20 May (NucNet): Atomic Energy of Canada Limited’s (AECL) National Research Universal (NRU) reactor in Ontario will remain out of service for more than one month, after the discovery of a heavy water leak.
The NRU reactor, which provides more than half of the world’s medical isotopes, was safely shut down on 14 May 2009 due to a loss of electrical power in parts of eastern Ontario and western Quebec. During routine monitoring in the early morning hours of 15 May, a small leak of heavy water was detected within the reactor facility.
In an updated report on the situation issued on 18 May 2009, AECL said the location of the leak had been identified at the base of the reactor vessel, where there is corrosion on the outside wall of the vessel. Repair options are currently under consideration.
AECL said it would be unable to meet demand for medical isotopes from 23 May 2009. The company had said on 17 May that the production of medical isotopes at the Chalk River facility continued and that it expected to meet is production requirements through most of the next week.
The heavy water leak rate has been estimated to be about 5 kilogrammes per hour total, which AECL said was comparable to a leaking tap dripping once per second. The heavy water is fully contained and is being stored in specially designed drums, the company said.
However, due to high airflow in the area, a small portion of the leakage evaporates and results in a monitored tritium release through the NRU ventilation system, AECL said. “Although the airborne release is well below regulatory limits, the release has reached action levels for tritium. While this level does not pose a threat to the public or our workers, this is the level at which AECL reports to stakeholders and the Canadian Nuclear Safety Commission."
