Some naïf ideas on cryostats , BNL-LBNF meeting D.Mladenov, M.Nessi

concrete floor cavern warm cryostat cryogenics + services 2 Cavern cross-section

LAr SS GTT membrane GTT isolation SS skin 6-10 mm Carbon steel structure ~300 mm Carbon steel belt ~ mm 3

Inner dimension (liquid): L = m W = m H = m outer warm structure SS skin possible supports to the cavern wall LAr = 9’915 tons belts 4 Warm Cryostat Top cap & Detector supports

Grid: 0.8m x 0.8m m m support to the floor: h=0.3 m Length 36.5 m 5 Outer structure : configuration

Materials used (warm vessel): Carbon steel :S355J2 Quantity : ~450 tons (to be optimised) SS plates : 304L Quantity: ~150 tons Mechanical properties : Yield strength:355MPa Tensile strength:500MPa With good low-temperature structural performance 6

7 The outer structure The stainless steel plates (form inside)

8 2 x 4’500 tons 2 x 2’000 tons On the long walls On the short wallsLoading 1. Hydrostatic pressure on the walls 2. Overpressure (100mBars) 2 x 470 tons 2 x 210 tons tons On the cap

9 Results 1. Deformations [mm]

10 Results 1. Stresses [MPa]

Remarks : From the mechanical point of view it looks feasible Supports towards the cavern to increase safety factors To go further it would need a real engineering study and a optimization of all parameters Cost ? ~ 12.3 M -membrane + isolation material + engineering:~ 2.5 M -membrane installation: ~ 4.0 M (20 FTE for 1 year) -stainless steel skin:~ 1.5 M -warm structure:~ 1.8 M -warm structure assembly and welding: ~ 0.9 M (10 FTE for 4 months) -transport:~ 0.6 M -various:~ 1.0 M 11

concrete floor cavern warm cryostat It might be simpler if the aspect ratio changes: For example H: ~10m W: ~21m 12 cryogenics + services