National Research Universal Reactor

The National Research Universal (NRU) reactor is one of Canada’s national science facilities. It is a multipurpose science facility that serves three main roles.

1. It generates isotopes 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).
2. It is 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.
3. It is the test bed for Atomic Energy of Canada Limited to develop fuels and materials for the CANDU reactor.

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Isotopes

With the construction of the earlier NRX reactor it was possible for the first time to commercially manufacture isotopes that were not commonly found in nature. In the core of an operating reactor there are billions of free neutrons. By inserting a piece of target material into the core, atoms in the target can capture some of those neutrons and become heavier isotopes. Manufacturing medical isotopes was a Canadian medical innovation in the early 1950s.

The NRU reactor continued the legacy of NRX and today produces more medical isotopes than any facility in the world.

• Cobalt-60 from NRU is used in Radiation therapy machines that treat cancer in 15 million patients in 80 counties each year.^[1] Cobalt-60 emits a lot of energy as it decays, enough to kill a cancer cell.
• Technetium-99m from NRU is used in the diagnosis of 5 million patients each year.^[2] Technetium-99m does not emit very much energy as it decays, but it is enough to be detected by a special camera which creates an image of the patient called a SPECT scan. (In fact NRU produces molybdenum-99 which decays into technetium-99m).
• NRU produces xenon-133, iodine-131 and iodine-125, which are used in a variety of diagnostic and therapeutic applications.
• Carbon-14 produced in NRU is sold to chemistry, bioscience and environmental labs to use as a tracer.
• Iridium-192 from NRU is used in several industries to inspect welds or other metal components to ensure they are safe for use.

The core of the NRU reactor is about 3 m wide and 3 m high, which is unusually large for a research reactor. That large volume enables the bulk production of isotopes. Other research reactors in the world produce isotopes for medical and industrial uses, for example the European High Flux Reactor at Petten in the Netherlands, and the OPAL reactor in Australia which began operation in April 2007.

Neutron Beam Research

The NRU reactor is home to Canada's national facility for Neutron scattering: the NRC Canadian Neutron Beam Centre. Neutron scattering is a technique where a beam of neutrons shines through a sample of material, and depending on how the neutrons scatter from the atoms inside, scientists can determine many details about the crystal structure and movements of the atoms within the sample.

An early pioneer of the technique was Bertram Brockhouse who built some of the early neutron spectrometers in the NRX and NRU reactors and was awarded the 1994 Nobel Prize in physics for the development of neutron spectroscopy.^[3]

The NRC Canadian Neutron Beam Centre continues that field of science today, operating as an open-access user facility allowing scientists from across Canada and around the world to use neutrons in their research programs.

It is common for a developed country to support a national facility for Neutron scattering and one for X-ray scattering. The two types of facility provide complementary information about materials.

An unusual feature of the NRU reactor as Canada's national neutron source is its multipurpose design: able to manufacture isotopes, and support nuclear R&D at the same time as it supplies neutrons to the suite of Neutron scattering instruments.

The NRU reactor is sometimes (incorrectly) characterized as simply a nuclear research facility. Neutron scattering however is not nuclear research, it is materials research. Neutrons are an ideal probe of materials including metals, alloys, biomaterials, ceramics, magnetic materials, minerals, polymers, composites, glasses, nano-materials and many others. The neutron scattering instruments at the NRC Canadian Neutron Beam Centre are used by universities and industries from across Canada every year because knowledge of materials is important for innovation in many sectors.^[4]

Nuclear Power R&D

The NRU reactor has test facilities built into its core that can replicate conditions inside a large electricity-producing reactor. NRU itself does not generate steam (or electricity); its cooling water heats up to approximately 55 degrees Celsius. Inside the test facilities though, high temperatures and pressures can be produced. It is essential to test out different materials before they are used in the construction of a nuclear generating station.

The fundamental knowledge gained from NRU enabled the development of the CANDU reactor, and is the foundation for the Canadian nuclear industry.

History

The NRU reactor design was started in 1949. 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.^[5] 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.^[5]

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, fuelled with natural uranium. NRU was converted to 60 MW with high-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.^[6][7] 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.^[8] No health effects were observed.

In October 1986 the NRU reactor was recognized as a Nuclear Historic Landmark by the American Nuclear Society.^[9]

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.^[10]

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.^[11]

In May 2007, the NRU reactor set a new record for the production of medical isotopes.^[12]

In June 2007 a new neutron scattering instrument was opened in NRU.^[13] 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.

2007 shutdown

On November 18, 2007, the National Research Universal reactor, which makes medical radioisotopes, was shut down for routine maintenance. This shutdown was 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), which had been required as part of its August 2006 operating license issued by the Canadian Nuclear Safety Commission (CNSC). This resulted in a worldwide shortage of radioisotopes for medical treatments because Chalk River makes the majority of the world's supply of radioisotopes, including two-thirds of the world's technetium-99 [1]. On December 11, 2007, the Canadian House of Commons, 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 accused the "Liberal-appointed" CNSC for this shutdown which "jeopardized the health and safety of tens of thousands of Canadians". [2] [3] [4] [5]

The NRU reactor was restarted on December 16, 2007.

References

See also

• Nuclear reactor
• Nuclear fission
• Nuclear medicine
• Radiation therapy
• Neutron scattering
• Bertram Brockhouse
• Nuclear power plant
• Nuclear power
• Nuclear accident
• Nuclear waste