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At least 1,117 records · Page 62
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Divergence in heritable life history traits suggests potential for local adaptation and trade‐offs associated with a coal ash disposal site

Abstract Globally, human activities have resulted in rapid environmental changes that present unique challenges for wildlife. However, investigations of local adaptation in response to simultaneous exposure to multiple anthropogenic selection pressures are rare and often generate conflicting results. We used an in situ reciprocal transplant design within a quantitative genetic framework to examine how adaptive evolution and phenotypic plasticity contribute to the persistence of an amphibian population inhabiting an environment characterized by high levels of multiple toxic trace elements. We found evidence of phenotypic divergence that is largely consistent with local adaptation to an environment contaminated with multiple chemical stressors, tied to potential trade‐offs in the absence of contaminants. Specifically, the population derived from the contaminated environment had a reduced risk of mortality and greater larval growth and in the contaminated environment, relative to offspring from the naïve population. Further, while survival in the uncontaminated environment was not compromised in offspring from the contaminant‐exposed population, they did show delayed development and reduced growth rates over larval development, relative to the naïve population. We found no evidence of reduced additive genetic variation in the contaminant‐exposed population, suggesting long‐term selection in a novel environment has not reduced the evolutionary potential of that population. We also saw little evidence that past selection in the ASH environment had reduced trait plasticity in the resident population. Maternal effects were prominent in early development, but we did not detect any trends suggesting these effects were associated with the maternal transfer of toxic trace elements. Our results demonstrate the potential for adaptation to multiple contaminants in a wild amphibian population, which may have facilitated long‐term persistence in a heavily impacted environment.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Soil Desiccation Treatability Testing at BC Waste Disposal Cribs

During Hanford’s production period, low-level waste products generated from chemical processing of uranium fuel rods were discharged directly to the ground through a system of cribs and trenches located in the 200-BC-1 Operable Unit (OU). The site consists of 6 cribs and 20 trenches that received more than 117,000 m3 of radioactive liquid waste discharged to the soil. These unlined infiltration galleries held volumes of liquid waste while it seeped into the ground, with the understanding that the 100 m (330 ft) thick vadose zone in the area would effectively capture the effluent and prevent groundwater impacts. A conceptual model showing the operation of cribs and trenches is shown in Figure 1. Data show effluent from the 26 cribs and trenches containing about 410 curies of Technetium-99 (Tc-99) is primarily located between 30 m and 70 m (98 ft and 230 ft) depth (Corbin et al., 2005; Ward et al., 2004). Despite no evidence indicating that the contamination has reached the groundwater at BC cribs and trenches, the mobility of Tc-99 had been demonstrated in laboratory tests and was recognized as a threat to groundwater at the site. Using data from numerical models, laboratory analyses, field investigations, and information on historical discharges, the EPA and Ecology identified Tc-99 and U contamination of the vadose zone as a remediation priority. The U.S. DOE was notified by EPA and Ecology regarding risks associated with Tc-99 contamination in a letter requesting development of a strategy for improved methods to understand the nature and extent of vadose zone contamination, specifically Tc-99, and to develop remedial options for addressing such contamination. To develop the appropriate technology for characterizing, remediating, and monitoring the deep vadose zone Tc-99 contamination, the U.S. DOE worked with the EPA and Ecology to create a Treatability Test Plan under a Remedial Investigation/Feasibility Study (RI/FS) for the Hanford 200 Areas. Under this RI/FS, it was determined that a treatability test for soil desiccation should be carried out as it was identified as a promising in-situ treatment technology for mitigating risks posed by Tc-99 contamination to the groundwater table. The BC Cribs and Trenches site was identified as a representative site for Tc-99 and U contamination and selected for the soil desiccation treatability test. In this chapter, we summarize the overlying regulatory framework of RI/FS and treatability tests and illustrate how development and experimentation supported the evaluation of selected remedies. We briefly discuss the RI/FS for the 200 Areas of the Hanford Site and focus on the soil desiccation treatability testing performed at the BC cribs and trenches site under the Deep Vadose Zone Treatability Test Plan for the Hanford Central Plateau (DVZ-TT). The DVZ-TT is one component of the remedial investigation/feasibility study for the Hanford 200 Areas and represents the underlying regulatory framework that drives site operations towards records of decision and site closure.

Mangel, Adam R.↗
DOE OSTI2012

Logistical simulation of spent nuclear fuel disposal in a salt repository with low temperature limits

Two logistical modeling cases evaluated the relative cost, schedule, and thermal results for strategies that would limit peak salt temperature in a spent-fuel repository to 90°C and 150°C. Runs with the code CALVIN 4.0 show that these low thermal limits are logistically feasible for a salt repository using relatively small waste packages (4-PWR/9-BWR or 12-PWR/24-BWR sizes). Attainment of low-thermal goals was represented using instantaneous waste package thermal power limits at emplacement (3,200 W and 6,800 W) which came from a correlation between package power and peak salt temperature that was developed by a previous study using the finite element method.

Kalinina, Elena Arkadievna↗
DOE OSTI2013

Evaluate Disposable Sample Chips and Complete the Evaluation of Sample Accuracy Through Evaluation of Chip Filling Methods

In FY-12, the glass sample chips were filled by capillary action when they were dipped into the solutions being sampled either by hand or by the robotic sampling system. Issues were noted at the end of FY-12 that many of the channels were not completely filling (10-15% of the 10 μl channels and up to 40% of the 2 μl channels). Therefore, testing was conducted in FY-13 on filling the glass sample chips by use of a flow-through header (Table 1). Results indicate flow through filling is better at completely filling the chip channels, although some amount of solution can be lost when the chip is removed from the filling header.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

Modeling and Field Test Planning Activities in Support of Disposal of Heat-Generating Waste in Salt

The modeling efforts in support of the field test planning conducted at LBNL leverage on recent developments of tools for modeling coupled thermal-hydrological-mechanical-chemical (THMC) processes in salt and their effect on brine migration at high temperatures. This work includes development related to, and implementation of, essential capabilities, as well as testing the model against relevant information and published experimental data related to the fate and transport of water. These are modeling capabilities that will be suitable for assisting in the design of field experiment, especially related to multiphase flow processes coupled with mechanical deformations, at high temperature. In this report, we first examine previous generic repository modeling results, focusing on the first 20 years to investigate the expected evolution of the different processes that could be monitored in a full-scale heater experiment, and then present new results from ongoing modeling of the Thermal Simulation for Drift Emplacement (TSDE) experiment, a heater experiment on the in-drift emplacement concept at the Asse Mine, Germany, and provide an update on the ongoing model developments for modeling brine migration. LBNL also supported field test planning activities via contributions to and technical review of framework documents and test plans, as well as participation in workshops associated with field test planning.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗