NPHWR stands for "Nuclear Power Heavy Water Reactor." It refers to a type of nuclear power reactor that utilizes heavy water as both the moderator and coolant. This type of reactor design differs from conventional pressurized water reactors (PWRs), which use regular (light) water for moderation purposes.
In an NPHWR, heavy water, which contains a higher concentration of deuterium, is used as a coolant and neutron moderator. This heavy water slows down the speed of neutrons, allowing them to efficiently collide with the fuel rods, initiating and sustaining the nuclear chain reaction. The fuel used in NPHWRs commonly consists of enriched uranium.
Compared to PWRs, NPHWRs have some distinct advantages. Heavy water provides better neutron moderation capabilities, leading to a more efficient reaction and enhancing fuel utilization. Additionally, NPHWRs can use natural or even depleted uranium as fuel, making them more flexible in terms of resource availability. Moreover, the use of heavy water as a coolant improves the reactor's safety features, as heavy water has excellent heat transfer properties and can effectively remove excess heat from the core.
NPHWRs have been utilized in various countries worldwide, including Canada, India, and Argentina, among others. The Chernobyl accident in 1986, however, reduced the global interest in heavy water reactors due to concerns over potential negative environmental and safety implications.
Overall, NPHWRs are a type of nuclear power reactor that utilizes heavy water as a moderator and coolant, offering unique advantages in terms of fuel utilization, resource flexibility, and safety features.
