United States Nuclear Regulatory Commission - Protecting People and the Environment

Priority for NRR Review of Risk-Informed Licensing Actions

WASHINGTON, D.C. 20555-0001

October 30, 1998



All holders of operating licenses for nuclear power reactors.


The U.S. Nuclear Regulatory Commission (NRC) is issuing this administrative letter to inform addressees about a revision to the priority assigned by the Office of Nuclear Reactor Regulation (NRR) for the review of risk-informed licensing actions. The assignment of a higher review priority for these actions is consistent with the NRC's policy statement on probabilistic risk assessment (PRA) and the staff's PRA Implementation Plan, which encourage greater use of this technique to improve safety decisionmaking and regulatory efficiency. This administrative letter does not transmit or imply any new or changed requirements or staff positions. No specific action or written response is required.


In August 1995, the NRC adopted its final policy statement regarding the expanded use of PRA (Reference 1). The final policy statement provided that the use of PRA technology should be increased in all regulatory matters to the extent supported by the state of the art in PRA methods and data, and in a manner that complements the NRC's deterministic approach and supports the NRC's traditional defense-in-depth philosophy. The policy statement and the staff's resulting PRA Implementation Plan were intended to improve the regulatory process in three areas: foremost, through safety decisionmaking enhanced by the use of PRA insights; through more efficient use of agency resources; and through a reduction in unnecessary burdens on licensees.

In general, the industry's response to the PRA policy statement and the implementation plan has been positive. Utilities are applying PRA in their licensing activities and in the maintenance and operation of their plants. Several utilities have participated with the NRC in pilot applications of risk-based initiatives. These initiatives have included the use of risk insights to support changes in programs such as in-service testing, technical specifications, and graded quality assurance. These pilot programs have helped to shape the development of regulatory guidance documents for using PRA in reactor-related activities. These regulatory guides (References 2-6) describe acceptable approaches for requesting changes to licensing requirements that are supported by risk information.


By memorandum dated June 6, 1993, the then-Director of NRR, Thomas E. Murley, defined a general framework for determining the priority of NRR review activities. A memorandum from Samuel J. Collins, Director of NRR, dated October 1, 1998, presented the following additional, specific guidance for reviewing risk-informed licensing actions. A risk-informed licensing action is defined as any licensing action that uses quantitative or qualitative risk assessment insights or techniques to provide a key component of the basis for the acceptability or unacceptability of the proposed action. Mere mention of quantitative or qualitative risk insights does not in itself make a licensing action risk-informed. Within the priority framework provided by the previous guidance, risk-informed licensing actions will be assigned a Priority 2, unless the previous guidance would assign them a Priority 1, because of safety significance or the need for immediate action. This priority elevation is intended to highlight those licensing actions that use risk-assessment insights from among the routine licensing actions. Licensing actions and activities that are assigned a Priority 2 on the basis of safety significance or a need for prompt action should be given review precedence over risk-informed licensing actions of lesser safety significance or immediacy that have been assigned a Priority 2 on the sole basis of this guidance.

The intent of this revised priority is to improve the efficiency and timeliness of NRR review and processing of risk-informed licensing actions, consistent with the Commission's stated goals.

This administrative letter requires no specific action or written response. If you have any questions about this letter, please contact the person listed below or the appropriate NRR Project Manager.

/s/'d by D. B. Matthews For

Jack W. Roe, Acting Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation


Contact: J. Randall Hall, NRR
E-mail: Randy.Hall@nrc.gov
Attachments: 1. List of References
2. List of Recently Issued NRC Administrative Letters

(NUDOCS Accession Number 9810270256)



  1. USNRC, "Use of Probabilistic Risk Assessment Methods in Nuclear Activities: Final Policy Statement," Federal Register, Vol. 60, p. 42622 (60 FR 42622), August 16, 1995.

  2. USNRC, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," Regulatory Guide 1.174, July 1998.

  3. USNRC, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice Testing," Regulatory Guide 1.175, August 1998.

  4. USNRC, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Graded Quality Assurance," Regulatory Guide 1.176, August 1998.

  5. USNRC, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications," Regulatory Guide 1.177, August 1998.

  6. USNRC, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice Inspection of Piping," Regulatory Guide 1.178, September 1998.

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