Stainless Steel Corrosion during H-Canyon Resin Digestion

Historically HB-Line has transferred a slurry of used anion exchange resin to the H-Canyon Tank 5.2 where caustic digestion using permanganate was performed prior to transfer to the tank farm. Recent digestions had switched to an acid flowsheet. During recent testing to investigate the hydrogen generation rate (HGR) for the resin acid digestion process, the experimental apparatus fabricated from stainless steel and nickel-chromium alloys was found to have suffered significant localized corrosion which failed a heating rod. This observed corrosion raised concerns about the integrity of Tank 5.2, which is fabricated of 304L stainless steel. An exploratory study was undertaken to better understand the cause of this corrosion as well as during a caustic digestion and to use these data to assess the viability of Tank 5.2 using the current acid digestion flowsheet versus the previous caustic flowsheet.