International Workshop to share knowledge about innovative systems and technologies related to the safety of future and current reactors, supporting the technology transfer from research to industry in the field. 

From October 2017, the Consortium Westinghouse Electric Spain, Westinghouse Electric Sweden and VUJE is implementing the Project: “D4.2 Dismantling of Reactor Coolant System Large Components” being a crucial part of V1 Nuclear Power Plant (two units with VVER– 440 reactors located in Jaslovské Bohunice site in Slovakia) decommissioning process managed by Slovak company Jadrová a vyraďovacia spoločnosť (JAVYS) and co-funded by the European Union through the European Bank for Reconstruction and Development.

In order to establish the Nuclear Safety Requirements Document (NSRD) for the post-operational phase (POP) of the Belgian NPPs, the licensee (Electrabel) applied an efficient Integrated Safety Approach (ISA) based on Bel V recommandations.

Light Water Reactors (LWRs) such as the ones operating in Switzerland work at relatively high temperatures and pressures. As a consequence, thermal-hydraulics experiments investigating relevant LWRs phenomena at prototypical conditions require test sections with relatively thick steel walls. This poses significant challenges for the implementation of suitable instrumentation to capture phenomena of interest, such as the flow regimes during transition from liquid to steam. The characterization of flow regimes in the presence of boiling is rather complex, and their better understanding would allow to develop mathematical modeling tools that can be used to optimize equipment and better assess safety margins. To perform in-situ measurements of the boiling process under high-pressure conditions, the team of authors from PSI, ETH, and the University of Michigan has developed a new high-fidelity and high-speed imaging system based on x-ray radiography, which provides high-resolution details on the boiling process while being non-intrusive. Since the instrumentation is located outside of the test section, it has also the advantage that can be easily moved to take measurements in different region of the test sections.

During the internship the phenomena of High Burnup Structure (HBS) formation was investigated. Working with locally developed mechanistic fission product release code called MFPR-F researcher participated in the code coupling effort, where MFPR code was integrated into TRANSURANUS fuel performance code.

An IAEA Coordinated Research Project (CRP) on Forced to natural circulation transition in the Heavy liquid metal loop NACIE-UP is currently ongoing. A numerical benchmark will assess the capabilty of numerical codes to reproduce experimental data.

VUJE has delivered a manipulator for remote controlled plugging of VVER-1000 steam generator heat exchanging tubes for Zaporizhzhia Nuclear Power Plant. Following South Ukraine NPP, Khmelnitsky NPP and Rivne NPP , Zaporizhzhia is the fourth nuclear power plant in Ukraine which will be using this unique device manufactured by VUJE, a.s.

This work aimed to produce intermetallic samples of platinoid metals (active metal matrix) and lanthanides (co-metal) and via the method of Coupled Reduction, i.e. a thermal treatment of the combination of the lanthanide oxide and noble metal at high temperature, as high as 1100 °C, under a constant flow of H2. We have demonstrated by means of several techniques, such as Scanning Electron Microscope, Energy Dispersive X-Ray Spectroscopy, Alpha Spectrometry and Radiographic Imaging, that this method, at defined experimental conditions (temperature, pressure and concentration) yields a metallic lanthanide thin film when using platinum as active metal matrix. Conversely, the formation of a bulk intermetallic compound was obtained when using Pd as matrix. Those systems will have applications in different nuclear physic and radiochemistry studies, such as irradiation targets for production of superheavy elements and for nuclear data determination.

ICONDE project conducts research into concrete design for hazardous waste management applications.

Instead of automated sampling for noble gases and analysing stations, manual system can be used to better accommodate costs for the equipment and flexibility of usage. One of this system has been developed by the Traceability Laboratory at the ENEA Research center of Brasimone, which was specially designed in order to keep the sampling equipment separate from the processing and measurement.

VUJE participation at Mochovce NPP Unit 3 commissioning.

This highlight presents a successful, in-house developed integration of an Electron Beam Ion Source (EBIS) able to ionize gases to high charge states with a customized commercial MC-ICP-MS. The successful joining of the two ion flight paths is a milestone towards comprehensive routine analyses of solids, liquids, and gases using THE SAME MASS SPECTROMETER, the latter analyses free from atmospheric contamination. After implementation of an introduction system for gas mass spectrometry, routine analyses will comprise isotope ratio and relative abundance determinations of fission gases in used nuclear fuel. In addition to the unique versatility of the MC-EBIS-ICP-MS, inclusion of the EBIS further opens the little-studied field of mass spectrometry of highly charged ions.

The Mochovce NPP Unit 3 is expected to be fully operational in 2023. Along with the commissioning of the NPP Mochovce Unit 3, the commissioning of the operational diagnostics system of the primary circuit also takes place. 

Water boiling control evolution of natural geothermal systems is widely exploited in industrial processes due to the unique non-linear thermophysical behavior. Even though the properties of water both in the liquid and gas state have been extensively studied experimentally and by numerical simulations, there is still a fundamental knowledge gap in understanding the mechanism of the heterogeneous nucleate boiling controlling evaporation and condensation. In this study, the molecular mechanism of bubble nucleation at the hydrophilic and hydrophobic solid–water interface was determined by performing unbiased molecular dynamics simulations using the transition path sampling scheme. Analyzing the liquid to vapor transition path, the initiation of small void cavities (vapor bubbles nuclei) and their subsequent merging mechanism, leading to successively growing vacuum domains (vapor phase), has been elucidated. The simulations reveal the impact of the surface functionality on the adsorbed thin water molecules film structuring and the location of high probability nucleation sites.

After several years of loyal and reliable services during heavy duty operation in a reactor, nuclear fuel must be discharged and go into retirement. For Switzerland, the final place of retirement is planned to consist of a deep geological repository where the used nuclear fuel will be disposed. Before the repository is constructed, the used fuel will need to be stored in wet pools and/or dry storage casks.

During all this time, safe handling of the fuel will remain the top priority for operators and regulators. To gain better knowledge on the relevant phenomena which could potentially affect the fuel thermo-mechanics and safety characteristics during long storage periods as well as to allow predicting their evolution, simulation models are being developed at PSI within the DRYstars project.

A first milestone was recently achieved with the development of models coupled to state-of-the-art fuel performance codes for each of the three main categories of phenomena considered as having high safety relevance for storage, namely helium behaviour, creep behaviour and hydrogen behaviour.