Corrosion Mechanisms of 304L NAG in Boiling 9M HNO3 Containing Cr (VI) IONS.

Abstract

In this research, mechanisms of end grain corrosion of 304L NAG tubes in boiling 9M HNO3-containing Cr (VI) ions are reported to manage the corrosion of nuclear fuel reprocessing plant components sustainably. 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 Cr (VI) concentration on 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 of 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 environment. This research work will help reduce power plant maintenance costs sustainably and will have significant impact on the delivery of long-term, clean, secure and tenable energy.