Inside Reactor Containment Vessel Aft of Reactor can be seen the Let Down Coolers (smaller cylinders painted in orange). These are part of the charging and let down system that adds and removes water from the primary cooling loop for treatment. The treatment equipment located under the containment vessel filters out unwanted ions in the water.
The air conditioning ventilation ducts are in white and yellow.
This photo shows technicians lowering a fuel assembly. Great care is taken to avoid contamination of the reactor core.