June 22, 2011
NRU back online
NRU is back up and running, ahead
of schedule and no worse for wear.
Atomic Energy of Canada Ltd announced last week that the National
Research Universal (NRU) reactor at Chalk River had returned to
operation from its planned extended outage.
AECL said vessel inspection results to date confirmed that there are no
detectable changes to the vessel wall, no detectable corrosion, and
that the inspected welds, applied during the 2010 repairs “continue to
be sound.”
“The NRU is currently operating at high power, producing medical
isotopes and providing vital research and testing support to the
science community, universities, and industry from across Canada and
around the world,” the company said.
The purpose of the 32-day outage was to perform maintenance and
inspection work designed to enhance the reliability of NRU and to
fulfill AECL’s commitment to the Canadian Nuclear Safety Commission
(CNSC).
This was the first annual planned extended outage for NRU following the
reactor's 15-month shutdown that ended last August.
That shutdown was required to repair areas of corrosion on the wall of
the reactor vessel.
As part of its approval to restart the reactor, the CNSC required that
AECL close down the reactor for a month at a time once a year to do
maintenance and repairs.
The first outage was to start no later than nine months after NRU
restarted last August.
Planning and preparations for the outage began in March 2010 and
continued up to the start of the outage on May 15, the company said.
“It was a complex endeavour, consuming over 25,000 hours of planning
and execution.
“Contributions were made from over 120 individuals representing AECL’s
skilled trades, technicians, engineers, radiation protection
specialists, and project staff.”
In addition to AECL staff, 50 contract employees representing seven
Canadian companies also contributed to the completion of the project,
the company said.
During the outage, AECL completed over 1,400 work activities, including
preventative maintenance, inspections, and condition assessments as
well as equipment repairs, upgrades, and replacements in priority areas
critical to the safe and reliable operation of the NRU.
Inspection activities examined the five highest priority vessel sites,
including three sites that were inaccessible prior to the development
and use of first of a kind inspection tooling, the company said.
“While improving accessibility, the tooling also allowed the vessel to
remain fuelled and filled with heavy water during inspections.
“Challenges experienced in the use of this new equipment provided AECL
staff and contractors insights into equipment limitations and learning
opportunities for use in future outages.”
Inspections and other activities not completed during this outage, such
as lower level preventative maintenance, have been deferred to future
scheduled short duration outages, AECL added.
In a video posted to the website nrucanada.ca, Ted Moryto, one of the
team leaders of the NRU Planned Extended Outage Project, said
inspection results showed to a “micron level” that there has been no
corrosion of the repairs to the reactor vessel.
The results were “as good as we could have expected,” he said.
“We have demonstrated and observed that the mitigation measures we have
undertaken over the past 18 months to address these concerns have been
very effective,” he said.
New data gained during subsequent inspections will be analyzed and the
results will be included in the NRU “Fitness for Service” report.
The completed report will be issued to the CNSC by September 2011.
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