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What We Heard Report – DIS-12-02

Process for Establishing Release Limits and Action Levels at Nuclear Facilities


Discussion papers play an important role in the selection and development of the regulatory framework and regulatory program of the Canadian Nuclear Safety Commission (CNSC). They are used to solicit early public feedback on CNSC policies or approaches.

The use of discussion papers early in the regulatory process underlines the CNSC’s commitment to a transparent consultation process. The CNSC analyzes and considers preliminary feedback when determining the type and nature of requirements and guidance to issue.


Any industrial facility will have releases of some nature into the air or water as part of its normal operation, and nuclear facilities are no exception. All Canadian nuclear facilities are regulated by the CNSC, which ensures the protection of workers, the public and the environment. Releases of radioactive or hazardous substances into the environment at CNSC-regulated facilities have always been subject to regulatory oversight and control, primarily through release limits established in licences. These licence release limits are of fundamental importance, as they help to:

  • protect human health and the environment
  • ensure the most appropriate pollution prevention and control technologies are adopted
  • drive continuous improvement in the realm of proactive pollution prevention and control

The approach taken to establishing release limits has often varied, depending on the nature of the facility or substance. Currently, two types of release limits have been established and applied at CNSC-regulated facilities: exposure-based release limits (EBRLs) and technology-based release limits (TBRLs). EBRLs are established with the objective of ensuring that releases to the receiving environment stay below certain levels in order to meet desired human health or environmental quality criteria. TBRLs are based on the available pollution prevention technologies and techniques and establish a minimum level of treatment as determined by technology and economics.

The CNSC also requires licensees to put in place action levels (ALs) to serve as an early warning system to indicate when releases from a regulated facility may be deviating from the norm. However, the methodology for establishing or calculating ALs has not always been applied consistently for nuclear and hazardous substances across all licensed nuclear facilities.

With the release of discussion paper DIS-12-02, Process for Establishing Release Limits and Action Levels at Nuclear Facilities, the CNSC proposed clarifying the approach to the control of releases to the environment, by implementing a more formal framework for establishing release limits and associated ALs for nuclear and hazardous substances.

The discussion paper also proposed a number of important modifications to the development of exposure-based release limits. The CNSC has often calculated derived release limits (DRLs) for protection of the public using the public dose limit of 1 mSv/year – a level that is recognized to be protective of human health. However, in DIS-12-02, the CNSC proposed the common international practice of calculating DRLs using a dose constraint. A dose constraint of 0.05 mSv/year was proposed for existing facilities, and a constraint of 0.01 mSv/yr was proposed as a design objective for new-build nuclear reactors. It was also proposed that new facilities with tritium releases incorporate an emission design objective of 100 Bq/L for tritium in groundwater at the margin of the facility’s control area.

DIS 12-02 also suggested that, when establishing release limits for hazardous substances, the CNSC intended to:

  • harmonize the limits with existing provincial permitting processes, where feasible
  • use TBRLs to establish minimum levels of pollution prevention
  • incorporate a restricted “mixing zone approach” where site-specific EBRLs were merited

It was also proposed that all liquid effluents released to fish-bearing waters should meet Environment Canada’s criteria for demonstrating non-toxic effluents.

With respect to atmospheric emissions, the CNSC proposed that releases to air should meet the pertinent air quality criteria or standards and be harmonized with relevant provincial regulations and approaches, unless site-specific risk assessment and environmental monitoring data indicate the need for more stringent requirements.

Broadly stated, with the publication of DIS-12-02, the CNSC expressed its desire to open a dialogue with stakeholders on proposals to:

  • introduce a more consistent methodology regarding effluent releases across sectors of the nuclear industry
  • align the CNSC with national and international best practices

Consultation process

Discussion paper DIS-12-02, Process for Establishing Release Limits and Action Levels at Nuclear Facilities, was published on the CNSC website on February 22, 2012 for a 60-day consultation period. At the request of the industry, this period was extended to June 30, 2012.

Following the consultation period, submissions from stakeholders were posted on the CNSC website for 14 days, from July 30, 2012 to August 14, 2012, to allow interested parties to provide feedback on the comments received. At the request of the industry, this period was extended to September 13, 2012.

The CNSC received 29 written submissions from stakeholders.

Summary of stakeholder comments

In general, comments were supportive of the CNSC’s efforts to develop a more transparent and consistent regulatory framework for environmental protection. Comments also supported incorporating existing standards and guides into the framework where possible. There was agreement that the core principles outlined in the discussion paper were sound and the proposed changes valid. However, some stated that the discussion paper should not consider proposing specific values for dose constraints and/or release limits, as it was the approach that was under discussion and not the limits themselves. Several comments also requested clarification or indicated that proposed approaches were not clear.

It was suggested that consultation with Environment Canada and provincial regulators should occur prior to establishing release limits. Comments were received that the CNSC should continue to rely on Environment Canada and provincial ministries of the environment with respect to the regulation of hazardous substances, and that the CNSC should only concern itself with nuclear substances.

While some suggested that the Canadian Standards Association (CSA) standards development process could be used to develop a standard for establishing release limits and action levels, this option was vigorously opposed by others.

The concept of case-specific TBRLs received a mixed response. Some considered the restricted use of case-specific TBRLs as a reasonable alternative to exposure-based limits, where the latter cannot be met with current technology and the overall risk is acceptable. Others were completely opposed to the use of case-specific limits in any form.

It was suggested that the CNSC should monitor the development of new technologies and require nuclear facilities to implement technological changes when they would result in significant reduction in the release of radionuclides (when implementation is cost-effective) and that, as new technologies are implemented, the CNSC should revise the technology-based release limits.

Stakeholder consultation

While the CNSC has recently started using discussion papers to obtain early input into regulatory approaches, many respondents indicated that they would have liked to have been involved even earlier in the development of the proposed approach. It is clear that stakeholders want to be consulted throughout the CNSC’s process of establishing a more consistent methodology concerning effluent releases in the nuclear sector. The CNSC will provide further opportunities to provide input into this matter.

Section 36(3) of the Fisheries Act and mixing zones

The proposal to use appropriately restrictive mixing zone when establishing EBRLs was favoured by most who commented. It was acknowledged that mixing zones are well accepted as a means for defining treatment requirements and are common to provincial permit systems. However, it was noted that the Fisheries Act does not have any provisions for the inclusion of a mixing zone for the deposit of a deleterious substance and therefore the proposal may contravene section 36(3) of the Fisheries Act. In light of this, an opinion was expressed that the mixing-zone concept should be removed or, at a minimum, be severely curtailed and used only in limited and/or exceptional situations.

Harmonization and equivalency with other regulators

Some respondents stated that the CNSC should harmonize its regulatory requirements with other federal and/or provincial regulatory requirements by enacting equivalency, thereby reducing regulatory duplication and burden.

Concern was expressed that the proposed approach may single out the uranium mining industry, imposing standards not expected of similar non-uranium mining operations in Canada. It was suggested that site-specific release limits should be developed through joint consultation and consensus between the CNSC and provincial governments.

Derived release limits and dose constraints

A common concern raised by the industry was the use of a dose constraint to establish release limits. The industry:

  • felt that the CNSC has misinterpreted the International Committee on Radiological Protection (ICRP) definition of a dose constraint, as well as its use in establishing release limits
  • believed that derived release limits (DRLs) should continue to be based on 1 mSv/year
  • had concern that a dose constraint will become the new dose limit under the Nuclear Safety and Control Act
  • maintained that no rationale for applying dose constraints was provided, and believes the proposed use of dose constraints undermines the current process of assessment, planning, continuous improvement and adaptive management (thereby making it appear deficient in protecting the public)

Others, including non-governmental organizations (NGOs), believe the current practice of establishing DRLs on the 1 mSv/year regulatory public dose limit is inappropriate. They feel this practice results in release limits that are often orders of magnitude greater than actual releases, and therefore provide no regulatory significance with respect to demonstrating the control of releases.

Proposing a value of 0.05 mSv/year dose constraint for existing facilities

Concerns were raised with the appropriateness and utility of using the proposed dose constraint of 0.05 mSv/year for existing facilities, as this value may be less than the variation in local background radiation exposure. It was also suggested that a dose constraint of 0.05 mSv/year for existing facilities and 0.01 mSv/year for new-build nuclear reactors might be cost prohibitive, if not impossible to achieve.

Some stated that the classification of uranium mines and mills as nuclear facilities was not based on a demonstrated need. Concern was raised that Canada’s competitiveness with regards to international investment in uranium mining could be reduced if the dose constraint is inappropriately set too low.

Risk-based release limits

Some comments stated that release limits should be based solely on risk (i.e., exposure) as opposed to pollution prevention (i.e., minimum technology-based limits).

Design objectives

The industry felt the discussion on design objectives has no place in a regulatory document but belongs in the environmental assessment process. While NGOs supported the proposal to reduce the design objective for new facilities on tritium in drinking water from 7,000 Bq/L to 100 Bq/L, they would prefer this guideline to be reduced to 20 Bq/L as proposed by the Ontario Drinking Water Advisory Council.

Process for establishing action levels

Some respondents did not support using a statistical method for establishing action levels. It was felt that such a practice would not enhance safety, and that the unnecessary increase in reporting would in turn increase public concern. Some even had concerns that action levels may evolve to become TBRLs. Other respondents acknowledged that the statistical method aligned well with the definition of an action level as intended for environmental protection and that it was scientifically defensible. Comments also proposed setting a maximum threshold, in addition to a statistically established action level that should be triggered after a certain number of exceedances.

It was stated that introducing changes in release limits and action levels may lead to more frequent reporting. The industry strongly believes that such changes would need to be preceded by a substantial effort of public communication by the CNSC and by licensees in order to make sure that the public has a good understanding of the reporting level changes and their meaning.

Next steps

Given the diversity of comments received on Discussion Paper DIS-12-02, the CNSC recognizes it needs to further clarify its proposed approach for establishing release limits and action levels at nuclear facilities before formally developing regulatory requirements and guidance.

In order to provide additional clarity and deepen the level of dialogue on these proposals, the CNSC will organize one-day workshops with stakeholders who provided comments. These workshops will take place in June 2013. Following a thorough assessment of the outcomes and feedback from these workshops, the CNSC will develop its regulatory approach for establishing release limits and action levels at nuclear facilities. Stakeholders and the public will have an opportunity to comment on the resulting approach.

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