Potential impact of enhanced fracture-toughness data on pressurized-thermal-shock analysis
The Heavy Section Steel Technology (HSST) Program is involved with the generation of enhanced'' fracture-initiation toughness and fracture-arrest toughness data of prototypic nuclear reactor vessel steels. These two sets of data are enhanced because they have distinguishing characteristics that could potentially impact PWR pressure vessel integrity assessments for the pressurized-thermal shock (PTS) loading condition which is a major plant-life extension issue to be confronted in the 1990's. Currently, the HSST Program is planning experiments to verify and quantify, for A533B steel, the distinguishing characteristic of elevated initiation-fracture toughness for shallow flaws which has been observed for other steels. Deterministic and probabilistic fracture-mechanics analyses were performed to examine the influence of the enhanced initiation and arrest fracture-toughness data on the cleavage fracture response of a nuclear reactor pressure vessel subjected to PTS loading. The results of the analyses indicated that application of the enhanced K{sub Ia} data does reduce the conditional probability of failure P(F{vert bar}E); however, it does not appear to have the potential to significantly impact the results of PTS analyses. The application of enhanced fracture-initiation-toughness data for shallow flaws also reduces P(F{vert bar}E), but it does appear to have a potential for significantly affecting the results of PTS analyses. The effect of including Type I warm prestress in probabilistic fracture-mechanics analyses is beneficial. The benefit is transient dependent and, in some cases, can be quite significant. 19 refs., 12 figs., 1 tab.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- DOE/NE; NRC
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6773256
- Report Number(s):
- CONF-9010185-2; ON: DE91001493
- Country of Publication:
- United States
- Language:
- English
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210200* -- Power Reactors
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Light-Water Moderated
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36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
ACCIDENTS
ALLOYS
CONTAINERS
CRACK PROPAGATION
CRACKS
FRACTURE MECHANICS
IRON ALLOYS
IRON BASE ALLOYS
LOSS OF COOLANT
MECHANICAL PROPERTIES
MECHANICS
PRESSURE VESSELS
PWR TYPE REACTORS
REACTOR ACCIDENTS
REACTORS
STEELS
THERMAL SHOCK
WATER COOLED REACTORS
WATER MODERATED REACTORS