MERC The Biology of Garveia franciscana and Potential Options to Limit Impacts of Cooling System Fouling - page 7

3. Limiting Impacts onCoolingPipeFouling
3.1. ProblemStatement
Constellation would like to identify, evaluate and implement a fouling control strategy, that
specifically prevents the settlement and/or extensive growth of
G. franciscana
in the cooling
system of CCNPP, and to eliminate or significantly reduce the need for unplanned cleaning of
screens, water tunnels, andwaterboxes.
While CCNPP experiences fouling due to a variety of organisms growing in and near the plant,
by far themost problematic is
G. franciscana
, which can significantly alter plant operations. All
gradual biofouling buildup in the cooling systems will ultimately result in lost generation of
power and increase maintenance costs during planned cleaning. However, it has been observed
that the gradual accumulation of most estuarine fouling organisms can be managed effectively
with anti-fouling coatings and scheduled, periodic maintenance. In contrast, the rapid seasonal
growth of
G. franciscana
, and unexpected release or sloughing of large clumps, leads to
emergent cleanings that can result in significant disruption to the quarterly system scheduleweek
and potential penalties for unplannedpower reduction.
Constellation has considered several options in the past, including debris filters (rejected as a
mitigating strategy) and mechanical cleaning of tunnels while in service (unacceptable due to
resulting loss in power production during cleaning and elevated plant risk). A silicone fouling-
release coating has been applied to the CCNPPwater tunnels and appears to be fairly successful
at limiting the growth of most organisms, but has had little, if any, noticeable impact on the
growth of
G. franciscana
The challenges associated with biofouling of power plant cooling systems are ubiquitous and
several facilities have also noted problems associated with
G. franciscana
. The most common
approach to address cooling system biofouling for power plants has been the application of
chlorine in various forms. This report reviews various options and approaches, and, based on
CCNPP operational requirements and logistic limitations, will provides recommendations for
additional pilot-scale assessments and future full-scale applications.
4. WaterTreatment
The industrial treatment of water dates back to the 19
century, and includes well-studied
disciplines such as drinkingwater andwastewater engineering. The treatment ofwater to prevent
fouling has also been utilized for many years and typically involves the use of chlorine or other
common oxidants (e.g., ozone). However, because of concern about and regulated prevention of
the spread of aquatic organisms (bacteria, phytoplankton and zooplankton) from ships’ ballast
water, there have been significant investments, research and development, and advancement of
several options thatmight also be effective in large-scale anti-fouling applications.
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