Theoretical Investigation of Rocking Frames under Horizontal Seismic Excitation with Application to Nuclear Facilities
Bibliographic record
Abstract
The seismic risk of a nuclear power plant (NPP) depends on structures, systems and components (SSCs) that are seismically qualified to a design basis earthquake (DBE) in Canada or a safe shutdown earthquake (SSE) in the United States. On the other hand, there exist some components that are not essential to safety but their seismic interaction with seismically-qualified SSCs adversely affects the seismic risk of such SSCs. Rocking frames consisting of a rigid beam freely supported by piers (e.g., a 150 Ton spare turbine rotor, or a 100 Ton idle steam generator resting on triangular or trapezoidal rigid piers) are common to NPPs. Seismic interaction of such frames with seismically-qualified safety components or their host structure may be detrimental to nuclear safety as witnessed in the 2013 Arkansas Nuclear One accident where the drop of a 500 Ton stator adversely impacted the severe core damage frequency of the entire plant, negatively affecting the nuclear risk. In order to ensure nuclear safety, it is essential to quantify the risk of a heavy component’s drop owing to a rocking frame’s instability caused by design basis accidents including seismic. A rocking frame’s beam support may be concentric or eccentric with respect to the pier’s center of mass depending on it’s geometry, for example, triangular or trapezoidal respectively. The current nuclear standards, ASCE 43-19 and CSA N289.1-2018 are silent about rocking frames. Literature has also not addressed the eccentricity variation. This thesis addresses the gap on seismic qualification of rocking frames by, establishing an equivalent rocking block for rocking frames with symmetrical support eccentricities, obtaining the response of frames with unsymmetrical support eccentricities and finally examining the stability of the two types of frames under slide restrained conditions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.015 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".