June 3, 2009 - The Chalk River Laboratories (CRL) nuclear reactor, which supplies about a third of the world’s medical isotopes, has been shut down since May 14 and is not expected to be back for at least three months, according to Atomic Energy of Canada Ltd. (AECL).
The reactor produces medical isotopes such as molybdenum-99 (Mo-99), which are used in diagnostic nuclear imaging scans.
AECL reported the NRU reactor at Chalk River would remain out of service for more than a month in order to investigate and repair a heavy water leak in the reactor vessel. The location of the heavy water leak has been identified at the base of the reactor vessel in a location where there is corrosion on the outside wall of the vessel.
“Sophisticated diagnostic procedures are required to determine the exact nature and extent of the repairs before returning the NRU reactor safely to service,” said Bill Pilkington, AECL’s senior vice-president and chief nuclear officer. “Based on our preliminary findings to date, we now believe that the NRU reactor will be out of service for at least three months.”
On June 2 AECL said it began the process of removing fuel rods from the NRU reactor as part of the process to repair the reactor and return it to service. There were about 100 rods in the reactor at the time NRU was shut down and officials said it will take an estimated three to four weeks to complete.
For more information: www.aecl.ca
October 16, 2026 
