Summer Co-op Experience: OPG Aditi Garg
Dec 17, 2015
Summer Co-op Experience: OPG
Aditi Garg
Darlington Nuclear G.S
Located in Bowmanville, ON
About the plant
4-unit station with a total output of 3,524 megawatts (MW)
20 per cent of Ontario’s electricity
Tritium Removal Facility extracts tritium from heavy water
COMPONENTS AND EQUIPMENT
Electrical and I&C Major Components Mech & Rotating Equipment Valves
Major Components
Fans Compressors Pumps Steam Generators (Boilers) Feeders Reactor Maintenance
Inside the plant…
Main Boiler Feed Pump Turbine Hall
Projects
Critical equipment and Critical spares List Root cause analysis of the seal failure Transient monitoring for Feeders Plant walk-down
Transient monitoring for Feeders
CNSC Keep track of transient events that have occurred in each unit. – For all nuclear class system piping
Plant Information System (PI)– Temperature, pressure, %Power, etc. for all
planned and forced outages
Feeder thinning
reduction in pipe wall thickness of the outletfeeders
High pH dissolves pipes; reduces thickness
The cause of feeder thinning is flow accelerated corrosion (FAC). – poor design defects, poor chemistry controls and
high temperature and pressure.
Face of the CANDU reactor
The face of a CANDU reactor (under construction).Some feeder pipes can be seen to the right of the reactor face.
Flow Accelerated Corrosion (FAC)
motion of a corrosive fluid and a metal surface. Outlet feeders
– Dissolution of magnetite (Fe3O4) Affects carbon steel components
– High flow and specific water chemistry conditions. – Resulted in excessive thinning and failure of
feedwater lines
Reduce thinning
Outlet feeders – Injected by Titanium Dioxide Uniform coating inside pipe to reduce thickness
Fe3O4 Dissolves with high temperature and pressure (pH >10.6)
Chemistry: pH 10.1- 10.4 rate of solubility is low
Feeder Integrity Project
The Project is actively pursuingmeans to:– Extend the life of the feeders– Developing tooling for eventual
feeder replacement– Further developing pipe inspection
techniques
Root Cause Evaluation
Second Stage Reheat Pumps– Seal temperature was high above the alarm set
pointPerform a failure modes analysis of the
historical seal failures Review modification packages and make
changes to design– Identify technical and human performance
related root cause
Thank you!!