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).
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
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:
impressive photos can be found at: http://zpravy.idnes.cz/foto.asp?r=domaci&c=A060412_120958_domaci_skr
Hana Gabrielová, Calla