Corrosion-erosion phenomena occurred in the cooling circuits of primary heat transfer systems of the prototype of the ITER-like ion source named SPIDER, in particular during the first phase of the experiment activity which began in May 2018. Demineralised water circulating in cooling channels of components subjected to high heat loads reacts with inner channel surfaces made of copper alloys, aluminium, and stainless steel thus producing thinning of cooling channel walls. Then, resistivity degradation phenomenon of the demineralised water occurred and resistivity was measured before and after a working cycle to plan water treatment operations in order to maintain maximum availability of the SPIDER plants. This degradation was observed to be particularly fast during experimental campaigns: despite predictions, this effect is more significant in the less complex cooling circuit linked to Ion Source and Extraction Power Supply (ISEPS), feeding the Ion Source polarized to ground at -100 kV dc. Corrosion-erosion phenomena were investigated considering dissolved O2 and CO2, pH, flow velocity and turbulence, galvanic corrosion at dissimilar metal junctions, leakage current through high voltage cooling breaks, temperature, and water conductivity. This paper presents the first data of water parameters, monitored during experimental sessions by using the Cooling Plant and ISEPS Local Control Systems. Basing on collected data, some hypotheses were put forward on the behaviour of circuits and components, in order to propose possible mitigation actions and to reduce the frequency at which the cooling water should be renewed to keep the resistivity value in the required operative range.
Investigation of corrosion-erosion phenomena in the primary cooling system of SPIDER
Dalla Palma Mauro;
2020
Abstract
Corrosion-erosion phenomena occurred in the cooling circuits of primary heat transfer systems of the prototype of the ITER-like ion source named SPIDER, in particular during the first phase of the experiment activity which began in May 2018. Demineralised water circulating in cooling channels of components subjected to high heat loads reacts with inner channel surfaces made of copper alloys, aluminium, and stainless steel thus producing thinning of cooling channel walls. Then, resistivity degradation phenomenon of the demineralised water occurred and resistivity was measured before and after a working cycle to plan water treatment operations in order to maintain maximum availability of the SPIDER plants. This degradation was observed to be particularly fast during experimental campaigns: despite predictions, this effect is more significant in the less complex cooling circuit linked to Ion Source and Extraction Power Supply (ISEPS), feeding the Ion Source polarized to ground at -100 kV dc. Corrosion-erosion phenomena were investigated considering dissolved O2 and CO2, pH, flow velocity and turbulence, galvanic corrosion at dissimilar metal junctions, leakage current through high voltage cooling breaks, temperature, and water conductivity. This paper presents the first data of water parameters, monitored during experimental sessions by using the Cooling Plant and ISEPS Local Control Systems. Basing on collected data, some hypotheses were put forward on the behaviour of circuits and components, in order to propose possible mitigation actions and to reduce the frequency at which the cooling water should be renewed to keep the resistivity value in the required operative range.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
