Effect of strontium and cesium on corrosion and contamination of 316L stainless steels during spent nuclear fuel reprocessing

摘要

The high-yield fission products of spent nuclear fuel (SNF), ~(90)Sr and ~(137)Cs, can deposit on the surface of facilities for SNF reprocessing plant, threatening to their safe decommissioning. To select and develop the efficient decontamination technology, the experiments for corrosion and contamination with strontium and cesium of 316 L stainless steels were performed in simulated environments of alkaline storage pond and HNO_3-based PUREX process. This study analyzed the mechanism and relations of corrosion and contamination with strontium and cesium on the surface of 316 L stainless steels by combining electrochemistry and ICP-MS for the first time. When steels were exposed to the environments of alkaline and low concentration of HNO_3, the presence of Sr~(2+) and Cs~+ decreased these three properties (corrosion potential, holes formed by local severe dissolution and the stability of the passive film). The results of ICP-MS demonstrated that the contamination evolution of Sr and Cs had a similar trend, and that there were significantly different contamination behaviors of steels exposed to alkaline and acidic environments. Strontium and cesium mainly deposited in the passive film of steels in both nitric acid and alkaline environments. The contamination of steels in an alkaline environment was more serious than in all nitric acid environments.