In order to be useful a physical measurement or calculation must be assigned a justifiable statement of theassociated total measurement uncertainty (TMU) which is fit for purpose. Uncertainty quantification (UQ) is the processof placing probabilistic bounds on the confidence we have in our state of knowledge or understanding, reporting thebounds, and explaining how the bounds were obtained. UQ is a vital aspect in quality nondestructive assays (NDA).Guidance available to the NDA community on formulating and expressing uncertainties is scattered throughouttechnique-specific reports. It is difficult to find, often not current, and can be confusing because of the variety ofnotations and terminology that have been used over the years. ASTM sub-committee C26.10 is responsible for writingand maintaining guides and standards on a diverse range of commonly used NDA methods for nuclear safety,safeguards, security, and waste. Constructing and verifying total measurement uncertainty budgets that are suitable forthe end user has been recognized as a complex and specialist task. Statistical methods and tools have advancedsubstantially in the past decade rendering certain previous assumptions and simplifications unnecessary. Theopportunity to create a rational and consistent UQ framework across techniques is also evident and will promote betterunderstanding and good practice. To address these issues, preparation of a consensus guide for the determination ofTMU in NDA measurement results has begun. This is intended to be a valuable resource for, amongst others, subjectmatter experts, instrument operators, instrument designers, facility managers, instructors, and end users of NDA data. Inthis paper we discuss the importance of this activity to the NDA measurement community and solicit input to theprocess. We illustrate the discussion with a pertinent few examples.
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