Neckarwestheim Nuclear Power Station is a nuclear power plant in Neckarwestheim, Germany. It is sometimes abbreviated GKN (Gemeinschaftskraftwerk Neckar).

Neckarwestheim Nuclear Power Plant 1

The nominal electrical power of block I, in service since 1976, is 840 megawatts. The 50 Hz three phase AC power is 567 megawatts and for the 16.7 Hz traction current power 174 MW. The traction current generator is the world's largest electrical generator for single phase AC. The generator block 1 is rated 21,000 volts at a current of 27,000 amperes, and the traction current generator is rated 14,500 volts and a current of 12,000 amperes. The current produced by the generators is stepped up to 220 kilovolts (three-phase alternating current) and/or 110 kilovolts (traction current) with the machine transformers. Block I is the only nuclear power station which produces traction current.

Neckarwestheim Nuclear Power Plant 2

The nominal electrical power of block 2, in service since 1988, is 1400 megawatts. The generator produces 50 Hz three-phase alternating current with a voltage of 27,000 V and a current of 35,000 amperes. Unlike Unit 1, no dedicated traction current generation takes place, but some of the power produced is converted at the traction current substation. This is transmitted through the 380 kV generator transformer block of the II and the 380 kV-machine transformer of the motor-generator sets.

Traction current converter plant

The GKN station also has a 16.7 Hz traction current converter plant. The traction converter plant at Neckarwestheim, which is situated close to the switchgear of block II, has two identical sets, consisting of a three-phase 50 Hz AC motor with 12 poles and a four pole single phase 16.7 Hz AC synchronous generator. The rated voltage of the three-phase AC asynchronous machine and the traction current machine is 12.5 kV. 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 110 kV balanced line traction power network through appropriate transformers. Power can be transferred from the Block II nuclear generator over the 380 kV transmission network.

Neckarwestheim Nuclear Power Plant Dimensions

Dimensions of the reinforced concrete building are:

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

Neckarwestheim Nuclear Power Plant 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. It was originally going to use a wet cooling tower, but then it was later decided to use dry cooling towers because it would have a smaller effect on the environment (though would be more expensive). This unique type of cooling tower causes the unique shape seen in pictures.

Neckarwestheim Nuclear Power Plant Hybrid cooling tower

• 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 in the German Federal Republic to that date. Numerous errors of a new crew led to damage of the secondary cycle and, at the same time, a defect of a valve led to an automatic reactor shutdown.
• 27 July 2004: Water contaminated with two megabecquerels leaked unnoticed from block II into the Neckar river. As a result, for the first time in the Federal Republic, the operator company of a nuclear power plant paid a fine of 25,000 Euro and a managing director was dismissed.

Neckarwestheim Nuclear Power Plant 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 220 kV-three phase AC and the 110 kV-traction current switchyard situated east of Neckarwestheim. This line is hung on pylons of unusual design with five 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 of the GKN 1, with 220 kV and in the case of the GKN 2 with 380 kV. On the highest cross beam two ground conductors are installed. It is notable that the traction current circuits were insulated for 220 kV, although they are operated only with 110 kV. This measure was taken because, in case of a disturbance of the parallel 380 kV-line, overvoltages can occur which insulation designed for 110 kV cannot stand.

The traction current lines from the GKN to the traction current switching station at Neckarwestheim, and from there to the central substation in Stuttgart Zazenhausen, are implemented as four-bundle conductors.

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

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

Neckarwestheim Nuclear Power Plant
Country	Germany
Locale	Neckarwestheim
Construction began	1971
Commission date	May 26, 1976
Owner(s)	EnBW
Operator(s)	EnBW
Reactor information
Reactors operational	2 reactors
Power generation information
Installed capacity	2,235 MW
Annual generation	17,060 GW·h
Net generation	354,779 GW·h