PRA Newly Developed Methods (NDM) Repository Wiki

Newly Developed Methods (NDM) is an increasingly important concept in the U.S. nuclear industry. This wiki provides an industry repository for important details on PRA methods that industry organizations (other than EPRI) have determined to be "Newly Developed".

Product Information

PRA Newly Developed Methods Wiki Version 1.0 - Proof of Concept Repository

Product ID: 3002022110

Overview of NDM Repository Wiki

With the issuance of Regulatory Guide 1.200 Revision 3, the US Nuclear Regulatory Commission (NRC) endorsed the concept of a “Newly Developed Method (NDM)” for use in Probabilistic Risk Assessments (PRAs). This Regulatory Guide also defined terms and references associated with determining what is an NDM and what options can be used to seek NRC acceptance or consensus that an NDM is acceptable for use in PRA.

This Wiki shares information from previous evaluations within the industry specifically that have been provided to EPRI for inclusion in the Wiki. These evaluations of interest are those related to whether a PRA method is considered an NDM, and whether an NDM Peer review has been conducted to determine the technical adequacy of the method for inclusion in risk applications as necessary.

Purpose of NDM Repository Wiki

Because EPRI members and other stakeholders will benefit from a repository of methods that have been considered previously by others in the context of whether they are an NDM, EPRI has created this PRA Newly Developed Methods Wiki to be a publicly available reference to meet this need. The repository is organized into broad categories and contains information provided to EPRI by stakeholders (utilities, vendors, NEI, others) about the following:

Has the method been evaluated previously to determine whether it is an NDM?
Is the method considered to be an NDM? A summary level justification for this YES/NO determination should be provided.
If the method is determined to be an NDM, has a peer review of the NDM been conducted? IF YES, then the public summary of the scope and findings of the NDM should be provided.

Scope of NDM Repository Wiki

Information in this Wiki is provided to EPRI by various stakeholders for inclusion in this repository. Inclusion of the method in this page does not imply that the method has been vetted or endorsed by EPRI, nor that EPRI has evaluated and agreed with the decision that a method is or is not a new method, nor with the conclusions of any NDM peer reviews. EPRI’s role is to organize the information provided by others into a publicly accessible repository for the benefit of members, regulators, and other stakeholders around the world.

For questions or additional information on the methods contained in the repository, contact the developer of the method directly.
For questions about the determination that a method is or is not a newly developed method, contact the person listed on the summary justification for that determination.
For questions on the scope or conclusions of a newly developed method peer review, please contact the peer review lead listed in the public summary of the NDM peer review of interest.

The content of the Wiki is not intended to be all-inclusive. It does not intend to capture and document all accepted state-of-practice methods. Instead, the content includes the information provided to EPRI by industry stakeholders about which PRA methods have been reviewed and considered as potential NDMs upon the release of NRC Regulatory Guide 1.200 Revision 3. Also, the content is organized by topical areas, e.g., Level 1 General PRA Methods, External Flooding PRA Methods, and others. These sections will be populated with NDMs as they are determined by industry organizations. Unpopulated sections will serve as placeholders until NDMs for those sections are identified and provided to EPRI.

EPRI Materials Referenced in NDM Repository Wiki

Any published EPRI results (reports, software products, etc.) referenced in the Wiki are fully documented by EPRI and accessible by EPRI members at [www.epri.com www.epri.com]. As a global, independent, scientific research organizations, EPRI supports the technical basis of all EPRI research which may be considered a PRA method. However, as a non-profit, EPRI does not engage directly in determining steps are required for regulatory acceptance of PRA methods in individual countries around the world. EPRI supports its members in understanding and applying the methods correctly and consistent with their technical bases. Thus, decisions on whether an EPRI method is an NDM are made by the users of the methods. Also, conduct of NDM peer reviews are organized by the users of the methods, though EPRI will support answering technical questions on the method, its development and basis as part of any conducted peer reviews on EPRI methods.

Definitions

The following definitions are based on NRC Regulatory Guide 1.200 Revision 3.

Definition of a Newly Developed Method

Newly Developed Method: A PRA method that has either been developed separately from a state-of practice method or is one that involves a fundamental change to a state-of practice method. An NDM is not a state-of practice or a consensus method.

Supporting Definitions

A number of definitions are needed to support the development of the NDM requirements and review process. Several important definitions used in determining whether something is a “newly developed method” are provided below:

PRA Upgrade: A change in the PRA that results in the applicability of one or more supporting requirements that were not previously included within the PRA (e.g., performing qualitative screening for Part 4 of ASME/ANS Level 1/LERF PRA standard when the related high-level requirement was previously not applicable, or adding a new hazard model), an implementation of a PRA method in a different context, or the incorporation of a PRA method not previously used.
PRA Method: An analytical approach in the PRA used to satisfy a supporting requirement or collection thereof from a national consensus PRA standard. An analytical approach is generally a compilation of the analyses, tools, assumptions, and data used to develop a model.
Model: A qualitative and/or quantitative representation that is constructed to portray the inherent characteristics and properties of what is being represented (e.g., a system, component or human performance, theory or phenomenon). A model may be in the form, for example, of a structure, schematic or equation. Method(s) are used to construct the model under consideration.
PRA: An approach that (1) provides a quantitative assessment of the identified risk in terms of scenarios that result in undesired consequences (e.g., core damage or a large early release) and their frequencies and (2) comprises specific technical elements in performing the quantification.
PRA Maintenance: A change in the PRA that does not meet the definition of PRA upgrade.
State-of–Practice: Practices that are widely accepted by and implemented throughout the commercial nuclear power industry, have been shown to be technically acceptable in well-documented analyses or engineering assessments that are publicly available, and are accepted by the NRC.
Consensus Method/Model: In the context of risk-informed regulatory decisions, a method or model approach that the NRC has used or accepted for the specific risk-informed application for which it is proposed. A consensus method or model may also have a publicly available, published basis and may have been peer reviewed and widely adopted by an appropriate stakeholder group.

Adding Newly Developed Methods to NDM Repository Wiki

Stakeholders can provide the following information to EPRI (or NEI) to be included in future updates to this Wiki.

Determination that a PRA Method is or is not an NDM

To add a method that your organization has determined is or is not an NDM according to the guidance in the associated industry references, a summary (document or hyperlink to a document) containing the answers to the following questions, along with appropriate technical justification, should be provided:

Is the new method a consensus method or has an NDM peer review already been completed? (Y/N)

Provide summary of basis for the answer to this question. If the method was already successfully reviewed through the NDM review process or is a consensus method, then the method is not an NDM and there is no need for assessment of its technical adequacy.

Has the method been developed separately from a state-of-practice method? (Y/N)

Provide summary of basis for the answer to this question. If the answer to this question is Yes, then the method is a NDM.

Does the method involve a fundamental change to a state-of-practice method? (Y/N)

Provide summary of basis for the answer to this question. If the answer to this question is Yes, then the method is a NDM.

Documentation of a completed peer review to determine the technical adequacy of an NDM

When a peer review to determine technical adequacy of an NDM has been completed, a summary (document or hyperlink to a document) containing the information specified in PWROG-19027-NP, Revision 2, Section 5.2 should be provided. The information should be non-proprietary and should include at least the following information:

Unique identification of the method reviewed
Process followed for the conduct of the NDM peer review)
Review team composition (full resumes are not required)
Characterization of the NDM summary of the peer review findings regarding the adequacy of the NDM
Listing of the associated ASME/ANS PRA Standard Supporting Requirements (SRs) along with the assessment findings and associated basis
Listing of any Facts and Observations (F&Os) from the NDM peer review along with the status of the F&Os (open/close) and the basis for closure if they are closed.
Listing of SRs that should be peer reviewed in a peer review for a stakeholder’s application of the method

Guidance Documents / References

NRC Regulatory Guide 1.200 Revision 3 - US Nuclear Regulatory Commission (NRC), Regulatory Guide 1.200, Revision 3, “Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities,” Washington, DC, December 2020. (ADAMS Accession No. ML20238B871)
PWROG-19027-NP, Revision 2 - Pressurized Water Reactor Owners Group (PWROG), Report PWROG-19027-NP, Revision 2, “Newly Developed Method Requirements and Peer Review,” Cranberry Township, PA, July 2020. (ADAMS Accession No. ML20213C660)
NEI 17-07 Rev 2 - Nuclear Energy Institute (NEI), NEI 17-07, Revision 2, “Performance of PRA Peer Reviews Using the ASME/ANS PRA Standard,” Washington, DC, August 2019. (ADAMS Accession No. ML19241A615)

Contacts for Additional Information

EPRI – For questions on EPRI research results or other EPRI questions, contact Fernando Ferrante.
NEI – For questions on NDM process or coordination, contact Victoria Anderson.