Risk Management Technical Specifications
Since the mid-1980s, the NRC has been reviewing and granting improvements to technical specifications that are based, at least in part, on probabilistic risk assessment (PRA). The Commission reiterated that it expects licensees to use any plant-specific PRA or risk survey in preparing technical specifications for NRC approval when it issued the revision to 10 CFR 50.36, "Technical Specifications," in July 1995. In August 1995, the NRC adopted a final policy statement on the use of PRA methods in nuclear regulatory activities that encourages greater use of PRA to improve safety decisionmaking and regulatory efficiency. Since that time, the industry and the NRC have been pursuing increased use of PRA in developing improvements to technical specifications.
Consistent with the Commission's policy statement on technical specifications and the use of PRA, the NRC and the industry continue to develop more fundamental risk-informed improvements to the current system of technical specifications. We use the term "risk management technical specifications" to emphasize the goal of constructing technical specifications that reinforce the pro-active management of the total risk presented by the plant configuration and actions that may be needed to respond to emergent conditions. These improvements are intended to maintain or improve safety while reducing unnecessary burden and to bring technical specification requirements into congruence with the Commission's other risk-informed regulatory requirements, in particular, the maintenance rule.
On this page:
- Incorporating Risk Management Technical Specifications
- Adjusting Completion Times and Surveillance Intervals
- Effect of the Maintenance Rule on Technical Specifications
Incorporating Risk Management Technical Specifications
The use of risk information and technology has long been a fundamental ingredient in improving technical specifications. In the 1983 publication "Technical Specifications - Enhancing the Safety Impact" (NUREG-1024), the NRC Task Group on Technical Specifications commented on the technical specifications of the era:
"The Task Group recognizes that the times associated with surveillance frequencies, allowable outage times, etc., have been established on a deterministic basis using engineering judgment. The Task group also believes that engineering judgment must be the primary basis for any changes to the Technical Specifications. However, the Task Group believes that the use of insights from probabilistic risk assessments could be a significant aid in arriving at these judgments."
Technical Specifications have taken advantage of risk technology as experience and capability have increased.
Adjusting Completion Times and Surveillance Intervals
Guidance documents have been prepared to assist in requesting risk-informed completion time (also called allowed outage time) and surveillance test interval extensions (Regulatory Guide 1.177 and Standard Review Plan Chapter 16.1 [NUREG-0800]). Use of this guidance (categorized as "Option 1" in the framework of the Risk-Informed Regulatory Improvement Program) has resulted in risk-informed amendments at numerous plants and in owners groups continuing to submit topical reports to support additional applications for Standard Technical Specification (STS) changes.
Effect of the Maintenance Rule on Technical Specifications
Before issuance of the maintenance rule, 10 CFR 50.65, in July 1991, technical specifications primarily governed plant operations. They dictated what equipment must normally be in service, how long equipment can be out of service, compensatory actions, and surveillance testing to demonstrate equipment readiness. The maintenance rule marked the advent of a regulation with significant implications for the evolution for technical specifications. The goal of these technical specifications is to provide adequate assurance of the availability and reliability of equipment needed to prevent and, if necessary, mitigate accidents and transients. The maintenance rule shares this same goal but operates at a more fundamental level with a dynamic and more comprehensive process.
In addition to specifying a process for monitoring the effectiveness of maintenance, including performance and condition monitoring, and for balancing maintenance unavailability and equipment reliability, the maintenance rule requires licensees to assess and manage plant configuration risk that results from maintenance. The maintenance rule has put in place many of the mechanisms, measures, and processes envisioned by staff as needed to enhance the safety impact of technical specifications. Thus, achieving synergy between the static technical specifications and the dynamic maintenance rule is a major aim of the effort to create risk management technical specifications.
Eight initiatives for fundamental improvements to the STS are being developed by the industry and discussed with the NRC staff in public meetings:
Initiative 1, TS Actions End States Modifications: This initiative would permit, for some systems, entry into hot shutdown rather than cold shutdown to repair equipment;
Initiative 2, Missed Surveillances, Surveillance Requirement (SR) 3.0.3: This initiative permits the extension of up to one surveillance interval of an inadvertently missed surveillance, after assessing and managing the risk (approved September 2001);
Initiative 3, Modification of Mode Restraint Requirements of Limiting Condition for Operation (LCO) 3.0.4 and SR 3.0.4: This initiative permits, for most systems, transitioning up in mode with inoperable equipment, relying on compliance with the technical specification actions of the higher mode, after assessing and managing the risk (approved April 2003);
Initiative 4b, Flexible Completion Times: This initiative would permit, contingent upon the results of a plant configuration risk assessment, temporary extension of the existing completion time within an LCO using a quantitative implementation of 50.65(a)(4);
Initiative 5b, Relocation of all SR Frequency Requirements out of TS: This initiative would permit SR frequencies to be determined in and relocated to a licensee-controlled TS program;
Initiative 6, Modification of LCO 3.0.3 Actions and Completion Times: This initiative would convert default or explicit entry into the LCO 3.0.3 shutdown track into a completion time for corrective action before beginning shutdown;
Initiative 7, Non-TS Support System Impact on TS Operability Determinations: This initiative would permit a risk-informed delay time before entering LCO actions for inoperability due to loss of support function provided by equipment outside of technical specifications;
Initiative 8a and 8b, Remove/Relocate Non-safety and Non-risk Significant Systems from TS that do not meet the four criteria of 10 CFR 50.36: Initiative 8a would review technical specifications to remove systems that were included solely because they were judged risk significant at one time and have now been shown by analysis not to be. Initiative 8b would make the scope of technical specifications depend only on risk significance.