This scheduled regularity may appear mundane, nevertheless it’s fairly the feat that operational reactors are as dependable and predictable as they’re. It leaves some huge sneakers to fill for next-generation expertise hoping to hitch the fleet within the subsequent few years.
Typically, nuclear reactors function at fixed ranges, as near full capability as attainable. In 2024, for business reactors worldwide, the typical capability issue—the ratio of precise vitality output to the theoretical maxiumum—was 83%. North America rang in at a mean of about 90%.
(I’ll word right here that it’s not at all times honest to only have a look at this quantity to check completely different sorts of energy vegetation—natural-gas vegetation can have decrease capability elements, nevertheless it’s principally as a result of they’re extra prone to be deliberately turned on and off to assist meet uneven demand.)
These excessive capability elements additionally undersell the fleet’s true reliability—a number of the downtime is scheduled. Reactors must refuel each 18 to 24 months, and operators are inclined to schedule these outages for the spring and fall, when electrical energy demand isn’t as excessive as after we’re all working our air conditioners or heaters at full tilt.
Check out this chart of nuclear outages from the US Vitality Data Administration. There are some days, particularly on the peak of summer time, when outages are low, and practically all business reactors within the US are working at practically full capability. On July 28 of this yr, the fleet was working at 99.6%. Examine that with the 77.6% of capability on October 18, as reactors have been taken offline for refueling and upkeep. Now we’re heading into one other busy season, when reactors are coming again on-line and shutdowns are getting into one other low level.
That’s to not say all outages are deliberate. On the Sequoyah nuclear energy plant in Tennessee, a generator failure in July 2024 took one in every of two reactors offline, an outage that lasted practically a yr. (The utility additionally did some upkeep throughout that point to prolong the lifetime of the plant.) Then, simply days after that reactor began again up, the whole plant needed to shut down due to low water ranges.
And who can neglect the incident earlier this yr when jellyfish wreaked havoc on not one however two nuclear energy vegetation in France? Within the second occasion, the squishy creatures acquired into the filters of kit that sucks water out of the English Channel for cooling on the Paluel nuclear plant. They pressured the plant to chop output by practically half, although it was restored inside days.