1.0 Background
The regulatory standard S-294 “Probabilistic Safety Assessment (PSA) for Nuclear Power Plants” was first issued by the Canadian Nuclear Safety Commission (CNSC) in April 2005 and was later incorporated in the licensees Power Reactor Operating Licence (PROL). The standard sets high level requirements for the conduct of Level 1 and Level 2 PSAs which include the consideration of internal and external events for at-power and shutdown operational states.
In May 2014, the regulatory standard S-294 was amended and issued as REGDOC 2.4.2. Both the previous S-294 and the updated REGDOC 2.4.2 versions focus on the development of PSA methodology, not on PSA use and application.
Thus far most NPP licensees in Canada have submitted their PSAs to the CNSC. With this in mind, licensees are using their PSA results and insights to support operational needs and to respond to regulatory requests. The industry has already proposed some potential PSA applications such as Risk Informed In-service Inspection (RI-ISI) and Risk Informed Fitness for Service (RI-FFS).
On the international level, PSA has evolved to the point that it is increasingly used as a tool in regulatory decision making, to the extent supported by the state-of-the-art in PSA methods and data in a manner that complements the deterministic approach.
With respect to the CNSC, a high level process known as Risk Informed Decision Making (RIDM) was established in 2009. The next step is to establish a regulatory framework that governs the use of PSA in regulatory decision making. This will serve as a basis for accepting or rejecting licensees’ risk informed requests.
2.0 Objectives
This research project seeks to gather and assess the current status of PSA use and application as it applies to licensees and regulators of select nuclear power generating states. Based on the assessed advantages and disadvantages of different approaches, expert recommendations are being sought concerning the path forward for PSA use and application as it applies to CNSC’s regulatory framework and RIDM process.
3.0 Scope of Work
The scope of work requires a review and assessment of international and Canadian PSA use and application concerning nuclear power plants. This work is to consider the regulatory framework and practice of select states (identified in Task 4.1).
4.0 Tasks to be Performed
4.1 Perform a literature review and summarize PSA use and application as it applies to licensees and regulators of select nuclear power generating states (United States, United Kingdom, France, Germany, Nordic countries, Japan and Korea), considering the following areas:
a. Policies on risk informed decision making using PSA, including acceptance criteria.
b. Use of PSA by regulators.
c. PSA use and application by licensees.
d. Regulations and/or guidance concerning PSA use and application.
e. Successful examples of PSA applications.
f. Pros and Cons of PSA applications.
g. Current consideration of PSA use and application after the Fukushima accident.
The source of the literature shall include:
- Publications from international organizations such as the International Atomic Energy Agency (IAEA) and Organization for Economic Cooperation and Development (OECD) Nuclear Energy Agency.
- Publications, documents from regulatory authorities, such as the U.S. Nuclear Regulatory Commission (U.S. NRC).
- Proceedings and papers from international conferences and workshops.
- Journal papers.
4.2 Prepare a set of questions and interview at least two senior CNSC staff members from the Probabilistic Safety Assessment and Reliability Division. The interview should seek information concerning current regulatory practice in Canada as it pertains to PSA use and application, as well as the RIDM process.
4.3 Based on the information compiled from Tasks 4.1 and 4.2, consider the advantages and disadvantages of the different approaches that were studied.
4.4 Based on the completion of Tasks 4.1 through 4.3, recommend:
a. Areas that PSA use and application should be encouraged in Canada.
b. Advancement of the CNSC regulatory framework, including an assessment of necessary regulatory documents that should be developed.
