Darlington Vault Vapor Recovery

Client: Ontario Power Generation
Location: Bowmanville, ON
Trades: Sheet Metal, Pipefitters, Electricians, Carpenter, Labourers
Engineer: Tetratech

The purpose of the reactor Vault Vapor
Recovery System (VVRS) is to recover D2O
vapors for economic reasons and to maintain
low tritium contamination levels in the
containment areas in order to minimize
internal dose to personnel.
The system is a vital component of the
Contain portion of the reactor safety 3Cs. It is
classified as a System Important to Safety as
part of the Negative Pressure Containment
system which maintains containment at
negative pressure compared to atmosphere
to prevent uncontrolled releases.
The VVRS project consists of upgrading
aging equipment, installing new redundant
containment boundary valves, installing a
connection for moderator vacuum drying
equipment and installing temporary bypass
fans to keep the vault at negative pressure
during the phase where airlock doors remain
open. Keeping the doors open is crucial: it
allows for efficient passage of equipment
and workers during the removal and
subsequent construction phases of
E.S. Fox Limited worked on the VVRS projects
for all 4 units, completing units 1, 3 and 4 on
schedule and under budget.