1DTN / STRI /LTCD 28/03/06 Chemistry aspects of the ITER cooling water : impact on the experiments in the CEA loops DEN/CAD/DTN

2DTN / STRI / LTCD 28/03/06 ITER CHEMISTRY and THERMODYNAMICS The ACP migration (release and deposit) in ITER circuits is : 1) driven by thermodynamics. Thermodynamics in ITER conditions is governed by : the « bulk » basic fluid conditions : –Pressure and temperature which are measured –pH, which is known by validated codes (or can be measured by industrial dedicated probes) –Redox is expected to be monitored by existing H2 probe –Chemical bulk composition of the fluid which is estimated by sampling (and cooling) and by the solid composition of the material in contact with the coolant (initially known).

3DTN / STRI / LTCD 28/03/06 2) kinetically limited by (physico)chemical mechanisms (mass/thermal diffusion, physico-chemical reactions, surface interactions….) These limitations can be measured through : – the corrosion potential of the material which can be monitored by existing probes (Ag/AgCl by A. Molanders or by SCK-CEN via the LIRES-EU project) – the composition of deposited oxydes which may be monitored by Raman spectrometry – else …. ITER CHEMISTRY and THERMODYNAMICS These measurements need to be adapted to the reference PACTITER V3 formalism

4DTN / STRI / LTCD 28/03/06 APPLICATION TO ACP TRANSFER EXPERIMENTS Experiments must cover the range of ITER conditions: Chemical conditioning (pH 20°C =7.0, [H2]=25 cm 3 /kg), OK Fluid temperature (50°C  240°C), OK Velocity (static water  12m/s), < 5 m/s Materials (stainless steel, copper alloy). OK For ensuring a neutral pH, Li can be added at low concentrations. Li (as LiOH) is also a convenient way to « buffer » the conductivity (i.e the redox) of the fluid. The ionic strength of the fluid may also have some influence and is buffered through the redox Extension to ITER operating conditions ? Behaviour vs Cu ? Chemical conditioning :

5DTN / STRI / LTCD 28/03/06 APPLICATION TO ACP TRANSFER EXPERIMENTS Temperature and velocity of the cooling fluid : temperature of the bulk or temperature of the walls ? Velocity or reynolds (magnitude of erosion ?) ? kinetics of the warm up of the circuit ? (competition between thermodynamics and diffusional limitations as in SS release ?) Chemical conditioning : - copper colloids formation and stability ? if colloidal formation, redox (and ionic strength) will play a major (?) role

6DTN / STRI / LTCD 28/03/06 APPLICATION TO ACP TRANSFER EXPERIMENTS Materials -metallurgy (surface potential, stresses…) -Surface roughness (magnitude of erosion ?) CuCrZr Application to copper net release rate measurement Temp, Velocity ? Chemical method Input data for PACTITER V3 (corrosion rate not taken into account)

7DTN / STRI / LTCD 28/03/06 Resin bed n°DayBed Release TimeMaterial Release Time 112 hourT0 + 2 hour 22 hourT0 + 4 hours 33 hourT0 + 7 hours 4217 hoursT hours 5324 hoursT hours 6424 hoursT hours 7524 hoursT hours Table 1 : Sampling Frequency of the copper release measurements for a set of 7 beds. COPPER net release rate measurement