Seasonal Comparison

% of its fleet is measured against each market's own installed nuclear capacity, so a small market with one unit down reads as heavily affected even when the megawatts are modest. That is the right read for a market operator and the wrong one for a national supply balance, which is what the Avg MW column is for.

Each line is a different market over the same calendar window, so the shapes are directly comparable. Markets differ enormously in size: read the percentages in the table above alongside these megawatts.

How to read older seasons. The megawatt columns are built from the daily power record of the units operating today, carried back; the outage counts include units that have since shut down. Across recent seasons those are the same fleet, so the two agree. Go back far enough and the megawatt figures describe today's fleet in an older year, which is the right basis for comparing supply but not for counting what the industry did at the time.

Season history follows the same backward window as the national curve and the ISO breakdown, so there is one rule across the product rather than a special case here. The full record runs to Spring 2000; for model fitting, take it through the API or the bulk export rather than a season at a time.