ACR-1000™ Level 1 PSA Summary
Bibliographic record
Abstract
The ACR-1000™ developed by Atomic Energy of Canada Limited (AECL) is a 1200 MWe - pressure tube type, light-water-cooled and heavy-water-moderated reactor, which has evolved from the well-established CANDU™ line of reactors. It retains the basic proven CANDU design features while incorporating innovations and state-of-the-art technologies to ensure fully competitive safety, operation, performance and economics. The major innovation in the ACR-1000 is the use of slightly enriched uranium fuel and light water coolant. ACR-1000 is a four-quadrant design (for easier maintenance and improved reliability). There are five safety systems in the ACR-1000; (i) two independent, diverse and fast acting shutdown systems (SDS1 and SDS2), which are physically and functionally independent from each other and from the reactor regulating system; (ii) Emergency core cooling system; (iii) Emergency Feedwater system; and (iv) Containment system, which includes a strong steel-lined containment structure. In addition the Reserve water system provides feedwater to the heat transport system, steam generators, moderator and shield cooling system for beyond design basis accidents. The Level 1 Probabilistic Safety Assessment (PSA) is conducted in support of the design phase of the ACR-1000. The purpose of Level 1 PSA is to identify whether the ACR-1000 design targets and the regulatory safety goal for severe core damage frequency (SCDF) are met with adequate margin and provide design feedback. An interim Level 1 PSA was conducted for internal at-power events. Interim assessments were conducted for shutdown state, internal fire and flood at-power events. An interim seismic margin assessment was conducted for the seismic events. The Level 1 PSA results show that the ACR™ design targets and safety goal for SCDF are met with significant safety margin. Based on the ACR-1000 Level 1 PSA, the accident behaviours of the ACR-1000 are well understood and their consequences can be predicted with a high-level of confidence. It also provides sufficient assurance that the release based regulatory safety goals are achievable for ACR-1000. The Level 1 PSA results also signify a robust design that provides a strong foundation for the ACR-1000 design. The paper summarizes the Level 1 PSA program, methodology followed, the results obtained, and insights gained during the development of the ACR-1000 Level 1 PSA.
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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 | 0.009 | 0.010 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.005 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.162 | 0.088 |
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".