Corrosion Studies on Containment Materials for Vitrified Heat Generating Nuclear Waste. Progress Report for Half-Year Ending 30 June 1984

摘要

Progress is reported of the work undertaken to assess containment materials for the disposal of heat generating nuclear waste under geological disposal conditions. Mean corrosion rates of carbon steels, monitored by Rsub(p) measurements on specimens in on-going long term immersion tests which have been underway from 340 to 500 days, range between 20 to 37 mu m/yr at 90 deg C, 9 to 32 mu m/yr at 50 deg C and 2 to 10 mu m/yr at 25 deg C. AC impedance measurements suggest that true corrosion rates may be a factor of ten lower than those at 90 deg C for the bentonite backfill. Recent tests with gamma -radiation have shown that after 5000h in deaerated groundwater at 90 deg C, and at a dose rate of 10 exp 5 Rads/h, the general corrosion rate of forged 0.2% carbon steel samples is <3 mu m/yr. Improved electrochemical kinetic data, required for the mathematical model, is being determined experimentally for temperatures from 20 to 90 deg C and pH values 5 to 10. Preliminary results from studies to assess the effect of gamma -radiation on the corrosion of Hastelloy C4 and Ti/0.2 Pd reference materials immersed in groundwater have provided visual evidence for pitting and crevice attack on the Hastelloy sample. (Atomindex citation 16:074120)