Operating a full tungsten actively cooled tokamak: overview of WEST first phase of operation

WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up to 1000 s. In support of ITER operation and DEMO conceptual activities, key missions of WEST are: (i) qualification of high heat flux plasma-facing components in integrating both technological and physics aspects in relevant heat and particle exhaust conditions, particularly for the tungsten monoblocks foreseen in ITER divertor; (ii) integrated steady-state operation at high confinement, with a focus on power exhaust issues. During the phase 1 of operation (2017–2020), a set of actively cooled ITER-grade plasma facing unit prototypes was integrated into the inertially cooled W coated startup lower divertor. Up to 8.8 MW of RF power has been coupled to the plasma and divertor heat flux of up to 6 MW m−2 were reached. Long pulse operation was started, using the upper actively cooled divertor, with a discharge of about 1 min achieved. This paper gives an overview of the results achieved in phase 1. Perspectives for phase 2, operating with the full capability of the device with the complete ITER-grade actively cooled lower divertor, are also described

Measurement of Fission Products and Chemical Species released by Experimental Samples irradiated in the Jules Horowitz Reactor

International audienceExperiments on nuclear fuels and materials in MTRs are a mandatory step for supporting their characterization and qualification before introduction at industrial scale in power reactors. They are the most often carried out in irradiation loops and capsules embarking a lot of instrumentation, either on-line or by integration. Besides measurement of local irradiation conditions (fast and thermal neutron flux, coolant temperature and pressure, stress applied to experimental load etc.), behavior of sample is monitored thanks to specific sensors measuring on-line important parameters for models and codes. However it presents a lot of constraints such as miniaturization, robustness, adapted measurement range with requested accuracy, negligible drift, materials compatibility etc. which can cause technical issues for long duration experiments. Some of these issues can be overcome by equipping with lines either the sample (internal free volume…) or the surrounding connected volumes (coolant pipe, gas gap…). Their role is to collect and route the fluids to specific out-of-pile measurement means which monitor by on-line and delayed techniques specific chemical elements and isotopes released by the sample: fission products, fissile material, activation or corrosion isotopes or molecules, either in normal conditions (high demanding conditions, power transients, innovative coolant chemistry, first barrier loss…) or during safety tests with sample damage (loss of coolant, power injection…). This paper presents the interest of such measurements for supporting the development process of nuclear fuels and materials. Relevant design data for implementation on experimental samples are given. Analysis equipment recommended to be installed in the Fission Product Laboratory and the Chemistry Laboratory of the Jules Horowitz MTR, for activity and for atoms counting, are presented. Such laboratories are underlined as a key service offered by a modern multipurpose irradiation infrastructure