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Canadian reactor shuts down…again

NRU is not getting any younger

By Hamish Johnston

In December 2007, medical physicists in North America were starting to worry about the dwindling supply of molybdenum-99 — from which the medical isotope technetium-99 is made.

The problem was that the NRU reactor in Chalk River, Ontario had been shut-down by Canada’s nuclear regulator over safety concerns — and the reactor was (and probably still is) the continent’s sole supplier of molybdenum-99.

The reactor was restarted after about a month when the Canadian government over ruled its own officials and production resumed.

But now, the reactor has stopped again thanks to a heavy water leak that was discovered on Friday. Atomic Energy of Canada, which owns the facility, is repairing the leak but says that NRU will be out of commission for more than one month.

The company also said that it will stop shipping medical isotopes from NRU on 23 May — and molybdenum-99 has a half-life of just 66 hours.

NRU produces isotopes for MDS Nordion — I just looked at their website and there is no mention of any possible shortages.

Recently, Nordion joined forces with the TRIUMF lab in Vancouver to explore the possibility of making molybdenum-99 using an accelerator.

If this scheme works, I think NRU deserves a dignified retirement after 52 years of service to physics — including supplying neutrons to the winner of the 1994 Nobel Prize in Physics.

Indeed, even I worked briefly at NRU in the late 1980s — the reactor seemed ancient even back then and its shut-down seemed imminent!

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