The beneficial effect of zinc to mitigate radio-cobalt uptake on stainless steel piping surfaces under BWR conditions is revisited by means of 1st principles modelling. A viable generic hydroxylated grain boundary interface (HGBI) model for magnetite, i.e., an inverse spinel, is formulated and interrogated in order to unravel how Zn may cause exclusion of Co by competing for the same sites. While Co2+ as well as Ni2+ reside preferentially in the octahedral lattice sites of the inverse spinel lattice, Zn2+ prefers to reside at the HGBI. The difference is consolidated for M(II), M being Cr, Mn, Fe, Co, Ni, Cu, or Zn. Similar affinities as well as mobilities of Co2+ and Zn2+ in the HGBI are taken to explain how, upon Fe2+ dissolution, Zn2+ may compete with Co2+ for the Fe2+ sites in the inner layer of the duplex oxide film. Impacts of Zn2+ and Ni2+ on Co2+ uptake in the outer oxide layer is also addressed. Zn2+ guided precipitation is found to be less effective than the Ni2+ guided process. Reported beneficial effects on radio-cobalt uptake upon sealing off the stainless steel acting Ni2+ source by coating with magnetite as well as hematite are discussed.

通过第一原理建模，重新探讨了锌减轻BWR条件下不锈钢管道表面上放射性钴吸收的有益作用。为磁铁矿，即反尖晶石，建立了可行的通用羟基化晶界界面模型（HGBI），并对其进行了研究，以揭示Zn如何通过竞争相同位点而导致Co的排斥。尽管Co2 +和Ni2 +优先存在于尖晶石反晶格的八面体晶格位点，但Zn2 +却更倾向于存在于HGBI。对于M（II），该差被合并，M为Cr，Mn，Fe，Co，Ni，Cu或Zn。HGBI中相似的亲和力以及Co2 +和Zn2 +的迁移率用于解释在Fe2 +溶解后，Zn2 +如何与Co2 +竞争双氧化膜内层中的Fe2 +位点。还讨论了Zn2 +和Ni2 +对外部氧化物层中Co2 +吸收的影响。发现Zn2 +引导的沉淀效果不如Ni2 +引导的方法有效。讨论了报道的通过覆盖磁铁矿和赤铁矿来密封不锈钢作为Ni2 +的源对放射性钴吸收的有益作用。