Experimental Investigation of Combined Axial Flow and Jet Cross-Flow on PWR Mock-Up Array
Bibliographic record
Abstract
Abstract Some pressurized water reactors (PWRs) are designed to relieve the pressure increase in the barrel-baffle region associated with a loss of coolant accident (LOCA). Flow holes, called LOCA holes, are introduced in the baffle plates to equalize the pressure difference between the core side and the barrel-baffle region. However, it has been found that jet flow emanating from LOCA holes induces fretting wear of the fuel rods at the spacer grid position during normal operation. The effect of jet in transverse flow (JITF) on a PWR mock-up array should be investigated in order to determine the rod array response and, as a result, to set safe operating conditions for these reactors. This research looks at the effect of axial flow velocity on the stability of a single-span 6 × 5 square rod bundle having a prototypical fuel assembly dimensions in some designs of pressurized water reactor cores. The axisymmetrically flexible rods in the highly compact array are instrumented with four strain gauges to measure the two-dimensional rod displacements. Then, the response of the rod bundle under combined flows (i.e. JITF) is measured for three test axial flow velocities, VAxial = 1.0 m/s, 1.5 m/s, and 2.0 m/s. The experimental results show that the critical jet cross-flow velocity increases with the axial flow velocity. This is attributed to the bending effect of axial flow on the jet flow (i.e. jet trajectory). The critical flow velocities are collected to provide a stability map of the arrays subjected to the jet in transverse flow.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".