Material alternatives to limit activation of ZS J. Borburgh With valuable input from: C. Theis, H. Vincke, W. Weterings 9/28/2016 SLAWG #7

Actual ZS Tank: 3.2m x Ø0.6m tank made of stainless steel 304L, 6 mm thick sheet. Anode support: 3.1m x 200 x 94 mm C-shaped support made of Invar or stainless steel. Accessories and supports neglected for the time being. 9/28/2016 SLAWG #7

Alternative materials mechanical components Low-Z materials could be selected for the vacuum vessel, or even anode support. J-Parc built a Ti vacuum vessel, anode support and endplates to reduce residual radioactivity [11] LEP used Al vacuum chambers PS SEH uses Al anode supports 9/28/2016 SLAWG #7

Alternatives considered Tank Stainless steel: dimensions as present Aluminium: 67% thicker material (10 mm tank body, 50 mm covers) Titanium: 33% thinner material (4 mm tank body, 25 mm covers) Anode (dimensions identical for all cases) Stainless steel Invar Titanium 9/28/2016 SLAWG #7

Material properties used Inox 304 Al (6061) Ti-A6-V Invar Young’s modulus [GPa] 200 69 120 148 Yield strength [MPa] 760 483 Density [Mg/m3] 7.85 2.7 4.43 8.05 Thermal expansion [1e-6/K] 17 23 9 1.5 Global Radiation risk at 400 GeV/c (operation)* 1.6 0.27 0.94 2.13 Global Radiation risk at 400 GeV/c (waste)* 0.83 0.35 1.16 0.81 *Activation occurring at 10 cm lateral distance to the target. Source: Actiwiz web catalogue 9/28/2016 SLAWG #7

Modelling Tank Anode Weight [kg] Volume [dm3] Stainless steel 367 47 239 30 Aluminium 211 78 n.c. n.c Titanium 146 33 135 Invar 245 ZS tank anode Case 1: Activation occurring at the beam impact area Case 2: Activation occurring at 10 cm lateral distance to the target 9/28/2016 SLAWG #7

Radiation hazard results Influence of the irradiation case on the results Global hazard results vs. 1 and 20 yrs operation results Optimal material choice 9/28/2016 SLAWG #7

Radiological hazard factors To establish the radiological hazard factors the following approach was used: Operational hazard factor: the volume of each topology (tank volume) is multiplied by the compound risk factor. Waste hazard calculation: a normalised hazard factor is calculated based on the weight of the anode and the tank ratio. 9/28/2016 SLAWG #7

Influence of the irradiation case on the results Although absolute values differ between the 2 cases, comparison of topologies within each case provide coherent indications of activation. 9/28/2016 SLAWG #7

Global hazard factor vs. 1 year and 20 yrs of operation Global hazard factor correlates well with cases of 20 yrs of operation. For 1 yr operation and in particular for titanium some small differences are visible. 9/28/2016 SLAWG #7

Activation in operation 9/28/2016 SLAWG #7

Global radiation hazard 9/28/2016 SLAWG #7

Aluminium alloys for tank easy to machine, easily weldable, most commonly used general-purpose alloy, compatible with vacuum applications, Al 6000 series looses strength when heated up: not recommended for bake-able tank. Al 2219 Strong, alloyed with copper, More difficult to weld than other Al alloys, Susceptible to stress corrosion cracking, increasingly replaced by 7000 series (alloyed with zinc), Can be used for bake-able application. Al 5083 Strong, alloyed with magnesium, More difficult to weld than Al 6061, 5083 retains strength after welding. It has the highest strength of the non-heat treatable alloys, but is not recommended for use in temperatures in excess of 65°C. 9/28/2016 SLAWG #7

Conclusions (1/2) The 2 different load cases in Actiwiz provide coherent results. The results after 1 yr and 20 yrs of operation are coherent with the global hazard assumptions in general. Changing the anode to Titanium is favourable, but: it is still unclear if the (thermal) stability is sufficient for using it for positions ZS1, 2 and 3 instead of Invar. Ti appears a valid candidate for ZS4 and 5 anodes. For the tank material, aluminium appears preferable over titanium, but: Bi-metal CF flanges (stainless steel/ aluminium) are commercially available, Conflat (CF) flanges made of Aluminium are being developed by TE/VSC, Larger flange diameters or aluminium flanges to replace ‘Suchet’ or ‘Wheeler’ flanges will have to be developed. Titanium tank dimensions are based on stress levels, but buckling is not yet considered; this may necessitate a thicker tank, or more reinforcements, leading to less favourable hazard factors. Impact of smaller components is neglected in the evaluation for the time being. 9/28/2016 SLAWG #7

Conclusions (2/2) Anode Titanium anode is readily feasible. Its cost limited to manufacturing and assembly. Can be considered for ZS3 and ZS5, possibly ZS2. Tank R&D is needed for an aluminium vacuum tank flanges. This will require a new tank design, as well as manufacturing and thorough testing. Not certain if the vacuum vessel can be made bake-able. 9/28/2016 SLAWG #7

Back up slides 9/28/2016 SLAWG #7

Tank body (SPS_8032050500) 9/28/2016 SLAWG #7

Anode support (SPS_8032050107) 9/28/2016 SLAWG #7

Wire tensioning spring (SPS_8032050579) Influence of springs not taken into account yet. 3000 springs per tank, 128 mm long, Ø1 mm, 9/28/2016 SLAWG #7

Vacuum flanges for Al alloy vacuum chambers TE/VSC have tested successfully CF flanges (up to CF100) made of Al-Li alloy. They use aluminium CF-type seals and proved to be bake-able (repeatedly) to 230⁰C. These Al-Li CF flanges are stir welded (by Sominex) to 5083 Al alloy tubes, which are butt welded to vacuum chambers of the same material. Bi-metal flanges proved prone to leaking, in particular when they have to be baked. Bimetal flanges (Al or Ti + Stainless steel) are commercially available from Atlas. 9/28/2016 SLAWG #7