United States Nuclear Regulatory Commission - Protecting People and the Environment
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Additional Information on Safety

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Integrated Plant Assessment

For some passive structures and components within the scope of the renewal evaluation, no additional action may be required where an applicant can demonstrate that the existing programs provide adequate aging management throughout the period of extended operation. However, if additional aging management activities are warranted for a structure or component within the scope of the rule, applicants will have the flexibility to determine appropriate actions. These activities could include, for example, adding new monitoring programs or increasing inspections.

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Time-Limited Aging Analyses (TLAAs)

Another requirement for license renewal safety review is the identification and updating of time-limited aging analyses. During the design phase for a plant, certain assumptions about the length of time the plant will be operated are made and incorporated into design calculations for several of the plant's systems, structures, and components. Under a renewed license, these calculations must be shown to be valid for the period of extended operation.  Alternatively, an applicant can show how the aging effects associated with these calculations will be adequately managed for the period or extended operation.

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"Passive" Structures and Components

An applicant must review all systems, structures and components within the scope of the rule to identify "passive" and "long-lived" structures and components. It must be demonstrated that the effects of aging will be managed in such a way that the intended functions of those structures and components will be maintained for the period of extended operation. Passive and long-lived structures and components include components such as the reactor vessel, reactor coolant system piping, steam generators, pressurizer, pump casings, and valve bodies.

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"Active" Structures and Components

The detrimental aging effects in "active" components are more readily detected and corrected by routine surveillance, performance indicators and maintenance. Surveillance and maintenance programs for active components are required throughout the period of extended operation. Active components include equipment such as motors, diesel generators, cooling fans, batteries, relays, and switches.

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Page Last Reviewed/Updated Thursday, March 29, 2012