High-power-rating [≥1000 MW(electric)] passive pressure tube light water-cooled reactors are described that have the ability to reliably discharge decay heat to the ultimate heat sink, without the need to replenish primary coolant in loss-of-coolant accidents, while ensuring the integrity of the fuel and reusability of major reactor components. Evaluation shows that pressure tube reactors have the attractive potential to dissipate the decay heat from voided fuel elements of large-power-rating cores without exceeding safe temperature limits. Two basic versions of a pressure tube light water-cooled and -moderated reactor—the dry and wet calandria concepts—are proposed, and their advantages and limitations are discussed.