Temelin NPP Retests the Containment

After the fuel charging in the reactor of Unit One has been successfully completed on 14th July 2000 by completion and sealing of the reactor by IAEA of Vienna on Wednesday, 26th July, the preparation of the unit for the reactor start-up continues with another important test. That is the reconfirmation test of containment started today. The containment is the basic security element and the fourth barrier between the nuclear fuel and the environment round the nuclear power plant. The containment also protects the most important parts of the nuclear power plant from external effects.

The first testing of strength of tightness of the containment had already been conducted from 14th December 1998 until 6th January 1999. The containment of Unit One passed all criteria of the strength test both with the maximal overpressure of 460kPa and with the pressure being relieved to the atmospheric one. The identified magnitude of leakage during the tightness test was lower in order rather than the value as prescribed in the design for the test. For illustration, the measured leakage in the containment of Temelin NPP can be compared to the leakage of air from a hole with diameter 1.7mm located on an area large 1.02 hectare. "The reconfirmation test of tightness of the containment which will be lasting for about a week is designed to reconfirm, before the reactor is started up, that its tightness parameters have not changed during completion works," comments the purpose of the test Ing. Milan Nebesar, NPP press spokesman.

"The reconfirmation test proper is preceded by negative pressure tests to identify leakages, if any, in the containment. During tests with negative pressure of 4 up to 5kPa, groups of specially trained and qualified workers of both the investor and contractors will be locked inside the hermetic containment. Using several methods these workers will identify the tightness of the building part and the technical part on the border of the hermetic zone. Only then the test of the containment integrity will be undertaken with overpressure of 70kPa, during which groups of workers check the containment from its external side and confirm its tightness by high-precision measurements. Measurements conducted during the reconfirmation test of integrity of the containment will be practically same as those conducted late in 1998, added Ing. Pavel Vojta, department of containment testing at Temelin NPP commenting the way of testing.

Milan Nebesar, Temelin NPP Press Spokesman

28. 7. 2000