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Chalk River Laboratories

Chalk River Laboratories seen from the Ottawa River.

Chalk River Laboratories (also known as CRL, Chalk River Labs and formerly Chalk River Nuclear Laboratories, CRNL) is a Canadian nuclear research facility located in Deep River, Renfrew County, Ontario, near the village of Chalk River, about 180 km (110 mi) north-west of Ottawa.

CRL is a site of major research and development to support and advance nuclear technology, in particular CANDU reactor technology. CRL has expertise in physics, metallurgy, chemistry, biology, and engineering and unique research facilities. For example, Bertram Brockhouse, a professor at McMaster University, received the 1994 Nobel Prize in Physics for his pioneering work in neutron spectroscopy while at CRL from 1950-1962. Sir John Cockcroft was an early director of CRL and also a Nobel laureate. CRL produces a large share of the world's supply of medical radioisotopes.[1] It is owned and operated by Atomic Energy of Canada Limited.


  • History 1
    • 1952 NRX-incident 1.1
    • 1958 NRU-incident 1.2
    • 2007 shutdown 1.3
    • 2008 radioactive leakage 1.4
    • 2009 NRU reactor shutdown 1.5
  • NRU shutdown in March 2018 2
  • Major facilities 3
  • See also 4
  • Further reading 5
  • References 6
  • External links 7


NRX and Zeep buildings, Chalk River Laboratories, 1945

The facility arose out of a 1942 collaboration between British and Canadian nuclear researchers which saw a Montreal research laboratory established under the National Research Council (NRC). By 1944 the Chalk River Laboratories were opened and in September, 1945 the facility saw the first nuclear reactor outside of the United States go operational (see Lew Kowarski). In 1946, NRC closed the Montreal laboratory and focused its resources on Chalk River.

In 1952, Atomic Energy of Canada Limited (AECL) was created by the government to promote peaceful use of nuclear energy. AECL also took over operation of Chalk River from the NRC. Throughout the 1950s-2000s various nuclear research reactors have been operated by AECL for production of nuclear material for medical and scientific applications. The Laboratories produce about one-third of the world's medical isotopes, and about half of the North American supply. Despite the declaration of peaceful use, from 1955 to 1976, Chalk River facilities supplied about 250 kg of plutonium, in the form of spent reactor fuel, to the U.S. Department of Energy to be used in the production of nuclear weapons.[2] (The bomb dropped on Nagasaki, Japan, used about 6.4 kg of plutonium.)

Canada's first nuclear power plant, a partnership between AECL and Hydro-Electric Power Commission of Ontario, went online in 1962 near the site of Chalk River Laboratories. This reactor, Nuclear Power Demonstration (NPD), was a demonstration of the CANDU reactor design, one of the world's safest and most successful nuclear reactors.

The Deep River neutron monitor operated once in Chalk river.[3]

1952 NRX-incident

Chalk River was also the site of two nuclear accidents in the 1950s\. The first incident occurred in 1952, when there was a power excursion and partial loss of coolant in the NRX reactor which resulted in significant damage to the core. The control-rods could not be lowered into the core, because of mechanical problems and human errors. Three rods did not reach their destination, and were taken out again by accident. The fuel-rods were overheated, resulting in a meltdown. The reactor and the reactor-building were seriously damaged by hydrogen-explosions. The seal of the reactor-vessel was blown up four feet. In the cellar of the building some 4.500 tons of radioactive water was found. This water was dumped in ditches around 1600 meters from the border of the Ottawa River. During this accident some 10,000 curie or 370 TBq was released.[4] Future U.S. president Jimmy Carter, then a U.S. Navy officer, was part of the cleanup crew.[5][6] Two years later the reactor was in use again.[7]

1958 NRU-incident

The second accident, in 1958, involved a fuel rupture and fire in the National Research Universal reactor (NRU) reactor building. Some fuel-rods were overheated. With a robotic crane, one of the rods with metallic uranium was pulled out of the reactor vessel. When the arm of the crane moved away from the vessel, the uranium caught fire and the rod broke. The largest part of the rod fell down into the containment vessel, still burning. The whole building was contaminated. The valves of the ventilation-system were opened and a large area outside the building was contaminated. The fire was extinguished by scientists and maintenance-men in protective clothing running along the hole in the containment vessel with buckets of wet sand, throwing the sand down at the moment they passed the smoking entrance.[8]

Both accidents required a major cleanup effort involving many civilian and military personnel. Follow-up health monitoring of these workers has not revealed any adverse impacts from the two accidents.[9][10] However, the Canadian Coalition for Nuclear Responsibility, an anti-nuclear watchdog group, notes that some cleanup workers who were part of the military contingent assigned to the NRU reactor building unsuccessfully applied for a military disability pension due to health damages.[5]

Chalk River Laboratories remain an AECL facility to this day and are used as both a research (in partnership with the NRC) and production facility (on behalf of AECL) in support of other Canadian electrical utilities.

2007 shutdown

On November 18, 2007, the NRU, which makes medical radioisotopes, was shut down for routine maintenance. This shutdown was extended when AECL, in consultation with the Canadian Nuclear Safety Commission (CNSC), decided to connect seismically-qualified emergency power supplies (EPS) to two of the reactor's cooling pumps (in addition to the AC and DC backup power systems already in place), which had been required as part of its August 2006 operating licence issued by the CNSC. This resulted in a worldwide shortage of radioisotopes for medical treatments because Chalk River makes the majority of the world's supply of medical radioisotopes, including two-thirds of the world's technetium-99m.[11]

On December 11, 2007, the House of Commons of Canada, acting on independent expert advice, passed emergency legislation authorizing the restarting of the NRU reactor and its operation for 120 days (counter to the decision of the CNSC), which was passed by the Senate and received Royal Assent on December 12. Prime Minister Stephen Harper criticized the CNSC for this shutdown which "jeopardized the health and safety of tens of thousands of Canadians", insisting that there was no risk, contrary to the testimony of then CNSC President & CEO Linda Keen. She would later be fired for ignoring a decision by Parliament to restart the reactor, reflecting its policy that the safety of citizens requiring essential nuclear medicine should be taken into account in assessing the overall safety concerns of the reactor's operation.[12][13][14][15][16] The NRU reactor was restarted on December 16, 2007.

2008 radioactive leakage

On December 5, 2008, heavy water containing tritium leaked from the NRU.[17] The leaked water was contained within the facility, and the Canadian Nuclear Safety Commission (CNSC) was notified immediately, as required.

In its formal report to the CNSC, filed on December 9, 2008 (when the volume of leakage was determined to meet the requirement for such a report) AECL mentioned that 47 litres of heavy water were released from the reactor, about 10% of which evaporated and the rest contained, but affirmed that the spill was not serious and did not present a threat to public health.[18] The amount that evaporated to the atmosphere is considered to be minor, accounting for less than a thousandth of the regulatory limit.[19] The public was informed of the shutdown at the reactor, but not the details of the leakage since it was not deemed to pose a risk to the public or environment. The leak stopped before the source could be identified, and the reactor was restarted on December 11, 2008 with the approval of the CNSC, after a strategy for dealing with the leak (should it reappear) was put in place.

In an unrelated incident, the same reactor had been leaking 7,001 litres of light water per day from a crack in a weld of the reactor's reflector system. This water has been systematically collected, purified in an on-site Waste Treatment Centre, and eventually released to the Ottawa River in accordance with CNSC, Health Canada, and Ministry of the Environment regulations. Although the leakage is not a concern to the CNSC from a health, safety or environmental perspective,[20] AECL has plans for a repair to reduce the current leakage rate for operational reasons.

2009 NRU reactor shutdown

In mid-May 2009 the heavy water leak at the base of the NRU reactor vessel, first detected in 2008 (see above), returned at a greater rate and prompted another temporary shutdown that lasted until August 2010. The lengthy shutdown was necessary to first completely defuel the entire reactor, then ascertain the full extent of the corrosion to the vessel, and finally to effect the repairs — all with remote and restricted access from a minimum distance of 8 metres due to the residual radioactive fields in the reactor vessel. The 2009 shutdown occurred at a time when only one of the other four worldwide regular medical isotope sourcing reactors was producing, resulting in a worldwide shortage.

NRU shutdown in March 2018

The NRU reactor licence will expire in 2016, the license has been extended to March 2018 and reactor will go into decommission after that. NRU Decommissioning operations will continue for many years into the future within the scope of future operating and/or decommissioning licences issued by the CNSC.

Major facilities

  • ZEEP — Zero Energy Experimental Pile Reactor (1945–1973).
  • NRX — NRX Reactor (1947–1992).
  • NRU — National Research Universal 135 MWt Reactor (1957–).
    • CNBC — Canadian Neutron Beam Centre
  • PTR — Pool Test 10 kW Reactor (1957–1990).
  • ZED-2 — Zero Energy Deuterium 200W Reactor (1960–).
  • NPD — Nuclear Power Demonstration 20MW(e) reactor; located north of CRL in Rolphton, Ontario (1960–1987).
  • SLOWPOKE — Safe Low-Power Kritical Experiment 5 kW Reactor (1970–1976) — moved to the University of Toronto in 1971.
  • TASCC — Tandem Accelerator Superconducting Cyclotron (1986–1996)
  • MAPLE-1 — Multipurpose Applied Physics Lattice Experiment Reactor (2000–2008; canceled).
  • MAPLE-2 — Multipurpose Applied Physics Lattice Experiment Reactor (2003–2008; canceled).
  • CRIPT — Cosmic Ray Inspection and Passive Tomography

See also

Further reading

  • Robert Bothwell, "Nucleus. The History of Atomic Energy of Canada Limited", University of Toronto Press, 1988.


  1. ^ "Chalk River makes 1st isotopes in 15 months". August 18, 2010. Retrieved 15 March 2011. 
  2. ^ letter from Dept. of Energy official, March 4, 1996, published at
  3. ^ [4]
  4. ^ Canadian Nuclear Society (1989) The NRX Incident by Peter Jedicke
  5. ^ a b Reactor Accidents at Chalk River: The Human Fallout
  6. ^ Jimmy Carter timeline
  7. ^ (English) The Canadian Nuclear FAQ What are the details of the accident at Chalk River's NRX reactor in 1952?
  8. ^ The Canadian Nuclear FAQ What are the details of the accident at Chalk River's NRU reactor in 1958?
  9. ^ What are the details of the accident at Chalk River's NRU reactor in 1958?
  10. ^ What are the details of the accident at Chalk River's NRX reactor in 1952?
  11. ^ [5]
  12. ^ [6]
  13. ^ Ljunggren, David (2007-12-12). "Canadian parliament orders isotope reactor restart". Reuters. Retrieved 2013-05-05. 
  14. ^ Sunday, May 5, 2013 3:49 PM EDT Facebook Twitter RSS (2007-12-13). "Much more at stake than medical isotopes | Toronto Star". Retrieved 2013-05-05. 
  15. ^ "Chalk River plant to begin making radioisotopes in a week - Canada - CBC News". 2007-12-13. Retrieved 2013-05-05. 
  16. ^ Citizen, Ottawa (2008-01-16). "Harper government fires Linda Keen over isotope crisis". Retrieved 2013-05-05. 
  17. ^ "Current Issues - CNSC Report to Minister of Natural Resources regarding recent events at National Research Universal (NRU) Reactor". Retrieved 2013-05-05. 
  18. ^ "Agency says it was told of nuke leak within hours | CTV News". 2009-01-27. Retrieved 2013-05-05. 
  19. ^
  20. ^ "News Releases". Retrieved 2013-05-05. 

External links

  • NRC Archives Photographs - Physics- Atomic Energy Project collection
  • Radioisotopes produced at Chalk River
  • Nuclear Accidents at Chalk River: The Human Fallout
  • What are the details of the accident at Chalk River's NRX reactor in 1952? (Canadian Nuclear FAQ, Dr. Jeremy Whitlock)
  • What are the details of the accident at Chalk River's NRU reactor in 1958? (Canadian Nuclear FAQ, Dr. Jeremy Whitlock)
  • AM 530 kHz CKML (see article) Emergency Broadcast Information Only (CRTC Approval November 25, 1998)

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