TY - GEN
T1 - Analysis of the Belgian surveillance fracture toughness database using conventional and advanced master curve approaches
AU - Lucon, Enrico
AU - Scibetta, Marc
AU - Gérard, Robert
PY - 2010
Y1 - 2010
N2 - The "classical" regulatory approach to the analysis of surveillance capsules in nuclear power plants entails an indirect estimate of the fracture toughness of the beltline materials, by inferring rather than measuring their toughness properties. Indeed, the irradiation-induced shift of the fracture toughness curve is assumed to be equal to the shift of the Charpy absorbed energy transition curve at a predefined level (41 J). An alternative surveillance approach, primarily based on direct fracture toughness measurements in the ductile-to-brittle transition region using the Master Curve procedure, has been applied to surveillance materials from several Belgian nuclear power plants in the past 15 years. This has led to the establishment of a significant database, consisting of 292 fracture toughness data points for 23 material conditions (unirradiated materials and surveillance capsules). In this study, different temperature normalization approaches are applied to the available data. The analyses show that data clearly follow the Master Curve formalism. Moreover, it is confirmed that both the static (KIc) and the dynamic (KIR) curves of the ASME Code Section XI provide an effective lower bound to the measured results, although more conservatism is evident when using RTNDT as the normalization parameter. Both the conventional (ASTM E1921-08, "Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range") and advanced (Multi-Modal) Master Curve analyses of the database clearly demonstrate that normalizing data by (T-RTT0) provides the best rationalization of the available information and the most effective representation of the experimental scatter.
AB - The "classical" regulatory approach to the analysis of surveillance capsules in nuclear power plants entails an indirect estimate of the fracture toughness of the beltline materials, by inferring rather than measuring their toughness properties. Indeed, the irradiation-induced shift of the fracture toughness curve is assumed to be equal to the shift of the Charpy absorbed energy transition curve at a predefined level (41 J). An alternative surveillance approach, primarily based on direct fracture toughness measurements in the ductile-to-brittle transition region using the Master Curve procedure, has been applied to surveillance materials from several Belgian nuclear power plants in the past 15 years. This has led to the establishment of a significant database, consisting of 292 fracture toughness data points for 23 material conditions (unirradiated materials and surveillance capsules). In this study, different temperature normalization approaches are applied to the available data. The analyses show that data clearly follow the Master Curve formalism. Moreover, it is confirmed that both the static (KIc) and the dynamic (KIR) curves of the ASME Code Section XI provide an effective lower bound to the measured results, although more conservatism is evident when using RTNDT as the normalization parameter. Both the conventional (ASTM E1921-08, "Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range") and advanced (Multi-Modal) Master Curve analyses of the database clearly demonstrate that normalizing data by (T-RTT0) provides the best rationalization of the available information and the most effective representation of the experimental scatter.
KW - Ductile-to-brittle transition region
KW - Fracture toughness
KW - Master curve
KW - Multi-modal master curve
KW - Surveillance capsules
UR - http://www.scopus.com/inward/record.url?scp=77954371192&partnerID=8YFLogxK
U2 - 10.1520/stp49001s
DO - 10.1520/stp49001s
M3 - In-proceedings paper
AN - SCOPUS:77954371192
SN - 9780803134256
T3 - ASTM Special Technical Publication
SP - 26
EP - 39
BT - Effects of Radiation on Nuclear Materials and the Nuclear Fuel Cycle
PB - American Society for Testing and Materials
T2 - 24th ASTM Symposium on Effects of Radiation on Nuclear Materials and the Nuclear Fuel Cycle
Y2 - 24 June 2008 through 26 June 2008
ER -