No it ' s not strange . I don ' t speak German but I do work in the nuclear power industry so I assume this article is referring to preheating makeup water for the emergency core cooling system ECCS or reactor makeup water system prior to injecting it into the reactor coolant system to avoid potential temperature deltas that could cool the core and reduce reactor power output . PWR reactor coolant water is usually about 550 degrees F when it exits the bottom of the core and moves into the steam generator transfer tubes . Dumping a bunch of makeup water at ambient temperature into the reactor coolant system could cause numerous issues with primary system water chemistry and coolant temperature , leading to a drop in secondary system steam pressure and high pressure turbine speed . Makeup water is heated numerous ways before being injected , it can be stored in high temperature areas inside or outside the plant , stored in heated tanks or circulated through heat exchangers .