Shepard interpolation of M05-2X/6-311+G(2df,p) electronic structure data. The RBDMC simulations yield zero-point energies (ZPE) and probability density histograms that describe the ground-state nuclear wavefunction. Binding a second H{sub 2} molecule to the H{sub 2}–Li{sup +}–benzene complex increases the ZPE of the system by 5.6 kJ mol{sup −1} to 17.6 kJ mol{sup −1}. This ZPE is 42% of the total electronic binding energy of (H{sub 2}){sub 2}–Li{sup +}–benzene and cannot be neglected. Our best estimate of the 0 K binding enthalpy of the second H{sub 2} to H{sub 2}–Li{sup +}–benzene is 7.7 kJ mol{sup −1}, compared to 12.4 kJ mol{sup −1} for the first H{sub 2} molecule. Anharmonicity is found to be even more important when a second (and subsequent) H{sub 2} molecule is adsorbed; use of harmonic ZPEs results in significant error in the 0 K binding enthalpy. Probability density histograms reveal that the two H{sub 2} molecules are found at larger distance from the Li{sup +} ion and are more confined in the θ coordinate than in H{sub 2}–Li{sup +}–benzene. They also show that both H{sub 2} molecules are delocalized in the azimuthal coordinate, ϕ. That is, adding a second H{sub 2} molecule is insufficient to localize the wavefunction in ϕ. Two fragment-based (H{sub 2}){sub 2}–Li{sup +}–benzene PESs are developed. These use a modified Shepard interpolation for the Li{sup +}–benzene and H{sub 2}–Li{sup +}–benzene fragments, and either modified Shepard interpolation or a cubic spline to model the H{sub 2}–H{sub 2} interaction. Because of the neglect of three-body H{sub 2}, H{sub 2}, Li{sup +} terms, both fragment PESs lead to overbinding of the second H{sub 2} molecule by 1.5 kJ mol{sup −1}. Probability density histograms, however, indicate that the wavefunctions for the two H{sub 2} molecules are effectively identical on the “full” and fragment PESs. This suggests that the 1.5 kJ mol{sup −1} error is systematic over the regions of configuration space explored by our simulations. Notwithstanding this, modified Shepard interpolation of the weak H{sub 2}–H{sub 2} interaction is problematic and we obtain more accurate results, at considerably lower computational cost, using a cubic spline interpolation. Indeed, the ZPE of the fragment-with-spline PES is identical, within error, to the ZPE of the full PES. This fragmentation scheme therefore provides an accurate and inexpensive method to study higher hydrogen loading in this and similar systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Captain Electronics Technical Report

This report details the current layout of the electronics for the mini-CAPTAIN detector system, as well as the lessons learned during commissioning. We will present some electronics suggestions for future LArTPC systems. Mini-CAPTAIN is one of three detectors used in the Cryogenic Apparatus for Precision Tests of Argon Interactions with Neutrino (CAPTAIN) project at Los Alamos National Lab (LANL). The detector uses many of the same electronic components as current and developing LArTPC experiments. This includes the motherboards, service cards, amplifiers and ADC made by Brookhaven National Laboratory (BNL) and the front-end modules (FEM) made by Nevis Labs. The cold electronics performed well in both vacuum and cryogenic environments after months of exposure. Mini-CAPTAIN was tested with two liquid nitrogen and three liquid argon run cycles. The final testing was performed at the Weapons Neutron Research (WNR) facility at LANSCE. Mini-CAPTAIN was able to maintain a clean electrical signal through most of the test cycles. Most noise reduction was achieved with power source filtering and careful attention to the ground configuration. Direct oscilloscope probing on the front-end output provided the fastest analysis and correction of noise sources. Ground path assumptions and integrity were verified with frequent impedance checks. A high voltage break down event damaged some of the channels on the motherboards and a number of the wire decoupling capacitors. This temporarily introduced significant noise on the wire planes due to current leakage. The detector was taken apart and reassembled three times, with successful noise reduction after each activity. The current raw signal-to-noise ratio is 9 to 1.

42 ENGINEERING↗
NASA NTRS2010

Testing of Liquid Metal Components for Nuclear Surface Power Systems

The Early Flight Fission Test Facility (EFF-TF) was established by the Marshall Space Flight Center (MSFC) to provide a capability for performing hardware-directed activities to support multiple in-space nuclear reactor concepts by using a non-nuclear test methodology. This includes fabrication and testing at both the module/component level and near prototypic reactor configurations. The EFF-TF is currently supporting an effort to develop an affordable fission surface power (AFSP) system that could be deployed on the Lunar surface. The AFSP system is presently based on a pumped liquid metal-cooled (Sodium-Potassium eutectic, NaK-78) reactor design. This design was derived from the only fission system that the United States has deployed for space operation, the Systems for Nuclear Auxiliary Power (SNAP) 10A reactor, which was launched in 1965. Two prototypical components recently tested at MSFC were a pair of Stirling power conversion units that would be used in a reactor system to convert heat to electricity, and an annular linear induction pump (ALIP) that uses travelling electromagnetic fields to pump the liquid metal coolant through the reactor loop. First ever tests were conducted at MSFC to determine baseline performance of a pair of 1 kW Stirling convertors using NaK as the hot side working fluid. A special test rig was designed and constructed and testing was conducted inside a vacuum chamber at MSFC. This test rig delivered pumped NaK for the hot end temperature to the Stirlings and water as the working fluid on the cold end temperature. These test were conducted through a hot end temperature range between 400 to 550C in increments of 50 C and a cold end temperature range from 30 to 70 C in 20 C increments. Piston amplitudes were varied from 6 to 1 1mm in .5 mm increments. A maximum of 2240 Watts electric was produced at the design point of 550 hot end, 40 C cold end with a piston amplitude of 10.5mm. This power level was reached at a gross thermal efficiency of 28%. A baseline performance map was established for the pair of 1kW Stirling convertors. The performance data will then be used for design modification to the Stirling convertors. The ALIP tested at MSFC has no moving parts and no direct electrical connections to the liquid metal containing components. Pressure is developed by the interaction of the magnetic field produced by the stator and the current which flows as a result of the voltage induced in the liquid metal contained in the pump duct. Flow is controlled by variation of the voltage supplied to the pump windings. Under steady-state conditions, pump performance is measured for flow rates from 0.5-4.3 kg/s. The pressure rise developed by the pump to support these flow rates is roughly 5-65 kPa. The RMS input voltage (phase-to-phase voltage) ranges from 5-120 V, while the frequency can be varied arbitrarily up to 60 Hz. Performance is quantified at different loop temperature levels from 50 C up to 650 C, which is the peak operating temperature of the proposed AFSP reactor. The transient response of the pump is also evaluated to determine its behavior during startup and shut-down procedures.

Polzin, Kurt A.↗
DOE OSTI2015

In-situ temperature-controllable shear flow device for neutron scattering measurement—An example of aligned bicellar mixtures

We have designed and constructed a temperature-controllable shear flow cell for in-situ study on flow alignable systems. The device has been tested in the neutron diffraction and has the potential to be applied in the small angle neutron scattering configuration to characterize the nanostructures of the materials under flow. The required sample amount is as small as 1 ml. The shear rate on the sample is controlled by the flow rate produced by an external pump and can potentially vary from 0.11 to 3.8 × 10{sup 5} s{sup −1}. Both unidirectional and oscillational flows are achievable by the setting of the pump. The instrument is validated by using a lipid bicellar mixture, which yields non-alignable nanodisc-like bicelles at low T and shear-alignable membranes at high T. Using the shear cell, the bicellar membranes can be aligned at 31 °C under the flow with a shear rate of 11.11 s{sup −1}. Multiple high-order Bragg peaks are observed and the full width at half maximum of the “rocking curve” around the Bragg’s condition is found to be 3.5°–4.1°. It is noteworthy that a portion of the membranes remains aligned even after the flow stops. Detailed and comprehensive intensity correction for the rocking curve has been derived based on the finite rectangular sample geometry and the absorption of the neutrons as a function of sample angle [See supplementary material at http://dx.doi.org/10.1063/1.4908165 for the detailed derivation of the absorption correction]. The device offers a new capability to study the conformational or orientational anisotropy of the solvated macromolecules or aggregates induced by the hydrodynamic interaction in a flow field.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Magnetic dipole γ-ray strength functions in the crossover from spherical to deformed neodymium isotopes

We calculate the magnetic dipole $\gamma$-ray strength functions in a chain of even-mass neodymium isotopes $^{144-152}$Nd in the framework of the configuration-interaction (CI) shell model. We infer the strength function by applying the maximum entropy method (MEM) to the exact imaginary-time response function calculated with the shell-model Monte Carlo (SMMC) method. The success of the MEM depends on the choice of a good strength function as a prior distribution. We investigate two choices for the prior strength function: the static path approximation (SPA) and the quasiparticle random-phase approximation (QRPA). We find that the QRPA is a better approximation at low temperatures (i.e., near the ground state), while the SPA is a better choice at finite temperatures. We identify a low-energy enhancement (LEE) in the MEM deexcitation $M1$ strength functions of the even-mass neodymium isotopes and compare with recent experimental results for the total deexcitation $\gamma$-ray strength functions. The LEE is already seen in the SPA strength function but not in the QRPA strength function, indicating the importance of large-amplitude static fluctuations around the mean field in reproducing the LEE. Our method is currently the only one which can reproduce LEE in heavy open-shell nuclei where conventional CI shell model calculations are prohibited. With the onset of deformation as number of neutrons increases along the chain of neodymium isotopes, we observe that some of the LEE strength transfers to a low-energy excitation, which we interpret as a finite-temperature ``scissors'' mode. Here, we also observe a finite-temperature spin-flip mode.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

A modified detector concept for SuperCDMS: The HiZIP and its charge performance

SuperCDMS (Super Cryogenic Dark Matter Search) is a leading direct dark mat-ter search experiment which uses solid state detectors (Ge crystals) at milliKelvintemperatures to look for nuclear recoils caused by dark matter interactions in the de-tector. `Weakly Interacting Massive Particles' (WIMPs) are the most favoured darkmatter candidate particles. SuperCDMS, like many other direct dark matter searchexperiments, primarily looks for WIMPs. The measurement of both the ionizationand the lattice vibration (phonon) signals from an interaction in the detector allow itto discriminate against electron recoils which are the main source of background forWIMP detection.SuperCDMS currently operates about 9 kg of Ge detectors at the Soudan under-ground lab in northern Minnesota. In its next phase, SuperCDMS SNOLAB plansto use 100-200 kg of target mass (Ge) which would allow it to probe more of theinteresting and and as of yet unexplored parameter space for WIMPs predicted bytheoretical models. The SuperCDMS Queen's Test Facility is a detector test facilitywhich is intended to serve as detector testing and detector research and developmentpurposes for the SuperCDMS experiment.A modifed detector called the HiZIP (Half-iZIP), which is reduced in complex-ity in comparison to the currently used iZIP (interleaved Z-sensitive Ionization and Phonon mediated) detectors, is studied in this thesis. The HiZIP detector designalso serves to discriminate against background from multiple scatter events occurringclose to the surfaces in a single detector. Studies carried out to compare the surfaceevent leakage in the HiZIP detector using limited information from iZIP data takenat SuperCDMS test facility at UC Berkley produce a highly conservative upper limitof 5 out of 10,000 events at 90% condence level. This upper limit is the best amongmany different HiZIP congurations that were investigated and is comparable to theupper limit calculated for an HiZIP detector in the same way using the same data. Areal HiZIP device operated at the Queen's Test Facility produced an exposure lim-ited 90% upper limit of about 1 in 100 events for surface event leakage. The dataused in these studies contain true nuclear recoil events from cosmogenic and ambientneutrons. This background was not subtracted in the calculation of the upper limitsstated above and hence they are highly conservative.A surface event source was produced by depositing210Pbfrom radon exposureonto a copper plate. This source was then used to take data for a surface eventdiscrimination study of the HiZIP detector operated at the Queen's Test Facility.A study of the contribution of the noise from capacitive crosstalk between chargesensors in a HiZIP detector configuration was investigated, conrming the expectationthat no signicant drop in performance compared to an HiZIP is to be expected dueto this effect.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Two- and three-nucleon contact interactions and ground-state energies of light- and medium-mass nuclei

Classes of two-nucleon (2N) contact interactions are developed in configuration space at leading order (LO), next-to-leading order (NLO), and next-to-next-to-next-to-leading order (N3LO) by fitting the experimental singlet np scattering length and deuteron binding energy at LO, and np and pp scattering data in the laboratory-energy ranges 0–15 MeV at NLO and 0–25 MeV at N3LO. These interactions are regularized by including two Gaussian cutoffs, one for T = 0 and the other for T = 1 channels. The cutoffs are taken to vary in the ranges R 0 = (1.5 –2.3) fm and R 1 = (1.5 –3.0) fm. The 780 (1100) data points up to 15 (25) MeV energy, primarily differential cross sections, are fitted by the NLO (N3LO) models with a χ 2 / datum about 1.7 or less (well below 1.5), when harder cutoff values are adopted. As a first application, we report results for the binding energies of nuclei with mass numbers A = 3 –6 and 16 obtained with selected LO and NLO 2N models both by themselves as well as in combination with a LO three-nucleon (3N) contact interaction. The latter is characterized by a single low-energy constant that is fixed to reproduce the experimental 3 H binding energy. The inclusion of the 3N interaction largely removes the sensitivity to cutoff variations in the few-nucleon systems and leads to predictions for the 3 He and 4 He binding energies that cluster around 7.8 and 30 MeV, respectively. However, in 16 O this cutoff sensitivity remains rather strong. Finally, predictions at LO only are also reported for medium-mass nuclei with A = 40 , 48, and 90.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Developing a microwave-driven reactor for ammonia synthesis: insights into the unique challenges of microwave catalysis

Rapid development of new ammonia (NH 3 ) synthesis techniques that enable modular, intermittent production is essential to actualizing NH 3 's potential as a clean energy carrier, since contemporary methods are configured to centralized, continuous production methods with high emissions and are incompatible with renewable sources. Here, in this mission, microwave-driven catalysis is promising for its ability to enhance reaction kinetics and apply targeted heating for efficient energy use. However, owing to an incomplete understanding of the interaction between microwave fields and catalyst beds, the development of such microwave-catalysis systems remains underexplored and challenging. This paper investigates the 10× scale-up of a microwave-based NH 3 synthesis reactor using numerical and experimental approaches, achieving the largest reported microwave-driven NH 3 reactor to date. Results elucidate phenomena unique to microwave processes that are only predictable through numerical modeling, including how a catalyst's dielectric properties influence microwave field distribution by affecting penetration depth and how energy utilization can be poor even with sufficient attenuation. These dynamics change with scale, constrain reactor geometry, and potentially hamper performance. Nonetheless, we demonstrate a production rate of 56.6 g NH$_3$ per day, the highest reported NH 3 synthesis rate for laboratory-scale alternative techniques; correspondingly, the benchmark energy efficiency achieved in this paper (45.6 g NH$_3$ kW h -1 ) is the highest reported for such reactors of sufficient scale. Even with this exemplary energy efficiency, energy losses were found in excess of 50%, an issue resolvable through scale and reactor design. The efficiencies imparted by microwaves were key in these achievements, warranting further investigation toward development of microwave-driven NH 3 systems.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2012

Special Analysis: Disposal Plan for Pit 38 at Technical Area 54, Area G

Los Alamos National Laboratory (LANL) generates radioactive waste as a result of various activities. Operational waste is generated from a wide variety of research and development activities including nuclear weapons development, energy production, and medical research; environmental restoration (ER), and decontamination and decommissioning (D&D) waste is generated as contaminated sites and facilities at LANL undergo cleanup or remediation. The majority of this waste is low-level radioactive waste (LLW) and is disposed of at the Technical Area 54 (TA-54), Area G disposal facility. U.S. Department of Energy (DOE) Order 435.1 (DOE, 2001) requires that radioactive waste be managed in a manner that protects public health and safety, and the environment. To comply with this order, DOE field sites must prepare site-specific radiological performance assessments for LLW disposal facilities that accept waste after September 26, 1988. Furthermore, sites are required to conduct composite analyses that account for the cumulative impacts of all waste that has been (or will be) disposed of at the facilities and other sources of radioactive material that may interact with the facilities. Revision 4 of the Area G performance assessment and composite analysis was issued in 2008 (LANL, 2008). These analyses estimate rates of radionuclide release from the waste disposed of at the facility, simulate the movement of radionuclides through the environment, and project potential radiation doses to humans for several on- and off-site exposure scenarios. The assessments are based on existing site and disposal facility data, and on assumptions about future rates and methods of waste disposal. The Area G disposal facility consists of Material Disposal Area (MDA) G and the Zone 4 expansion area. To date, disposal operations have been confined to MDA G and are scheduled to continue in that region until MDA G undergoes final closure at the end of 2013. Given its impending closure, efforts have been made to utilize the remaining disposal capacity within MDA G to the greatest extent possible. One approach for doing this has been to dispose of low-activity waste from cleanup operations at LANL in the headspace of selected disposal pits. Waste acceptance criteria (WAC) for the material placed in the headspace of pits 15, 37, and 38 have been developed (LANL, 2010) and the impacts of placing waste in the headspace of these units has been evaluated (LANL, 2012a). The efforts to maximize disposal efficiency have taken on renewed importance because of the disposal demands placed on MDA G by the large volumes of waste that are being generated at LANL by cleanup efforts. For example, large quantities of waste were recently generated by the retrieval of waste formerly disposed of at TA-21, MDA B. A portion of this material has been disposed of in the headspace of pit 38 in compliance with the WAC developed for that disposal strategy; a large amount of waste has also been sent to off-site facilities for disposal. Nevertheless, large quantities of MDA B waste remain that require disposal. An extension of pit 38 was proposed to provide the disposal capacity that will be needed to dispose of institutional waste and MDA B waste through 2013. A special analysis was prepared to evaluate the impacts of the pit extension (LANL, 2012b). The analysis concluded that the disposal unit could be extended with modest increases in the exposures projected for the Area G performance assessment and composite analysis, as long as limits were placed on the radionuclide concentrations in the waste that is placed in the headspace of the pit. Based, in part, on the results of the special analysis, the extension of pit 38 was approved and excavation of the additional disposal capacity was started in May 2012. The special analysis presented here uses performance modeling to identify a disposal plan for the placement of waste in pit 38. The modeling uses a refined design of the disposal unit and updated radionuclide inventories to identify a disposal configuration that promotes efficient utilization of the pit and ensures continued compliance with DOE Order 435.1 performance objectives. Section 2 describes the methods used to conduct the analysis; the results of the evaluation are provided in Section 3. The disposal plan for pit 38 is provided in Section 4 and the conclusions of the investigation are provided in Section 5. Throughout the report, pit 38 is used to refer to the entire disposal unit, including the existing pit and the extension that is currently under construction. Where a distinction between the two portions of the pit is necessary, the existing unit is referred to as pit 38 proper and the new portion of the pit as the pit 38 extension or, more simply, the extension.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Search for baryon junctions in e+A collisions at the electron ion collider

Constituent quarks in a nucleon are the essential elements in the standard “quark model” associated with the electric charge, spin, mass, and baryon number of a nucleon. Quantum chromodynamics (QCD) describes nucleon as a composite object containing current quarks (valence quarks and sea (anti-)quarks) and gluons. These subatomic elements and their interactions are known to contribute in complex ways to the overall nucleon spin and mass. In the early development of QCD theory in the 1970s, an alternative hypothesis postulated that the baryon number might manifest itself through a non-perturbative configuration of gluon fields forming a Y-shaped topology known as the gluon junction. In this work, we propose to test such hypothesis by measuring (i) the Regge intercept of the net-baryon distributions for e+(p)Au collisions, (ii) baryon and charge transport in the isobaric ratio between e+Ru and e+Zr collisions, and (iii) target flavor dependence of proton and antiproton yields at large rapidity, transported from the hydrogen and deuterium targets in e+p(d) collisions. Our study indicates that these measurements at the EIC can help determine what carries the baryon number.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Solid Secondary Waste Form Testing Activities for the Integrated Disposal Facility Performance Assessment Support - 17567

Solid secondary waste (SSW) that will be generated at the Waste Treatment and Immobilization Plant (WTP) and from other activities at the Hanford site is destined for disposal at the Integrated Disposal Facility (IDF). Construction of the IDF was undertaken based on a Performance Assessment (PA) performed in 2001. In 2016, a SSW data package was prepared to support the development of an updated PA (2017 IDF PA). There are many inputs required to support the IDF PA. Data needs were identified based on experience from the previous PAs and from the development of conceptual models and modeling approaches to be applied for the 2017 PA. Interactions with the IDF PA team and the inventory data package developer helped to focus detailed efforts on a few key waste streams, contaminants of concern, and disposal configurations that are expected to be the primary contributors to the dose resulting from SSW disposed at the IDF. The key waste streams include: High Efficiency Particulate Air (HEPA) filters, ion exchange resins, granular activated carbon, and Ag-mordenite. The key parameters addressed in the 2016 data package include: saturated hydraulic conductivity, moisture characteristic curves, effective diffusion coefficient, distribution coefficient and porosity. The IDF PA team also identified a set of key contaminants that are expected to be the primary concern for the PA calculations (Tc-99, I-129, Cs-137, Sr-90, uranium isotopes (and total uranium), chromium, mercury and nitrate). These contaminants were the focus of the SSW data package. Specific formulations had not been identified for cementitious materials that will be used to encapsulate or stabilize SSW, and no IDF-specific experiments had been conducted to obtain the data for the PA. Thus, for the 2016 SSW data package, recommended property values were provided for a range of representative candidate materials based on a review of existing literature. However, starting in FY17, IDF-specific experiments will be performed for Hanford SSW expected to contribute most significantly to the dose for the IDF. This paper will summarize the information obtained for the 2016 data package and the plans for further testing to refine key inputs for the IDF PA. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Validation Testing for Molten Chloride Reactor Experiment Equipment Removal and Disposal Techniques

The Molten Chloride Reactor Experiment (MCRE) will be the first reactor featuring a fast-spectrum molten chloride circulating nuclear fuel system in the world. Planning for equipment removal and disposal (ERD) of MCRE has identified several technology gaps due to the unique environment of this nuclear experiment. Some of the gaps arise from the application of existing disassembly and/or sizing methods to novel material forms or in novel configurations. Others arise from unknown material behavior. This paper summarizes proposed test plans for ERD validation experiments to address these complicated or unknown equipment removal procedures. At the Waste Management Symposia in 2024, the Idaho National Laboratory (INL) MCRE ERD team presented the challenges associated with hosting multiple nuclear experiments in series with only brief transition periods between systems. Such difficulties include higher dose rates, the presence of radioisotopes infrequently encountered in reactor decommissioning and radioactive waste management, lack of intrinsic remote-operations infrastructure in the test bed, space constraints in the test bed, and contamination minimization requirements. To address these challenges, remote or semi-remote technologies are planned to be implemented in a non-hot cell environment with limited space availability. The team also discussed how a systems engineering approach is being used for conceptual development and design of equipment removal systems to address these challenges. For example, to reduce constraints for the removal of more difficult components, non-activated, noncontaminated elements are planned to be taken out first where possible. Still, there are complexities associated with the remaining components. In this work, the operational framework for MCRE ERD was reviewed for technical gaps and open questions, and test plans were drafted to address these areas. The tests plans were written for the following categories: vision systems, pipe cutting, drill/grout/filler, flush salt, and miscellaneous, with the miscellaneous group consisting of tests like techniques for removing bearings and reflector bricks. The test plans explore material, infrastructure, and staffing requirements needed for test execution. The test plans additionally focus on the evaluation of success. Determining the outcome of a test is imperative - as these explorative actions have the potential to rearrange or re-scope planned ERD activities. Success criteria identified thus far include required tool output, required area(s), debris production and mitigation, and repeatability. Test plans are an essential aspect of the systems engineering approach to MCRE ERD. They are used as the beginning steps in defining use cases for the ERD system. Performance of the validation tests is expected to begin in the summer of 2025 and will take approximately 9 to 12 months to complete. Execution of these plans will be expedited by specifying test needs ahead of time, facilitating efficient interactions with any subcontractors tasked with running the requested tests. Evaluating the outcomes of these tests will inform MCRE ERD procedures and timing and will also identify additional technical constraints for the MCRE ERD System. This upfront process optimization effort will help the project save time and resources at the end of the experiment.

21 - SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLAN↗
DOE OSTI2024

Impact of moment-based, energy integrated neutrino transport on microphysics and ejecta in binary neutron star mergers

We present an extensive study of the effects of neutrino transport in three-dimensional general relativistic radiation hydrodynamics (GRHD) simulations of binary neutron star (BNS) mergers using our moment-based, energy-integrated neutrino radiation transport (M1) scheme. Here, we consider a total of eight BNS configurations, while varying equation of state models, mass ratios, and grid resolutions, for a total of 16 simulations. We find that M1 neutrino transport is crucial in modeling the local absorption of neutrinos and the deposition of lepton number throughout the medium. We provide an in-depth look at the effects of neutrinos on the fluid dynamics and luminosity during the late inspiral and postmerger phases, the properties of ejecta and outflow, and the postmerger nucleosynthesis. The simulations presented in this work comprise an extensive study of the combined effect of the equation of state and M1 neutrino transport in GRHD simulations of BNS mergers, and establish that the solution provided by our M1 scheme is robust across system properties.

150 ≤ A ≤ 18959 ≤ A ≤ 8990 ≤ A ≤ 149↗
DOE OSTI2015

A new B-dot probe-based diagnostic for amplitude, polarization, and wavenumber measurements of ion cyclotron range-of frequency fields on ASDEX Upgrade

A new B-dot probe-based diagnostic has been installed on an ASDEX Upgrade tokamak to characterize ion cyclotron range-of frequency (ICRF) wave generation and interaction with magnetized plasma. The diagnostic consists of a field-aligned array of B-dot probes, oriented to measure fast and slow ICRF wave fields and their field-aligned wavenumber (k{sub //}) spectrum on the low field side of ASDEX Upgrade. A thorough description of the diagnostic and the supporting electronics is provided. In order to compare the measured dominant wavenumber of the local ICRF fields with the expected spectrum of the launched ICRF waves, in-air near-field measurements were performed on the newly installed 3-strap ICRF antenna to reconstruct the dominant launched toroidal wavenumbers (k{sub tor}). Measurements during a strap current phasing scan in tokamak discharges reveal an upshift in k{sub //} as strap phasing is moved away from the dipole configuration. This result is the opposite of the k{sub tor} trend expected from in-air near-field measurements; however, the near-field based reconstruction routine does not account for the effect of induced radiofrequency (RF) currents in the passive antenna structures. The measured exponential increase in the local ICRF wave field amplitude is in agreement with the upshifted k{sub //}, as strap phasing moves away from the dipole configuration. An examination of discharges heated with two ICRF antennas simultaneously reveals the existence of beat waves at 1 kHz, as expected from the difference of the two antennas’ operating frequencies. Beats are observed on both the fast and the slow wave probes suggesting that the two waves are coupled outside the active antennas. Although the new diagnostic shows consistent trends between the amplitude and the phase measurements in response to changes applied by the ICRF antennas, the disagreement with the in-air near-field measurements remains. An electromagnetic model is currently under development to address this issue.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗