Status SuperFRS Subproject Target Area Helmut Weick 5
Status Super-FRS Subproject Target Area Helmut Weick 5 th MAC meeting GSI Darmstadt, 9 th May 2011 v v v Overview Target Beam Catcher Shielding Handling, Hot cell
Subproject: Target Area • Target • Beam Catchers • Iron Shielding + Transport Container • Hot Cell • Degraders Iron Beam Catchers iron shielding Target m fro S SI Hot cell Degrader
Graphite Wheel Target for Super-FRS Material: Temperature • 238 U Wheel: SGL Carbon R 6400 P distribution • N = 1012 ions/s Spokes: INCONEL 600 Bearing: Si 3 N 4 (Ag-coated cages), • σx = 1 mm Thickness: • σy = 2 mm 2 5 steps, 1 – 8 g/cm , 16 mm wide • w = 1 Hz Size: r = 22. 5 cm • d = 4 g/cm 2 Speed: w = 1 Hz • P = 12 k. W 750 ºC Hub: TMax = 35 ºC Tlimit: = 150 ºC • cooling only by radiation
C. Karagiannis et al. Prototype Target Development (Graphite Wheel Target) New design: Adoped for remote handling purpose Dummy shielding • Prototype target developed • Extended off-line tests performed (e. g. inductive heating) • Commissioning planned at FRS
Target chamber motor connections (hands on) vacuum seals target plug devices in beam
Beam Catchers Trajectories of primary beams for different Br settings. Dump the beam only on dedicated beam catchers (BC)! linear drive § Front part: graphite (20 cm+) copper ite graph 4 m 60 m to absorb strong pressure waves, copper heat sink brazed to graphite, P_max. = 23 k. W ANSYS simulation shows water cooling works well. Designed for remote handling in hot cell. last catchers (BC 3) movable like slit. § Back part: iron (60 cm) to absorb protons and neutrons.
Vacuum Chamber (BC-2) vacuum pump Cut at beam level 2500 set fragment primary beam graphite iron 1410
Power Distribution in Beam Catcher 6 x 1011 238 U starting at 740 Me. V/u for the primary beam after target. at 740 Me. V/u 1500 Me. V/u almost no peak anymore ! carbon r = 1. 84 g/cm 3
Pressure Waves Slow extraction is easy, but fast extraction causes instantaneous temperature rise (100 ns), followed by pressure wave. Limits given by yield strength (plastic deformations) and spall strength (rupture) after deflection of wave. Graphite or carbon-carbon composites are best materials for low stress. Pulse 2486 in exp. S 334 at GSI: - Intensity: 2. 5 e+9 238 U part/spill - Beam-spot size: s = 0. 365 mm - Graphite sample R=5 mm, L = 10 mm - DE/Dm ~ 1. 5 k. J/g in max. of peak - DT (from deposited energy) = 650 K - calc. pressure +42. . -25 MPa Tested so far only with few pulses, and simple geometry. Larger beam spot required on target: 1 x 2 -> 4 x 6 mm 2 Laser. Doppler Vibrometer
Radiaton Damage Graphite swelling after irradiation at UNILAC with 1013 238 U ions/cm 2. mask Target Wheel Lifetime ? • Increased area over wheel. 100 days full intensity on same step => 5 x 1016 ions/cm 2. Track yield is highly reduced at high ion velocity and target temperature Liu et al, PRB 64 (2001) 184115. Dz/z = 1 % Heavy ions cause tracks, at >1013/cm 2 tracks start to overlap, binding structure changes, confirmed by crystallographic methods (Raman spectr. , positron annihilation), No graphitic carbon but glass structure. Increased Young’s modulus, lower thermal conductivity. M. Tomut • 10 -3 efficiency of track formation at Super-FRS beam velocities. • 10 -3 efficiency of track formation at temperatures above 800 K J. Liu et al. / NIM B 245 (2006) 126. Estimation of the track density/ year in the Super-FRS target: 5 x 1010 tracks/cm 2 But worse by factor 1000 in beam catcher!
K. Kozlova Shielding of the Target Area Prompt dose rate for 1. 5 Ge. V/u 238 U 1012/s , through C-target on beam catcher concrete iron design goal M. Winkler, FAIR-India Meeting, January 11 -15, 2010, VECC Calcutta, India
Iron Shielding in Target Area Variant 1: Rounded shapes to follow bend Use activated iron from dismantled reactors, up to 10 Bq/g (mainly 60 Co) ~13 –> ~8 M€ with 70% recycled material Stone (long) – 120 St. mass: 20. 7 t Stone (short) – 80 St. mass: 15. 9 t Base plate mass: 1918 t volume: 273 m 3 plates from KIT (3800 t) ? Core mass: 500 t volume: 71 m 3 Total mass: ~8000 t A. Kratz, Chr. Schlöhr
K. -H. Behr, P. Neufingerl, C. Schlör, et al. Iron Shielding in the Target Area Variant 2: ‘Simple Iron Blocks’ Energy Solutions S 2 standard ingot: 133 x 67 cm 3 • $1 per piece + shipping (~10 M$), • more gaps in shielding
E. Kozlova Activation Nuclide inventory for most parts after pessimistic scenario • Overall air, cooling water, He activation. • Calculations for release rates by diffusion and machining in hot cell Inventory after cycle + 3 days cooling graphite BC iron BC limit … transport bottle design Hot cell layout for low amount of contamination so called beta cell, not alpha cell
Shielding Flask Concept like at PSI but for lower dose rates < 0. 5 m. Sv/h with closed flask, wall thickness bottom 40 cm total weight ~ 60 t. 5. 35 m 4. 7 m 0. 1 m 0. 4 2. 2 m
Hot Cell and Storage Cell Study together with Siempelkamp Nuclear Technology ¯ Phase 1 ‘Feasibility Study', (finished 13. 11. 09) ¯ Phase 2 ‘First Layout' (finished 08. 07. 10) → detailed cost accounting (5. 800 k€) ¯ Phase 3 ‘Approval for Radiation Safety Authorities’ (25. 11. 2010) → application to get radiation protection construction permission ¯ Phase 4 ‘Call for tender‘ option, not approved for 2011 Design study on definition of: • Hot cell design • Radiological and legal aspects • Material flow and handling concept • Interfaces to neighbouring installations • Hot cell components like: - radiation safety window - Sleuces (ceiling and wall): - radiation safety doors - cranes and manipulators
Summary • Slow extraction no problem (P < 23 k. W). Wheel prototype is available, beam catcher only simulation. Graphite design is more risky due to fast extraction demands. • Radiation damage in graphite target wheel looks ok, for beam catcher it is uncertain (Be alternative ? ). • More effort for pressure wave testing needed. Eo. I partner will not do this R&D part. • Shielding needs long term planning to acquire reactor material. • Activation calculated and not dramatic compared to other facilities. • Shielding flask and hot cell follow approved concepts.
- Slides: 17