Control rod

Powering each reactor at the Susquehanna nuclear plant is about 135 metric tons of enriched uranium dioxide in the form of ceramic pellets. A single pellet can produce the same amount of energy as 1,000 pounds of coal or 100 gallons of gasoline.

About 30 million of these pellets, which are about the size of a standard pencil eraser, fuel each reactor. Fuel pellets are stacked 12.5 feet high inside rods that are about 13.5 feet long.

The rods are arranged in assemblies. Each assembly is made up of 91 rods. The reactor core contains 764 of these fuel assemblies.


Reactor vessel


Each of Susquehanna’s reactor vessels is a 750-ton cylinder about 21 feet in diameter standing more than 73 feet tall with 4-inch to 9-inch thick steel walls.

The reactor vessel contains about 130,000 gallons of water used to create steam and to cool the reactor fuel.

Heat released during fission boils water to make steam.

Plant operators control the nuclear reaction by inserting or withdrawing control rods between the fuel assemblies in the reactor. Each Susquehanna reactor has 185 control rods.



More than 14 million pounds of steam per hour from the reactor passes through an assembly of four turbines, each with hundreds of fan-like blades on rotating parts.

The turbines are connected to a generator.



After the steam turns the turbine, it passes into a condenser and is cooled back into water.

Nearly 450,000 gallons of cooling water from the unit’s cooling tower and the Susquehanna River flow every minute through a piping system made up of more than 81,000 condenser tubes (about 600 miles of tubing).

When the steam hits the cool pipes, it condenses back into water. The condenser can turn more than 8 million pounds of steam back into water in one hour.

The resulting water is pumped back to the reactor.


Cooling tower

Cooling Tower

After passing through the condenser tubing, the non-radioactive cooling river water is pumped back to the towers where it trickles down over a series of baffles.

As the water falls, it is cooled by evaporation. Heat and water vapor rise from the towers.

At full power, each tower evaporates about 10,000 gallons of water per minute.

Cooled water collects at the tower base and is pumped back to the condenser.

Water from the Susquehanna River makes up for cooling water lost to evaporation.

This cooling method is used on non-nuclear power plants as well.