Sandia Labs FY21 LDRD Annual Report

FY21 ANNUAL REPORT

Predicting stability of infrastructure following disasters. Environmentally assisted brittle fracture in infrastructure (bridges, dams, tunnels) can occur following man-made threats or natural disasters. For accurate prediction of catastrophic failure and collapse, integrated multiphysics modeling requires the incorporation of environmental impacts into modeling efforts. Through this LDRD project, the team developed new modeling capabilities for evaluating multiphase phenomena in cement-based materials in energy and infrastructure applications. They also developed a chemo-mechanical model for cement fracture, identified sources of uncertainty in cement degradation and concrete fracture, and created six new capabilities for modeling brittle fracture in open- source code, Peridigm. Academic collaborations with University of Colorado Boulder, the University

of New Mexico, and Purdue University provided evaluation of concrete fracture in gravity dam structures and the degradation and clay composition on evolving cement fracture. A funded strategic initiative on decarbonization of cement manufacturing incorporated the work; DOE Earthshot included content on the project; and a white paper was authored for the U.S. Army Corp of Engineers. (PI: Jessica Rimsza)

Peridynamic simulation of concrete fracture under tension with cracks forming in the mortar between the solid aggregates.

Evaluating metabolic energy for black molds. Melanin-containing fungi (black molds) can thrive under extreme environmental conditions such as the high radiation levels inside the former Chernobyl reactors. These fungi have been hypothesized to use gamma radiation as an energy source (radiotrophism), but the literature has not clearly addressed which energies of the electromagnetic spectrum, if any, positively affect the growth of fungi. This LDRD team sought to assess the existence of radiotrophism in this class of fungi, as it could have broad scientific implications and provide novel approaches for radiation measurement, monitoring and managing nuclear and radiological materials, dosimetry, and environmental remediation. The project evaluated a range of electromagnetic energies using a technical approach that coupled analyses from optical engineering, nuclear engineering, and fungal biology, but the data did not establish evidence supporting

radiotrophic behavior in the dose regime used by the team. (The regime was representative of gamma emissions from fission products and would signal applicability for global security and nonproliferation.) Future work to expand on these findings and evaluate other signals may enable significant new solutions to national security challenges. (PI: Jesse Bland) The image series shows the melanized fungi Cladosporium cladosporioides grown under gamma irradiation over seven days. The hexagonal shape in the center is a 352 microcurie cesium-137 source. The experiment found no evidence of radiotrophism for this fungi and dose regime.

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LABORATORY DIRECTED RESEARCH & DEVELOPMENT