scholarly journals Irradiation Embrittlement of Pressure Vessel Steels of The BWR Plants in Japan—An Analysis of the Surveillance Data—

2008 ◽  
Vol 72 (4) ◽  
pp. 261-267 ◽  
Author(s):  
Hiromitsu Ino ◽  
Chihiro Kamisawa ◽  
Yoshinori Ito
Keyword(s):  
Pressure Vessel ◽  
Surveillance Data ◽  
Irradiation Embrittlement ◽  
Pressure Vessel Steels

Industry Practice for the Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels in Japan

2009 ◽  
Author(s):  
Norimichi Yamashita ◽  
Masanobu Iwasaki ◽  
Koji Dozaki ◽  
Naoki Soneda
Keyword(s):  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Correlation Method ◽  
Surveillance Data ◽  
Surveillance Program ◽  
Irradiation Embrittlement ◽  
Term Operation ◽  
Pressure Vessel Steels ◽  
Reactor Pressure

Neutron irradiation embrittlement of reactor pressure vessel steels (RPVs) is one of the important material ageing issues. In Japan, almost 40 years have past since the first plant started its commercial operation, and several plants are expected to become beyond 40 years old in the near future. Thus, the safe operation based on the appropriate recognition of the neutron irradiation embrittlement is inevitable to ensure the structural integrity of RPVs. The amount of the neutron irradiation embrittlement of RPV steels has been monitored and predicted by the complementally use of surveillance program and embrittlement correlation method. Recent surveillance data suggest some discrepancies between the measurements and predictions of the embrittlement in some old BWR RPV steels with high impurity content. Some discrepancies of PWR RPV surveillance data from the predictions have also been recognized in the embrittlement trend. Although such discrepancies are basically within a scatter band, the increasing necessity of the improvement of the predictive capability of the embrittlement correlation method has been emphasized to be prepared for the future long term operation. Regarding the surveillance program, on the other hand, only one original surveillance capsule, except for the reloaded capsules containing Charpy broken halves, is available in some BWR plants. This situation strongly pushed establishing a new code for a new surveillance program, where the use of the reloading and reconstitution of the tested specimens is specified. The Japan Electric Association Code, JEAC 4201–2007 “Method of Surveillance Tests for Structural Materials of Nuclear Reactors,” was revised in December, 2007, in order to address these issues. A new mechanism-guided embrittlement correlation method was adopted. The surveillance program was modified for the long term operation of nuclear plants by introducing the “long-term surveillance program”, which is to be applied for the operation beyond 40 years. The use of the reloading, re-irradiation and reconstitution of the tested Charpy/fracture toughness specimens is also specified in the new revision. This paper reports the application and practice of the JEAC4201–2007 in terms of the prediction of embrittlement and the use of tested surveillance specimens in Japan.

Irradiation Embrittlement of Advanced Pressure Vessel Steels

2008 ◽  
pp. 408-408-12
Author(s):  
KS Sivaramakrishnan ◽  
S Chatterjee ◽  
S Anantharaman ◽  
UK Viswanathan ◽  
KS Balakrishnan ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Irradiation Embrittlement ◽  
Pressure Vessel Steels

Characteristics of the New Embrittlement Correlation Method for the Japanese Reactor Pressure Vessel Steels

2009 ◽  
Author(s):  
Naoki Soneda ◽  
Akiyoshi Nomoto
Keyword(s):  
Pressure Vessel ◽  
Correlation Method ◽  
Reactor Pressure Vessel ◽  
Surveillance Data ◽  
New Method ◽  
Rate Equations ◽  
Mathematical Form ◽  
Microstructural Changes ◽  
Pressure Vessel Steels ◽  
Reactor Pressure

Neutron irradiation embrittlement of reactor pressure vessel steels is an important ageing issue for the long term operation of light water reactors. A new embrittlement correlation method was developed by CRIEPI and the Japanese electric utilities in 2007. This method is primarily based on the fundamental understandings on the embrittlement mechanisms: i.e. microstructural changes were modeled by the mathematical form of rate equations, and the predicted microstructural changes were further correlated with the mechanical property changes in transition temperature region. The coefficients of the rate equations were optimized using the Japanese surveillance data of RPV embrittlement. This method was adopted as the revision of the Japanese code, JEAC 4201–2007, in 2007. In this paper, after a brief explanation on the new correlation method, the predictions of the new method will be investigated through comparisons with the previous correlation, JEAC4201–2004, and the US surveillance data in order to identify the characteristics of the new method.

Estimation of Master Curve Based RTTo Reference Temperature From CVN Data

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.

scholarly journals Mechanisms and Modeling of Irradiation Embrittlement of Reactor Pressure Vessel Steels.

1998 ◽  
Vol 47 (11) ◽  
pp. 1112-1118
Author(s):  
Sumio MURAKAMI ◽  
Atsushi MIYAZAKI ◽  
Kazuki TSUGIHASHI ◽  
Mamoru MIZUNO ◽  
Morio JINCHO ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Irradiation Embrittlement ◽  
Pressure Vessel Steels ◽  
Reactor Pressure

scholarly journals Modeling of Irradiation Embrittlement of Reactor Pressure Vessel Steels

1997 ◽  
Vol 46 (2) ◽  
pp. 124-130
Author(s):  
Sumio MURAKAMI ◽  
Kazuki TSUGIHASHI ◽  
Atsushi MIYAZAKI ◽  
Morio JINCHO ◽  
Tetsuya SUZUKI
Keyword(s):  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Irradiation Embrittlement ◽  
Pressure Vessel Steels ◽  
Reactor Pressure
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