CANDU reactors, like those operated by Bruce Power, incorporate dozens of safety features to respond to the stringent safety requirements imposed by the Canadian Nuclear Safety Commission. These systems works independently of each other and are redundant (back-ups to the back-ups of our back-up systems).
These safety systems include:
• Two independent and diverse shutdown systems. Shutdown System No. 1 is the primary means of shutting down a reactor using neutron-absorbing rods that are suspended above the reactor and can be dropped into the core as needed. Shutdown System No. 2 sees a substance called gadolinium nitrate injected into the moderator, which absorbs neutrons to shut the nuclear reaction down within seconds.
• A vacuum building designed to prevent the release of radioactive material. The building is enclosed in nearly four-foot thick concrete walls. In the unlikely event of a large leak in the reactor cooling system, radioactive steam and water would be sucked into the vacuum building and cooled by roughly 12 million litres of water from a dousing tank. High-efficiency filters and charcoal absorbers would then remove 99.9% of the radiation.
• An Emergency Coolant Injection System that ensures water continues to circulate over the fuel if there were a leak in the heat transport system.
• A design that can use passive convection cooling for the primary systems to keep the reactor cool in the absence of power.
In the wake of the nuclear event in Fukushima, Bruce Power also implemented further back-up emergency systems at the Bruce A and B stations including five new fire trucks that can pump cold water from Lake Huron into our fuelling system in the unlikely case our depth of safety systems no longer work. Two of these specially-designed fire trucks will keep our nuclear fuel cool in the unlikely loss of our numerous layers of back-up systems. The trucks are stored on site and three will be stored offsite in a safe and dry area.
Nine new back-up generators are also stored in a dry area, off site and on high ground, and ready for deployment in the unlikely case all existing back-up power systems fail.