Pressurized heavy-water reactor

Pressurized heavy-water reactor (PHWR) is a type of nuclear reactor that uses heavy water (deuterium oxide D2O) as its coolant and neutron moderator. This design of reactor is unique due to its use of heavy water, which allows it to use natural, unenriched uranium as its nuclear fuel.

Design and Operation

The PHWR's design is characterized by its use of heavy water as a coolant and moderator, a pressurized fuel channel design, and fueling with natural uranium. The heavy water coolant is kept under pressure to avoid boiling, allowing it to reach higher temperatures without forming steam bubbles, a condition known as cavitation. This high-pressure coolant system is separate from the low-pressure heavy water moderator system, reducing the likelihood of a loss-of-coolant accident.

The fuel used in PHWRs is natural uranium, which is composed mostly of the isotope U-238. This isotope is not fissile, but it can be converted into a fissile isotope, plutonium-239, in the reactor. This process, known as breeding, allows PHWRs to extract more energy from their fuel than other types of reactors.

Advantages and Disadvantages

One of the main advantages of PHWRs is their fuel efficiency. Because they use unenriched uranium, they can operate on a much larger fuel supply than reactors that require enriched uranium. This makes them a good choice for countries with large uranium reserves but limited access to enrichment facilities.

However, PHWRs also have some disadvantages. They are more expensive to build and operate than other types of reactors due to the cost of heavy water. They also produce more nuclear waste than other types of reactors, and the plutonium they produce can be used to make nuclear weapons, raising proliferation concerns.

Examples

There are several examples of PHWRs in operation around the world. The CANDU reactor design, developed in Canada, is one of the most well-known. Other examples include the Indian Rajasthan Atomic Power Station and the Argentine Atucha Nuclear Power Plant.

See Also

• Nuclear power
• Nuclear reactor technology
• Nuclear fuel cycle
• Nuclear proliferation