VUJE played a key role in Mochovce 3 NPP commissioning

In 2008, VUJE allocated a group of its experts exclusively for the completion of the 3rd and 4th nuclear units of Mochovce NPP. The participation on this project started after signing an EPC contract with Slovenské elektrárne, a. s. This created a completely new, young division. At the time of the largest scope of work it had 120 employees. Currently, the number of the division's employees has already dropped to 52 and they are responsible for the work related to the completion of unit 4 of the NPP. "The construction activities on unit 4 are 99% completed, now it is necessary to perform functional tests and move on to the commissioning process of the whole unit 4", says the division director, Mr. Pavel Ševera.

The Preparation and Construction of New Nuclear Power Plants Division is within VUJE appointed to manage the works resulting from the engineering, procurement, and commissioning contract. The commissioning of unit 3 with a capacity of 471 megawatts for Slovenské elektrárne was completed last October under the management of VUJE. The new nuclear reactor will cover approximately 13% of Slovakia's total electricity consumption and the commissioning of this unit has contributed to the fact that our country is now completely self-sufficient in electricity generation.

"The largest functional technological system that we delivered to the power plant on a turnkey basis was the ventilation and air conditioning system for the primary part of the power plant," explains Mr. Rudolf Hronkovič, deputy director of the division. "We designed, supplied, consequently installed and then tested the system under strict safety conditions of the power plant, into almost every room."

In addition, VUJE supplied, installed and tested radiation control systems in Mochovce, which are applied throughout the plant. They monitor the radiation of the working environment, the media of technological systems as well as the employees themselves. "Every worker must be equipped with a personal detector when moving around in the so-called controlled zone," says Mr. Pavel Ševera, project manager. "All areas are closely monitored, even though the majority of the environment there has radiation doses of zero or close to zero," he explains. Therefore, VUJE can design and implement the entire radiation monitoring system, with components purchased from reputable foreign manufacturers.

Nevertheless, the contract for the completion of Mochovce NPP for VUJE is much broader. We are also supplying other turnkey technological systems, such as primary circuit diagnostics, hydrogen concentration monitoring system, industrial camera system or system for physical and power start-up support, system for decontamination of premises and equipment, sampling system and emergency response center. These are large-scale projects and to achieve 100% safety, they require high expertise and detailed testing.

Commissioning of NPP

The commissioning of unit 3, which is a process spanning from loading the fuel into a reactor, to the achievement of the first minimum power to 100% reactor power, took about a year. The reactor did reach 100% of its rated power on  September 22, 2023. The final test was a so-called trial run, when a 144 hours long stable operation of the unit was confirmed.

"This is one of the most important stages in the life of a power plant," says Mr. Rudolf Hronkovič. "Everything that was designed and implemented had to be tested in detail. Literally every single button and component, of which there are thousands in the plant, is being tested. It is necessary to prove that everything is in accordance with the approved design, documentation and meets all operational and safety requirements."

Special staff training

VUJE also provides highly professional plant personnel training, including operators, without whom the start of a full operation would not be possible at all. These are very demanding technical trainings. This program on top of university is completed by a state examination under the Nuclear Regulatory Authority. "Some compare the professional difficulty of a reactor operator to the one of an airplane pilot," adds Mr. Rudolf Hronkovič. “On top of this, they have to renew their exams regularly," he points out.

Before the testing and commissioning of unit 4 of the Mochovce NPP starts in the near future, the staff will have to repeat the professional examinations again. "We both passed them once and they are honestly very demanding, but necessary to ensure the operation and safety of the nuclear power plant," concludes Mr. Pavel Ševera, division director and project manager.