The National Research Universal (NRU) reactor was a 135 MW nuclear research reactor built in the Chalk River Laboratories, Ontario, one of Canada's national science facilities. It was a multipurpose science facility that served three main roles. It generated radionuclides used to treat or diagnose over 20 million people in 80 countries every year (and, to a lesser extent, other isotopes used for non-medical purposes). It was the neutron source for the NRC Canadian Neutron Beam Centre: a materials research centre that grew from the Nobel Prize-winning work of Bertram Brockhouse. It was the test bed for Atomic Energy of Canada Limited to develop fuels and materials for the CANDU reactor. At the time of its retirement on March 31, 2018, it was the world's oldest operating nuclear reactor.
History The NRU reactor design was started in 1949. It is fundamentally a Canadian design, significantly advanced from NRX. It was built as the successor to the NRX reactor at the Atomic Energy Project of the National Research Council of Canada at Chalk River Laboratories. The NRX reactor was the world's most intense source of neutrons when it started operation in 1947. It was not known how long a research reactor could be expected to operate, so the management of Chalk River Laboratories began planning the NRU reactor to ensure continuity of the research programs. NRU started self-sustained operation (or went "critical") on November 3, 1957, a decade after the NRX, and was ten times more powerful. It was initially designed as a 200 MW reactor, fueled with natural uranium. NRU was converted to 60 MW with highly-enriched uranium (HEU) fuel in 1964 and converted a third time in 1991 to 135 MW running on low-enriched uranium (LEU) fuel. On Saturday, 24 May 1958 the NRU suffered a major accident. A damaged uranium fuel rod caught fire and was torn in two as it was being removed from the core. The fire was extinguished, but a sizeable quantity of radioactive combustion products had contaminated the interior of the reactor building and, to a lesser degree, an area of the surrounding laboratory site. The clean-up and repair took three months. NRU was operating again in August 1958. Care was taken to ensure no one was exposed to dangerous levels of radiation and staff involved in clean-up were monitored over the following decades. A corporal named Bjarnie Hannibal Paulson who was at the clean up developed unusual skin cancers and received a disability pension. NRU's calandria, the vessel which contains its nuclear reactions, is made of aluminum, and was replaced in 1971 because of corrosion. The calandria has not been replaced since, although a second replacement is likely needed. An advantage of NRU's design is that it can be taken apart to allow for upgrade and repair. In October 1986, the NRU reactor was recognized as a nuclear historic landmark by the American Nuclear Society. Since NRX was decommissioned in 1992, after 45 years of service, there has been no backup for NRU. In 1994, Bertram Brockhouse was awarded the Nobel Prize in Physics, for his pioneering work carried out in the NRX and NRU reactors in the 1950s. He gave birth to a scientific technique which is now used around the world. In 1996, AECL informed the Canadian Nuclear Safety Commission (then known as the Atomic Energy Control Board) that operation of the NRU reactor would not continue beyond December 31, 2005. It was expected that a replacement facility would be built inside that time. However, no replacement was built and in 2003, AECL advised the CNSC that they intended to continue operation of the NRU reactor beyond December 2005. The operating licence was initially extended to July 31, 2006, and a 63-month licence renewal was obtained in July 2006, allowing operation of the NRU until October 31, 2011. In May 2007, the NRU set a new record for the production of medical isotopes. In June 2007, a new neutron scattering instrument was opened in NRU. The D3 Neutron Reflectometer is designed for examining surfaces, thin films and interfaces. The technique of Neutron Reflectometry is capable of providing unique information on materials in the nanometre length scale.
2007 shutdown On November 18, 2007, the NRU reactor was shut down for routine maintenance. This shutdown was voluntarily extended when AECL decided to install seismically qualified emergency power systems (EPS) to two of the reactor's cooling pumps (in addition to the AC and DC backup power systems already in place), as required as part of its August 2006 operating license extension by the Canadian Nuclear Safety Commission (CNSC). This resulted in a worldwide shortage of radioisotopes for medical treatments because AECL had not pre-arranged for an alternate supply. On December 11, 2007, the House of Commons of Canada, acting on what the government described as "independent expert" advice, passed emergency legislation authorizing the restarting of the NRU reactor with one of the two seismic connections complete (one pump being sufficient to cool the core), and authorizing the reactor's operation for 120 days without CNSC approval. The legislation, C-38, was passed by the Senate and received Royal Assent on December 12. Prime Minister Stephen Harper accused the "Liberal-appointed" CNSC for this shutdown which "jeopardized the health and safety of tens of thousands of Canadians". Others viewed the actions and priorities of the Prime Minister and government in terms of protecting the eventual sale of AECL to private investors. The government later announced plans to sell part of AECL in May 2009. The NRU reactor was restarted on December 16, 2007. On January 29, 2008, the former President of the CNSC, Linda Keen, testified before a Parliamentary Committee that the risk of fuel failure in the NRU reactor was "1 in 1000 years", and claimed this to be a thousand times greater risk than the "international standard". These claims were refuted by AECL. On February 2, 2008, the second seismic connection was complete. This timing was well within the above 120-day window afforded by Bill C-38.
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