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Nuclear Accident in Chalk River - Ontario, Canada

Nuclear accident in Chalk River - Ontario, Canada

The Chalk River suffered two nuclear accidents in 1952 and 1957 at the Chalk River Laboratories.

Chalk River Laboratories is a facility located in Ontario, Canada. During the 1950s, these facilities suffered two major nuclear accidents.

The first Chalk River nuclear disaster occurred in 1952 when the NRX reactor suffered a violent explosion that destroyed the reactor core. The explosion of the reactor caused the fusion of nuclear fuel. The descent of the control rods failed so the chain nuclear fission reactions could not be stopped. As a result, thousands of radioactive particles were released into the atmosphere.

The second nuclear accident at the Chalk River facility took place 5 years later. In this case, several uranium nuclear fuel rods overheated and broke in the core of the NRU reactor. Due to the rupture of the fuel rods, they caught fire causing serious consequences for the Canadian facility.

What Are the Chalk River Laboratories?

The Chalk River Laboratories or Chalk River Labs and formerly called Chalk River Nuclear Laboratories are facilities located near the town of Chalk River, Ontario (Canada) dedicated to the investigation of nuclear reactions .

The facility was born in 1942 as a result of collaboration between British and Canadian nuclear researchers. The Chalk River Laboratories were opened in 1944 and in September 1945 the facility put the first nuclear reactor outside the United States into operation.

The NRX is a research nuclear reactor, moderated by heavy water, cooled by light water. It was built in wartime with the aim of using it for military purposes, although the designers considered many other civil applications. Today the Chalk River Laboratories are of great importance in the medical applications of nuclear energy.

How Did the First Nuclear Accident Happen on the Chalk River?

The first accident occurred on December 12, 1952. The NRX reactor suffered a shutdown failure which, along with several poor decisions by facility operators, caused a nuclear Fission chain reaction that more than doubled the power of the nuclear reactor.

Operators opened the 4 pressure containment valves in the cooling system of the nuclear power facility, causing an explosion that destroyed the nuclear reactor core, causing a nuclear fuel spill.

Inexplicably, the closure of the control rods did not drop completely into the reactor core. A series of hydrogen gas explosions (or steam explosions) launched the four-ton dome through the air.

Thousands of nuclear fission particles were released into the atmosphere along with a million liters of radioactively contaminated water. The contaminated water had to be pumped out of the basement and dumped into shallow ditches near the Ottawa River.

The core of the NRX reactor could not be decontaminated, but had to be buried as radioactive waste. In its place, a new nuclear reactor, even more powerful, was placed to continue its operation.

What Role Did Jimmy Carter Play in the Chalk River Disaster?

Nuclear accident on Chalk River - Ontario, CanadaOut of curiosity, a young Jimmy Carter (a U.S. Navy nuclear engineer) was one of hundreds of Canadian and American servicemen who were ordered to participate in NRX cleanup as a result of this nuclear accident. Later he would be president of the USA.

At that time, the INES Scale (International Nuclear Events Scale) had not yet been created, but currently, due to the characteristics of the accident, it would be at level 5 of the INES scale (accident with risk off site).

How Did the Second Chalk River Nuclear Accident Happen?

Five years later, in 1958, several metal uranium nuclear fuel rods from the NRU reactor overheated and broke inside the reactor core. One of the damaged bars caught fire and broke in two, while it was being removed from the base by a robotic crane. It fell into a shallow maintenance well.

The burning of nuclear fuel was left there, spreading deadly nuclear fission products and the emission of alpha particles throughout the Chalk River reactor building. The ventilation system was clogged in the "open" position, thus contaminating the building's access areas, as well as a significant downwind area at the reactor site.

A relay team of scientists and technicians finally extinguish the fire. More than a thousand men were involved in cleanup operations after these two accidents on the Chalk River.

What Were the Consequences of the Chalk River Nuclear Accidents?

More than 600 men were needed just to clean up the NRU. The official reports of the AECL (Atomic Energy of Canada Limited) highlight that very few of these men were exposed to excessive radiation, that is, most of the registered doses of radioactivity did not exceed the levels considered acceptable for workers. at nuclear facilities right now. The reports also indicated that there were no adverse health effects caused by the radioactive exposures received.

However, no medical follow-up has been done to see if the population of men involved in the future Chalk River accidents showed a higher than normal incidence of cancer.

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Published: October 26, 2010
Last review: January 22, 2020