[en] The Nuclear Power Plant licenses are granted by the US Nuclear Regulatory Commission (NRC) for a 40-year term. There is at present consideration being given to extending the authorized service lifetime beyond that, perhaps for a total of 60 or 70 years total. A logical concern for such a length of operation is whether the plant ages in such a way as to be significantly less safe as it gets older. As a corollary to this, there would be the question as to how to measure a diminution in plant safety. Each operating utility has, of course, ways to observe the plant performance. It has maintenance and surveillance programs which are used for this purpose. The NRC maintains a presence at each operating plant in the form of resident inspectors. The NRC also receives utility reports which may then be used to synthesize operating performance. It also reviews plant performance directly through what is known as the Systematic Assessment of Licensee Performance (SALP). In the paper the various data management programs used by the NRC will be described. The results of each program is presented, and observations are made as to the potential effect of age on safety performance. It is also necessary to define the size of the population being examined. There are at present 109 operating reactors. The age distribution is used to normalize the data. Some of the indicators discussed in this paper are concerned more with the indirect effect of aging, such as inadvertent shutdown. The regulated industry maintains a program known as the Nuclear Power Reliability Data System (NPRDS) to which the electric utilities participate in a voluntary manner. Data from NPRDS can be accessed to observe the direct aging effect; this is not covered in this paper. To the degree that plant operating staff learns how to cope with aging equipment and operate in a safe manner nonetheless, the performance indicators would not fully reflect the aging effect