Why Canada’s new medical isotope reactors failed

New Scientist : Canada is one of the world’s biggest suppliers of radioactive isotopes for medical use through an aging 50-year-old reactor based at Chalk River in Ontario .Two brand-new reactors, constructed on the same site for more than Can$350 million ($330 million), called MAPLE 1 and MAPLE 2 were built as replacements.But the sad truth is that the MAPLEs have never been officially switched on, and the chances are they never will be.This has led to a furious row over who is to blame for this costly and embarrassing debacle.Many in the nuclear industry point the finger at Canada’s nuclear regulator. The regulator’s view is that the reactors’ manufacturer failed to deliver a crucial safety feature that it had promised would underpin the design.Others blame the Canadian government for killing off the project before crucial technical questions had been resolved.Alison Motluk takes a look at the technical difficulties faced by the reactors, why the Canadian government shut them down, and why it is building a billion-dollar replacement.