Rating Definitions

CNSC inspector

A CNSC inspector at the Pickering Nuclear Generating Station. The white tower is part of an emergency
injection cooling system, one of the facility's many safety features. Pickering, Ontario, Canada

Updated July 18, 2012

Performance rating definitions

The performance ratings used in the 2011 report on the safety of Canada's nuclear power plants are defined as follows:

Fully satisfactory (FS) - Safety and control measures were highly effective

Safety and control measures implemented by the licensee are highly effective. In addition, compliance with regulatory requirements is fully satisfactory and compliance within the safety and control area (SCA) or specific area exceeds requirements and CNSC expectations. Overall, compliance is stable or improving, and any problems or issues that arise are promptly addressed.

Satisfactory (SA) - Safety and control measures were sufficiently effective

Safety and control measures implemented by the licensee are sufficiently effective. In addition, compliance with regulatory requirements is satisfactory. Compliance within the area meets requirements and CNSC expectations. Any deviation is minor, and any issues are considered to pose a low risk to the achievement of regulatory objectives and CNSC expectations. Appropriate improvements are planned.

Below expectations (BE) - Safety and control measures were marginally ineffective

Safety and control measures implemented by the licensee are marginally ineffective. In addition, compliance with regulatory requirements falls below expectations. Compliance within the area deviates from requirements or CNSC expectations to the extent that there is a moderate risk of ultimate failure to comply. Improvements are required to address identified weaknesses. The licensee is taking appropriate corrective action.

Unacceptable (UA) - Safety and control measures were significantly ineffective

Safety and control measures implemented by the licensee are significantly ineffective. In addition, compliance with regulatory requirements is unacceptable and is seriously compromised. Compliance within the overall area is significantly below requirements or CNSC expectations, or there is evidence of overall non-compliance. Without corrective action, there is a high probability that the deficiencies will lead to an unreasonable risk. Issues are not being addressed effectively, no appropriate corrective measures have been taken, and no alternative plan of action has been provided. Immediate action is required.

Rating methodology

CNSC site staff member

A CNSC site staff member inspects an instrument panel at the pumphouse that draws cooling water from Lake Ontario, at the Darlington Nuclear Generating Station.
Bowmanville, Ontario

The determination of the rating in each safety and control area is based on considerations of individual findings from inspections, event reports and desktop reviews.

Step 1: Identify findings

The findings are identified for each specific area using information from a variety of sources, including inspections, event reviews and desktop reviews. Findings are evaluated against a set of compliance criteria developed for each specific area that measure the degree of conformity with legal requirements.

Step 2: Assess findings

CNSC staff evaluate the findings against the compliance criteria and assign one of five possible finding assessments, high, medium, low, negligible or positive. The finding assessment category depends on the degree of negative impact on the effectiveness of the specific area as given in the manner defined in table 1 below.

Table 1: Findings assessment categories
Findings Category Definition
High Major negative impact on effectiveness of safety and control measures in the specific area; evidence of breakdown.
Medium Significant negative impact on effectiveness of safety and control measures in the specific area.
Low Small negative impact on effectiveness of safety and control measures in the specific area.
Negligible Insignificant impact on effectiveness of safety and control measures in the specific area.
Positive Evidence that the specific area is effective.

Step 3: Rate the specific areas

CNSC staff consider the relevant findings for the specific area and determine the effectiveness using a CNSC-developed guideline. The findings are judged in the context of the performance objective for the relevant SCA. The assessed effectiveness categories for all findings of a specific area are converted into a performance rating of FS, SA, BE, or UA (see performance rating definitions above).

Step 4: Rate the safety and control areas

The specific area ratings are converted to a number. Individual specific area ratings are then averaged to determine the SCA rating.

Determining the Integrated Plant Rating

The integrated plant rating (IPR) is determined for each station through averaging the values for ratings obtained in all 14 safety and control areas for each station.

The industry average SCA and IPR ratings are determined through averaging the seven individual ratings for the stations: Bruce A, Bruce B, Darlington, Pickering A, Pickering B, Gentilly-2 and Point Lepreau.