자료유형  

 학위논문

Control Number  

0017162426

International Standard Book Number  

9798383045565

Dewey Decimal Classification Number  

539.76

Main Entry-Personal Name  

Fang, Ming.

Publication, Distribution, etc. (Imprint  

[S.l.] : University of Illinois at Urbana-Champaign., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

219 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-01, Section: B.

General Note  

Advisor: Di Fulvio, Angela.

Dissertation Note  

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2024.

Summary, Etc.  

요약Tristructural-isotropic (TRISO) fuel is currently one of the most mature fuel types for pebble bed reactor (PBR) designs, such as pebble-bed high-temperature gas-cooled reactors (HTGCR) and fluoride-salt-cooled high-temperature reactors (FTR). Fuel units in PBR are made in the form of a billiard-size ball, which contains thousands of randomly-distributed TRISO fuel particles of 500-1000 µm diameter surrounded by graphite or silicon carbide (SiC). In PBRs, TRISO-fueled pebbles can be re-introduced into the reactor core several times to thoroughly burn the fuel. Reliable techniques to individually tag and identify fuel pebbles are therefore needed to maintain accountability of special nuclear material and gain a detailed understanding of pebble history, burnup, and structural integrity throughout the pebble's lifespan. The identification techniques should be non-destructive, fast, and robust to meet the PBR's operational constraints.In this dissertation, two non-destructive assay (NDA) methods for TRISO-fueled pebble characterization, namely neutron multiplicity counting and X-ray computed tomography (CT), have been developed, simulated, and experimentally demonstrated. Based on these two NDA methods, unique identification of a pebble was achieved for a PBR core consisting of 100,000 pebbles in 150 s.The identification relies on retrieving unique features associated with each fuel pebble, namely the 235U mass and the three-dimensional (3D) spatial distribution of TRISO fuel particles. Within this framework, a new type of neutron multiplicity counter (NMC) was designed to assess the 235U mass in TRISO fuel pebbles. The NMC is based on pie-shaped boron-coated straw (BCS) detectors and features superior gamma-ray insensitivity, thermal neutron detection efficiency, and assay accuracy, when compared to multiplicity counters based on 3He or organic scintillators. The NMC achieved a die-away time of 16.7 µs, approximately 61% lower than the 3He-based and 35% lower than the round BCS-based counter. A short die-away time is desirable to minimize the impact of random coincidence due to uncorrelated events and improve assay accuracy. The experimentally validated NMC model showed that this approach allows the estimation of the 235U mass in 100 seconds with a relative uncertainty below 2.5% (1-SD). The 3D spatial distribution of TRISO particles in a mock-up TRISO fuel compact was reconstructed with a North Star X5000 industrial CT system and custom image reconstruction algorithms. A point cloud registration-based identification algorithm was developed to retrieve the pebble identity in the presence of noises and arbitrary rotations. The CT scan, image reconstruction, particle segmentation, and pebble identification process took approximately 50 s for one pebble. An identification accuracy of 100% was achieved for a PBR core consisting of 100,000 pebbles.

Subject Added Entry-Topical Term  

Nuclear engineering.

Subject Added Entry-Topical Term  

Nuclear physics.

Subject Added Entry-Topical Term  

Engineering.

Subject Added Entry-Topical Term  

Medical imaging.

Index Term-Uncontrolled  

Neutron multiplicity counting

Index Term-Uncontrolled  

Pebble bed reactor

Index Term-Uncontrolled  

Pebble identification

Index Term-Uncontrolled  

Boron-coated straw

Index Term-Uncontrolled  

Safeguards

Index Term-Uncontrolled  

Tristructural-isotropic

Added Entry-Corporate Name  

University of Illinois at Urbana-Champaign Physics

Host Item Entry  

Dissertations Abstracts International. 86-01B.

Electronic Location and Access  

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Control Number  

joongbu:654685