Furthermore, they both use enriched Uranium as fuel with cylindrical vessel types. The general structure of both reactors are also very similar, as they both consist of the main components of a nuclear reactor: a containment vessel, a reactor vessel, which houses the reactor core, and a steam generating turbine. A PWR generates steam indirectly by using two water circuits, a primary one and a secondary one.
On the other hand, a BWR produces steam directly using a single water circuit. This water is kept liquid under high pressure.
Thus PWR power plants consists of two different loops — the primary loop where heat is taken from the reactor and is transferred to the working fluid, and the secondary loop where turbine is rotated. On the other hand, the coolant water is allowed to boil or change its phase from water to steam in the Boiling Water Reactor BWR.
Thus the steam can be directly fed to the turbine without utilizing an intermediate heat exchanger. Hence BWR consists of only one loop. Although it offers higher thermal efficiency owing to elimination of intermediate heat exchanger, it is associated with the risk of radioactive contamination in case of any leakage.
Skip to content. Both PWR and BWR are thermal reactors, which indicate that the nuclear fission reaction is initiated by the thermal neutron it has energy of 0. On the contrary, fast reactors utilize fast neutrons 1 — 10 MeV energy. An enriched fuel has higher percentage of U isotope. In the naturally available uranium, U isotope is only about 0. But this U isotope is not fissile material thus cannot be used as nuclear fuel. On the contrary, heavy water reactors, gas cooled reactors and graphite reactors can employ other materials like heavy water, carbon dioxide, graphite for such purposes.
A heat exchanger HE is employed to transfer heat from primary loop to the secondary loop. Boiling Water Reactor BWR power plants consist of a single loop where the coolant that takes away heat from the reactor is directly fed to the turbine.
Thus no heat exchanger is desired. In the primary loop, normal water H 2 O acts as coolant-cum-moderator. In the secondary loop, the normal water acts as working fluid. However, water from one loop is not allowed to mix with the water of other loop. High amount of energy that is released is used to turn a turbine that produces electricity.
Coming back to the topic, both BWR and PWR are classified as light water reactors as they make use of ordinary water and not heavy water. Water absorbs the energy of the reactor core and is then sent into a pressure vessel where it turns into steam that is able to turn the turbine blades to produce electricity.
We know that the temperature of boiling water increases if it is covered by a lid.
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