For pressurized water reactors the coolant is not permitted to boil in the core of the PRW, however the coolant in boiling water reactors is permitted to do so in the core of BWR. Pressurized water reactors have an indirect cycle. Whereas, the boiling water reactors go through a direct cycle. Both are light water reactors.
The main difference between the pressurized water reactors and boiling water reactors is in the process of generation of steam. A boiling water reactor uses a single water circuit to produce steam directly while a pressurized water reactor produces steam indirectly using two water circuits. In a boiling water reactor steam is directly produced by boiling the water coolant while in pressurized reactor the heat from the reactor core is used.
