Canada’s Chalk River complex contains the 60-year-old National Research Universal reactor, the world’s oldest operating nuclear reactor. 

Canadian Nuclear Laboratories

Canada’s neutron scientists lament closure of world’s oldest nuclear reactor

The world’s oldest operating nuclear reactor is in the twilight of its life, but the scientists who rely on it for their research are not going gentle into that good night. Canadian scientists are upset about the imminent closure of the Chalk River research reactor and are lobbying the government for a CA$200 million ($162 million) commitment so they can continue to perform materials research using the neutron beams that research reactors provide.

“You need an organization somewhere that’s providing central support and stewardship for a national program,” says John Root, director of the Canadian Neutron Beam Centre in Chalk River, Ontario, which relies on the 60-year-old reactor. “If you don’t have this central hub, you don’t really have a national program. You have somebody sending checks to laboratories in the United States or Europe, and Canadian individual researchers are on their own.”

In February executives of the University of Saskatchewan in Saskatoon and McMaster University in Hamilton, publicly launched the Canadian Neutron Initiative to lobby the federal government for a 10-year, CA$200 million commitment, a figure that sounds large but pales in comparison to the CA$100 million the government spends annually to keep the reactor running. Root would like to see this funding open up beam time at other neutron sources around the world, as well as maintain a critical amount of neutron beam research within Canada until another large-scale neutron source might be built. The Canadian government has remained silent on the matter so far.

Officially called National Research Universal (NRU) reactor, the Chalk River reactor began its life in 1957 and in short order became the centerpiece of Canada’s nuclear research enterprise. Housed in a boxy building some 30 meters tall on the banks of the Ottawa River, NRU is owned by the Atomic Energy of Canada Ltd. (AECL), the corporation created by the Canadian government to develop commercial nuclear technologies.

For several decades, the NRU served as the test bed for the development of Canada’s own nuclear power technology and a fleet of reactors that continue to provide a substantial portion of the country’s electricity. The reactor itself became a globally dominant supplier of radioisotopes—in particular, molybdenum-99 (Mo-99), a workhorse of medical imaging employed for millions of scans every year.

This dependence on a single source for such a vital commodity became problematic by the 1990s, when AECL administrators began to talk seriously about retiring the NRU. Work began on a pair of dedicated, Mo-99-producing reactors, but the project was abandoned by 2008. When a water leak caused by corrosion unexpectedly took the NRU offline later that same year, a global medical radioisotope shortfall ensued. AECL allowed the NRU to limp along, in part to allow other sources of the medical commodity to come online. But finally, in 2015, the federal government announced that the reactor would be shuttered for good in March 2018.

Molybdenum-99 production isn’t the only thing that will die along with NRU. Nuclear reactors produce ample amounts of high-energy neutrons as a byproduct of fission reactions. Directed as beams, these particles become potent tools, because their neutral charge enables them to penetrate dense materials and scatter off nuclei. The scattering can be used to create imagery of these materials in much the same way that X-ray crystallography reveals the structure of complex molecules. Led by Bertram Brockhouse, a physicist who would go on to win a share of the 1994 Nobel prize in physics for his development of neutron scattering techniques, NRU became the national center for neutron beam research. In the 1980s, universities attracted funds to expand NRU’s capabilities and spawned the Canadian Institute for Neutron Scattering (CINS), a professional association that represents academic interests and promotes this technology as a tool for materials science. Today, nearly 400 people belong to CINS, drawn from dozens of Canadian universities and government departments, as well as foreign institutions in 22 other countries.

Some scientists worry this body of talent and experience is all too likely to disperse permanently after next year’s NRU shutdown, which could leave many researchers and organizations at an important crossroads. And not just academic scientists: the NRU is also prized by an industrial clientele, such as car-engine manufacturers, who use the beams to check for potentially catastrophic stresses deep inside prototypes. Some of this activity already takes place at a much smaller research reactor, which is only 2 years younger than the NRU, maintained by McMaster University. However, with just a fraction of the power put out by the NRU, this facility will not be able to take up this displaced research traffic. Users will be forced to look further afield, to places such as the Spallation Neutron Source, the flagship U.S. neutron beam facility at Oak Ridge National Laboratory in Tennessee. As outsiders, however, finding time at these places is bound to be challenging. Some also worry about the experimental design expertise that will be lost along with the NRU.

“This kind of expertise grows up organically and requires continuity,” says Dominic Ryan, a physicist at McGill University in Montreal and former CINS president who invests about 100 research days a year at NRU on work to predict the magnetic properties of new materials that could reduce the cost of components for wind turbines and electric automobile motors. “The stuff I do will probably stop happening.”

Ryan did manage to obtain some limited access to a neutron source at the Institut Laue-Langevin in Grenoble, France, but found it difficult. He expects to have better luck finding beam time on Australia’s OPAL reactor, but notes “it’s a hell of a commute”.