Show simple item record

dc.contributor.authorHaji, Maha N.  Concept link
dc.date.accessioned2017-08-09T13:21:52Z
dc.date.available2017-08-09T13:21:52Z
dc.date.issued2017-06
dc.identifier.urihttps://hdl.handle.net/1912/9160
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2017en_US
dc.description.abstractSeawater is estimated to contain 4.5 billion tonnes of uranium, approximately 1000 times that available in conventional terrestrial resources. Finding a sustainable way to harvest uranium from seawater will provide a source of nuclear fuel for generations to come, while also giving all countries with ocean access a stable supply. This will also eliminate the need to store spent fuel for potential future reprocessing, thereby addressing nuclear proliferation issues as well. While extraction of uranium from seawater has been researched for decades, no economical, robust, ocean-deployable method of uranium collection has been presented to date. This thesis presents a symbiotic approach to ocean harvesting of uranium where a common structure supports a wind turbine and a device to harvest uranium from seawater. The Symbiotic Machine for Ocean uRanium Extraction (SMORE) created and tested decouples the function of absorbing uranium from the function of deploying the absorbent which enables a more efficient absorbent to be developed by chemists. The initial SMORE concept involves an adsorbent device that is cycled through the seawater beneath the turbine and through an elution plant located on a platform above the sea surface. This design allows for more frequent harvesting, reduced down- time, and a reduction in the recovery costs of the adsorbent. Specifically, the design decouples the mechanical and chemical requirements of the device through a hard, permeable outer shell containing uranium adsorbing fibers. This system is designed to be used with the 5-MW NREL OC3-Hywind floating spar wind turbine. To optimize the decoupling of the chemical and mechanical requirements using the shell enclosures for the uranium adsorbing fibers, an initial design analysis of the enclosures is presented. Moreover, a flume experiment using filtered, temperature- controlled seawater was developed to determine the effect that the shells have on the uptake of the uranium by the fibers they enclose. For this experiment, the AI8 amidoxime-based adsorbent fiber developed by Oak Ridge National Laboratory was used, which is a hollow-gear-shaped, high surface area polyethylene fiber prepared by radiation-induced graft polymerization of the amidoxime ligand and a vinylphosphonic acid comonomer. The results of the flume experiment were then used to inform the design and fabrication of two 1/10th physical scale SMORE prototypes for ocean testing. The AI8 adsorbent fibers were tested in two shell designs on both a stationary and a moving system during a nine-week ocean trial, with the latter allowing the effect of additional water flow on the adsorbents uranium uptake to be investigated. A novel method using the measurement of radium extracted onto MnO2 impregnated acrylic fibers to quantify the volume of water passing through the shells of the two systems was utilized. The effect of a full-scale uranium harvesting system on the hydrodynamics of an offshore wind turbine were then investigated using a 1/150th Froude scale wave tank test. These experiments compared the measured excitation forces and responses of two versions of SMORE to those of an unmodified floating wind turbine. With insights from the experiments on what a final full-scale design might look like, a cost-analysis was performed to determine the overall uranium production cost from a SMORE device. In this analysis, the capital, operating, and decommissioning costs were calculated and summed using discounted cash ow techniques similar to those used in previous economic models of the uranium adsorbent. Major contributions of this thesis include fundamental design tools for the development and evaluation of symbiotic systems to harvest uranium or other minerals from seawater. These tools will allow others to design offshore uranium harvesting systems based on the adsorbent properties and the scale of the intended installation. These flexible tools can be tuned for a particular adsorbent, location, and installation size, thereby allowing this technology to spread broadly.en_US
dc.description.sponsorshipThis work was supported by the U.S. Department of Energy Office of Nuclear Energy under Contract No. DE-NE0008268 and by the National Academies Keck Futures Initiative. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. #1122374.en_US
dc.language.isoen_USen_US
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Thesesen_US
dc.titleExtraction of uranium from seawater : design and testing of a symbiotic systemen_US
dc.typeThesisen_US
dc.identifier.doi10.1575/1912/9160


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record