NDT ( RT ) Theory and Demonstration

A: Governing principle: contractual invocation of a standard fixes the technical acceptance basis. Applied here: ISO 17636 density limits exist to bound contrast and noise for defect detectability, and changing editions shifts assumptions on film systems and viewers. Unless the contract or MOC updates the reference, the invoked edition controls. The trap is option B, which appeals to good intent but ignores that acceptance criteria are not retroactive without contract language.

A: Governing principle: exposure is proportional to source strength and time, and inversely proportional to distance squared. Applied here: converting 3.5 TBq to 3500 GBq and applying the constant at 0.6 m yields a time on the order of tens of seconds to a couple of minutes, not single digits or many minutes. Option C catches people who overweight thickness without running the math.

A: Governing principle: environment and temperature control dominant degradation modes. Applied here: wet insulation and moderate temperature favor external CUI, which RT can reveal as uneven wall reduction, while internal mechanisms need different conditions. Option D tempts process engineers who focus on flow but ignore the external moisture driver.

A: Governing principle: sensitivity metrics are standard-specific and not directly interchangeable. Applied here: ISO and ASTM define IQI performance differently, so using the system tied to the invoked standard is how 2% sensitivity is made meaningful. Option B catches engineers who know what 2% means but forget how each system measures it.