Estimation of Master Curve Based RTTO Reference Temperature From CVN Data

The ASME code cases N-629 and N-631 permit the use of a master curve-based index temperature (RTTo≡T0+19.4°C) as an alternative to traditional RTNDT-based methods of positioning the ASME KIC and KIR curves. This approach was adopted to enable the use of master curve technology without requiring the wholesale changes to the structure of the ASME code that would be needed to use all aspects of master curve technology. For the brittle failure analysis considering irradiation embrittlement an additional procedure to predict the adjustment of fracture toughness for end of life (EOL) from irradiation surveillance results must be available as by NRC R.G. 1.99 Rev. 2, e.g., the adjusted reference temperature is defined as ART=initialRTNDT+ΔRTNDT+margin. The conservatism of this procedure when RTNDT is replaced by RTTo is investigated for western nuclear grade pressure vessel steels and their welds. Based on a systematic evaluation of nearly 100 different irradiated material data sets, a simple relation between RTToirr, RTToref, and ΔT41JRG is proposed. The relation makes use of the R.G. 1.99 Rev. 2 and enables the minimizing of margins, necessary for conventional correlations based on temperature shifts. As an example, the method is used to assess the RTTo as a function of fluence for several German pressure vessel steels and corresponding welds. It is shown that the method is robust and well suited for codification.

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Estimation of Master Curve Based RTTo Reference Temperature From CVN Data

Volume 6: Materials and Fabrication ◽

10.1115/pvp2005-71135 ◽

2005 ◽

Author(s):

Kim R. W. Wallin ◽

Gerhard Nagel ◽

Elisabeth Keim ◽

Dieter Siegele

Keyword(s):

Fracture Toughness ◽

Pressure Vessel ◽

Brittle Failure ◽

Master Curve ◽

Simple Relation ◽

Systematic Evaluation ◽

Data Sets ◽

Irradiation Embrittlement ◽

Pressure Vessel Steels ◽

Asme Code

The ASME code cases N-629 and N-631 permits the use of a Master Curve-based index temperature (RTTo ≡ T0 + 19.4°C) as an alternative to traditional RTNDT-based methods of positioning the ASME KIc, and KIR curves. This approach was adopted to enable use of Master Curve technology without requiring the wholesale changes to the structure of the ASME Code that would be needed to use all aspects of Master Curve technology. For the brittle failure analysis considering irradiation embrittlement additionally a procedure to predict the adjustment of fracture toughness for EOL from irradiation surveillance results must be available as by NRC R.G. 1.99 Rev. 2 e.g.: ART = Initial RTNDT + ΔRTNDT + Margin. The conservatism of this procedure when RTNDT is replaced by RTTo is investigated for western nuclear grade pressure vessel steels and their welds. Based on a systematic evaluation of nearly 100 different irradiated material data sets, a simple relation between RTToirr, RTToref and ΔT41JRG is proposed. The relation makes use of the R.G. 1.99 Rev. 2 and enables the minimizing of margins, necessary for conventional correlations based on temperature shifts. As an example, the method is used to assess the RTTo as a function of fluence for several German pressure vessel steels and corresponding welds. It is shown that the method is robust and well suited for codification.

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Validation of RTT0 for German Reactor Pressure Vessel Steels

Journal of Pressure Vessel Technology ◽

10.1115/1.2937737 ◽

2008 ◽

Vol 130 (3) ◽

Cited By ~ 2

Author(s):

Dieter Siegele ◽

Elisabeth Keim ◽

Gerhard Nagel

Keyword(s):

Fracture Toughness ◽

Pressure Vessel ◽

Master Curve ◽

Reactor Pressure Vessel ◽

Reference Temperature ◽

Data Sets ◽

Asme Code ◽

Definition Of ◽

Size Adjustment ◽

Reactor Pressure

For the introduction of the new reference temperature RTT0 of the ASME Code Cases N-629 and N-631 into the German Standard KTA 3201.2, the applicability of RTT0 was validated by the reevaluation of the existing fracture toughness database of German reactor pressure vessel. (RPV) steels including unirradiated and irradiated base materials and weld metal data. The test temperatures of the database were standardized to the reference temperature T0 of the master curve of the data sets and the database was compared with the ASME KIC-curve as adjusted by RTT0. The KIC-curve adjusted by RTT0 enveloped both the 1T-size adjusted database and also the as-measured database, corresponding to the definition of RTT0. Thus, the results also prove the validity of the KIC(RTT0)-curve for allowable flaw sizes and up to the crack length spectrum of the ASME KIC-database without size adjustment of T0. The results of both investigations confirmed the validity of RTT0 for German RPV steels. The majority of existing fracture toughness data are based on KIC-values. More recent data are (KJC) related to the issuing of ASTM E 1921 in 1997 and to the success of the master curve-based T0 approach. Therefore, the possible difference between T0 determined from KJC and from KIC was investigated with available databases for RPV steels. The comparison of T0(KJC) and T0(KIC) showed a 1:1 correlation proving the equivalence of KJC and KIC in the determination of T0.

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Application of the Master Curve Approach for the Irradiation Embrittlement Evaluation of Pressure Vessel Steels

steel research international ◽

10.1002/srin.200300235 ◽

2003 ◽

Vol 74 (9) ◽

pp. 577-583

Author(s):

Hans-Werner Viehrig ◽

Jürgen Böhmert

Keyword(s):

Pressure Vessel ◽

Master Curve ◽

Irradiation Embrittlement ◽

Pressure Vessel Steels

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Validation of RTTo for German Reactor Pressure Vessel Steels

Volume 6: Materials and Fabrication ◽

10.1115/pvp2005-71197 ◽

2005 ◽

Author(s):

Elisabeth Keim ◽

Dieter Siegele ◽

Gerhard Nagel

Keyword(s):

Data Base ◽

Base Material ◽

Measured Data ◽

Reference Temperature ◽

Data Sets ◽

Pressure Vessel Steels ◽

Asme Code ◽

Definition Of ◽

Size Adjustment ◽

Reactor Pressure

For the introduction of the new reference temperature RTTo of the ASME Code Cases N-629 and N-631 into the German KTA rules the equation RTTo = T0 + 19,4 °C (35 °F) was validated by the re-evaluation of the existing fracture toughness data base of German RPV steels, including unirradiated and irradiated base material and weld metal data. The test temperatures of the data base were standardized to the reference temperature T0 of the Master Curve of the data sets and the data base was compared with the ASME KIc-curve as adjusted by RTTo. The KIc-curve adjusted by RTTo enveloped both, the 1T-size adjusted data base and also the as measured data base, corresponding with the definition of RTTo. Thus the results also prove the validity of the KIc(RTTo)-curve for allowable flaw sizes and up to the crack length spectrum of the ASME KIC-data base without size adjustment of T0. The results of both investigations confirmed the validity of RTTo for German RPV steels.

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Effect of Loading Rate on Fracture Toughness of Pressure Vessel Steels

Journal of Pressure Vessel Technology ◽

10.1115/1.556176 ◽

2000 ◽

Vol 122 (2) ◽

pp. 125-129 ◽

Cited By ~ 8

Author(s):

K. K. Yoon ◽

W. A. Van Der Sluys ◽

K. Hour

Keyword(s):

Fracture Toughness ◽

Pressure Vessel ◽

Master Curve ◽

Loading Rate ◽

Dynamic Fracture Toughness ◽

Reference Temperature ◽

Ferritic Steels ◽

Transition Range ◽

High Loading Rate ◽

Pressure Vessel Steels

The master curve method has recently been developed to determine fracture toughness in the brittle-to-ductile transition range. This method was successfully applied to numerous fracture toughness data sets of pressure vessel steels. Joyce (Joyce, J. A., 1997, “On the Utilization of High Rate Charpy Test Results and the Master Curve to Obtain Accurate Lower Bound Toughness Predictions in the Ductile-to-Brittle Transition, Small Specimen Test Techniques,” Small Specimens Test Technique, ASTM STP 1329, W. R. Corwin, S. T. Rosinski, and E. Van Walle, eds., ASTM, West Conshohocken, PA) applied this method to high loading rate fracture toughness data for SA-515 steel and showed the applicability of this approach to dynamic fracture toughness data. In order to investigate the shift in fracture toughness from static to dynamic data, B&W Owners Group tested five weld materials typically used in reactor vessel fabrication in both static and dynamic loading. The results were analyzed using ASTM Standard E 1921 (ASTM, 1998, Standard E 1921-97, “Standard Test Method for the Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range,” 1998 Annual Book of ASTM Standards, 03.01, American Society for Testing and Materials, West Conshohocken, PA). This paper presents the data and the resulting reference temperature shifts in the master curves from static to high loading rate fracture toughness data. This shift in the toughness curve with the loading rate selected in this test program and from the literature is compared with the shift between KIc and KIa curves in ASME Boiler and Pressure Vessel Code. In addition, data from the B&W Owners Group test of IAEA JRQ material and dynamic fracture toughness data from the Pressure Vessel Research Council (PVRC) database (Van Der Sluys, W. A., Yoon, K. K., Killian, D. E., and Hall, J. B., 1998, “Fracture Toughness of Ferritic Steels and ASTM Reference Temperature T0,” BAW-2318, Framatome Technologies. Lynchburg, VA) are also presented. It is concluded that the master curve shift due to loading rate can be addressed with the shift between the current ASME Code KIc and KIa curves. [S0094-9930(00)01302-0]

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