Uncertainty Characterization of Reactor Vessel Fracture Toughness

Conference · Mon Jul 01 04:00:00 EDT 2002

OSTI ID:21070103

Li, Fei; Modarres, Mohammad ^[1]

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1. University of Maryland, College Park, MD 20742 (United States)

To perform fracture mechanics analysis of reactor vessel, fracture toughness (K{sub Ic}) at various temperatures would be necessary. In a best estimate approach, K{sub Ic} uncertainties resulting from both lack of sufficient knowledge and randomness in some of the variables of K{sub Ic} must be characterized. Although it may be argued that there is only one type of uncertainty, which is lack of perfect knowledge about the subject under study, as a matter of practice K{sub Ic} uncertainties can be divided into two types: aleatory and epistemic. Aleatory uncertainty is related to uncertainty that is very difficult to reduce, if not impossible; epistemic uncertainty, on the other hand, can be practically reduced. Distinction between aleatory and epistemic uncertainties facilitates decision-making under uncertainty and allows for proper propagation of uncertainties in the computation process. Typically, epistemic uncertainties representing, for example, parameters of a model are sampled (to generate a 'snapshot', single-value of the parameters), but the totality of aleatory uncertainties is carried through the calculation as available. In this paper a description of an approach to account for these two types of uncertainties associated with K{sub Ic} has been provided. (authors)

• Research Organization: The ASME Foundation, Inc., Three Park Avenue, New York, NY 10016-5990 (United States)
• OSTI ID: 21070103
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CALCULATION METHODS
DECISION MAKING
FRACTURE MECHANICS
FRACTURE PROPERTIES
FRACTURES
RANDOMNESS
REACTOR VESSELS