Find out about the unique parameters of this project, and how TÜV SÜD experts overcame the challenges.
TÜV SÜD’s containment leakage test of the Finnish reactor Olkiluoto 3 in February 2014 broke new ground as the first pressure and leak-tightness test ever conducted on an EPR reactor. The third-generation pressurized water reactor is one of the largest industrial projects ever carried out in Northern Europe.
The tests posed special challenges for the TÜV SÜD experts, due to the unique containment parameters of Olkiluoto 3. The test systems had to operate within extreme conditions – with a vessel volume of 80,000 m3, significantly higher test pressures of up to 6 bar, ambient temperatures of around 30 °C and high levels of humidity. None of the instrument manufacturers could provide assurance that the sensors would be able to function correctly in these conditions. Additionally, the individual signal transmission lines of the instruments could not pass through the reactor walls, so the electronic data recording systems were placed inside the containment vessel for the entire ten-day test period.
To account for the unprecedented leak-testing conditions, TÜV SÜD specialists undertook extensive design, preparation and set-up of the measurement system. 75 temperature sensors and 15 humidity sensors had to be installed and interlinked, connected by ten kilometres of cable. To reduce uncertainty of the containment leakage test, the air in the containment shell was homogenised by running four compressor units with dryers and filters for 24 hours prior to the execution of the test.
Test conditions were simulated beforehand in a thorough preparation phase prior to the project test to assess how the equipment would perform under high pressure and whether the measurement precision will be affected. TÜV SÜD also developed test software that could handle the requirements, allowing for continuous monitoring of data. Contingency measures were also in place, which included the set-up of all instruments as redundant and diverse systems, to enable the tests to continue without interruption in case of equipment failure.
Pressure and leak-tightness tests play an important role in assessing nuclear safety and form a significant milestone in the completion of the Olkiluoto 3 project. The exceptionally challenging conditions of this project placed high demands on the expertise of the TÜV SÜD specialists. The specialists carried out careful preparations and logistics, both on-site and off-site prior to the project test, which were critical to the success of the measurement process.