Pre-registration, Version 8: Does the Tube Wall, the Heating Method, the Detection Method or the Coolant Change Water CHF? A Blind Test in Matched Same-Rig Comparisons

Pre-registration of a blind test, frozen on 12 October 2026 before any CHF value of a test source was seen. The 2006 look-up table predicts critical heat flux (CHF) in water from pressure, mass flux and quality, with a factor for diameter. It has no term for the tube wall, the way the tube is heated, the way CHF is detected, or the state of the water. This record tests whether those factors change measured CHF. The test uses pairs of measurements from one rig that differ in a single factor under matched conditions. The score is d = ln(q_x/q_y) − c, where c removes only the condition mismatch the tolerances allow, using the table at each variant’s own inlet conditions. Fifteen hypotheses are scored, each on its own: wall thickness and wall material (whether their effects exceed noise at low flow and fade at high flow), the author’s committed directions that thicker walls and walls of higher thermal effusivity give higher CHF, four heating methods, detection method, dissolved gas, additives, and heavy against light water, with an equivalence claim that scaling by latent heat accounts for the heavy-water difference. Verdicts come from exact sign tests on rig means, so laboratories that differ from each other cannot pass a hypothesis by themselves. Test sources were found by searches that recorded no results; two separate agents will classify them without seeing CHF values and then extract the data. A development round that added a tube-material term to version 7 failed on the NRC data and is reported. Unseen same-rig data on wall thickness in flowing water appear not to exist, and most other factors have too few rigs for a verdict, so many results are expected to be void or underpowered. The author keeps every hypothesis and treats that shortage as a finding: wall thickness and material, heating method, detection method, water condition and coolant should be reported as standard in CHF experiments. An independent AI audit found 2 critical, 10 major and 15 minor problems in the first draft; all were addressed before freezing, and the audit and the response are deposited. The consistency pass, executed in code, is deposited with both of its runs. Archive SHA-256: 2d54289cbc82ac6a0ae9a7788471445a10f3a2f60d8a733603df05b8477f4c0c