First-Of-A-Kind Decommissioning: Helping Slovakia Tackle Its Nuclear Legacy

Jacobs is taking part in a pioneering project to clean up Slovakia's nuclear legacy.

JAVYS, the nation's decommissioning company, tasked a consortium of Westinghouse Electric Company and VUJE with the first ever dismantling of a VVER-440 nuclear reactor.

The consortium reached a key milestone in June 2020 when it safely removed the Unit 1 reactor pressure vessel (RPV) at the Jaslovské Bohunice V1 nuclear power plant. Jacobs designed and manufactured remotely operated equipment to carry out underwater handling, baskets to hold fragments of the RPV components, and equipment for radiological characterization.

A significant milestone as reactor pressure vessel is removed

Using the main 250 tonne crane in the reactor hall, the RPV was placed on a prepared platform in a specially built pool, so that segmentation work could be carried out by Westinghouse.

JAVYS described this as 'a significant milestone' in the decommissioning process, adding: 'One of the main tasks of the project is the dismantling and fragmentation of RPVs and internal parts of reactors, whose radioactivity represents almost 100% of the total radioactivity of the power plant.

'Before dismantling activities began, the project team, comprising Westinghouse, VUJE and Jacobs, conducted extensive tag-out and lock-out activities, asbestos removal, radiological characterization, sampling and decontamination to ensure that operations could be conducted as safely as possible. Removal of the RPV was preceded by months of preparations, technical negotiations, design, production of handling equipment and approval of the necessary documentation by supervisory authorities,' the company stated.

COVID safety requires additional health and safety regulations

The RPV removal was performed with additional health and safety regulations in place to prevent the spread of COVID-19. In awarding the contract, JAVYS required bidders to have proven decontamination, dismantling and waste packaging expertise, and to be innovative in planning and meeting a very tight schedule, while meeting the highest safety standards.

The overall project includes: studies and procedures; designing and manufacturing new tools and equipment; site preparation; and decontamination, dismantling, segmentation, packaging and management of waste arising from 9,500 tonnes of contaminated and activated components.

These components include the primary circuits (steam generators, main circulation pumps, main insulation valves, pressurizers, bubble tanks and primary piping), reactor vessel internals, reactor vessels, auxiliary equipment, plant systems and other elements such as the annular water tank.

They also include high-activated operational waste, which is stored in a dedicated location.

Jacobs' scope of work includes complete waste management of the project including delivery of containers and radiological measuring equipment, regulatory and engineering support.

The consortium built two new pools where the segmentation of highly radioactive waste can be carried out under a depth of water necessary to shield workers from radiation.

Each pool is equipped with two gantry cranes and two working bridges, on which four crews of operators can work simultaneously. The operators cut and package components remotely with cutting tool manipulation and handling systems. They can observe the work using underwater cameras from which live images are projected onto screens on the working bridges.

The fragments are characterized before being placed into the prepared baskets, which were designed and delivered by Jacobs. Jacobs is performing the manipulation with the baskets, from the bottom of the pool to the final destination. The baskets, based on the radiological status of the content, are placed in concrete containers with additional external shielding, which has also been designed and delivered by Jacobs.

The turbine building was adapted and reclassified as a dry cutting workshop so that it can be used to segment six steam generators from each unit. The approach for wet and dry cutting will help to meet the compressed schedule while satisfying all safety and regulatory requirements.

Safety culture and decommissioning skills are key to project's success

Helena Mrázová, Jacobs Project Manager, shares 'We have achieved a very significant milestone, thanks to the hard and effective work of all the team members. I am really glad to have the opportunity to work with such professionals and see the results of their hard work.

'COVID-19 interrupted our operations in March and early April 2020, when we introduced restrictions to safeguard the project team. We did this successfully and returned to site in early April, with strict measures in place to ensure that everyone remained safe.'

Marek Mečiar, Jacobs Business Unit Director, says: 'The professional decommissioning skills and high level of safety culture of the Jacobs team have impressed the nuclear regulator's representatives and all the organizations we are working with.'

The Jacobs team at Bohunice is able to reach back to specialists at the company's suite of laboratories in Trnava, which has extensive experience of developing analysis methods and decontamination technologies for surface treatment, including electrochemical sampling and scanning electron microscopy. The laboratories are also responsible for the deployment and development of SIAL, Jacobs' proprietary waste solidification and encapsulation technology. SIAL has been used at nuclear power plants in Slovakia and the Czech Republic.

Bohunice's two Soviet-designed VVER-440 V-230 reactors were connected to the grid in 1978 and 1980 and operated until they were shut down in 2006 and 2008.

Decommissioning of Bohunice V1 NPP, led by JAVYS, is co-financed by the European Union through the Bohunice International Decommissioning Support Fund administered by the European Bank for Reconstruction and Development (EBRD).

Originally published as part of Jacobs' Nuclear Engineering International supplement. Click to view the full publicationand discover how, from next generation systems for a climate-resilient future to managing complex decommissioning, site closure, radioactive waste and remediation efforts, we're helping solve the world's most complex nuclear challenges safely and effectively on jacobs.com.

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