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At least 361 records · Page 20

Probabilistic Programming for Transportable Source Characterization and Uncertainty Quantification of the North Korean Nuclear Tests 2006–2017

Here, we introduce a transportable technique to determine the yield and depth of burial (DOB) from seismic source spectra of underground nuclear explosions. We demonstrate this technique on the six declared North Korean nuclear tests. This approach derives source spectra in absolute units from regional phase (Pg) amplitudes by correcting the observations for geometric spreading, attenuation, and site amplification. We couple the source spectra and explosion source models with a probabilistic programming framework that integrates deep learning techniques and Bayesian modeling. This approach permits the exchange of information across various data categories to quantify both the data and model uncertainty. This technique stands out as an innovative use of broad‐area propagation models, making it transportable across various geologic settings. This method proves to be effective in scenarios with diverse and/or limited observational data, even when the source depth is unknown. We present new independent estimates of absolute yield and DOB that are consistent with the prior assessments, underscoring the potential of this method in enhancing transportable nuclear explosion monitoring capabilities.

58 GEOSCIENCES↗

Raman spectroscopic investigation of selected natural uranyl sulfate minerals

Uranyl sulfates are important constituents of uranium ores and represent a significant fraction of U(VI) minerals discovered in recent years owing to their propensity to form in mine tailings and legacy sites related to uranium exploration. Recently, we surveyed all published Raman spectra for uranium minerals and found significantly less easily accessible data available for uranyl sulfates relative to other groups of uranium minerals (Spano et al. 2023). In that work, we described average spectra for groups of uranyl minerals to understand common vibrational spectroscopic features attributable to similarities in oxyanion chemistry among U(VI) minerals, but only data for three uranyl sulfate minerals were included in the study. The present work reports on Raman spectra collected for 18 additional uranyl sulfate minerals. In conclusion, to better understand underlying structural and chemical features that give rise to spectroscopic observables, we relate differences in structural topology, charge-balancing cations, and locality of origin to features observed in the Raman spectra of selected natural uranyl sulfates.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Is it time to review the 1978 Nonproliferation Act? What is the future of nuclear sciences in the U.S.?

With an aging ‘nuclear experienced’ workforce that is retiring and leaving the workplace, we are concerned about the erosion of skills in radiochemistry, uranium and plutonium metallurgy and other related disciplines. In the context of losing manufacturing base in the U.S. and strict delineation between nuclear power engineering and nuclear weapons programs, it is more difficult to find experienced staff. As an example of a program to correct this situation, Los Alamos National Laboratory’s Nuclear Security Education Center has the capabilities to prevent this erosion by organizing the national laboratories and academia to provide training programs and career paths ensuring long-term experienced staff are available for the enduring mission.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

PBX-9501 High Explosive Infrared Thermography Test Report

High explosive safety requirements put in place by the Department of Defense necessitate that Los Alamos National Laboratory verify that high melting explosive-based plastic bonded explosive 9501 will not present a health or safety risk to personnel when exposed to various accident scenarios. The JT5R-14C test is being developed to validate this requirement in a scenario where PBX-9501 is exposed to a hydrocarbon fuel fire. Preliminary testing is required to establish benchmark data on the burning characteristics of PBX-9501. The PBX-9501 High Explosive Infrared Thermography test was designed to provide the benchmark burning characteristics of PBX-9501 in a simulated fuel fire environment using propane burners as a fuel source. The PBX-9501-HEIT was successfully completed using a 20.32 cm tall cylindrical sample of PBX-9501 with a radius of 10.16 cm, a volume of 6,589.63 cm 3 , a density of 1.83 g/cm 3 , and a mass of 1.2 kg. The PBX-9501-HEIT test was captured and recorded video sequence using a Telops Inc., Multispectral Infrared camera. The infrared sequence was reviewed to identify key events throughout the test and serves as a visual tool to cross reference against future testing to aid in the identification of PBX-9501 high explosive ignition and deflagration characteristics. The data obtained in the thermographic sequence confirmed that the temperatures emitted by the PBX-9501 were higher than the temperatures of the propane burner ignition source. The propane burner flames had a temperature range of 700-850 °C. The cylindrical sample of PBX-9501 burned at an average temperature of 1000-1200 °C on the surface with off-gassing temperatures averaging 1100-1250 °C. The heat map of the PBX-9501 obtained through the test was between 250-550 °C higher than the propane gas temperatures. The temperature differential between the PBX-9501 and the propane flame allowed for the identification of key burning features.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

The Radiological and WMD Threat Posed to National Security By Hezbollah in Latin America

Beginning in the 1980s, Hezbollah and other international terrorist organizations took root in unstable portions of Latin America. Over the years, they have built up considerable capabilities that threaten US national security and the security of allies in the region. However, Hezbollah has separated itself from its counterparts through its actions in Latin America, namely the Israeli Embassy and AMIA bombings in the early 1990s, and continues to do so. While it mainly operates out of the Tri-Border Area (TBA) of Paraguay, Brazil, and Argentina in South America, Hezbollah commands cells that span the Western Hemisphere. In the modern-day, Hezbollah conducts drug, weapons, and contraband trafficking and smuggling operations, in addition to its violent attacks. New revelations, involving the increased trafficking and stealing of nuclear and WMD material, populate the world’s nonproliferation roundtables. Latin America is no exception to this trend. It is possible that terrorist organizations, such as Hezbollah, could acquire, develop, and use stolen or illegally obtained nuclear material in a radiological dispersal device (RDD) or some form of WMD. In light of these revelations, the United States should focus more on Hezbollah’s illicit activities in Latin America in the interests of its own national security and its allies’.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Simulation-based Design of a Shadow Shield for the MIND Backpack System

Modeling and simulation is a cost- and time-saving method to study conceptual designs of radiation detection systems. MCNP radiation transport code has been an indispensable tool in development of radiation detection systems, and the PINS systems have also utilized MCNP modeling and simulation in the system development. MCNP models of the PINS systems have been used to understand detector responses and to fill the gap in experimental data. Recently, the MIND backpack system was announced to be developed, and its prototype design was required to conduct laboratory tests and demonstrations. A shadow shield is the component to be designed by Idaho National Laboratory in order to maximize the performance of a backpack system while meeting the sponsor’s requirements. MCNP modeling and simulation was utilized to find the best specification of a shadow shield. This study was performed to down-select a shadow shield design for the MIND system. A total of 24 designs for a shadow shield were identified to build MCNP models, and their simulation results were used to prioritize each design. As a quantitative performance metric, an equation of Figure-of-Merit was introduced in the decision making analysis. In addition, the Analytic Hierarchy Process was adopted to prioritize and recommend best performing shadow shield designs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Advanced Simulation and Computing FY20 Implementation Plan (Rev. 0)

The Stockpile Stewardship Program (SSP) is an integrated technical program for maintaining the safety, surety, and reliability of the U.S. nuclear stockpile. The SSP incorporates nuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. The suite of data analyzed comes from activities including stockpile surveillance, experimental research, and development and engineering programs. This integrated national program requires the continued use of experimental facilities and the computational capabilities to support the SSP missions. These component parts, in addition to an appropriately scaled production capability, enable the National Nuclear Security Administration (NNSA) to support stockpile requirements. The ultimate goal of the Stewardship Program, and thus the Advanced Simulation and Computing (ASC) Program, is to ensure that the U.S. maintains a safe, secure, and effective strategic deterrent.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

MagMicro with Ultra-High Energy Resolution (FY19 Q3 Progress Report)

The fabrication of the MMC detector arrays involves two photolithographic procedures. The first is to fabricate the Nb magnetization coil and pick-up coils, the SQUID preamplifiers and the associated wiring. This is done on a full 4” Si wafer, which is subsequently diced into ~0.5 cm2 SQUID chips and ~1 cm2 detector chips. The detector chips are then processed separately by depositing and patterning the paramagnetic Ag:Er sensor and support structures and then electroplating the Au absorber. In Q3, we have successfully completed the full wafer processing for the 32-pixel MMC detector arrays, diced the 4” wafer into the smaller chips and tested the individual components. The coils have the required critical current, the heat switches have a critical temperature in the desired range, and the SQUIDs have the required low noise. Unfortunately, the sputter deposition of the paramagnetic Ag:Er sensor failed several times. We spent considerable time to trace the problem to contaminations of the purifier for the Ar sputtering gas that had been exposed to atmosphere for an extended time during an earlier clean room upgrade. We then determined that the purifier is not essential for high-quality Ag:Er sensor films (Fig. 1), and successfully deposited the Ag:Er sensor film on the ~1 cm 2 detector chip.

42 ENGINEERING↗

Bunker 801 Personnel Accountability System Upgrade

The experimentation facilities at Site 300 of the Lawrence Livermore National Laboratory (LLNL) all require a reliable, real-time accounting of personnel in each facility. In smaller facilities, this is often done simply by writing a name on a board. As our facilities develop, a whiteboard methodology becomes challenging because there are many names to list at one time, and multiple entry points may exist in a facility. In many cases, a facility resident may have a significant distance to travel (including stairs) to sign in to the facility and sometimes forget to do so. Allowing a sign in at another point of entry or from a personal computer could help to alleviate this. Personnel frequently move between multiple facilities. When this is the case, it would be useful for a user to be signed off automatically if they failed to do so upon leaving a previous facility and to give an indication of their present location at other facilities. There is no official consequence to individuals who fail to sign out upon departure, however intense peer pressure is applied to bring donuts to the bunker on the following business day. Currently, no electronic sign-in systems are in place at S300.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

SAM User's Guide

The System Analysis Module (SAM) is a modern system analysis tool being developed at Argonne National Laboratory for advanced non-LWR safety analysis. It aims to provide fast-running, whole-plant transient analyses capability with improved-fidelity for Sodium-cooled Fast Reactors (SFR), Lead-cooled Fast Reactors (LFR), and Molten Salt Reactors (MSR) or Fluoride-cooled High-temperature Reactors (FHR). SAM takes advantage of advances in physical modeling, numerical methods, and software engineering to enhance its user experience and usability. It utilizes an object-oriented application framework (MOOSE), and its underlying meshing and finite-element library (libMesh) and linear and non-linear solvers (PETSc), to leverage the modern advanced software environments and numerical methods. This document provides a user’s guide, which will help users understand the input description and core capabilities of the SAM code. A brief overview of the code is presented, as well as how to obtain and run it. The input syntax for various parts of the code is provided. Additionally, a number of example problems, starting with simple unit component problems to problems with increasing complexity, are provided. Because the code is still under active development, this SAM User’s Guide will evolve with periodic updates.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

Stochastic Approaches for Calculating and Aggregating Detection Probabilities for Nuclear Material Diversion

The goal of this project is to develop statistical methods and tools that can be used to rigorously calculate achieved DPs on individual material strata and then aggregate these to the facility and state levels. In particular, this project is evaluating the utility of stochastic ("Monte Carlo") methods as a potentially more powerful and flexible option to the analytical solutions traditionally employed by IAEA statisticians.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

OSIRIS Validation and Verification Report

The On-Site Inspection RadioIsotopic Spectroscopy (OSIRIS) system is a gamma-ray spectroscopy instrument for on-site inspections conducted under the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The OSIRIS software filters spectral analysis data, revealing information to users on only 17 CTBT-relevant fission-product isotopes. In this report, we review the CTBT requirements for on-site inspection radionuclide identifiers, plus additional requirements imposed by the design team. Then a series of validation tests conducted during OSIRIS development are described. The validation tests were designed to gauge if the nascent OSIRIS system met those requirements. We conclude with a set of recommended verification tests to ensure that newly-manufactured OSIRIS systems also will meet the requirements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Separations for Radiochronometry and Forensics: Chemistry - Nuclear and Radiochemistry [Slides]

The term “separation” means multiple things when applied to radiochronometry efforts in C-NR: 1) How efficiently and rapidly can we separate trace-level nuclides used for age dating from bulk matrices? 2) Do we have pure (separated) well-calibrated single isotope tracers needed for high-precision trace level quantification of nuclides? 3) How much knowledge do we have about how nuclides used for radiochronometry are separated during uranium and plutonium production?

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗