Finnish EPR passes integrity tests

The Olkiluoto EPR moved a step closer to commissioning with the successful completion of pressure and leak-tightness tests on its containment. However, the plant owner says it cannot provide an estimated start-up date.

The Olkiluoto EPR moved a step closer to commissioning with the successful completion of pressure and leak-tightness tests on its containment. However, the plant owner says it cannot provide an estimated start-up date.

Olkiluoto 3 (Image: TVO)

The Olkiluoto 3 reactor has a double-shell containment building. The inner containment is a pre-stressed steel cylinder in reinforced concrete. The outer containment is also made of reinforced concrete and protects the inner containment from any external interference.

A series of tests have recently been conducted over a two-week period to demonstrate that the inner containment, which houses the reactor primary circuit, is leak-tight and pressure-resistant. During the tests, large compressors were used to pressurize the containment up to a maximum 6 bar (6.12 kg/cm2). The longest continuous period of pressurization was about 30 hours. During the tests, sensors measured containment temperature, pressure and humidity. Finnish utility Teollisuuden Voima Oyj (TVO) said, "The sequenced measurement procedure verified that the structural behaviour of the containment is consistent with the design."

Areva's commissioning engineer Guillaume Douet noted, "This was the first pressure and leak-tightness test conducted on an EPR unit, and the first pre-operational test of a reactor containment conducted since 2001 in Europe. We are extremely pleased with the good results of the test."

TVO said that the leak-tightness test will be repeated at the unit three times in every 15-year period.

New start-up schedule?

Olkiluoto 3, the first-of-a-kind EPR, is being built by the Areva-Siemens consortium under a fixed-price €3 billion ($4 billion) turnkey contract. Construction started in 2005 but has faced many challenges which has resulted in several revisions to its estimated start-up date. Last February TVO said it was "preparing for the possibility" that the unit may not start operating until 2016.

In December 2013, Areva-Siemens informed TVO that it was planning to focus work at Olkiluoto 3 on "urgent design tasks, which are the most critical to the project." The consortium said it would reduce the number of workers and sub-contractors on the construction site accordingly. At that time TVO said, "We now expect Areva to provide us with a detailed clarification concerning the planned changes and focus areas. At this stage we cannot evaluate how the plans might impact in overall schedule."

TVO has now said that it is still waiting for the Areva-Siemen consortium to provide it with an updated overall schedule for the project. It added that it will not therefore provide an estimated start-up time for the reactor at this time. "Information about the start-up date of electricity production at Olkiluoto 3 is pending the finalization of the plant supplier's schedule clarification."

EPRs are also under construction at Flamanville in France and Taishan 1 and 2 in China. Flamanville 3 has been under construction since 2007 and is expected to start up in 2016. Taishan 1, which has been under construction since 2009, is expected to start up this year, while Taishan 2 is scheduled to begin operating in 2015.

Researched and written
by World Nuclear News