Coolant circuit
A refrigerant circuit is a system that is used to cool a self-heating or externally heated device to an appropriate level. Generally this system consists of pipes, pumps and a heat sink. A coolant circulating in the circuit (e.g. water) is guided along the heat source, heats up in the process and releases the absorbed heat at the heat sink .
Application in nuclear technology
In nuclear technology , the coolant circuit is used to dissipate the heat generated in the reactor core by nuclear fission and to convert it into electrical energy with the help of the turbines . At the same time, this prevents inadmissible overheating of the reactor core, which could lead to core meltdown .
The technical design of the cooling circuits in nuclear power plants depends on the type of reactor.
- Pressurized water reactors have two large cooling circuits: a primary circuit and a secondary circuit. In the primary circuit, the coolant water is in direct contact with the fuel assemblies . It consists of the reactor pressure vessel , the primary coolant pumps, the steam generator , the pressurizer and the pipes connecting them. The secondary circuit leads the live steam from the containment to the turbine. There are also emergency and after-cooling systems.
- In contrast to pressurized water reactors, boiling water reactors only have one cooling circuit for normal operation. The steam is generated directly in the reactor pressure vessel and fed directly to the turbine .
- In the case of high-temperature reactors , cooling is carried out using a gas. Usually this is helium , which is under a pressure of 40 to 60 bar.
- Because of their specific physical properties, breeder reactors require a coolant that moderates and absorbs neutrons as little as possible, but has good heat transfer properties. Liquid sodium is therefore preferred, but it has the disadvantage that it catches fire when exposed to air.