IFMIF-DONES, the International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source, is the planned facility in Granada/Spain for fusion materials investigations using neutron irradiation in the scale of DEMO-oriented energies. This irradiation is generated by the interaction of deuteron beams with a liquid lithium flow-target system, containing huge amounts of this very reactive alkaline-metal. An important and critical issue during the operation of IFMIF-DONES is the enrichment of dissolved impurity components in the Li-melt and in the liquid melt concerning reactivity, corrosivity and radiation hazards. In the case of hydrogen, there is the danger of H-introduced embrittlement of the loop structure components as well as effects and hazards of the radioactive tritium. The application of liquid lithium in the scope IFMIF-DONES unconditionally hence requires a suitable impurity control. Regarding this subject, an electrochemical sensor for a continuous hydrogen monitoring is being developed in the frame of an international EUROFusion-WPENS task. This sensor was designed as single-rod-measuring-cell with niobium as the relevant membrane-material and a hydrogen conducting electrolyte. Potentials (Electro-Motive Force EMF) are being measured between the Li melt and a reference electrode by voltmeters with high impedances and can easily converted into H concentrations. Long-term tests (campaign-units of several hundred hours) in stagnant Li-melts with different sharply controlled hydrogen concentrations showed, that the sensor fulfills the requirements of chemical and mechanical stability and functionality also under harsher conditions (temperatures up to 500 °C). The obtained results and operational experiences will be discussed, e.g., concerning application windows, reproducibility and calibration needs. Additionally, recommendations will be outlined for upgraded systems and future qualification needs.
Detection of hydrogen as impurity in liquid lithium: An electrochemical hydrogen-sensor for IFMIF-DONES
Nitti F. S.
2022-01-01
Abstract
IFMIF-DONES, the International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source, is the planned facility in Granada/Spain for fusion materials investigations using neutron irradiation in the scale of DEMO-oriented energies. This irradiation is generated by the interaction of deuteron beams with a liquid lithium flow-target system, containing huge amounts of this very reactive alkaline-metal. An important and critical issue during the operation of IFMIF-DONES is the enrichment of dissolved impurity components in the Li-melt and in the liquid melt concerning reactivity, corrosivity and radiation hazards. In the case of hydrogen, there is the danger of H-introduced embrittlement of the loop structure components as well as effects and hazards of the radioactive tritium. The application of liquid lithium in the scope IFMIF-DONES unconditionally hence requires a suitable impurity control. Regarding this subject, an electrochemical sensor for a continuous hydrogen monitoring is being developed in the frame of an international EUROFusion-WPENS task. This sensor was designed as single-rod-measuring-cell with niobium as the relevant membrane-material and a hydrogen conducting electrolyte. Potentials (Electro-Motive Force EMF) are being measured between the Li melt and a reference electrode by voltmeters with high impedances and can easily converted into H concentrations. Long-term tests (campaign-units of several hundred hours) in stagnant Li-melts with different sharply controlled hydrogen concentrations showed, that the sensor fulfills the requirements of chemical and mechanical stability and functionality also under harsher conditions (temperatures up to 500 °C). The obtained results and operational experiences will be discussed, e.g., concerning application windows, reproducibility and calibration needs. Additionally, recommendations will be outlined for upgraded systems and future qualification needs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
