Inlet Water Temp vs Feeder Water Temp in a BWR

[Luxdot]

TL;DR

Inlet water temp vs feeder water temp

How can the inlet water temp be higher than the one of the feeder water that is in the reactor tank of a BWR?

 

[anorlunda]

If you mean feeder temperature is feedwater temperature.
If you mean inlet temperature is measured as water enters the core.

Then you need to consider recirculation flow. Some of the water exiting the core is recirculated back to the inlet and mixed with feedwater. The mixture goes to the core inlet.

 

[Astronuc]

Summary:: Inlet water temp vs feeder water temp

How can the inlet water temp be higher than the one of the feeder water that is in the reactor tank of a BWR?

The feedwater is the water returning from the balance of plant, i.e., from the turbine condensation and condenser following the low pressure turbine. The water is at a lower temperature than core inlet. In a BWR, moisture (at core exit temperature) is separated in 'moisture separators' or 'steam dryers', and that is sent to the annulus where it is mixed with the cooler 'feedwater' from the balance of plant. The mixture is then pumped back to the core inlet.

https://en.wikipedia.org/wiki/Boiling_water_reactor#Condensate_and_feedwater
https://en.wikipedia.org/wiki/Feedwater_heater