ifmif lithium target d. bernardi, p. agostini, g. miccichè, f.s. nitti, a. tincani, m. frisoni enea...
TRANSCRIPT
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 28th 2011
Outline
Main aspects of TA engineering design:
TA mechanical design Thermohydraulics Neutronics Thermomechanics Lifetime assessment
• Average heat flux 1 GW/m2
• Footprint area 100 cm2 (20 x 5 cm)• Jet width/thickness 260 / 25 mm• Li velocity 10-20 m/s• Damage rate on the BP 50-60 dpa/y• Erosion/corrosion rate 1 μm/y (nozzle and BP)• BP replacement frequency 11 months
IFMIF Target Assembly (TA) requirements:
TA mechanical design
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
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
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
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
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
02
2322
g
vxD
x
yCarctg
x
yBarctg
x
yAarctgyx
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
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]
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 + 6,7Li) 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
HFTMLithium jet
Neutronics
Mapping on BP via “superimposed mesh tally”feature of MCNP5 code
zzz zz
y
Atom Displacement, dpa/fpy 4.7×10-1
He production, appm/fpy 2H production , appm/fpy 9
Total heating W/cm3 3.8×10-1
Atom Displacement, dpa/fpy 54He production, appm/fpy 598H production , appm/fpy 2742
Total heating W/cm3 23.8
x = 0 (axis of symmetry)
Neutronics
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/cm3
161 kW/cm3
Power deposition profile in the Lithium
Neutronics
Effect of beam gaussian energy dispersion
(FWHM=1.177)
The energy dispersion slightly increases the beam penetration range in the target
Neutronics
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 ~ 1.2x106 tetrahedral elements
EVEDA Target Assembly
Materials• EUROFER : back-plate• INCONEL X-750 : gasket• F82H: remaining TA components
Thermomechanics
Back plate
T field
Nominal scenario
Thermomechanics
Li Temp. = 275°C Internal pressure = 0.18 MPa
Von Mises stress
NO Yielding !
Thermomechanics
Li Temp = 275°C Internal pressure = 0.18 MPa
Nominal scenario
Displacements
Thermomechanics
Nominal scenario
Li Temp = 275°C Internal pressure = 0.18 MPa
Thermomechanical calculations for IFMIF TA are underway
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
Tirr = 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 assessmentSwelling/creep effect
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 assessmentSwelling/creep effect
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 assessmentNeutron-induced embrittlement effect
T = 300-350 °C
SDC-IC rule IC-3214.1
a = max (4au, t/4) ; au largest undetectable crack by applied NDE technique
Very few data for KC !!KC min ~ 30-40 Mpa√m
Lifetime assessmentNeutron-induced embrittlement effect
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
Thank you !Thank you !