Effects of irradiation on fracture toughness

Similar but varying results accrue as a result of other sensitizing elements, such as nickel, manganese, silicon and phosphorus. Moreover, the effects are similar for the WWER steels, with copper and phosphorus being the dominant elements present in the WWER-440 reactors, but with nickel and manganese being the dominant elements present in the WWER-1000 reactors. 

In a manner similar to the effects of irradiation on the CVN impact toughness, the fracture toughness is reduced by irradiation and exhibits a transition temperature shift as well as a reduction in/i and tearing modulus. Examples of these effects are shown in Figs 10.9a (Nanstad et al, 1992) and 10.9b Hiser et al, 1984) for two western RPV steels, while the effects on WWER steels are similar. As with CVN impact toughness, the effects of irradiation on the fracture toughness of RPV steels are dependent on the radiation sensitivity of the material which is primarily determined by the specific chemical composition. 

2 Effects of irradiation on dynamic fracture toughness and crack-arrest toughness 

In comparison with initiation fracture toughness data, there are substantially fewer data on effects of irradiation on dynamic fracture toughness and crack-arrest toughness. Some early results of vs temperature are shown in Fig. 10.11 (Davidson et al, 1976), while more recent results of Ki are shown in Fig. 10.12 (Iskander et al, 1992). In general, the 

Irradiated base and weld metals, total number N = 851 

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C J Bolton, W Charnock and R H Priest, The effect of irradiation on fracture toughness transition temperature of Magnox reactor pressure vessel materials, Proceedings of the International Conference on Nuclear Power Plant Life Extension, Snowbird, UT, USA, July 1988. American Nuclear Society, IL, USA, pp. 197-203. 

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