1. IFMIF Lithium Target D. Bernardi, P. Agostini, G. Miccichè, F.S. Nitti, A. Tincani, M. Frisoni ENEA with the contribution of Prof. A. Di Maio and the staff of DIN Department (University of Palermo) ISLA 2011 - Princeton April 28 th 2011

2. Outline Main aspects of TA engineering design:  TA mechanical design  Thermohydraulics  Neutronics  Thermomechanics  Lifetime assessment

3. Average heat flux 1 GW/m 2 Footprint area100 cm 2 (20 x 5 cm) Jet width/thickness260 / 25 mm Li velocity 10-20 m/s Damage rate on the BP 50-60 dpa/y Erosion/corrosion rate1 μm/y (nozzle and BP) BP replacement frequency 11 months IFMIF Target Assembly (TA) requirements: TA mechanical design

4. INTEGRAL Target - SS (JAEA) TA with BAYONET Back-Plate – RAFM steel (ENEA) Lower activated waste Easier replacement operations More complex than integral concept EVEDA Loop prototype (already installed in the loop) TA mechanical design

5. Each skate consists of a chassis in which triple bearings are mounted on six parallel axes. Each bearing axis comprises three wheels: the two outside wheels push on the fixed frame while the central wheel runs on the inclined plane and transmits the pushing force to the back-plate The skate tightening concept has been successfully tested and qualified on experimental mock-ups realized at ENEA Brasimone for a previous BP design. However, qualification for the new IFMIF design will be performed in the future One driving screw for each skate Tightening bolts Skate Gasket groove TA mechanical design

6. Qualification of the sealing gasket HELICOFLEX ® HNV200 Gasket  Static Li  Ti getter @ 550 °C  Li Temp = 350 °C  Exp. time = 1800 h SS316 home-made test rigs (soft iron) (SS304) (Nimonic) TA mechanical design

7. Thermohydraulics The back-plate geometry reported in the CDR is made by a straight wall of 90 mm at nozzle exit + curved wall of 250 mm radius up to the beam axis Pressure increase Curved wall creates centrifugal force producing a pressure increase in the Li that avoids boiling Onset of centrifugal force

8. Experiments and numerical simulations of the behaviour and stability of the IFMIF-like lithium jet flowing on a straight + curved wall were made by IPPE. Two main issues were observed at the straight-curve transition: 1)Detachment of the jet from the straight wall 2) Instability of the jet due to sudden appearance of centrifugal force when it moves from straight to curved wall Experiments confirmed the numerical results Thermohydraulics

9. In order to have a gradual pressure increase, ENEA designed a new profile by imposing: Using simplified Navier-Stokes equations: A, B, C, D are determined from geometrical constraints Thermohydraulics Pressure increase

10. Preliminary assessment done with REGEL code (ENEA) Updated detailed calculations are being carried out by ULB (Belgium) within ED03-EU PA in coordination with ENEA Li Temperature and saturation point Boiling margin Thermohydraulics Li depth [mm] Li velocity [m/s]

11. Preliminary neutron/gamma transport calculations have been performed at ENEA for the BP via Monte Carlo MCNP5 code The McDeLicious-05 neutron source code provided by KIT was used This code uses the newly evaluated (d + 6,7 Li) cross section data files, produced under a collaboration of IPPE (Obninsk) and KIT (Karlsruhe), containing the cross sections and the energy-angle distributions of the reaction products for deuteron energies up to 50 MeV. The neutron-induced cross section data files used in the calculations are mainly from IPPE-50 library, developed at IPPE-KIT, for neutron energies up to 50 MeV,)and LANL-150N, developed at Los Alamos National Laboratory, for neutron energies up to 150 MeV. Back Plate HFTM Lithium jet Neutronics

12. Mapping on BP via “superimposed mesh tally” feature of MCNP5 code z z z z z y x = 0 (axis of symmetry) Neutronics

13. The calculations of deuteron energy deposition in lithium were firstly performed with the “standard” MCNPX 2.7d code. New calculations were performed with the MCUNED code that allows to describe better the deuteron nuclear interactions with matter. 209 KW/cm 3 161 kW/cm 3 Power deposition profile in the Lithium Neutronics

14. Effect of beam gaussian energy dispersion (FWHM=1.177) The energy dispersion slightly increases the beam penetration range in the target Neutronics

15. Thermal loads and boundary conditions Forced convection with Lithium Internal irradiation External irradiation Mechanical loads and boundary conditions Thermal deformations Internal and external pressures Tightening screws loads Skate-based clamping system loads Target Assembly system constraints ABAQUS code ~ 280 000 nodes ~ 1.2x10 6 tetrahedral elements EVEDA Target Assembly Materials EUROFER : back-plate INCONEL X-750 : gasket F82H: remaining TA components Thermomechanics Back plate

16. T field Nominal scenario Thermomechanics Li Temp. = 275°C Internal pressure = 0.18 MPa

17. Von Mises stress NO Yielding ! Thermomechanics Li Temp = 275°C Internal pressure = 0.18 MPa Nominal scenario

18. Displacements Thermomechanics Nominal scenario Li Temp = 275°C Internal pressure = 0.18 MPa Thermomechanical calculations for IFMIF TA are underway

19. Miwa Y. et al., J. Nucl. Mater., 283 (2000) 13 He appm/dpa SS 316 RAFM steel RAFM steel is considered as reference material due to its lower activation, better swelling resistance and higher mechanical properties compared to SS In the BP footprint region : ~ 11 He appm/dpa (similar to F82H-3) → ~ 0.015 x 60 dpa = 0.9 % ΔV/V max. = 0.3 % Δl/l max. @ 400 °C T irr = 400°C 0.015 % / dpa SDC-IC ITER code Linear swelling ~ 0.3 % > 0.017 % (negligible swelling test from B 3022 SDC-IC rule) swelling analysis is requested considering also the mitigating effect of irradiation- creep stress relaxation Lifetime assessment Swelling/creep effect

20. A more detailed analysis is needed to assess the stresses due to constrained swelling caused by irradiation and temperature gradients at the footprint A numerical assessment considering the competitive effects of irradiation swelling and creep can be performed using the approach of ITER SDC-IC code (rule B3024.1.1.1) Visco-elastic analysis Numerical calculations with evaluated dpa and T maps are ongoing at ENEA Simplified elastic analysis Lifetime assessment Swelling/creep effect

21. Gaganidze, et al., J. Nucl. Mater., 355 (2006)Schaaf B. et al., J. Nucl. Mater., 386 (2009) ΔDBTT up to 240 °C ( corresponding to DBTT max  150 °C @ 60 dpa) Apparent “saturation” might be due to T sensitivity High T sensitivity in [300 – 350 °C] range 16 dpa (4 month) “Optimistic” approach: BP Temp. > DBTT max ( 150 °C) always → > 1 year Very conservative approach: ~20 ΔDBTT /dpa → ~16 dpa to reach -80 °C → 250 °C → ~ 4 months T unirr. = -80 °C Lifetime assessment Neutron-induced embrittlement effect T = 300-350 °C

22. SDC-IC rule IC-3214.1 a = max (4a u, t/4) ; a u largest undetectable crack by applied NDE technique Very few data for K C !! K C min ~ 30-40 Mpa√m Lifetime assessment Neutron-induced embrittlement effect

23. Other important factors can limit the lifetime of the BP:  Erosion/corrosion of the channel and the nozzle  Thermal fatigue due to Li surface oscillations More detailed assessment of these effects will be possible once that experimental results will be available from LIFUS 3 facility at ENEA Brasimone and EVEDA Li Loop at Oarai (Japan) Lifetime assessment

24. Thank you !