The Nuclear Regulatory Commission (NRC) places restrictions on the maximum amount of electricity a nuclear power plant can produce. The NRC determines this maximum output for each nuclear unit, which is based on individual factors and specifications. The purpose of this imposed limitation is to ensure plant safety and operability.
Occasionally, a nuclear plant will request an “uprate” as a way to increase the amount of electricity the unit is allowed to produce. An uprate, however, must be approved by the NRC. Approximately 139 uprates, resulting in a net gain of more than 18,000 MW have been approved by the NRC. The NRC lists three different types of power uprates:
Robinson Nuclear was one of the first plants in the country to request an uprate.
1) Measurement uncertainty recapture uprates are improved techniques for calculating reactor power. As technology improves, the nuclear industry is able to more precisely measure and calculate reactor power, which can have a very limited impact on a generating unit’s power output. Typically, this is less than 2 percent.
2) Stretch power uprates. This results from minor changes to the plant’s operation, all within design capacity, such as settings or new equipment that typically increase output by 2 to 7 percent.
3) Extended power uprates. This is the largest type of power uprate with approved increases as high as 20 percent. The increase in production is achieved by the installation of new equipment, such as turbines, generators or transformers.
There is a governed process for applying for a power uprate. While the application is lengthy and highly detailed, uprates are given a high priority by the NRC. The NRC uses a review standard, which provides the process and guidance for reviews for the NRC and information to consider for the nuclear operators who submitted the request. Once submitted, the NRC must notify the public and allow 30 days for comment and 60 days to request a hearing regarding the uprate.
While there is an enormous amount of work and planning that must go into an uprate application, the benefits are significant.
The U.S. Energy Information Administration notes that uprates can increase substantially increase the amount of power output from the nuclear industry while avoiding the time and cost of constructing a new unit.
The Harris Nuclear Plant, located just outside of Raleigh, N.C., is in a five-year project that should result in adding 60 to 70 megawatts of generation. That’s enough electricity to supply about 70,000 homes with electricity. Robinson Nuclear was the fourth nuclear plant in the country to apply for and receive uprate approval. Robinson added 100 megawatts in 1979.
Overall, it’s no surprise that 98 of the 100 nuclear units in the country have applied for an uprate at some point in their operating life.