Fukushima response

Immediately after the March 2011 accident at Fukushima Daiichi, the operators of Canadian nuclear power plants inspected their stations to verify their preparedness for external hazards and severe accidents.

Supported by the Canadian Nuclear Safety Commission (CNSC), the operators looked at each plant’s earthquake risk, its fire-protection readiness, its ability to produce back-up power, its ability to control excess hydrogen inside containment structures, and its ability to keep its spent fuel cool.

The CNSC Task Force was only the first wave of Canadian investigation following the Fukushima accident; the CNSC shares information with other organizations monitoring the nuclear industry worldwide and will continue to assess health effects of the disaster for decades. The CNSC posts relevant documents and findings on the Fukushima and Health page of its website.

Minimal earthquake and tsunami risks

The CNSC’s Fukushima Task Force Report stated that the tsunami risk at the Darlington, Pickering, and Bruce Power generating stations is very low, given their location on the Great Lakes. The geological stability of the underlying Canadian Shield also minimizes the risk of earthquakes and tsunamis.

Seismic hazard map of ontario

Source: Natural Resources Canada.

The Gentilly-2 plant in Bécancour, Quebec faces a minimal tsunami risk. No tsunamis have ever occurred in the region. The nearest probable source of earthquakes,the Charlevoix region,is more than 100 km away.

The Point Lepreau generating station near Saint John, New Brunswick could face a tsunami risk from an earthquake in the Bay of Fundy or Passamaquoddy Bay. There is no evidence, however, that such an earthquake has ever occurred.

Reviewing the inspection reports, the CNSC Task Force concluded that all Canadian nuclear power plants met or exceeded the safety requirements of their design. The CNSC also reported minor concerns– particularly, that analyses had not yet shown that a hot and pressurized reactor that has lost its core cooling could be brought to a cold, depressurized state and held there for a prolonged period.

Safety recommendations

portable power generators

Portable power generators, which are part of the emergency mitigation equipment at nuclear power plants. Source: Bruce Power.

Since the review, operators of nuclear power plants and other major nuclear facilities worked diligently to implement CNSC’s recommendations. These recommendations targeted four areas:

  • strengthening multiple layers of defence against severe accidents,
  • improving emergency responsiveness,
  • improving government regulations and processes, and
  • improving international collaboration.

The CNSC set deadlines for its recommendations to be implemented at nuclear power plants: short-term (December 2012), medium-term (December 2013) and long-term (December 2015). With the exception of one action item that was delayed until the end of March 2016, all of the deadlines were met.

The CNSC noted that nuclear facilities other than power plants do not face the same fuel-cooling challenges as nuclear power plants do. Nevertheless, they too needed to complete safety assessments within the same short- and medium-term deadlines, and a long-term deadline of December 2016.

Requirements for nuclear power plants

Each generating station has assessed how it would respond in the unlikely event that an accident that eliminates the use of all cooling systems. The results varied for each station, but common themes emerged:

  • Pressure tubes that house nuclear fuel bundles could fail earlier than predicted by previous analyses.
  • The duration of battery power, which feeds instruments and control equipment, may need to be extended.
  • Relief valves that would vent steam from overheated coolant into containment structures might not be able to handle the task fully.
  • Operators should be able to model severe accidents in multi-unit power stations, rather than focus on single-reactor accidents.
  • Generating stations should consider upgrading their ability to replace water leaking from their used-fuel bays.

Regulatory review

The CNSC concluded that the Canadian government’s regulatory framework and processes need not be revised in light of the Fukushima accident.However, CNSC also concluded that it should improve ten aspects of its own regulatory framework, and work to improve its communications and public-education functions.