* Supplies a third of medical isotopes * Repair needs still undetermined * Extended shutdown not ruled out * Supply shortages feared (Updated throughout) TORONTO, May 21 (Reuters) - Canadian authorities said on Thursday it is too early to predict how long an aging nuclear reactor that produces much of the world's medical isotope supply will be idled, but said they could not rule out an extended shutdown. The 50-year-old Chalk River nuclear reactor in eastern Ontario, which supplies a third of the world's medical isotopes, was taken offline last week after Atomic Energy of Canada Ltd discovered a small leak of heavy water, used in the nuclear reaction process. Officials downplayed a media report on Thursday that the facility was likely to be shut for at least a year, but later said that could not be ruled out until they determine what kind of repairs are required. The only official estimate is that the plant will down for a month or more. "As to what it might be beyond that, that really depends on what we find in our inspections," Bill Pilkington, AECL's vice-president in charge of the Chalk River plant, told reporters. The National Post newspaper quoted an unnamed engineer on Thursday as saying: "A month to repair is a dream," because one option for repairs involves removing the fuel rods from the reactor and draining the vessel that holds the heavy water." That process normally takes about eight months, but the Post, citing sources, said it would more likely keep the facility offline for at least a year. "So your suggestion of it being in the realm of eight months or more is certainly not crazy, but at the same time we don't have the facts yet to determine what that is. So we have to complete the inspections, " Pilkington said. Canada said it is working with four other countries, including South Africa, that also produce medical isotopes, to deal with a possible shortage while Chalk River is out of operation. The isotopes are used in medical research and in some cancer treatments. When injected into the body, they give off radiation that can be imaged with a camera to diagnose cancer, heart disease and other medical conditions. Medical isotopes have a limited shelf life and doctors fear the supply could run short, forcing some treatments to be canceled or postponed [ID:nN21297747]. ($1=$1.14 Canadian) (Reporting by Allan Dowd and Scott Anderson; editing by Rob Wilson)
Former U.S. President Bill Clinton gives a speech as he attends the amfAR's Cinema Against AIDS 2009 event in Antibes during the 62nd Cannes Film Festival May 21, 2009. REUTERS/Regis Duvignau ...
