Results are reported for the continuation1 of extensive corrosion testing of carbon and other steels exposed in a dynamic test loop simulating the various environments found in a nuclear boiling-water reactor system. Water and steam conditions were based on 10 to 20 ppm oxygen and 1 to 2 ppm hydrogen in the 546 F saturated steam, a condition representative of the radiolytic water decomposition in boiling-water reactors. The pH of the high-purity water was about 7, and no chemical additives were used in the loop water.
Tests were conducted to determine (1) whether stress-corrosion cracking would occur and (2) the effect of simulated reactor startup and shutdown on corrosion, including pitting, rusting and local attack. The results of the investigation show that: (a) There was little, if any, difference in corrosion among the various steels tested containing up to 5 percent chromium. (b) Stress-corrosion cracking was not detected in steels containing up to 5 percent chromium or in austenitic and ferritic stainless steels, (c) Stress-corrosion cracking was detected in one specimen of hardened AISI Type 431 martensitic steel tested in steam-water environment. (d) Pitting, rusting and local attack of steels containing up to 5 percent chromium can occur in reactor-grade water during simulated reactor shutdowns when the water is at or near room temperature and has access to air. 6.2.3, 6.2.5, 3.5.8, 7.11.2, 8.4.5, 3.2.2.
