Flux effect analysis in WWER-440 reactor pressure vessel steels

The results of long term research programme concerning the determination of irradiation embrittlement dependence on fast neutron flux for WWER-440 reactor pressure vessel steels before and after annealing are presented in this paper. The study of flux effect was carried out on commercial WWER-440 steels which differ significantly in phosphorous (0.013–0.036 wt%) and copper (0.08–0.20 wt%) contents. All specimens were irradiated in surveillance channel positions under similar conditions at high 4 1012 - cm2 s1 and low 6 1011 cm2 s1 fluxes (E > 0.5 MeV) at a temperature of 270 C. The radiation embrittlement was evaluated by transition temperature shift on the basis of Charpy specimens test results. In case of low flux, the measured Tk shifts could be 25–50 C bigger than the Tk shifts obtained from high flux data. A significant flux effect is observed in WWER-440 reactor pressure vessel steels with higher copper content (>0.13 wt%). Microstructural studies show that copper content decreases in the ferrite matrix and that there is formation of copper-enriched clusters and precipitates under irradiation and subsequent thermal annealing. Due to this fact the radiation damage does not depend on copper re-irradiation after annealing. Dependence of transition temperature shift on neutron flux is not expected for WWER-440 steels under re- irradiation after annealing.

KRYUKOV Alexander;  BLAGOEVA Darina;  DEBARBERIS Luigi; 

2013-12-11

ELSEVIER SCIENCE BV

JRC86552

0022-3115,   

http://www.sciencedirect.com/science/article/pii/S0022311513008891,    https://publications.jrc.ec.europa.eu/repository/handle/JRC86552,   

10.1016/j.jnucmat.2013.07.011,