Niederaichbach reactor

The 100-MWe Niederaichbach reactor was designed by Siemens in the early 1960s and constructed between 1965 and 1970 in the Isar Valley, about 70 km northwest of Munich. The reactor contained 351 vertical channels on a square pitch of 24.5 cm. The channels penetrated a tank or calandria containing heavy water. Basic control was achieved by adding a burnable poison, CdS04, to the moderator. The moderator level could also be adjusted and the moderator dumped to shut down the reactor. 

The Niederaichbach reactor reached full power in 1970 and was connected to the grid in 1973. It was shut down in 1974 when it was deemed to have become uneconomic compared with other water-cooled reactors, and the subsequent decommissioning activity had the objective of demonstrating the ability to return a reactor site to a greenfield condition. 

The Niederaichbach nuclear plant Is a prototype of a COg cooled, D2O moderated pressure tube reactor, with an output of 100 MWe (refs 6). If construction proceeds according to schedule the plant will be commissioned in 1970. A noteworthy feature of this reactor Is the high coolant temperature of 550°C at the reactor outlet, requiring, of course, steel as canning material for the fuel. 

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