Atomic Energy of Canada Limited (AECL) has announced that the National Research Universal (NRU) reactor in Chalk River, Ontario, is now projected to reopen in the first quarter of 2010, due to ongoing repairs that shuttered the 52-year-old facility in May.

In July, AECL said that the generator, which produces approximately 50 percent of medical isotopes used in North America – including molybdenum-99 – would be back online by “late 2009.”

The announcement extending the reopening of the NRU reactor will continue to exacerbate fears over an already disconcerting global shortage of medical isotopes, in particular because the High Flux Reactor in Petten, Netherlands, is currently closed for scheduled maintenance.

According to AECL, analysis of non-destructive examination data collected to date confirms nine sites likely requiring repair. In addition, high-resolution scanning data has identified both wall thinning and localized pitting that suggests “different corrosion effects. The data points to the need to better understand the nature of the corrosion mechanism.”

As a result, AECL is considering further testing by taking samples from the vessel wall in order to provide more comprehensive data.

Investigations are ongoing; however, based on evidence collected to date, AECL is considering applying a “band weld build-up technique”--a band at the inside base of the reactor vessel wall--over a broader area, which will address all nine sites that have been identified. In view of the number and locations of the repair sites, the band weld build-up application may be a more efficient and durable way to proceed in repairing the reactor vessel, the agency reported.

Due to the application of the band weld build-up technique, and the increased number of sites, AECL is now predicting that the NRU will return to service during the first quarter of 2010.