Safety System and Control System Separation Requirements for ACR-1000™ and Operating CANDU® Reactors
Bibliographic record
Abstract
Digital control and safety plus the complete functional and physical separation between control and safety and also between the safety systems have been key long standing principles of CANDU® nuclear reactor technology. This paper presents a historical evolution of these principles that make CANDU reactors one of the safest technologies in the world today. The original Generation II CANDU 6 reactors started with complete separation of control from safety and the division of safety systems into two groups having strong physical separation such as opposite sides of the reactor or reactor building. Within each group a more moderate distance separation was employed. With the advent of distributed computer technology for control and display functions, key processing equipment is now moved out remote from the control rooms and distributed into channelized field equipment rooms around the reactor building as in the Four-Quadrant concept for ACR-1000™. This new approach is immune to total unavailability of any control room or equipment room due to events such as fire with minimal impact to any of the safety systems regardless of their grouping. In addition to physical separation, appropriate functional partitioning, design rules to avoid communication cross links, and diversity principles are applied to computer based I&C systems as defences against common cause faults.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.013 | 0.006 |
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".