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MACCS is used by the Nuclear Regulatory Commission (NRC) and various national and international organizations for probabilistic consequence analysis of nuclear power accidents. This User Guide is intended to assist analysts in understanding the MACCS/WinMACCS model and to provide information regarding the code. This user guide version describes MACCS Version 4.2. This User Guide provides a brief description of the model history, explains how to set up and execute a problem, and informs the user of the definition of various input parameters and any constraints placed on those parameters. This report is part of a series of reports documenting MACCS. Other reports include the MACCS Theory Manual, MACCS Verification Report, Technical Bases for Consequence Analyses Using MACCS, as well as documentation for preprocessor codes including SecPop, MelMACCS, and COMIDA2.

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TYPE SAND Report YEAR 2023

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2023 Annual Report of Available Drawdowns for Each Oil Storage Cavern in the Strategic Petroleum Reserve

Hart, David

DOE maintains an up-to-date documentation of the number of available full drawdowns of each of the caverns at the U.S. Strategic Petroleum Reserve (SPR). This information is important for assessing the SPR’s ability to deliver oil to domestic oil companies expeditiously if national or world events dictate a rapid sale and deployment of the oil reserves. Sandia was directed to develop and implement a process to continuously assess and report the evolution of drawdown capacity, the subject of this report. This report covers impacts on drawdown availability due to SPR operations during Calendar Year 2022. A cavern has an available drawdown if, after that drawdown, the long-term stability of the cavern, the cavern field, or the oil quality are not compromised. Thus, determining the number of available drawdowns requires the consideration of several factors regarding cavern and wellbore integrity and stability, including stress states caused by cavern geometry and operations, salt damage caused by dilatant and tensile stresses, the effect of enhanced creep on wellbore integrity, and the sympathetic stress effect of operations on neighboring caverns. Finite-element geomechanical models have been used to determine the stress states in the pillars following successive drawdowns. By computing the tensile and dilatant stresses in the salt, areas of potential structural instability can be identified that may represent red flags for additional drawdowns. These analyses have found that many caverns will maintain structural integrity even when grown via drawdowns to dimensions resulting in a pillar-to-diameter ratio of less than 1.0. The analyses have also confirmed that certain caverns should only be completely drawn down one time. As the SPR caverns are utilized and partial drawdowns are performed to remove oil from the caverns (e.g., for oil sales, purchases, or exchanges authorized by the Congress or the President), the changes to the cavern caused by these procedures must be tracked and accounted for so that an ongoing assessment of the cavern’s drawdown capacity may be continued. A methodology for assessing and tracking the available drawdowns for each cavern is reiterated. This report is the latest in a series of annual reports, and it includes the baseline available drawdowns for each cavern, and the most recent assessment of the evolution of drawdown expenditures. A total of 222 million barrels of oil were released in calendar-year 2022. A nearly-equal amount of raw water was injected, resulting in an estimated 34 million barrels of cavern leaching. Twenty caverns have now expended a full drawdown. Cavern BC 18 has expended all its baseline available drawdowns, and has no drawdowns remaining. Cavern BM 103 has expended one of its two baseline drawdowns, and is now a single-drawdown cavern. All other caverns with an expenditure went from at-least-5 to at-least-4 remaining drawdowns.

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TYPE SAND Report YEAR 2023

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MiSSCyM: A Manufacturing Simulation Framework for Cyber Experimentation

Williams, Bethanie D.

Abstract not provided.

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TYPE Conference Poster YEAR 2023

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Hydrogen and Deuterium Reactivity with Carbon Surface Impurities on the TPBAR Getter Ni Plate Studied in situ with Environmental XPS

El Gabaly, Farid

Tritium for the U.S. Department of Energy’s Tritium Readiness Program is produced in tritium-producing burnable absorber rods (TPBARs) inserted into light-water nuclear reactors. The rods are stainless-steel-clad tubes with a permeation barrier coating and internal components. The internal components have been designed and selected to produce and retain tritium. The TPBAR incorporates a Ni-plated Zircaloy-4 getter tube to capture tritium and prevent it from reaching the rod cladding and permeating into the environment. The role of the Ni coating is to protect the Zircaloy-4 getter from oxidation while allowing for maximum tritium permeability. Ubiquitous surface impurities on the Ni, such as carbon, could limit its protective functionality and permeability if they exist in relatively large concentrations. The reactivity of impurity carbon with permeating tritium can also result in tritiated hydrocarbon impurities on the gas phase. The goal of this work is to determine quantitatively the chemical state and reactivity of potential Ni coating impurities in actual TPBAR getter samples. Using Environmental X-ray Photoelectron Spectroscopy (eXPS), a very sensitive gas/surface chemistry diagnostic, we reveal in situ the source and evolution of carbon on the Ni surface at different hydrogen and deuterium pressure conditions, and how carbon reactivity may result in hydrocarbon gas-evolution at application-relevant temperatures.

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TYPE SAND Report YEAR 2023

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