What is a Boiled Water Reactor?
In the Boiled Water Reactor (BWR), water is used both as a coolant as well as moderator.
The arrangement of the boiling water reactor is shown in the figure.
|Boiled Water Reactor Power Plant|
Boiled Water Reactor uses enriched uranium as fuel. These reactors do not need heat exchangers as needed in Pressurized Water Reactor (PWR) since water is directly converted into saturated steam at about 285-degree centigrade at 70 bar pressure.
For the above reasons, this system is also called a Direct cycle Boiled Water Reactor power plant.
The feed water circulated in the reactor is converted into saturated vapor or steam by transfer of heat energy released in the reactor core in the fission process.
This steam is supplied to the steam turbine in a conventional power plant working on the cycle.
Thus, the mechanical power developed by the turbine is converted into electrical energy by the generator. The exhaust of the steam from the turbine is condensed into the condenser.
The condensate is returned to the reactor as feedwater by the feedwater pump.
Advantages of Boiled Water Reactor
- It eliminates the use of a heat exchanger, pressurizer, circulating pump, and piping. Therefore, the system is simple and cheap.
- The efficiency of the system is high.
- The use of a low-pressure reactor further reduces the cost of the plant.
Disadvantages of Boiled Water Reactor
- It cannot meet sudden changes in load on the plant.
- It has the possibility of radioactive contamination of the steam turbine.
- The system requires extensive safety devices against radioactive radiation which are costly.