RPV embrittlement

Irradiation simulation techniques for the study of reactor pressure vessel (RPV) embrittlement 

FUKU YA, Institute of Nuclear Safety System, Inc., Japan 

Abstract This chapter discusses the role of simulation irradiation techniques in studies of radiation embrittlement mechanisms. The chapter first reviews characteristics and examples of test reactor irradiation, ion irradiation and electron irradiation. The chapter then discusses advantages and limitations of these techniques from the viewpoint of damage rate, sample volume and damage characteristics. 

Key words test reactor, heavy ions, protons, electrons, accelerators, damage rate, damage depth, recoil energy, cascade, damage efficiency. 

It is widely known that radiation embrittlement behaviour of reactor pressure vessel (RPV) steels depends on various parameters such as material composition, neutron flux and irradiation temperature. Sound understanding and modelling of embrittlement mechanisms require systematic knowledge of effects of individual parameters and their synthesis on microstructural development and then mechanical properties. Most such knowledge has been obtained from single-parameter experiments using test reactor irradiation. This is because test reactor irradiation allows researchers to obtain mechanical property data together with microstructural data on materials with well-controlled chemical compositions under well-controlled irradiation conditions such as flux and temperature. Surveillance data in commercial power reactors are non-systematic in this context and relevant microstructural data are very scarce. 

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This section provides a description of Western PWR RPVs which includes design features, applicable material specifications and differences among the various RPV components, and describes the characteristics of PWR RPV embrittlement. 

Characteristics of PWR RPV embrittlement, including the effects of variables, are described in this section. The degree of embrittlement and hardening induced in ferritic steels after exposure to fast neutron radiation is an issue of the utmost importance in the design and operation of NPPs. The beltline region of the RPV is the most critical region. The effects of variables on the embrittlement are briefly explained as follows ... 

Abstract In this chapter, the development of an understanding of the mechanisms that control reactor pressure vessel (RPV) embrittlement is explored. It is shown how these insights were strongly coupled with developments in microstructural techniques and how research in this field has underpinned the development of dose-damage correlations. 

To be able to understand the detailed mechanisms whereby matrix damage influences RPV embrittlement, one needs to determine ... 

Studies of the mechanisms whereby solute might influence RPV embrittlement have been dominated by studies focused on determining the... 

N. Soneda, Multi-scale modelling of RPV embrittlement , Ma/ena/s Issues for Generation IV Systems, V. Ghetta, D. Gorse, D. Maziere and V. Pontikis, eds. Springer, Dordrecht, 2008, 245-262. 

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