Case Studies › Power Generation
Case StudyNuclear PowerUSService Water / CCWIndependent · No Chemistry Sold

Online biofilm removal and heat-transfer recovery in nuclear service water CCW exchangers

A US nuclear plant's Critical Cooling Water (CCW) exchangers were losing heat transfer to biofilm fouling. EHS and Operations restrictions ruled out bleach, hydrogen peroxide and surfactant biodispersants — leaving the plant facing NRC-directed shutdown unless an online cleanup could be designed inside those constraints.

Unit Served
Nuclear · Service Water / CCW
Key Issue
Biofilm fouling · Heat-transfer loss
Risk
NRC-directed shutdown
ROI · Consulting
< 2 days
Value Avoided
$27M+
Challenge — What Was Happening

Two consecutive operating cycles of declining heat transfer in the Critical Cooling Water (CCW) exchangers. Deposit analysis confirmed 50–75% biological forms — including filamentous and exopolymer-encapsulated bacteria — with viable sulfate-reducing bacteria present.

Bleach, hydrogen peroxide, and surfactant biodispersants were all ruled out by plant EHS and Operations constraints. Mechanical tube cleaning meant an unacceptable unit shutdown.

The plant was facing NRC-directed shutdown unless an effective online cleanup program could be designed and validated within the plant's strict chemical and operational constraints.

Intervention — What We Did

Designed a two-phase online cleanup program built entirely inside the plant's constraints — no bleach, no peroxide, no surfactant biodispersants, no shutdown required.

Selected a novel pairing of stabilized bromine biocide with a non-surfactant dendrimer polymer biodispersant. Validated the combination on a Bridger Scientific DATS (Deposit Accumulation Test System) sidestream test rig before full deployment to the operating system.

Executed a startup phase at higher application rates to mobilize and remove existing biofilm, followed by a lower-dose steady-state phase designed to hold heat transfer performance through the 18-month operating cycle.

Results Confirmed at Three Levels
  • Sidestream trial (DATS): Cleanliness factor improved from 80% to 96% in four days at startup-phase dosing — validated before full deployment.
  • Microbiological: ATP measurements and bacterial activity trended consistently downward throughout the application period.
  • Plant operational data: CCW-A and CCW-B heat transfer recovered above the administrative limit and continued to improve through the full 18-month steady-state operating cycle at significantly lower application rates than the startup phase.
$27M+
avoided — plus NRC-directed shutdown prevented
Avoided Downtime
$20M in lost revenue
Avoided Capex
$7M engineering + new HX install
Service-Co. Uplift
>$1M in 3 months
ROI · Consulting
< 2 days
ROI · Consult + Chem
14 days
The right answer often lives outside the standard playbook. In nuclear, where EHS, regulatory and operating constraints rule out the obvious tools, a first-principles, independent review can build a program that fits the plant — and keeps it running. Your critical system deserves a second look.

Facing heat-transfer loss or biofilm challenges in a constrained environment?

Independent cooling water program design for power generation — nuclear, gas, coal and combined cycle. No chemistry sold. Novel solutions built inside your plant's constraints.