(20e) Early-Stage Insights into the Quantitative Risk Assessment of Electrolytic Hydrogen Production at Nuclear Power Plants

Nuclear power plants (NPPs) present an attractive opportunity to enable cost-efficient electrolytic hydrogen production in the United States, enabling a new mechanism for clean energy storage and more flexible operating paradigms for NPPs. The ability to deploy electrolyzers at NPPs will rely, in part, on the use of quantitative risk assessment (QRA) to conduct safety analysis that demonstrates conformity with the Nuclear Regulatory Commission (NRC) regulations. Furthermore, QRA can provide insights into design and safety requirements, such as recommendations for plant layout and features that balance in the interplay between risk, safety, reliability, and costs.

To contribute towards this goal, we conducted a failure modes and effects analysis (FMEA) on a proton exchange membrane (PEM) electrolyzer with a maximum input power of 1 MW and hydrogen production capacity of 18 kg per hour. The electrolyzer system was organized and split into six functional groups based on their functional purpose. We identified 740 failure scenarios that lead to four events: hydrogen release, oxygen release, nitrogen release, or hydrogen-oxygen mixing. For each of those four events, we created fault trees (FTs) to provide an overview of the failure logic that can lead to their occurrence. Next, we quantified these fault trees using component failure data from reliability data banks such as the Offshore and Onshore Reliability Database (OREDA), the Center for Chemical Process Safety Process Equipment Reliability Database (PERD), the PDS Reliability Data Handbook, and the Nonelectronic Parts Reliability Database (NPRD). Using the obtained top event probabilities, we developed event sequence diagrams (ESDs) to quantify the frequency of jet fires and explosions and study the effects these events can have on the system. In addition, we conducted a techno-economic analysis to quantify the financial impacts of system downtime due to the failure events identified in the QRA study.

Future work will focus on refining the QRA results and developing system design variants based on component importance measures analysis. Then, these variants will be compared based on the extent of their risk reduction, additional incurred costs, and the benefits of increased uptime and lower maintenance costs.