Kevan D. Weaver

Theoretical Design of a Thermosyphon for Efficient Process Heat Removal from Next Generation Nuclear Plant (NGNP) for Production of Hydrogen

The work reported here is the preliminary analysis of two-phase Thermosyphon heat transfer performance with various alkali metals. Thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. Heat transport occurs via evaporation and condensation, and the heat transport fluid is re-circulated by gravitational force. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. For process heat, intermediate heat exchangers (IHX) are required to transfer heat from the NGNP to the hydrogen plant in the most efficient way possible. The production of power at higher efficiency using Brayton Cycle, and hydrogen production requires both heat at higher temperatures (up to 1000oC) and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. The purpose for selecting a compact heat exchanger is to maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. The IHX design requirements are governed by the allowable temperature drop between the outlet of the NGNP (900oC, based on the current capabilities of NGNP), and the temperatures in the hydrogen production plant. Spiral Heat Exchangers (SHE’s) have superior heat transfer characteristics, and are less susceptible to fouling. Further, heat losses to surroundings are minimized because of its compact configuration. SHEs have never been examined for phase-change heat transfer applications. The research presented provides useful information for thermosyphon design and Spiral Heat Exchanger.

Engineering and Physics Optimization of Breed and Burn Fast Reactor Systems

This project is organized under four major tasks (each of which has two or more subtasks) with contributions among the three collaborating organizations (MIT, INEEL and ANL-West): Task A: Core Physics and Fuel Cycle; Task B: Core Thermal Hydraulics; Task C: Plant Design Task; and D: Fuel Design.

Using Traveling Wave Reactor (TWR) Technology to Provide Globally Scalable and Sustainable, Carbon-Free Energy

Energy security, reducing air pollution, and carbon emissions are topics of high importance to many countries throughout the world, particularly in Asia where energy use is expected to grow at 3.7 % per year, the highest growth rate in the world. According to the International Energy Agency (IEA), China alone is expected to account for almost one-fourth of world energy demand in the next 20 years. Although low-carbon options like wind and solar have seen large strides in deployment, growing by double and triple digits, the building of new coal plants still outpaces them all by orders of magnitude. In addition, most intermittent sources currently use fossil fuel generators as back up, lowering the potential gains that can be made in emission/carbon reduction goals. To further exacerbate this issue, worldwide electricity production is expected to double by 2040 to meet global needs, where coal is expected to play a major role in supplying that electricity unless an alternative can be found. Given the need to reduce the use of fossil fuels due to emissions/pollution/carbon concerns, and a desire for sustainable and globally scalable energy sources, an “all of the above” strategy for electricity generation has become an imperative. Nuclear power meets the requirements of a non-emitting source, and thus will need to be considered as part of the global energy strategy. However, nuclear energy in its current form has limitations, both perceived and real, regarding economics, waste, proliferation, and safety. In order to further improve on the current generation of reactors, TerraPower has developed the Traveling Wave Reactor (TWR), a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. As a fast reactor, the TWR allows up to a ~35-fold gain in uranium utilization when compared to conventional light water reactors (LWRs) using enriched fuel. Compared to other fast reactors, TWRs represent the lowest cost and lowest risk alternative: (1) they provide the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation and cost concerns of fuel reprocessing; (2) they require less lifetime enrichment than LWRs, translating to a reduced number of enrichment plants that need to be built; (3) they produce less waste by volume than an LWR, resulting in less needed waste capacity requirements and reduced waste transportation costs; and (4) they require less uranium ore to be mined or purchased since natural or depleted uranium can be used directly as fuel. In addition to the benefits described above, the paper also describes the origins and current status of the TWR engineering, design, development, and test programs at TerraPower. Areas covered include the key TWR design challenges, and brief a description of the TWR-Prototype (TWR-P) reactor.

Engineering and Physics Optimization of Breed and Burn Fast Reactor Systems; NUCLEAR ENERGY RESEARCH INITIATIVE (NERI) QUARTERLY PROGRESS REPORT

This project is organized under four major tasks (each of which has two or more subtasks) with contributions among the three collaborating organizations (MIT, INEEL and ANL-West): Task A: Core Physics and Fuel Cycle; Task B: Core Thermal Hydraulics; Task C: Plant Design; Task D: Fuel Design The lead PI, Michael J. Driscoll, has consolidated and summarized the technical progress submissions provided by the contributing investigators from all sites, under the above principal task headings.