Irradiated Dynamic and Arrest Fracture Toughness Compared to Lower-Bound Predictions PDF Download
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Author: TR. Mager Publisher: ISBN: Category : Crack arrest Languages : en Pages : 8
Book Description
Pressure-temperature operating curves for nuclear reactor pressure vessels are based upon a lower-bound fracture toughness curve which bounds rapid load dynamic initiation and crack arrest fracture toughness data. The ASME Boiler and Pressure Vessel Code defines the reference toughness (KIR) curve as this lower bound, and this KIR curve was developed solely from unirradiated dynamic and arrest fracture toughness data from one heat of SA533B-1 steel (HSST Plate 02) and two heats of SA508-2 steel. The effects of radiation embrittlement on the shape and shift of the KIR curve to account for the increase in reference temperature is thought to be conservative, but this conservatism has not been fully verified. This study reviews available data from past dynamic and arrest toughness tests on irradiated vessel steels from test reactor irradiations and compares the data to the shifted KIR curve using the transition temperature shift approach detailed in Regulatory Guide 1.99, Revision 2. Dynamic initiation and crack arrest fracture toughness data are available from only a few irradiated large specimen tests (that is, test specimens with thicknesses greater than about 51 mm [2 in.]); small specimen tests (including precracked Charpy) are used for the other comparisons. The limited results indicate that the Regulatory approach for shifting the KIR curve is very conservative even when the Regulatory Guide 1.99, Revision 2 "margin term" is not used and a correction for fluence rate is ignored. No change in shape for the dynamic toughness and arrest data (in particular for low upper shelf materials) was observed.
Author: TR. Mager Publisher: ISBN: Category : Crack arrest Languages : en Pages : 8
Book Description
Pressure-temperature operating curves for nuclear reactor pressure vessels are based upon a lower-bound fracture toughness curve which bounds rapid load dynamic initiation and crack arrest fracture toughness data. The ASME Boiler and Pressure Vessel Code defines the reference toughness (KIR) curve as this lower bound, and this KIR curve was developed solely from unirradiated dynamic and arrest fracture toughness data from one heat of SA533B-1 steel (HSST Plate 02) and two heats of SA508-2 steel. The effects of radiation embrittlement on the shape and shift of the KIR curve to account for the increase in reference temperature is thought to be conservative, but this conservatism has not been fully verified. This study reviews available data from past dynamic and arrest toughness tests on irradiated vessel steels from test reactor irradiations and compares the data to the shifted KIR curve using the transition temperature shift approach detailed in Regulatory Guide 1.99, Revision 2. Dynamic initiation and crack arrest fracture toughness data are available from only a few irradiated large specimen tests (that is, test specimens with thicknesses greater than about 51 mm [2 in.]); small specimen tests (including precracked Charpy) are used for the other comparisons. The limited results indicate that the Regulatory approach for shifting the KIR curve is very conservative even when the Regulatory Guide 1.99, Revision 2 "margin term" is not used and a correction for fluence rate is ignored. No change in shape for the dynamic toughness and arrest data (in particular for low upper shelf materials) was observed.
Author: Roger E. Stoller Publisher: ASTM International ISBN: 080311477X Category : Materials Languages : en Pages : 1315
Book Description
Symposium held in Nashville, Tennessee, June 1990. Almost two-thirds of these 91 papers are authored by researchers outside of the US (including information on research in the former USSR, Japan, and Europe). Topics include: current commercial power reactor systems; microstructural characterization
Author: William L. Server Publisher: ISBN: Category : Charpy energy Languages : en Pages : 12
Book Description
Transition temperature shift effects arising from neutron radiation embrittlement in ferritic nuclear pressure vessel materials are currently being evaluated using changes in the Charpy V-notch energy curve; typically, the temperature shift at the 41-J (30 ft-lb) energy level is used. Estimates of the 41 J (30 ft-lb) transition temperature are also projected based upon Nuclear Regulatory Commission Regulatory Guide 1.99, Revision 2. The estimated or measured Charpy shift is then applied to a lower-bound reference toughness KIR curve by moving the curve by the Charpy shift amount. Similarly, the flaw evaluation procedures in nonmandatory Appendix A of Section XI of the ASME Boiler and Pressure Vessel Code utilize the shifts in the equivalent of the KIR curve (termed the KIa curve for crack arrest) and a lower-bound static crack initiation toughness KIc curve. This study reviewed and tested this Code's approach, as well as the statistically based reference toughness method developed by W. Oldfield for estimating global tolerance bounds. Comparisons of actual, but limited, fracture toughness data and the predicted bounding curves indicate that the shifted KIR/KIc curves are generally very conservative. The Oldfield reference toughness approach for 95%-95% tolerance bounds is not as conservative, but may provide a better method. In terms of mean toughness shift behavior, the shifts predicted by Charpy V-notch results are not always a true indicator of the mean fracture toughness shift; however, the other margins included in Regulatory Guide 1.99, Revision 2 and those in the original unirradiated KIR/KIc curves appear to compensate for any nonconservatism in using the Charpy V-notch shift approach.
Author: TR. Mager
Author: TR. Mager
Author: Ravinder Chona
Author: W. L. Server
Author: Roger E. Stoller
Author: Welding Research Council (U.S.)
Author: 
Author: Welding Research Council (U.S.)
Author: 
Author: William L. Server
Author: ASTM International