Canadian cannot continue to update to nuclear reactors, due to lack of funding. Source: Nuclear Threat Initiative

Atomic Energy of Canada Ltd. (AECL) has stopped the development of two isotope-producing reactors in Chalk River, Ontario, but will continue to provide an ongoing supply of medical isotopes.

The Canadian government conducted tests on the reactors this spring and could not find a solution to a design flaw that would make the reactors more prone to a meltdown, according to AECL.

MDS - which has battled AECL over previous delays to the Maple program - said it was not consulted on the decision and plans to "evaluate all options and pursue appropriate steps" to protect its shareholders and customers. MDS Nordion, a business unit of MDS, purchases the isotopes from Chalk River reactors, then refines and markets them globally.

The AECL and MDS Nordion have spent several hundred million dollars on the development of the Maple reactors, tackling the problem of positive power coefficient of reactivity (PCR). The reactor is supposed to have a negative coefficient of reactivity, meaning the nuclear reaction would slow down if the power in the core increased. Instead, the nuclear reaction increased with additional power, heightening the chances of a meltdown, according to Globes & Mail.

The problems come as AECL competes with larger international companies to sell several reactors to Ontario, AECL CEO Hugh MacDiarmid told Globes & Mail.

Globes & Mail reported that MacDiarmid said the AECL now plans to supply the North American medical isotopes market by extending the life of the 50-year-old Chalk River research reactor. The so-called NRU reactor was shut down last November over safety concerns, disrupting supplies of the medically critical isotopes that are used in diagnosing and treating cancer and heart disease.

As a result of the shutdown, the federal government regulator Linda Keen, former president of the Nuclear Safety Commission, as well as both the government's outside experts and AECL, argued the reactor was operating safely.

The commission said that AECL failed to finish some safety upgrades ordered by the commission, work that has since been completed. The closure caused a global shortage of medical isotopes and threatened critical diagnostic testing and cancer treatments, according to the Canadian government.

The Office of the Auditor-General has estimated it would cost $600 million to refurbish the Chalk River site and bring it to modern standards, including an undisclosed investment in the research reactor itself, according to Globes & Mail.