Optimization of the RELAP model for the E-SCAPE pool facility based on CFD analysis (Master)

MYRRHA is a flexible fast spectrum research reactor cooled by Lead-Bismuth. Conceived as an accelerator driven system prototype, it is able to operate in sub-critical mode. Operating in critical mode, MYRRHA serves as demonstrator for the Lead Cooled Fast Reactor (LFR) which is one of the Generation IV reactor concepts. This kind of nuclear system is highly economical, has enhanced safety, produces minimal waste and is proliferation friendly. In addition, such systems can be used to transmute transuranic elements in shorter-lived waste, thus lowering the burden on deep geological storage.

SCK•CEN is involved in the THINS project of the European Commission's 7th Framework Programme. THINS deals with Thermal-Hydraulics of Innovative Nuclear Systems. Within this project, SCK•CEN will execute a thermal-hydraulic experiment in order to assess flow patterns in a liquid-metal pool-type fast reactor. For this purpose, a scaled model of the MYRRHA reactor, E-SCAPE (European Scaled Pool Experiment), has been designed.

In April 2012 the design of a 1:6 scale model of the MYRRHA reactor, E-SCAPE, will be completed and the construction will start. The facility is made up of the reactor pool vessel mockup, a primary Lead-Bismuth Eutectic (LBE) circuit and a secondary oil cooling circuit.

Simulations to be performed in E-SCAPE will allow to characterize the temperature and velocity profiles within the pool and to reproduce the main thermal-hydraulic phenomena, including the ones involving natural circulation, with high relevance for the safety.

A simplified RELAP model of the facility is already available, based on a preliminary design. As an initial task, this model has to be updated to the actual design status.

The main objective of the work is to optimize and validate the RELAP model with the results coming from a local CFD analysis, with particular attention on the upper and lower plena.

In an iterative process, the RELAP model will provide boundary conditions for the CFD models, then the results of the three-dimensional CFD models will provide input for the one dimensional RELAP nodalization, in order to adapt and tune the model to represent the correct results coming from the full 3-D analysis.

Both the CFD and system analysis models will later be validated using the experimental results. This has to be intended as a further development and is however beyond the scope of this work.