Risk-Informed Design of Hydrogen Generation Systems in Nuclear Power Plants
Anthony Ruzzo, Nalin Gadihoke, Junxian Li
A hydrogen economy refers to the envisioned future where hydrogen is the primary fuel for energy storage, transportation, heat, and more. There are numerous methods to generate hydrogen, such as water electrolysis and steam-methane reforming. The former involves processing purified water and running it through electrolyzer cells, which are electrically powered to create a voltage potential across an anode and cathode, thus splitting the water molecules into hydrogen gas and oxygen gas. The electrolyzer may be powered by any source of electricity that can supply the necessary voltage and current, such as solar, wind, or nuclear power. Exelon, the largest single owner of nuclear power plants in the United States, has partnered with Nel Hydrogen and others to implement the design and operation of a 1.0 MW Proton Exchange Membrane (PEM) electrolyzer at one of their nuclear power plants. Since these renewable hydrogen productions methods are relatively new, a comprehensive database for failure events and probabilities does not as exist as does in more developed industries like nuclear and aerospace. Our project involves utilizing several probabilistic risk assessment (PRA) techniques to analyze a medium-scale PEM electrolyzer system. This assessment will lead to design recommendations based on coupling the associated risk of the system along with a cost-benefit analysis of how the recommendations impact reliability and cost.
Lunar Nuclear Reactor
Andrew Christensen, Erik Smith, Kip Kleimenhagen
In order to fulfill the DOE/NASA joint goal of establishing a permanent human presence on the Moon, this design study is intended to create a nuclear power unit capable of meeting the specifications proposed in the Fission Surface Power Request For Proposals (RFP). The RFP details the need for a fission-based nuclear power unit capable of providing 10 kWe to a proposed lunar base while minimizing inhabitant dose rate, in addition to other criteria. The ultimate goal of this design study is to design a lightweight, reliable, safe, and efficient nuclear reactor capable of satisfying the technical requirements set forth by the RFP. The authors reviewed literature and prior studies related to nuclear fission power in space to form an understanding of previous designs in this field. Both a deterministic diffusion reactor core model as well as a SERPENT Monte Carlo simulation model were constructed to perform core neutronics analysis. Additionally, a thermal model was created to determine sufficient heat pipe geometry for core heat removal. Neutron and gamma dosimetry calculations were performed based on the core diffusion model to ensure sufficient reactor shielding. These systems were combined with a free-piston Stirling engine energy conversion cycle and a liquid sodium thermal radiator system to complete the power unit. Finally, a brief analysis beyond technical specifications considered factors such as economics, system reliability, and system scalability