On April 25, operations staff discovered a leak of heavy water from the Unit 4 heat transport system. Operations staff followed procedure and safely removed the unit from service and then took actions to stop the spill and safely clean it up.
There have been no adverse impacts to employees, the environment or the public.
Heavy water from the heat transport system contains levels of tritium which is a radioactive isotope of hydrogen.
Testing of airborne radiological emissions confirmed that no regulatory limits were reached or exceeded. While initial observations suggested the spill was contained within the Bruce A station, investigations following the spill identified approximately 20 litres of heat transport water reached a drain and potentially made its way into the lake.
An analysis of the amount of tritium present in the water indicated that any potential release would have no adverse impact on the environment or risk to the public. Operations staff monitored water entering the lake frequently during the event and no abnormal or elevated levels of tritium were detected.
Unit 4 was returned to service on April 30 and an investigation to determine the cause of the event is complete and a number of steps are being taken to implement corrective actions
