POWER November 2020 - 19

TOP PLANT
sequence, OPG said. Construction was
finally deemed complete in late March,
2020. After a restart process, the refurbished
unit reached first criticality in April,
and it returned to full service in June.
In-Depth Training
A notable
aspect
1. A worker trains at Darlington's full-scale
reactor " mock-up " facility located inside
of the 2014-established Darlington Energy
Centre. The facility accurately represents the
size, space, and lighting constraints within
Darlington's reactor vaults. Every door, hallway,
pipe-down to their exact bend-and
overhead light has been replicated, simulating
all interferences that could be encountered
during actual re-tube and feeder replacement
work. Courtesy: OPG
components, including the calandria vessel,
and cleaning and conditioning all other
areas, workers began installing new
Cameco-manufactured calandria tubes
in an intensive four-month process. " The
installation process involved installing
the calandria tube into a lattice site, verifying
correct positioning on both reactor
faces, then rolling the calandria tube, finishing
with a leak test, " OPG said.
Work then progressed into assembly
of the unit's 480 fuel channels. " Each
fuel channel requires a fuel channel subassembly,
consisting of a pressure tube
made of zirconium, two stainless steel
end fittings, and four annulus spacers,
which play a critical role in maintaining
the gap between the pressure tube and
calandria tube. This ensures there is no
contact between the components, " OPG
said. The fuel channel installation work
series, which OPG described as " one of
the most complex phases on the project, "
wrapped up in April 2019.
Along with these new components,
OPG notably also added a third, more
robust emergency power generator and
updated fire protection systems. " Our
refurbishment-related overhauls and replacements
mean greater reliability from
both an operational and safety perspective, "
said Dietmar Reiner, chief project
officer. " It will ensure Darlington remains
among the best in the nuclear industry
through its extended life. "
Loading Fuel, Testing, and Restarting
the Reactor. By June 2019, the team
had inspected fuel bundles that were
sequenced and packed by BWXT, and
were readying for fuel load. The process
required the manual loading of 6,240
new fuel bundles into the actual reactor,
according to a serialized numbering
November 2020 | POWER
at
Darlington
that
bolstered the refurbishment project's
detailed planning and preparation is a distinctive
training facility (Figure 1), where
highly skilled workers can perform full
" dress rehearsals " to practice using the
more than 400 specialized tools developed
by Ontario manufacturers to remove
and install components, as well as
conduct inspections and repairs on the
project. Among these tools is the " ReTube
Tooling Platform, " a half-ton elevating
work surface that is connected to
four columns to allow it to move vertically
across the reactor face.
" The integrated team undertook more
than 765,000 training hours in the project's
leading-edge mock-up and training
facility to safely shut down, defuel,
disassemble and reconstruct the reactor, "
OPG said. " This in-depth training
enabled the team to practice complex
tasks before performing them in the
field, resulting in improved efficiencies. "
Overcoming Crucial Challenges
Because OPG is wholly owned by Ontario,
every one of Unit 2's 450 tasks were
under scrutiny by an assortment of parties
to ensure the refurbishment would
stay on track to meet OPG's January
2016-announced estimated total project
cost of C$12.8 billion and schedule. External
oversight came from the Canadian
Nuclear Safety Commission, which oversaw
project safety; the provincial Ministry
of Energy, which represented Ontario's
government as OPG's sole shareholder
and monitored project status and performance;
and the Ontario Energy Board,
the province's electricity regulator, which
reviewed project costs. But OPG also had
three internal oversight bodies, including
a dedicated committee of board directors,
a construction review board, and a senior
management team. Keeping an eye on
overall risks, meanwhile, was the Office
of the Auditor General of Ontario, which
scrutinized the company's public reporting
and compliance with applicable legislation
and standards.
In a 2018 report-issued midway
through the project-that office lauded
OPG's application of lessons learned
from previous large construction projects
and nuclear refurbishments to
www.powermag.com
POWER POINTS
Winning Attributes
✔ Executing a broad scope of work to
keep to a tight schedule.
✔ Innovating efficient project planning
and management, including through
a notable scaled " mock-up " training
facility.
✔ Navigating project complexities
while prioritizing worker safety,
and balancing costs, oversight, and
compliance.
keep the project within its original time
and cost estimates, but it warned final
project costs remain uncertain. Despite
impacts from the COVID-19 pandemic,
OPG affirmed in an August 2020 investor
briefing that total project costs continue
to track the C$12.8 billion budget, and
that the full project will be completed by
the end of 2026.
The audit office also flagged a shortage
of skilled trades, a risk that it warned
could prompt delays, especially during
the 2020 outage season, when OPG
would be in competition with other
nuclear plants. OPG indicated it took
pointed action to address potential shortages
by ensuring access to a sufficient
pool of qualified trades. At its peak, the
refurbishment project will require 11,800
workers per year across the industry, it
said, and it has continued several programs
to attract, retain, align, and develop
qualified resources for the project.
COVID, notably, posed new workforce
constraints that prompted OPG to postpone
the start of the Unit 3 refurbishment
by three months to May 2020.
However, the company has resumed
hiring of skilled trades workers to safely
start this next phase on the project. Unit
2's success, which provided more lessons
on how to navigate challenges, is
now also driving optimism for the remainder
of the project. The milestone remains
" a truly historic moment for Ontario, " as
Ken Hartwick, OPG's president and CEO,
noted in June, as Unit 2 began producing
100% power. " I want to thank our
refurbishment team, project partners,
vendors and construction building trades
workers for more than 24 million hours
worked safely and for returning Darlington's
Unit 2 reactor to the grid at a time of
unprecedented circumstances. " ■
-Sonal Patel is senior associate editor
for POWER.
19
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POWER November 2020

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