When you hear the words “Nuclear Meltdown” you probably think of the famous incidents
at Fukushima, Chernobyl, or Three Mile Island . But not many people know that the world’s
first nuclear meltdown occurred in 1952 at Chalk River Labs in Canada . But what’s
even more surprising is that future US President Jimmy Carter was involved in the clean up
operation for this meltdown.
So how did this accident occur, and why was a future American President helping to clean
up a Canadian reactor?
Well, our story begins just before World War 2, when the allies were in a race against
Germany to develop the first nuclear bomb.
By 1937 France, the UK, and the US were anticipating conflict with the axis powers and began research
to develop the atomic bomb in anticipation of the war.
Scientists in Paris identified that heavy water could work as a moderator to sustain
a nuclear reaction . At the time the only source of heavy water in the world was a 180
kg stockpile in Norway which was produced by a fertilizer company . To continue the
research into atomic weapons, the heavy water had to be transported to France while evading
Germany, who also realized the importance of heavy water and wanted the Norwegian stockpile
for their own nuclear weapons program.
In 1940 a secret mission was conducted to bring the heavy water to France.
The French sent a decoy plane to Norway to ‘purchase’ the water which was intercepted
by the Germans – all the while the real mission was conducted undercover and the water
made it safely back to France.
When France began to fall to the German invasion later that same year , the heavy water was
sent to Cambridge in England in order to keep it out of Germany’s hands.
But England’s research capabilities were limited by the conditions of the war , and
a partnership with the US was the only viable route to continue nuclear development.
Canada became a mediator between the UK and US.
Canada was well positioned to be a mediator for a couple of reasons.
First, Uranium could be mined at the Great Bear Lake in Canada’s Northwest Territories.
Second, Canada had significant expertise in Nuclear Physics thanks in part to Ernest Rutherford’s
research on radioactive materials at McGill University in the early 20th century, which
had helped create a strong nuclear physics program at the university.
By 1942, the heavy water and researchers from Cambridge arrived in Montreal and they began
planning a National Research Experimental (NRX) reactor to be located in Chalk River,
Ontario.
Ultimately, it was determined that the heavy water method would not yield nuclear weapons
before the end of the war, and the US found ways to bypass the need for heavy water.
Chalk River Labs was then reassigned to developing the peaceful use of nuclear technology to
generate electricity and the NRX reactor was built for that purpose.
That brings us to the NRX incident which would be the first nuclear meltdown in the world.
In 1952, during preparations for low power experiments, one of NRX’s operators was
in the basement at the Chalk River facilities and accidentally raised some of the reactor’s
control rods.
The supervisor upstairs noticed this and immediately called the operator to tell them to stop what
they were doing.
The supervisor then went downstairs to fix the problem, leaving his assistant at the
desk upstairs.
The supervisor fixed the operator’s mistake but due to a mechanical defect the control
rods did not properly drop back down into the reactor.
Unfortunately though, while the rods did not fully drop down they did drop just enough
for the warning lights to turn off.
Additionally, some of the cooling arrangements at the time were adequate only for the low-power
experiments and not for higher power operations.
The combination of the operator error, mechanical defect, and inadequate cooling resulted in
some of the natural-uranium metal melting and rupturing the aluminum sheathing and tubes
which separated the heavy-water, air, and cooling-water systems.
As a result, 20,000 curies of fission products from long-irradiated uranium were carried
by a flood of 1,000,000 gal of cooling water into the basement.
Fused masses of highly irradiated uranium and uranium oxide were left inside the calandria,
and the core vessel of the reactor and tubes of the calandria were severely damaged.
Thankfully, no one was killed as a direct result of the incident.
The Canadian government determined that outside assistance was needed with the clean up operation
and asked the US government for help . At the time, Jimmy Carter was a trained nuclear
engineer and Lieutenant in the US Navy, and he was asked to lead a team in the clean up
operation.
The reactor had to be shut down, disassembled, and replaced, and the clean up team also had
to clean up the spilled radioactive material . The reactor was so radioactive that each
team member could only be in the core for 90 seconds before being exposed to maximum
permissible levels , which in 1952 were 1000 times higher than what we consider safe today.
An exact replica of the reactor was built on a nearby tennis court where Carter and
his men could practice their operation.
Carter’s team had to disassemble the reactor, and they were each tasked with removing as
many bolts from the reactor as possible in their 90 second shift.
When it came time for the actual operation, the men had to be lowered into the reactor
core, which was underground, and they raced to remove their bolts.
While the operation was underway, the same bolts were removed from the nearby replica
to keep track of their progress.
Afterwards, Carter’s urine tested positive for radioactivity for 6 months, and he was
told he would likely never be able to have children.
He would go on to have 4.
After the NRX incident, nuclear research at Chalk River continued and another reactor,
the NRU, was built in 1957.
In 1958 the NRU reactor experienced a fuel rupture which caused a fire outbreak and massive
contamination of the area.
But the NRU was repaired and would continue to operate until 2018 . The research at Chalk
River yielded the CANDU heavy water reactor design which is used in Canada and has been
exported to many nations around the world such as China and India.
The Chalk River reactors have also provided as much as 40% of the world’s supply of
medical isotopes used primarily in the diagnosis and treatment of cancer.
In fact, when the NRU reactor was temporarily shut down in 2009 it created a worldwide shortage
of isotopes.
Even though the NRU reactor has now ended its operations, that doesn’t mean that nuclear
research at Chalk River has ended.
In fact, a new reactor is in development right now and is planned to be complete by 2026.
The Ultra Safe Nuclear Corporation has designed a Micro-Modular Reactor which could produce
5MW of electricity and could be used to provide electricity to remote mines and communities
which currently rely on diesel generators.
The company will build its first reactor at the Chalk River site.
But if you want to learn more about this innovative new reactor design, you’ll have to watch
this video next.