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Corrosion of Temelín reactor

1. deformations of fuel rods
Fuel rods fabricated by Westinghouse show serious changes in geometry, and the deformations exceed expectations and operator's experiences so far. Deformations may cause have influence on control rod insertion. In mid 2005, there was an event when half of the control rods did not insert fully. In addition, this can lead to damage of fuel rod cladding due to friction and increased releases of fission products to the primary circuit. This forced CEZ to release larger amounts of radionuclides into air in 2005 (in total there were eight larger than normal releases).

2. reactor vessel head corrosion
In may 2005, when the second unit reactor was being prepared for start-up, water with boron acid escaped and flooded numerous components affilliated to the reactor vessel. This lead to corrosion of all deviced that were not made of stainless steel. CEZ, in its own internal report, states that "it is not possible to operate reactor for longer term with corrosion of such a scale" - nevertheless, reactor has been in full operation since then until now. Because the corrosion affected also bolts of reactor flange, problems with opening the reactor may occur during next refueling. Thousands of litres of boron acid solution leaked already several times, in one accident in 2004 and recently again in January 2006.

3. tritium releases
Tritium concentrations in river of Vltava are higher than was expected, altgough still bellow the limits.

Photos showing corrosion of reactor No. 2 at Temelin, as of May 2005:

More impressive photos can be found at:

Hana Gabrielová, Calla

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