Assessment of Biogrowth at Two Different Environments of Nuclear Power
Plant Cooling Water System Located at Southern Coast of India

A systematic assessment of biogrowth development on titanium coupons exposed to ambient seawater
(intake) and chlorinated seawater (pump house) environments of a coastal nuclear power plant was
carried out. Titanium coupons were exposed for a period of 2 years and periodically removed at
monthly intervals for biogrowth assessment. Biofouling biomass at the seawater intake station ranged
from 0.8-12.5 kg m-2 during the 2 years of study. Continuous chlorination of 0.2 ± 0.1 mg L-1 and
shock dose chlorination for 1 h/day at residuals of 0.4 ± 0.1 mg L-1 was very effective in reducing the
biofouling load in the cooling water system. A reduction in fouling biomass of 95% was observed on
titanium coupons between the intake and the pump house stations. Biofoulants recruitment was found
to occur throughout the year at varying intensities. Diversity of organisms on the coupon was influenced
by seasonality and distinct successional patterns were observed at the seawater intake. Barnacles were
the dominant fouling organisms followed by mat forming ascidians, bryozoans, oysters, hydroids and
seaweeds at the intake station. Sluggish biofouling development was observed on coupons at the
intake due to the sub-tidal intake system (-5 m), which had a lesser load of meroplanktonic organisms.
The study also showed that low dose continuous chlorination was an effective strategy for biofouling
control in the cooling water system of the tropical power station which uses titanium heat exchangers
for steam condensation.