EOS for critical slurry and solution systems

In a fire involving fissile material, the mixture of the fissile material ash with fire fighting water may lead to a criticality excursion if there are nearby sumps that permit a critical geometry. The severity of the resulting energy release and pressure pulse is dependent on the rate at which the mixing occurs. To calculate these excursions, a non-equilibrium equation of state for the water ash mixture or slurry is needed that accounts for the thermal non-equilibrium that occurs due to finite heat transfer rates. We are developing the slurry EOS as well as a lumped neutronic and hydrodynamic model to serve as a testing ground for the non-equilibrium EOS before its incorporation into more sophisticated neutronic-hydrodynamics codes. Though the model lacks spatial dependence, it provides estimates of energy release and pressure pulses for various mixture assembly rates. We are also developing a non-equilibrium EOS for critical solution systems in which the fissile material is dissolved in water, which accounts for chemical non-equilibrium due to finite mass transfer rates. In contrast to previously published solution EOS, our solution EOS specifically accounts for mass diffusion of dissolved radiolytic gas to bubble nucleation sites. This EOS was developed to check our overall modeling against published solution excursion experiments and to compare solution excursions with slurry excursions initiated under the same conditions. Preliminary results indicate a good match between solution EOS calculations and experiments involving premixed 60-80 g U/l solutions for both low rate and high rate reactivity insertions. Comparison between slurry and solution calculations for the same composition show comparable energy release and pressure peaks for both low and high rate reactivity insertions with the slurry releasing less energy but generating more pressure than the solution for the amount of energy released. Calculations more appropriate to actual fire fighting scenarios will also be presented

Extension to 3-D of the low-frequency electromagnetic plasma simulation models, LDRD Final Report 95-ERD-036

Low-frequency electromagnetic simulation models have a wide range of industrial applications. We have built several models, differentiated by slightly different physics approximations or computational solution methods, that have proven quite useful in a variety of applications. Our models been used to investigate beam plasma interactions in ICF targets, antenna plasma coupling in plasma processing, and magnetic implosion drive in Z-pinch pulsed power generators. The common feature of these models is that they retain inductive effects but implicitly ignore computationally intensive, fully electromagnetic effects. However, the preponderance of our work has been limited to only two dimensions. We have made significant progress modeling low-frequency electromagnetic physics with a new model in 2-D that is now capable of modeling antenna structures in 3-D. Although LLNL`s interest in plasma processing has diminished, we have certainly added to LLNL`s capabilities. Interestingly, we have already found another application, the magnetic behavior of read/write heads in the magnetic storage industry, that can make use of many of the computational methods described here, rewarding us again for maintaining a strong core competency in low-frequency EM plasmas

High-power laser source evaluation

This document reports progress in these areas: EXPERIMENTAL RESULTS FROM NOVA: TAMPED XENON UNDERDENSE X-RAY EMITTERS; MODELING MULTI-KEV RADIATION PRODUCTION OF XENON-FILLED BERYLLIUM CANS; MAPPING A CALCULATION FROM LASNEX TO CALE; HOT X RAYS FROM SEEDED NIF CAPSULES; HOHLRAUM DEBRIS MEASUREMENTS AT NOVA; FOAM AND STRUCTURAL RESPONSE CALCULATIONS FOR NIF NEUTRON EXPOSURE SAMPLE CASE ASSEMBLY DESIGN; NON-IGNITION X-RAY SOURCE FLUENCE-AREA PRODUCTS FOR NUCLEAR EFFECTS TESTING ON NIF. Also appended are reprints of two papers. The first is on the subject of ``X-Ray Production in Laser-Heated Xe Gas Targets.`` The second is on ``Efficient Production and Applications of 2- to 10-keV X Rays by Laser-Heated Underdense Radiators.`

Numerical approximation of the Euler-Maxwell model in the quasineutral limit

International audienceWe derive and analyze an Asymptotic-Preserving scheme for the Euler-Maxwell system in the quasi-neutral limit. We prove that the linear stability condition on the time-step is independent of the scaled Debye length $\lambda$ when $\lambda \to 0$. Numerical validation performed on Riemann initial data and for a model Plasma Opening Switch device show that the AP-scheme is convergent to the Euler-Maxwell solution when $\Delta x/ \lambda \to 0$ where $\Delta x$ is the spatial discretization. But, when $\lambda /\Delta x \to 0$, the AP-scheme is consistent with the quasi-neutral Euler-Maxwell system. The scheme is also perfectly consistent with the Gauss equation. The possibility of using large time and space steps leads to several orders of magnitude reductions in computer time and storage

Native American mtDNA prehistory in the American Southwest

This study examines the mtDNA diversity of the proposed descendants of the multiethnic Hohokam and Anasazi cultural traditions, as well as Uto-Aztecan and Southern-Athapaskan groups, to investigate hypothesized migrations associated with the Southwest region. The mtDNA haplogroups of 117 Native Americans from southwestern North America were determined. The hypervariable segment I (HVSI) portion of the control region of 53 of these individuals was sequenced, and the within-haplogroup diversity of 18 Native American populations from North, Central, and South America was analyzed. Within North America, populations in the West contain higher amounts of diversity than in other regions, probably due to a population expansion and high levels of gene flow among subpopulations in this region throughout prehistory. The distribution of haplogroups in the Southwest is structured more by archaeological tradition than by language. Yumans and Pimans exhibit substantially greater genetic diversity than the Jemez and Zuni, probably due to admixture and genetic isolation, respectively. We find no evidence of a movement of mtDNA lineages northward into the Southwest from Central Mexico, which, in combination with evidence from nuclear markers, suggests that the spread of Uto-Aztecan was facilitated by predominantly male migration. Southern Athapaskans probably experienced a bottleneck followed by extensive admixture during the migration to their current homeland in the Southwest. Am J Phys Anthropol 120:108–124, 2003. © 2003 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34277/1/10138_ftp.pd

The Republican Divide on Wilderness Policy

Wilderness is an issue that exposes a deep political fault line within the Republican Party. Republican leaders such as Theodore Roosevelt are credited with laying the philosophical and legal groundwork that resulted in establishment of the National Wilderness Preservation System. Republicans who worked for wilderness protection cited benefits such as protecting the nation\u27s natural and historical heritage, conserving resources for the future, and providing opportunities for beneficial outdoor recreation. Other Republican leaders, however, have fought wilderness protection on the grounds that preservation is an inappropriate government constraint on free markets and is harmful to the economy by limiting commodity production of timber, forage, and minerals

New tools to study the consequences of micronucleation and micronucleus rupture

Thesis (Ph.D.)--University of Washington, 2023Micronuclei are aberrant nuclear compartments that trap a portion of a cell's chromatin in a distinct organelle separate from the nucleus and are drivers of inflammation, DNA damage, chromosome instability, and chromothripsis. Many of the consequences of micronucleus formation stem from micronucleus rupture: the sudden loss of micronucleus compartmentalization, resulting in mislocalization of nuclear factors and the exposure of chromatin to the cytosol for the remainder of interphase. Micronuclei form primarily from segregation errors during mitosis, errors that also give rise to other, non-exclusive phenotypes, including aneuploidy and chromatin bridges. The stochastic formation of micronuclei and phenotypic overlap confounds the use of population-level assays or hypothesis discovery, requiring labor-intensive techniques to visually identify and follow micronucleated cells individually. In this work, I present a novel technique for automatically identifying and isolating micronucleated cells generally and cells with ruptured micronuclei specifically using a de novo neural net combined with Visual Cell Sorting. As a proof of concept, I compare the early transcriptomic responses to micronucleation and micronucleus rupture with previously published responses to aneuploidy, revealing micronucleus rupture to be a potential driver of the aneuploidy response. In addition, I present an unfinished tool using the bacterial enzyme deoxyadenosine methyltransferase (Dam) for the population-level identification of chromatin, rather than cells, that were trapped in a ruptured micronucleus. This tool, dubbed Dam Tracker, depended on the sequestration of Dam in the cytosol away from chromatin in intact nuclear compartments, which is made difficult during mitosis when nuclear envelopes are disassembled. Should this obstacle be overcome, this tool could open new avenues of research on the long-term consequences of micronucleus rupture to chromatin

Cold X-Ray Impulse Estimates

The purpose of this short note is to document comparisons between a simple analytic model and the BUCKL[1]x-ray deposition and impulse code and to briefly demonstrate the effect of deposition time on impulse

Analytic and experimental validation of thermo elastic plastic material response calculation

We compare the thermo-elastic-plastic response of fissionable metals calculated by the solid mechanics code DYNA to an analytic model for the case of a uniformly heated thin spherical shell and to experimental data for the case of a thin rod heated in a pulsed reactor. In both cases, the materials are volumetrically heated by neutron exposure. We find good agreement between the code and the analytic model and experimental data for the first and second case, respectively. For very fast heating times, macroscopic displacement may be replaced by microscopic plastic flow. To verify this behavior, an experiment to be done at SNLA SPR III is described. Validation of the code in these simple geometries is a necessary step if calculations involving more complicated geometries are to be understood and trusted