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!!