Bwr how does it work

The most important feature of the Boiling Water Reactor BWR is that it uses light water ordinary water as a neutron moderator and a core coolant. Unlike the pressurized water reactor PWR , it does not have a steam generator. This type of light water reactor has a primary circuit and a secondary circuit. In this case, the BWR reactor operates with a single water circuit in the core. As it does not have to withstand such high pressures, this type of reactor does not need such a robust casing.

The boiling water reactor power generation starts in the reactor core. The reactor core generates nuclear fission reactions of the fuel element to obtain thermal energy in a heat generation process.

The reactor power is regulated by inserting or removing the control rods from the core, where nuclear chain reactions occur. In the BWR reactor, the water used is light water ordinary water.

This type of nuclear reactor uses a single cooling circuit. Light water circulates through the nucleus, capturing the heat from nuclear reactions, it reaches the boiling temperature ang generates steam.

A neutron moderator is a medium that reduces the velocity of fast neutrons, thereby turning them into thermal neutrons —doing that, the probability that a fission reactor happens increases. The steam produced in the reactor core goes out from the top. Boiling water reactors must use enriched uranium as their nuclear fuel , due to their use of light water. This is because light water absorbs too many neutrons to be used with natural uranium , so the fuel content of fissile Uranium must be increased.

This is done through uranium enrichment —which increases the concentration of Uranium from 0. The enriched uranium is packed into fuel rods, which are assembled into a fuel bundle, as seen in Figure 3. There are about rods in each bundle, with up to bundles in a reactor.

As mentioned before, light water is used as the coolant and moderator for a boiling water reactor. Light water is much more abundant than heavy water, as it makes up The use of light water as a coolant is beneficial as it can cool down the fuel at the same time as it heats up to steam.

The steam moves through the turbines which spin a generator to generate electricity. This simplifies the design of boiling water reactors, as there is only one primary loop see Figure 4 needed which results in a lower cost of development.

Light water does not make as good of a moderator as heavy water or graphite due to its relatively high absorption of neutrons.

However, its use as a moderator makes for an interesting and important safety feature; if there is a "loss of coolant accident: LOCA , the moderator will also decline, causing the nuclear chain reaction to stop.

In addition, if the moderating water overheats and turns to steam inside the bottom reactor core, there will be less moderator and therefore the chain reaction will stop. The heat created by fission turns the water into steam, which spins a turbine to produce carbon-free electricity.

All commercial nuclear reactors in the United States are light-water reactors. This means they use normal water as both a coolant and neutron moderator. These reactors pump water into the reactor core under high pressure to prevent the water from boiling.

The water in the core is heated by nuclear fission and then pumped into tubes inside a heat exchanger. Those tubes heat a separate water source to create steam. The steam then turns an electric generator to produce electricity. BWRs heat water and produce steam directly inside the reactor vessel. Water is pumped up through the reactor core and heated by fission. Pipes then feed the steam directly to a turbine to produce electricity.