Neckarwestheim

Neckarwestheim is a municipality with 3562 inhabitants in the district Heilbronn, Baden-Württemberg, south-west Germany. It is located at the Neckar river and is well-known as the location of a nuclear power station.

History

Neckarwestheim was called Kaltenwesten until 1884.

Nuclear Power Station

Neckarwestheim is the location of the joint nuclear power station Neckar (GKN) with 2 pressurized water reactors.

• GKN 1: The nominal electrical power of block I, in service since 1976, is 741 megawatts. The nominal three phase AC power is 567 megawatts and for the traction current power 174 megawatts. The traction current generator is the world's largest generator for single phase AC. The generator block 1 is rated 21,000 V at a current of 27,000 amperes, and the traction current generator is rated 14,500 V and a current of 12,000 amperes. The current produced by the generators is stepped up to 220kV (three-phase alternating current) and/or 110kV (traction current) with the machine transformers. Block I is the only nuclear power station, which produces traction current.

• GKN 2: The nominal electrical power of block 2, in service since 1988 , is 1365 megawatts. The generator produces three-phase alternating current with a voltage of 27,000 V and an amperage of 35,000 ampere. Unlike Unit 1, no dedicated traction current production takes place, but some of the power produced is converted at the traction current substation. This is transmitted through the 380kV generator transformer block of the II and the 380kV-machine transformer of the motor-generator sets.

• Traction current converter plant: the GKN station also has a traction current converter plant. The traction converter plant Neckarwestheim, which is situated close to the switchgear of block II, has two identical sets, consisting of a three-phase AC motor with 12 poles and a four pole single phase synchronous generator. The rated voltage of the three-phase alternating current asynchronous machine and the traction current machine is 12,5kV. The set has a length of 17.5 meters and a maximum width of 7 meters. The nominal power rating for each set is 70 megawatts, which are the largest traction current motor-generator sets ever built. The traction current converter plant feeds the 110kV traction power network through appropriate transformers. Power can be transferred from the Block II nuclear generator over the 380kV transmission network.

Dimensions of the reinforced concrete building are:

• Height: 26.80 meters
• total width: 40.4 meters
• width cultivation: 12 meters
• height cultivation: 19.25 meters
• machinery building: 42.40 meters
• of overall length: 52.40 meters

Cooling towers

In order to avoid overheating of the river Neckar, both blocks have cooling towers. These are not built in the usual way. Block I uses two rows of cell cooling towers. Each row has a length of 186.8 meters and a height of 18 meters. Block II uses a hybrid cooling tower with a height of 51.22 meters.

Hybrid cooling tower Neckarwestheim

• Overall height: 51.22 m
• overall height over basin level: 48.0 m
• mouth diameter: 160.0 m
• basin diameter: 120.0 m
• chimney height: 24.97 m
• air outlet diameter: 73.6 m
• cooling performance: 2500 MW

Malfunctions

• In 1977 block I had the second most serious incident of a nuclear power plant of the German Federal Republic to that date. Numerous errors of a new crew lead to damage of the primary cycle, and at the same time a defect of a valve leads to the reactor shutdown.
• 27 July 2004: Water contaminated with two Megabecquerel leaks unnoticed from block II into the Neckar river. As a result, for the first time in the Federal Republic the operator company of an atomic power plant has to pay a fine (25,000 Euros). A managing director is dismissed.

Powerlines

Power produced at GKN is transmitted over a transmission line carrying two circuits of traction current and three-phase alternating current line to the 220kV-three phase AC and the 110kV-traction current switchyard situated east of Neckarwestheim. This line is hung on pylons of unusual design with 5 cross beams. On the lowest cross bar there are two traction current circuits, while the second, third and fourth cross beam carry the three-phase circuits. These are operated in the case for the GKN 1 with 220kV and in the case of the GKN 2 with 380kV. On the highest cross beam two ground conductors are installed. It is remarkable that the traction current circuits were insulated for 220kV, although they are operated only with 110kV. This measure was taken, because in case of a disturbance of the parallel 380kV-line overvoltages can occur, which insulation designed for 110kV cannot stand.

The traction current lines from the GKN to the traction current switching Neckarwestheim and from this to the central substation in Stuttgart Zazenhausen are the only traction current lines constructed with four bundled conductors.

The three-phase 380kV circuit leading away from the nuclear power station GKN 2 runs past the 220kV-three phase switchyard Neckarwestheim to the transformer station Großgartach near Heilbronn. To the GKN also runs another 110kV-line for three phase AC with one circuit, which takes its origin in the switchgear of the coal fired power station Walheim. This line is not for transport of the power produced by the GKN, but for start-up power of the nuclear plant.

It is also remarkable that Neckarwestheim and the GKN never had a track connection to the railway network.