(December 19, 1994) Cracks in welds have often been found in nuclear power plants over the last years. But now, for the first time in German reactors cracks have appeared that endanger a reactor's whole structure.
(424.4200) WISE Amsterdam - In the Würgassen NPP in North Rhine-Westphalia (FRG), cracks were found in the core shroud and in the core support grid for fuel assemblies and control rods. The length of the cracks add up to about 8 meters. Their depths have not been measured yet. Würgassen's owner, PreussenElektra, wants to replace the whole core shroud and core support grid. It will be the first attempt worldwide to do this.
Similar cracks had akeady been found in core shrouds in Switzerland and the US, but these were repaired by installing clamps around the welds to prevent the shroud from separating. To replace the core will be a huge operation -- the core shroud has a height of 6 meters and a radius of 4 meters. It is a thick stainless steel shell inside the vessel that contains the fuel rods and directs the flow of the coolant. PreussenElektra thinks that it will take 18 months to repair it and cost 15 to 120 millions US$. And it will decrease the volume of PreussenElektra's business up to 2.4 billion US$.
The North Rhine-Westphalia safety authorities point out that a new atomic licensing procedure will be necessary for the repairs, because it the first time to try this. Such a procedure can take a long time and its outcome is uncertain. Würgassen is the oldest boiling water reactor (BWR) in Germany and the discovery of the cracks could mean its closure.
Sources:
- Die Tageszeitung (FRG), 31 Oct. and 26 Nov. 1994
- Spiegel, 48/1-994
- Nucleonics Week (US), 13 Oct. and 10 Nov. 1994