Material Type  

 학위논문

 

0017164362

Date and Time of Latest Transaction  

20250211152953

ISBN  

9798384042082

DDC  

539.76

Author  

Welker, Zachary.

Title/Author  

High-Resolution Fluid Dynamic Experiments of Selected High-Temperature Gas-Cooled Reactor Accident Scenarios.

Publish Info  

[S.l.] : University of Michigan., 2024

Publish Info  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Material Info  

189 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-03, Section: A.

General Note  

Advisor: Manera, Annalisa;Petrov, Victor.

학위논문주기  

Thesis (Ph.D.)--University of Michigan, 2024.

Abstracts/Etc  

요약Two experimental Separate Effect Test (SET) facilities were designed and constructed to study the Pressurized Loss of Forced Cooling (PLOFC), Depressurized Loss of Forced Cooling (DLOFC), and Air Ingress accident scenarios for High-Temperature Gas-cooled Reactors (HTGRs). The facilities had the dual goals of physics discovery and generating a validation database for simulation codes that can be used for HTGR accident analysis. The first facility, the Helium Air Ingress gas Reactor Experiment (HAIRE), is a scaled SET based on the General Atomics GT-MHR. Experiments with HAIRE focused on small- and medium-sized air ingress scenarios, which have few experimental campaigns in comparison to less frequent, larger air ingress accidents. In addition to providing high-resolution validation data, HAIRE's data showed that the air ingress rate for smaller-sized breaks will be larger than previous theories would predict. HAIRE showed that the increase in exchange rate is due to a combined buoyant-diffusive flow. A modified correlation was made that combines previously understood unstable buoyant exchange theory and a new non-dimensional number. The new correlation well captures the exchange rate prediction seen from the experimental campaign. The new correlation considers the ratio between buoyant forces and diffusion forces for unstable buoyant flows, and the correlation converges to the previous theory in the case where diffusion effects are negligible. The second facility, the Refractive Indexed Matched PebbLe bEd (RIMPLE), is a scaled SET based on the HTR-PM. The RIMPLE takes a step forward in high-resolution pebble bed experiments, where 15,000 pebbles are present in a quarter-core experiment. The facility is designed to study the pebble bed to upper plenum transition regions during PLOFC and DLOFC accident scenarios. For high-resolution pebble bed experiments, the pebble bed must be 3D reconstructed to create a relevant model for comparison. The 3D reconstruction technique was evaluated for error sources and propagation so that experiments and simulations can be compared, and grounded with appropriate error consideration. This study is novel because it is the first to propagate the effects into positional uncertainty in the pebble bed reconstruction, rather than reporting as camera pixel uncertainty. HAIRE has generated a database for simulation tool validation, and RIMPLE is poised to do the same. These databases are invaluable for HTGRs simulation validation, and showing these tools can be confidently used for licensing of HTGRs for power generation. Additionally, HAIRE has provided insight into an infrequently studied flow condition of combined buoyant-diffusive flow where a possible new non-dimensional was utilized.

Subject Added Entry-Topical Term  

Nuclear engineering.

Subject Added Entry-Topical Term  

Computer engineering.

Subject Added Entry-Topical Term  

Energy.

Subject Added Entry-Topical Term  

Sustainability.

Index Term-Uncontrolled  

High temperature gas cooled reactors

Index Term-Uncontrolled  

Buoyo-diffusive flow

Index Term-Uncontrolled  

Air ingress

Added Entry-Corporate Name  

University of Michigan Nuclear Engineering & Radiological Sciences

Host Item Entry  

Dissertations Abstracts International. 86-03A.

Electronic Location and Access  

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Control Number  

joongbu:657368