Original sentence: A modern, large, efficient plant is within 20% of the cost of developing a new, local source of fresh water in some places.Nuclear-powered desalination might be economical on a large scale
Edited sentence: A modern, large, efficient plant is within 20% of the cost of developing a new, local source of fresh water.Nuclear-powered desalination could be economical on a large scale, however, that involves the known unsolved problems of risk management and long term nuclear waste disposal.The long term cost estimates of nuclear technology are clearly prohibitive