Organically moderated and cooled reactor
An organic moderated and cooled reactor ( English organically moderated and cooled reactor, OCR , also organic moderated reactor experiment, Omre ) is a type of nuclear reactor in which an organic substance as coolant and moderator is used. A mixture of biphenyl and terphenyl has been used in all reactors of this type built to date . In principle, however, all hydrocarbons can be used because they consist of the elements carbon and hydrogen, both of which moderate neutrons very well. For example, used Otto Hahn in the discovery of nuclear fission a block of paraffin as a moderator.
The structure of an organically moderated and cooled reactor essentially corresponds to a pressurized water reactor : in a large reactor there are numerous fuel elements that are washed by the organic coolant. The nuclear chain reaction takes place in the fuel rods. The heat released is carried away by the coolant. In a heat exchanger , the organic coolant transfers its energy to water, which evaporates in the process. The steam drives the turbines , which in turn drive a generator that generates the electricity.
disadvantage
In addition to the known dangers of all nuclear power plants, organically moderated and cooled reactors have one major disadvantage: the coolant is cracked over time due to the high temperatures in the vicinity of the fuel rods . This process is promoted by the strong radioactivity ( radiolysis ). As a result, elemental carbon ( soot ) is deposited on the fuel elements , which is why they have to be cleaned very laboriously from time to time.
Units built
Very few reactors of this type have been built to date, and there will be no new builds for the foreseeable future. There are four examples in the following list:
| Location | Plant name | status | power | Installation | Shutdown |
|---|---|---|---|---|---|
| Germany | Obrigheim nuclear power plant | originally planned as OMRE, but completed as a pressurized water reactor | |||
| United States | Piqua nuclear power plant | Shut down | 45.5 MW thermal, 12 MW electrical |
July 1, 1963 | January 1, 1966 |
| United States | OMRE at the Idaho National Laboratory | Shut down | ? | ? | ? |
| Canada | WR-1 | Shut down | 60 MW thermal | 1965 | May 17, 1985 |