CREATE TABLE nuclear_power_plants (id TEXT, name TEXT, latitude TEXT, longitude TEXT, country TEXT, status TEXT, reactortype TEXT, reactormodel TEXT, constructionstartat TEXT, operationalfrom TEXT, operationalto TEXT, capacity TEXT, lastupdatedat TEXT, source TEXT)

What nuclear reactor model is the most popular?
SELECT reactormodel FROM nuclear_power_plants GROUP BY reactormodel ORDER BY COUNT(*) DESC LIMIT 1
SELECT "reactormodel" FROM "nuclear_power_plants" GROUP BY "reactormodel" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1