Session: 07-13: SMR and Advanced Reactors - II

Paper Number: 135160

135160 - Customising a System Code for the Analysis of the Thermal-Hydraulic Behaviour of a Supercritical Pressure Light Water Small Modular Reactor 

Abstract: 

The present efforts to decarbonize the energy sector are resulting in a new emphasis on the development of innovative nuclear reactor concepts capable to replace fossil fuelled plants with a reliable, low carbon and dispatchable energy source. Small Modular Reactors (SMRs) are particularly targeted in this purpose in worldwide research for their promise to become an efficient way to complement intermittent renewable energy sources with a stable and affordable production of energy. Their postulated flexibility and load-following capabilities makes them also particularly interesting for deployment in the frame of cogenerating parks of hybrid energy systems, covering the needs for electricity and heat to be used for different purposes, including hydrogen generation, district heating, desalination and more.

Supercritical water reactors (SCWRs) represent one of the advanced concepts proposed in the frame of the Generation IV International Forum, being the only one of the six proposed nuclear reactor types to fully inherit the experience of the widespread light water reactor technology. The higher temperatures achieved at reactor core outlet make this reactor more suitable for cogeneration applications than other light water concepts existing or under development; however, as for all the other GEN-IV concepts, this also results in corresponding challenges to be coped with by research in terms of material resistance. Combining the promising features of SCWRs with those of SMRs in a SCW-SMR design, the EU ECC-SMART Project is aiming to tackle some of these challenges.

The paper reports about the work performed in customizing the RELAP/SCDAP code features for an easier assessment of a conceptual design of an SMR operating at supercritical pressure proposed by the Karlsruhe institute of Technology (KIT) in the frame of the EU ECC-SMART Project. First unsuccessful attempts to make use of the NRC version of the RELAP5 code in the analysis of the thermal-hydraulic behaviour of the SCW SMR revealed numerical difficulties at the transition from supercritical to subcritical pressures. This suggested to activate a cooperation for customising an already existing version of the RELAP/SCDAP code, aiming to overcome similar numerical problems and to implement heat transfer correlations in principle more appropriate for supercritical pressure conditions. In particular, the improved version of the code, featuring a user defined generalised correlation for heat transfer encompassing several of the presently available literature proposals, was applied in predicting rod-bundle experiments performed by the National Technical University of Ukraine and in analysing the behaviour of the seven core passage reactor proposed by KIT. In the paper, the present capabilities of the code are discussed in front of the obtained results and perspectives for future developments are suggested.

Presenting Author: Walter Ambrosini Università di Pisa

Presenting Author Biography: Walter AMBROSINI is Full Professor in Nuclear Plants at the University of Pisa, Italy. His Research interests involve the field of Nuclear Reactor Thermal-hydraulics: Heat and mass transfer, System code use and development for safety analyses of nuclear reactors, Flow stability, Heat transfer to fluids at supercritical pressure, CFD and numerical modelling of thermal-hydraulic systems. His teaching activities include: Computational Thermal Fluid-dynamics, Single and two-phase thermal-hydraulics, Numerical methods for nuclear reactors, Nuclear Safety. He has been President of the Research Doctorate in Nuclear Engineering in Pisa (2008-2016), President of the MSc in Nuclear Engineering in Pisa (2011-2018), President of the European Nuclear Education Network (2013-2016), Member of the ASN Commission for Energetics and Nuclear Engineering (2018-2021), Present Member of the CDs of CIRTEN and of the Associazione Italiana Nucleare (AIN). His relevant Memberships: AIN, ENS, ANS, ASME.

Authors:

Omar Chaaraoui Università di Pisa
Andrea Pucciarelli Università di Pisa
Walter Ambrosini Università di Pisa
Ivan Otic Karlsruhe Institute of Technology
Thomas Schulenberg Karlsruhe Institute of Technology
Chris Allison Innovative Systems Software
Zheng Fu Innovative System Software