The stranglehold an aging nuclear reactor two hours outside Ottawa has on the world's supply of medical isotopes was known to few outside the nuclear-imaging community until this week.
The dependence was exposed only when repairs to the half-century-old Chalk River facility took longer than expected, sparking a worldwide shortage of a material needed for nuclear scans. But it didn't have to be this way. The reliance on this reactor for medical isotopes is a habit that was supposed to have been kicked years ago.
If even one of the two new reactors begun in the 1990s had been finished then, this crisis would not have happened. Either Maple 1 or Maple 2 could have met the world's need for molybdenum-99, from which the technetium-99m used in nuclear imaging is produced.
One reactor could supply the world, with the other acting as backup.
Only a handful of the world's reactors are built in such a way that molybdenum-99 can be extracted from the fission process. Long aware of the need to replace Chalk River, MDS Nordian – a processor and distributor of “moly” – signed a deal in the 1990s with Atomic Energy of Canada Ltd. Under the terms, AECL would build and operate two new reactors, both of which would be owned by MDS.
The new reactors were to cost $140-million and were to become operational in 1999 and 2000. The partnership fell apart amid cost overruns, delays and safety concerns and, hundreds of millions over budget, MDS and AECL underwent mediation in 2005. The unfinished reactors became the property of AECL early in 2006.
The reactors remain plagued by a problem known as a positive power coefficient of reactivity (PCR). This type of reactor is supposed to have a negative PCR, which means that the nuclear reaction will slow if the power in the core increases.
“After they did the first set of commissioning tests, they found they had a problem with the reactor physics in the core,” explained Barclay Howden, an official with the Canadian Nuclear Safety Commission. “If you had an event where power was going up [in the core] … power would go up at a faster rate [than with a negative PCR].”
Mr. Howden, whose responsibilities include the original Chalk River facility and both Maple 1 and 2, said that AECL has been unable to discover the cause of the problem.
Dale Coffin, a spokesman for AECL, said it remains confident the first of these reactors will be operational by the end of next year. But the goal was dismissed by an investment analyst who watched the dispute unfold between MDS and the Crown corporation. “They have been saying that for 12 years,” said Neeraj Monga, a vice-president at Veritas Investment Research who noted that AECL had controlled construction from the start, long before it assumed ownership.
“I have zero confidence that AECL will be able to finish in that time.”
