1.0 Background
The Canadian Nuclear Regulator has been a pioneer in setting reliability performance targets for select Nuclear Power Plant systems. Over time these performance measures have evolved and are supported by the use of modern computer based fault tree analysis, generally derived from plant-specific probabilistic safety assessments (PSAs).
The current Canadian nuclear regulatory framework concerning system reliability and maintenance aspects addresses reliability requirements, maintenance requirements and reporting requirements. This includes establishing yearly reliability targets for systems important to safety (based on the RD/GD-98 reliability program), as well as reporting on a number of performance indicators, such as Predicted Future Unavailability (PFU), Actual Past Unavailability (APU), system impairments and their effects.
Other international approaches are used to achieve similar objectives in equipment reliability and maintenance. For instance, both the Maintenance Rule and the Mitigating System Performance Index (MSPI) developed by the United States Nuclear Regulatory Commission (US NRC) are also adopted in other countries.
This study proposes to compare the present-day Canadian approach to reliability and maintenance indicators with the U.S. Maintenance Rule and MSPI. The study will also propose areas for further enhancement in the reliability program and future areas of research and development.
This project fits under the Fitness for Service Program Area (E-DOCS-#4401886) in the Equipment Reliability Sub-Program Area.
2.0 Objectives
The objective of this research project is to compare the Canadian regulatory requirements of nuclear power plant reliability program with the US NRC approach (Maintenance Rule (a(1) and a(2)) and MSPI). This comparison will identify the benefits and limitations of each approach. This study will also outline potential future avenues to explore with respect to reliability and maintenance requirements and performance measures. The study should also propose further potential areas of research and development.
3.0 Scope of Work
By using the CANDU plant specific fault tress system model and probabilistic safety assessment (PSA) model, the project will compare the Canadian reliability requirements and performance measures to the requirements of the US NRC Maintenance Rule (a (1) and a (2)) and MSPI. In order to do so, application of the Maintenance Rule and MSPI to a Canadian plant will be performed.
The successful contractor shall examine the Canadian regulatory reliability targets and requirements, (such as Predicted Future Unavailability, Actual Past Unavailability…) and the US NRC Maintenance Rule (a(1) and a(2)) and MSPI requirements to provide a thorough and comprehensive comparison of the two approaches. Furthermore, potential improvements or future area of research and development should be identified.
4.0 Tasks to be Performed
4.1 Review and familiarize oneself with the CNSC and USNRC maintenance and reliability requirements found in Ref 1-7 and other relevant information as applicable, if not already done.
4.2 From the Plant Annual Reliability Report and the system fault tree models[1], extract the information on the Canadian reliability performance measures (predicted future unavailability, actual past unavailability, etc.), for the Emergency Coolant Injection (ECI) and the Class III power system. Extract the failure data of these systems to be used in task 4.3
4.3 Apply the US NRC Maintenance Rule[2] and MSPI to the selected CANDU mitigating systems (ECI and Class III power)
4.3.1 Use the CANDU system information (flow sheet and design information) and create a system model to be used for the application of the USNRC maintenance rule and MSPI.
4.3.2 Establish the performance criteria as described in the Maintenance Rule, to the appropriate components/trains of the system.
4.3.3. Develop a process for establishing the baseline data to be used for the MSPI from the Annual Reliability Reports Data provided.
4.3.4 Use the actual data from the Annual Reliability Report (the data used in 4.2) to apply the maintenance rule (using the performance criteria established in 4.3.2)
4.3.5 Use the actual data from the Annual Reliability Report (the data used in 4.2) to apply the MSPI (using the baseline data established in 4.3.3)
Note: The data in Annual Reliability Reports may not be sufficient to apply the US NRC maintenance rule and MSPI, if that is the case, the contractor is expected to develop a set of hypothetical data to apply fully the MSPI and MR. The rationale for the use of the hypothetical data should be discussed and sensitivity case should be performed if needed.
4.4. Compare the results of the two regulatory approaches (from Tasks 4.2. and 4.3), and discuss with supporting rationale, the benefits and limitations of each method. Potential enhancements of each approach can also be discussed.
4.5 Based on the review of the Canadian and US approach; propose further areas of research or development in reliability and maintenance program.
References:
1- CNSC Regulatory Document, RD/GD-98, Reliability Programs for Nuclear Power Plants, June 2012, http://www.nuclearsafety.gc.ca/pubs_catalogue/uploads… Regulatory Document,
2- CNSC RD/GD-210, Maintenance Programs for Nuclear Power Plants, November 2012, http://www.nuclearsafety.gc.ca/pubs_catalogue/uploads…
3- CNSC Regulatory Document, CNSC REGDOC 3.1.1, Section 3.7, Reporting Requirements for Nuclear Power Plants, May 2014, http://www.nuclearsafety.gc.ca/pubs_catalogue/uploads…
4- USNRC 10CFR 50.65, Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, http://www.nrc.gov/reading-rm/doc-collections/cfr/par…
5- Nuclear Energy Institute, Regulatory Assessment Performance Indicator Guideline, NEI 99-02 Rev. 7, August 2013, http://pbadupws.nrc.gov/docs/ML1326/ML13261A116.pdf
6- CANDU NPP samples of Annual Reliability Report
7- COG-05-9011 Rev, “Guidelines for CANDU Nuclear Plant Reliability Programs”, June 2012
*Access to the system fault trees and the associated reliability reports will be limited to CNSC premises only, and only to the successful bidder after they have been successfully security cleared. Anticipate a two-week visit to the CNSC for this activity. The CNSC will provide access to the CAFTA software to the contractor while on-site.
[1] Both the Annual Reliability Report and the System Fault tree will be provided to the successful bidder under a Non-Disclosure Agreement.
[2] The CANDU plant PSA will be provided for application of the maintenance rule.
