ABSTRACT
Boiling water reactors (BWRs) are the second most popular type of reactor in the world. A BWR is fundamentally different than a pressurized water reactor because the coolant in the core is intentionally designed to boil. The water in a BWR begins to develop vapor bubbles about one-fifth of the way up the core, and by the time it reaches the core midplane, it begins to boil vigorously. BWRs also use cylindrical fuel rods with uranium oxide fuel pellets clad with zirconium metal. The RBMK is a power reactor similar in some aspects to a Western BWR. The advanced BWR is an attempt by the General Electric Company to simplify existing BWRs without having to completely redesign them. The characteristics of the power plant thermal cycle for a BWR depend upon who is designing it and where it is located. The stable operating region of a BWR is defined by what is called an operating map.
