NRU Reactor

The National Research Universal reactor (NRU) design was started in 1949, with plans for it to be built as the successor to the NRX reactor at the Chalk River Laboratories. At the time that NRX was built, 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 on November 3, 1957, a decade after NRX, and was much more powerful. It was initially designed as a 200 MW reactor fuelled with natural uranium; however in 1964 it was converted to 60 MW with high-enriched uranium (HEU) fuel and then converted a third time in 1991 to 135 MW running on low-enriched uranium (LEU) fuel.

On May 24, 1958, less than a year after it began operation, the NRU suffered a substantial 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 only three months so NRU was operating again in August 1958. Care was taken to ensure no one was exposed to dangerous levels of radiation. Staff involved in the clean up were monitored over the following decades. No health effects were observed.

NRU Reactor
The NRU is among the most versatile research reactors in the world.

One of the major advantages of NRU’s design is that it can be taken apart fairly easily and quickly to allow for replacement of major parts. For example, since the reactor’s calandria, the vessel which contains its nuclear reactions, is made of aluminum, it has required replacement because of corrosion. Another design advantage of the NRU is its ability for on-power refuelling, meaning that used fuel can be removed and new fuel can be inserted without shutting down the reactor. Both of these innovations – core refurbishment and on-power refuelling – eventually found their way into Canada’s CANDU power reactor design.

NRU is also one of the world’s leading sites for medical isotope production. Medical isotopes are tiny radioactive particles that can be injected into the body to assist doctors with diagnosing and treating certain illnesses. During the course of its operation, NRU has been responsible for the production of just over half of the supply of the medical isotopes around the world that doctors have used for their patients. As an example, NRU is the world’s largest single source of the isotope cobalt-60, which has been used in cancer treatment for more than half a century.

The nuclear medicine industry has grown considerably over the years. NRU makes more medical isotopes than any other facility in the world. On an annual basis over 21 million people in 80 countries are treated with isotopes from the NRU reactor at Chalk River Laboratories. This initial innovation has grown to make a huge impact on global health. Those raw isotopes are manufactured into medical products by the world’s leading medical isotope business – MDS Nordion, located in Ottawa, Ontario.

The demand for medical isotopes worldwide continues to rise. And in a young field of science like this, there is great potential for new innovation with a large impact on society: new isotopes and new applications.

The medical isotope business in Canada today is an excellent example of why governments invest in large-scale national science infrastructure. If the proper tools are in place, bright Canadian minds can achieve great things.

Additionally, NRU is the source of the fundamental knowledge that was required to develop Canada’s fleet of nuclear power stations. Fuel and structural material needed to build a CANada Deuterium Uranium or CANDU reactor are tested and proved in NRU.

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 nanometer length scale.

Based on its impressive record in the medical isotope, neutron scattering, and nuclear power research fields, NRU is considered by many to be the most ambitious and productive science research reactor in Canada.