Page 13 - Darlington Refurbishment Project

the unit begins to warm up. Workers restore
The last step is powering up the unit by following
several step-by-step approvals. These confirm the
quality of the work and ensure that staff, equipment
systems and operating procedures are ready for
the start-up process. Workers, meanwhile, refill
the moderator with heavy water, load fuel into the
fuel assemblies in the reactor core, and fill and
pressurize the heat transport system.
Then the nuclear fission process is started and
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containment and then begin reconnecting the unit
to the rest of the operating station. The goal now is
for the unit to achieve criticality, OPG explained.
After final high power testing, control room
operators gradually raise the unit to full-power
operation.
The project has remained on budget and on
schedule, OPG has reported, despite the COVID-19
pandemic.
Refurbishment of Unit 1 has been scheduled to
start in the second quarter of 2022, and is expected
to be finished in the second quarter of 2025.
Refurbishment of Unit 4 is to begin in the fourth
quarter of 2023, with completion set for the fourth
quarter of 2026.
The refurbishment of Unit 2 was ahead of schedule
to meet the revised completion date in May.
More than 99 per cent of Unit 2 work has been
completed as of mid-May, and 58 of 58 systems
have been returned to service. OPG declared
construction complete on Unit 2 in March, following
the successful restoration of the airlocks and vault
containment pressure tests.
Prior to the pandemic, the team was on track to
begin Unit 3’s refurbishment in April. OPG has now
decided to keep Unit 3 running to ensure a stable
supply of clean electricity for Ontario, and to defer
the start of its refurbishment to the third quarter of
2020.
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