McMaster Nuclear Reactor, Nuclear research reactor at McMaster University in Hamilton, Canada.

The McMaster Nuclear Reactor is a research facility at McMaster University in Hamilton with two connected pools housing the reactor core. The system produces characteristic blue Cherenkov light during operation and features two cooling towers for heat dissipation.

The facility began operation in 1959 and was the first university-based research reactor in the Commonwealth of Nations. It has remained a center for nuclear research and radioisotope production since its opening.

The reactor is used for undergraduate teaching in neutron activation analysis, reactor physics experiments and radioisotopes for tracers and counting experiments. Graduate work uses neutron beams for neutron radiography, neutron diffraction, prompt gamma NAA and geochronological techniques. Commercial activity covers radioisotope production and neutron radiography, and researchers come from McMaster and universities in Canada and abroad.

The reactor sits on the McMaster University campus in Hamilton, Ontario, with two cooling towers beside the reactor building. The core can be moved between the two connected pools for maintenance, so the operating position varies. Access is controlled; arrange any group visit through the university in advance.

The facility produces about half of the global supply of iodine-125, a radioisotope used for cancer treatments in hospitals worldwide. This medical production is one of the reactor's main applications alongside scientific research.