Mochovce 3 completes commissioning test

16 April 2019

Slovakia's new reactor Mochovce 3 has successfully completed hot testing. Owner Slovenské Elektrárne (SE) said the plant could be ready for fuel loading this summer, although it will then have to wait for regulatory approval which could take up to eight months.

The Mochovce site (Image: SE)

Mochovce 3 is 98.8% complete, SE said, the remainder of work being the process to test and prove its safety and operational systems to satisfy regulators to grant licences to proceed to operation.

Yesterday SE announced the conclusion of hot hydrostatic testing, the verification of the leak-tightness of the reactor cooling system and the containment under operational conditions. Under the observation of regulators, SE said, the system met expectations at 50% overpressure. The tests also cover performance of the secondary circuit, which carries steam to the turbine generator, as well as systems for control, security, heating, cooling and ventilation.

Juraj Krasňanský, in charge of the work, said the results were twice the regulatory demand and this "demonstrated the strength and tightness of the containment and definitively refute the misleading and false claims of the Austrian antinuclear activists".

Earlier this month SE issued a strongly worded response to Austrian anti-nuclear group Global2000 who it accused of "scaremongering through reports about Mochovce" based on what it said were anonymous accusations that its containment was not safe enough due to seismic reinforcement work done on site.

The final verdict on the hot tests will be issued by the nuclear safety regulator after hearing official opinions from national authorities on public health, labour and fire and rescue.

Shifting schedules

Construction of the first two units at the four-unit Mochovce nuclear power plant started in 1982. Work began on units 3 and 4 in 1986, but stalled in 1992. The first two reactors were completed and came into operation in 1998 and 1999 with a project to complete units 3 and 4 beginning ten years later. The final design includes many upgrades to safety and security, including increased aircraft impact protection and emergency management measures based on lessons from the Fukushima accident which were incorporated during the project.

SE said testing had been completed later than planned, and this, together with delays in construction works, meant it would need to re-schedule commissioning. The company said it expects to be "technically" ready to load fuel into the reactor core by the summer, but before this can happen the regulator must be fully satisfied that the reactor is safe and the operator competent to operate it.  The exact date of commissioning will therefore depend on the licensing process, and it could be up to 8 months between technical readiness for fuel loading to the actual date of fuel loading.

The delay will also add an estimated EUR270 million (USD305 million) to the total cost of the Mochovce 3 and 4 project, representing 5% increase in total costs. This will be fully covered by SE's majority shareholder Slovak Power Holding BV, the company said.

Chairman and CEO of SE Branislav Strýček said at present there are over 3500 employees and contractors on site, of which about two-thirds are working on Mochovce 3 and the rest on unit 4, which is at 84.6% completion.

The company expects the two new reactors to  produce about 7 billion kWh per year, which it said is enough for Slovakia to be self sufficient in electricity by 2020, a status it lost in 2007 when a condition of accession to the European Union was the shutdown of two reactors at Bohunice V1. In 2017, SE said, it imported almost 10% of the country's 31 billion kWh electricity consumption.

Researched and written by World Nuclear News