Technical Basis for Revisions to ASME Section XI Acceptance Standards for Surface Flaws in Piping in Stress Corrosion Cracking Susceptible Materials
Bibliographic record
Abstract
Acceptance Standards for flaws in piping are provided in Section XI of the ASME B&PV Code to permit acceptance of relatively small flaws without the need to perform an analytical evaluation. The Acceptance Standards are based on maintaining large margins against failure, and are based on the assumption that flaw growth will be insignificant. The assumption of a small amount of flaw growth is justified when fatigue crack growth is the only crack growth mechanism. However, when stress corrosion cracking is operative, flaw growth could be significant. This conclusion was illustrated by comparison of the crack growth results due to fatigue and stress corrosion cracking in Pressurized Water Reactor (PWR), and Boiling Water Reactor (BWR), coolant environments. For this reason, IWB-3514 of Section XI prohibits use of the Acceptance Standards for planar surface-connected flaws that are detected in piping materials that are susceptible to stress corrosion cracking and are in reactor coolant environments. As part of a recent Code revision to include new Acceptance Standards tables for flaws in piping, restrictions on use of the Acceptance Standards of IWB-3514 have been refined and clarified. The recent Code revision now specifies different restrictions and requirements for use of the Acceptance Standards for such planar surface-connected flaws detected by preservice and inservice examination. In addition, similar restrictions have been imposed on use of the new Acceptance Standards for such planar surface-connected flaws in Class 2 piping in IWC-3514 of Section XI. The technical basis for the restrictions and requirements for use of the Acceptance Standards for planar surface-connected flaws in piping materials that are susceptible to stress corrosion cracking is provided in this paper.
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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 | 0.024 | 0.073 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.007 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.005 | 0.004 |
| Open science | 0.005 | 0.003 |
| Research integrity | 0.006 | 0.006 |
| Insufficient payload (model declined to judge) | 0.037 | 0.047 |
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".