Corrosion mechanisms of 304L NAG in boiling 9M HNO3 containing Cr (VI) ions

In this research, the mechanisms of end-grain corrosion of 304L NAG tubes in boiling 9M HNO3-containing Cr (VI) ions are reported to sustainably manage the corrosion of nuclear fuel reprocessing plant components. Specific heat treatments were applied to as-received specimens to produce phosphorus and/or sulphur intergranular segregation. End-grain corrosion on heat-treated specimens and the effect of a Cr (VI) concentration on a 304L NAG tube (as-received) were investigated. It has been reported that an increase in Cr (VI) ions leads to the acceleration of end-grain corrosion due to high electrochemical potential. After systematic heat treatments on the 304L NAG specimens, it is concluded that the primary causes of heat-induced end-grain corrosion are phosphorus or sulphur segregation to the grain boundaries. The key findings of this research are highly significant in terms of understanding the corrosion mechanisms and controlling the end-grain corrosion of NAG steel in boiling HNO3 environments. This research will help to sustainably reduce power plant maintenance costs and will have a significant impact on the delivery of long-term, clean, secure, and tenable energy.