Pickering B Nuclear Power Generating Station Condenser Performance Improvement
Bibliographic record
Abstract
The Ontario Power Generation (OPG) Pickering B Facility consists of four 540 MW nuclear generating units. Each unit is furnished with a once-through Condenser Cooling Water (CCW) System that uses Lake Ontario water. Zebra mussels (Dreissena polymorpha) are infesting the condenser cooling water intakes at Pickering. The mature mussels and their shells become entrained in the CCW, are deposited in the condenser inlet water boxes, and become lodged in the condenser tube sheets and within the tubes. As a result, the flow through the condenser is reduced, and the existing Condenser Tube Cleaning System (CTCS) performance is degraded. This reduces the Turbine-Generator generating capability that results in a loss of electric generation revenues for OPG, and increased maintenance costs to manually remove the zebra mussels from the condenser. OPG decided to install Debris Filters in the six 72-inch diameter inlets of each of the four Pickering B units to automatically remove the zebra mussels before they enter the condensers and discharge them back into the lake. The Debris Filters for Unit 8 were installed during a scheduled outage in the winter of 2001/2002. The Unit 5 installation was completed at the end of 2002 and the Unit 6 & 7 installations are scheduled for 2003. The installed equipment is performing as expected. The zebra mussels are intercepted by the Debris Filter, and are automatically discharged into the condenser bypass and returned to the lake. The CTCS system can again perform its intended function to prevent bio-fouling buildup inside the condenser tubes. As a result, generation capacity increased and maintenance expenditures decreased with a net result of increased revenues for OPG.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.020 | 0.004 |
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".