ABSTRACT
Spent nuclear fuel (SNF) pool is an essential unit of a nuclear power plant infrastructure, where radioactive fuel rods arekept for cooling and shielding, before reprocessing. This study explored the presence of bacteria in SNF pool water withemphasis on their capability to form biofilms on pool wall cladding material stainless steel (SS-304L). Bacteria wereisolated from SNF pool water and were characterized using 16S rRNA gene sequencing. The six bacterial isolates (Bacillussubtilis, Staphylococcus sps., S. arlettae, S. epidermidis, S. auricularis and Chryseobacterium gleum) can grow and formbiofilms at very low nutrient condition as well as in chronic radioactivity. The bacterial isolates formed biofilm on SS-304Land glass. However, the biofilm parameters assessed by CLSM microscopy showed that the strains preferred SS-304Lsurface for biofilm formation. On SS-304L, the maximum biomass (0.45 lm3/lm2) was formed by S. arlettae whencompared to maximum biomass (0.054 lm3/lm2) by Staphylococcus sp., on glass. Maximum biofilm thickness on SS304L was observed by Staphylococcus sp. (8.81 lm) when compared to that of S. epidermidis (4.16 lm) on the glasssurface. The biofilm formation on SS-304L surface suggests the possible risk of microbial-induced corrosion of SNF poolcladding material. This study highlights the need for mandatory monitoring of microbial biofilm formation in an extremeenvironment such as SNF pool.