Non-hardening embrittlement

Overall, it can be seen that techniques have been successfully developed that can be applied to characterising P and C segregation in unirradiated and irradiated RPV steels. In the case of Mn-Mo-Ni steels, the majority of authors conclude that irradiation to typical end-of-life doses results in relatively modest increases in P coverage at the grain boundaries and that there is little evidence of significant non-hardening embrittlement. 

However, because of the limited amount of surveillance data available, non-hardening embrittlement is subsumed into an increased, dose-dependent, MD term. DDRs of the following form are applied for Magnox RPV steels and weld metals ... 

As an alternative to X-750 the equally age hardening alloys Inconel 718 (2.4667), Incoloy alloy 925 (UNS N09925), Incoloy alloy 926 (UNS N09926) as well as the non age hardening alloys Inconel 600 (2.4816), 625 (2.4856) and in particular Inconel 690 (2.4642) were tested for their behaviour to stress corrosion cracking and hydrogen embrittlement under the conditions of a boiling water reactor, see Table 12 [162]. 

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