Accelerator R&D for ADS/MYRRHA
A 600 MeV, 4 mA cw operated proton Linac is required to feed the subcritical MYRRHA reactor.
The accelerator has to deliver the 2.4 MW beam with very high reliability and with minimum beam losses.
After the successful beam tests of the source and the Low Energy Beam Transport section in Grenoble the front-end has moved to CRC (Centre du Ressources du Cyclotron) in Louvain-la-Neuve (Belgium). It was possible to create first beams at CRC and the systematic investigation of the front-end has started. The Radio Frequency Quadrupole (RFQ) has been shipped to CRC. After finishing the installation of the required infrastructure, the RFQ has been RF commissioned in cw operation. The RF amplifier developed for this purpose was tested and shows very reliable operation. The Low Level RF) control system, which is required to control the RF phases and amplitudes of the injector cavities, has been finished and shipped to CRC. The control system which has been developed in the context of high reliability is ready for the first beam tests. For measuring the beam properties, several diagnostics devices have been developed and tested.
Beam simulation tools have been further optimized to perform updated end-to-end simulations and to implement a virtual accelerator tool. A reliability model of LINAC-4 (CERN) has been developed and validated experimentally.
Prototypes of the superconducting cavities have been performed successfully. As result, all cavities exceeded the MYRRHA specifications. Additionally, the first beam test of a superconducting CH-cavity has been performed successfully.
Thermal hydraulics
In this work package, experiments and simulations go hand in hand. The experimental program has provided many new reference data. Additionally, with respect to turbulent heat transfer model development, high fidelity simulations are providing complementary reference data for pragmatic engineering model developers.
The flow induced vibration experiments finished successfully and revealed hardly any vibrations in the fuel assembly. Fuel assembly blockage experiments show that particles of a certain size might be blocked in the assembly. However, experiments and simulations also show that these blockages do not grow rapidly as new particles are following the enhanced crossflow and will not meet the initial blockage. Finally, a new coupled simulation tool coupling state-of-the-art sub-channel and neutronics codes has been validated and applied to a number of MYRRHA transients confirming results of earlier studies.
Chemistry of volatile radionuclides
Deals with studying chemical effects that influence the release of radioactive elements from the lead-bismuth eutectic (LBE) coolant of the MYRRHA reactor. Some of these are formed by activation of the coolant, while others may be transferred to the coolant from the nuclear fuel. The three tasks of WP4 cover experimental as well as theoretical studies on the behaviour and properties of the above-mentioned volatile elements in LBE. The results of all these studies will provide a deeper understanding of evaporation and deposition processes in MYRRHA and thus contribute to its safety.
Experiments in support of the MYRRHA design evolution
First, the critical core was assembled and studied in the VENUS-F reactor as a MYRRHA like core without any perturbations. Then several IPS units one by one in the core to obtain the final critical configuration as a MYRRHA like core with all types of perturbations present in the current design. Various reactivity effects were measured inside the active core and on the periphery. These include the loading of thermal spectrum IPS mock-ups for Mo production, fast spectrum IPS for material tests inside the active zone and loading of Pb, Bi reflector assemblies in specific positions.
A water evaporation accident in IPS for Mo production was simulated
Finally, a sub-critical configuration was coupled with the GENEPI-3C accelerator at the end of the MYRTE WP5 experiments.
Actinide fuel
Work package 6 investigated three major issues related to the safe use of (U,Am)O2-x fuel as basis for transmutation of americium in MYRRHA, namely the high-temperature thermo-physical properties of sub-stoichiometric (U,Am)O2-x, the helium release behaviour during irradiation and storage, and the compatibility and potential interaction of the fuel in contact with liquid LBE in case of a pin failure.
Dissemination & Communication
In order to disseminate and communicate the different achievements obtained during the project, an international Workshop on “Accelerator driven HLM nuclear reactor for transmutation and high-tech applications” was held at the von Karman Institute in February 2019.
