After months of delays, repairs to a nuclear reactor responsible for supplying much of the world's medical isotopes are now complete, says the company fixing it.

On Wednesday, Atomic Energy Canada Limited said repair crews had finished all welding repairs on the aging National Research Universal Reactor in Chalk River, Ontario.

Before the discovery of a radioactive heavy-water leak in one of its vessels, the 52-year-old NRU reactor supplied nearly 40 percent of the world's radioisotope molybdenum-99, the parent isotope of technetium-99, critical for many nuclear medicine procedures.

The reactor's shut down has greatly disrupted the supply of the isotopes, causing the number of nuclear medicine exams in Canada to drop by almost one-fifth compared with the previous year, according to a Canadian Institute for Health Information report released this week.

Repairs of the reactor were extremely tricky and have been hailed as a major achievement in engineering, with the AECL forced to train repair teams for months on mock vessels.

Originally set to restart in March, the deadline slipped as the company had to develop specially made repair tools and meet other difficulties. The AECL now expects to fully fuel it up and turn it on at the end of July.

As repairs are finished, the AECL is working to return the reactor's operating systems to service. So far, about 23 out of 35 are back up, the AECL said.

The main hurdle now is perhaps a regulatory, not an engineering one: the AECL has to get permission to restart from the Canadian Nuclear Safety Commission. A public hearing on the re-start is set for June 28.

Because of the ongoing medical isotope shortages, the commission said it has decided to speed up its review process.

"We will be issuing a summary decision within two days [of the hearing]," commission spokesman Aurele Gervais told DOTmed News. "Normally, we have a standard of six weeks."

Read More on DOTmed:

NRU Reactor weld repairs "98 percent" complete
https://www.dotmed.com/news/story/12892/

NRU Re-start Date Pushed Back to July
https://www.dotmed.com/news/story/12108/

Medical Isotope Shortage Could Affect 20,000 Patients
https://www.dotmed.com/news/story/12091/

High Flux Reactor Shutdown Begins
https://www.dotmed.com/news/story/11748/

NRU Delay Confirmed
https://www.dotmed.com/news/story/11527/

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