Operating a steam turbine propulsion unit at reduced speed, in an area with extremely cold seawater, with the main circulating pump providing full cooling water flow to the condenser will result in __________.

Correct Answer: Option A — decreased plant efficiency due to increased condensate depression

Excessive cooling water flow at reduced speed over-condenses steam, lowering hotwell temperature significantly below saturation temperature corresponding to condenser vacuum. This condensate depression wastes thermal energy, requiring extra heat in the boiler and reducing overall thermodynamic plant efficiency.