Predictions and Measurements of Helium and Hydrogen in PWR Structural Components Following Neutron Irradiation and Subsequent Charged Particle Bombardment

摘要

PWR structural components built from austenitic steels accumulate large amounts of helium and hydrogen during service and it is desired to predict the concentrations of these gases not only for higher neutron exposures, but also for subsequent ion-induced extension of the damage dose. While the neutron-induced sources of helium are well-known, there is often uncertainty in the local thermal neutron fluence, which constitutes the major uncertainty for prediction of helium production. Combining earlier measurements of helium at lower dpa levels with knowledge of the ~(59)Ni behavior we can extrapolate to higher dpa levels since the helium concentration is an excellent retrospective dosimeter of the thermal fluence. Predictions of hydrogen are more difficult, however, due to helium-nucleated cavities storing both transmutant and environmental hydrogen. Subsequent ion irradiation of neutron-irradiated material can then use double-ion and triple-ion injection to maintain the neutron-relevant gas cogeneration rates.