Light water reactor

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Vessel lid with control rod drives for a light water reactor (here pressurized water reactor)

Light water reactor ( LWR , English Light Water Reactor ) is the name of a nuclear reactor in which so-called light water is used as a coolant and moderator . "Light water" refers to ordinary water, the hydrogen atoms of which are predominantly protium , the lightest hydrogen isotopic . Light water reactors generate almost 90% of nuclear energy worldwide and 100% in Germany.

The atomic nuclei of light hydrogen (protons) tend to trap neutrons . Therefore, compared to heavy water reactors, a larger reactor volume and a higher content of the isotope uranium-235 in the nuclear fuel are necessary. The degree of enrichment of the uranium must be around 3 to 4%; with natural uranium (0.7% uranium-235 and 99.3% uranium-238) a light water reactor is not critical .

The term light water reactor almost always refers to a power reactor , i.e. a system for generating electricity. There are two basic types of light water reactors: The pressurized water reactor (PWR) and the boiling water reactor (BWR). Their nuclear fuel is almost always in the oxide form , either pure uranium oxide or uranium-plutonium mixed oxide . However, light water also serves as a moderator and coolant in many research reactors . Pressurized water reactors are the most common form worldwide (68% of the installed capacity). In some countries, such as France, only PWR are used.

The first nuclear power plant with a boiling water reactor in the world was the US plant 24 MW-Vallecitos , built and operated by General Electric in 1957. The first nuclear power plant with a pressurized water reactor worldwide was the US plant 68 MW-Shippingport , built by Westinghouse as a successor to the U -Boot reactors, 1958. The world's first large nuclear power plant with pressurized water reactor of the 1300 MW class was the German nuclear power plant Biblis A , built by Kraftwerk Union AG (KWU) in 1975.


Individual evidence

  1. a b Nuclear power plants, world-wide, reactor types; European Nuclear Society