Microbial Corrosion of a Process Water Cooling System in a Nuclear Power Generating Unit
Toleti Subba Rao,
Nitin Shirish More,
Sovan Kumar Mandal,
Chandrakant Rajaram Kakade,
Suresh Kisanrao Datir.
A 316 stainless steel plate heat exchanger of a process water cooling system failed due to
microbial corrosion during operation at a nuclear power station. A detailed failure analysis was done
on the heat exchanger plate and described in this paper. The results established that inadequate
chlorination has resulted in the infestation of the heat exchanger unit by corrosion and biofilm forming
bacteria and caused the breakdown. Optical microscopy revealed concentric ring patterns on the SS-
316 plate, which is typical of sulphate reducing bacteria which induced microbial corrosion. SEM
EDAX showed the presence of significant sulphur peak. XRD and Raman spectroscopy analysis
showed the presence of FeS2 peak. Various observations recorded in the study were characteristic to typical microbial
corrosion failure, particularly by SRB. The paper further highlights the remedial measures taken to prevent microbial
corrosion by optimizing biocide dosing and water chemistry changes in the power plant.
Keywords: Microbial corrosion, heat exchanger plate, cooling water system, nuclear power plant.
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