Document: NRC Regulatory Guide
Document ID: e0d690ec-277f-4fe2-b92f-7f95d0f589a7
Document Type: regulatory_guide
Title: Preparing Probabilistic Fracture Mechanics (Rev. 0)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2133/ML21334A158.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.245
CFR Part: 
CFR Title: 

Content:
t must be met to achieve success for the desired application. aleatory uncertainty Uncertainty based on the randomness of the nature of the events or phenomena that cannot be reduced by increasing the analyst’s knowledge of the systems being modeled. assumptions A decision or judgment that is made in the development of a model or analysis. best estimate Approximation of a quantity based on the best available information. Models that attempt to fit data or phenomena as best as possible; that is, models that do not intentionally bound data for a given phenomenon or are not intentionally conservative or optimistic. code The computer implementation of algorithms developed to facilitate the formulation and approximation solution of a class of problems. conservative analysis An analysis that uses assumptions such that the assessed outcome is meant to be less favorable than the expected outcome. convergence analysis An analysis with the purpose of assessing the approximation error in the quantity of interest estimates to establish that conclusions of the analysis would not change solely due to sampling uncertainty. correlation A general term for interdependence between pairs of variables. deterministic A characteristic of decision-making in which results from engineering analyses not involving probabilistic considerations are used to support a decision. Consistent with the principles of determinism, which hold that specific causes completely and certainly determine effects of all sorts. Also refers to fixed model inputs. distribution A function specifying the values that the random variable can take and the likelihood they will occur. epistemic uncertainty The uncertainty related to the lack of knowledge or confidence about the system or model; also known as “state-of-knowledge uncertainty.” The American Society of Mechanical Engineers/American Nuclear Society PRA standard (Ref. 24) defines epistemic uncertainty as “the uncertainty attributable to incomplete