This project has received funding from the European Union's Horizon 2020 research and innovation programme under agreement No 945275

Investigating new innovative options for increasing the safety of European Nuclear Powerplants

Including Safety Condenser (SACO) and Containment Wall Condenser (CWC) to future generations of nuclear power plant (NPP) are possible options to potentially increase safety and resilience during a Station Blackout (SBO) given that they do not need any external electrical power supply to operate. Furthermore, passive systems can provide an interesting alternative to active systems in terms of capital installation and maintenance costs. Several sources agree that the introduction of innovative passive systems significantly lower the core damage frequency (CDF) of nuclear power plants.

Enhancing reliability of industrial design capabilities for European actors

With PASTELS, European reference thermohydraulic codes will first be tested and validated by separate and combined effect test that include the interaction of a limited number of elementary phenomena. Thus, the performance of these codes will also be measured on the results of the integral test facilities (PASI and PKL). Coupling methodologies between system and CFD codes will be developed to improve the prediction of passive systems behaviour. Through the improved predictive numerical capabilities, it will be possible for European actors to propose optimised high-performance SACO and CWC for the future nuclear powerplants markets as the exploration and qualification of reliable solutions will be possible.

Participating to qualification of SACO and CWC technology for future implementation in nuclear powerplants

Because PASTELS results will have been elaborated within a consortium consisting of operators, designers, academics and regulatory bodies, using PASTELS’ sound experimental basis, a reduction of 1-2 years is expected in the licensing timeframe for the introduction of such innovative passive systems. This reduction is estimated based on the advances made on the qualification of the codes for passive systems and the design activities (using different parametric studies and operating scenarios) performed on the SACO and CWC components. Extrapolation to the reactor scale is foreseen in this context.

Increasing the competitiveness of European nuclear powerplants’ solutions

PASTELS will provide valuable inputs to allow the European nuclear community to obtain an informed opinion of the interest of having these innovative passive systems in European nuclear power plants. With this demonstration made, the ability for European NPP designers/ manufacturers to incorporate SACOs and CWCs in future nuclear powerplants’ designs as is already being done by non-European organisations. By being able to offer these components, Europe is safeguarding its competitive edge over foreign competitors.

Increasing test facility expertise

As the SACO will remain in the PKL facility after the end of the PASTELS project, an integral test facility will be available in Europe to further investigate the SACO behaviour under various operational and accidental transients (e.g. steam generator tube rupture).

Moreover, other components to be tested in the future will take benefit from the modifications made to the PKL test facility. Hence, once the investigations of the vertical SACO are completed, the vertical SACO could be easily substituted with other test components.

The PASI test campaign will close a major gap in European knowledge base about low-pressure open loop naturally circulating heat removal systems. The tests will shed light on the performance and failure modes of passive systems having no moving parts, creating a foundation for passive safety system analysis both in the deterministic and probabilistic domains. This enables subsequent assessment of passive systems’ reliability and their potential to reduce plant-level risk of nuclear reactors.

Increasing European academic and scientific knowledge

Through the University of Stuttgart, and LUT University, knowledge gained from PASTELS will filter down into the syllabuses of under- and post-graduate courses. Also, several research centres involved in PASTELS, will produce publications that will be publicly available for the science community at large.


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Assessment of TRACE code for modeling of passive safety system during long transient SBO via PKL/SACO facility
Frequency and amplitude of flashing-induced instability in an open natural circulation loop
PASTELS project - overall progress of the project on experimental and numerical activities on passive safety systems
TRACE code simulation of the interaction between reactor coolant system and containment building with passive heat removal system