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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Upscaling of U(VI) Desorption and Transport from Decimeter-Scale Heterogeneity to Plume-Scale Modeling

Scientifically defensible predictions of field scale U(VI) transport in groundwater requires an understanding of key processes at multiple scales. These scales range from smaller than the sediment grain scale (less than 10 μm) to as large as the field scale which can extend over several kilometers. The key processes that need to be considered include both geochemical reactions in solution and at sediment surfaces as well as physical transport processes including advection, dispersion, and pore-scale diffusion. The research summarized in this report includes both experimental and modeling results in batch, column and tracer tests. The objectives of this research were to: (1) quantify the rates of U(VI) desorption from sediments acquired from a uranium contaminated aquifer in batch experiments;(2) quantify rates of U(VI) desorption in column experiments with variable chemical conditions, and(3) quantify nonreactive tracer and U(VI) transport in field tests.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Development of U isotope fractionation as an indictor or U(VI) reduction in uranium plumes

This is the final report for a university research project that advanced development of a new technology for identifying chemical reduction of uranium contamination in groundwater at the Rifle Field Challenge site. Reduction changes mobile hexavalent uranium into immobile U(IV). The stable isotope ratio (238U/235U) measurements of U using multicollector ICP-mass spectrometry were performed to understand the chemical reduction and sorption processes during various field experiments. In addition laboratory experiments were performed to better understand the isotopic fractionations. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Carbon Dioxide Plume Evolution Following Injection into a Depleted Natural Gas Reservoir: Modeling of Conformance Uncertainty Reduction Over Time

The uncertainty in the long-term fate of CO 2 injected for geologic carbon sequestration (GCS) is a significant barrier to the adoption of GCS as a greenhouse gas emission mitigation approach for industry and regulatory agencies alike. Here we present a modeling study that demonstrates that the uncertainty in forecasts of GCS site performance decreases over time as monitoring data are used to inform and update operational models. The approach we take is to consider a case study consisting of a depleted natural gas reservoir that is used for GCS with CO 2 injection occurring over 20 years, with a 50-year post-injection site care (PISC) period. We constructed a detailed model of the system and ran this model out to 200 years to generate the actual site data. A series of simpler operational models based on limited data and assumptions about how an actual operator would model such a site are then run and compared against the actual model output at various specific monitoring points after one year, two years, etc. The operational model is then updated and improved using the observations (synthetic data from the actual model) at the same time intervals. We found that both model parameter values and model features needed to be added over time to improve matches to the actual system. These kinds of model adjustments are expected to be a normal part of reservoir engineering and site management at GCS sites. We found that the uncertainty in two key measures related to site performance at various locations decreases with time. This overall conclusion should help allay the concerns of industry and regulators about the uncertainty in GCS operations.

03 NATURAL GAS↗
DOE OSTI2020

Radioactive Plume Avoidance and Aircraft Decontamination – Best Practices

Response to an incident involving the release of radioactive material will most likely involve aircraft for disaster relief and radiological monitoring. Aircraft flying into a radiologically contaminated area risk becoming contaminated, and in the worst cases having to be removed from service. Contamination is avoidable, and decontamination is possible, but both require planning and forethought.

61 RADIATION PROTECTION AND DOSIMETRY↗