National Research Universal Reactor - History

History

The NRU reactor design was started in 1949, and 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 and had attracted a large scientific community who were using those neutrons in research that was then possible for the first time. 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 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 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. No health effects were observed.

NRU's calandria, the vessel which contains its nuclear reactions, is made of aluminum, and was replaced in 1971 because of corrosion. But it has not been replaced since, although this second replacement is likely needed. A complete shutdown of perhaps one year would be needed for the replacement. One strong advantage of NRU's design is that it can be taken apart to allow for replacements such as this. Since NRX was decommissioned in 1992, after 45 years of service, there has been no backup for NRU.

In October 1986, the NRU reactor was recognized as a nuclear historic landmark by the American Nuclear Society.

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 full operating of NRU until October 31, 2011.

In May 2007, the NRU reactor 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 relatively new, and capable of providing unique information on materials in the nanometre length scale.