Pressurized-water reactor

Pressurized-water reactor


A BWR operates on the principle of a direct power cycle. Water passing through the core is allowed to boil at an intermediate pressure level. The saturated steam that exits the core region is transported through a series of separators and dryers located within the reactor vessel that promote a superheated state. The superheated water vapour is then used as the working fluid to turn the steam turbine.


  • Simpler plumbing reduces costs
  • Power levels can be increased simply by speeding up the jet pumps, giving less boiled water and more moderation. Thus, load-following is simple and easy.
  • Very much operating experience has been accumulated and the designs and procedures have been largely optimized.


  • With liquid and gaseous water in the system, many weird transients are possible, making safety analysis difficult
  • Primary coolant is in direct contact with turbines, so if a fuel rod had a leak, radioactive material could be placed on the turbine. This complicates maintenance as the staff must be dressed for radioactive environments.
  • Can’t breed new fuel — susceptible to “uranium shortage”
  • Does not typically perform well in station blackout events, as in Fukushima.