1. Thermal-hydraulic analysis of unit cell for solid breeder TBM
Presented by
P. Calderoni
ITER-TBM meeting
March 3, 2004
UCLA

2. ¼ port sub-module analysis already presented
1 of 10 alternative cooling flow paths
First wall inlet manifold
(Tin= 300oC)
First wall outlet manifold (also layer breeding units inlet manifold)
(T= 353oC)
Layer breeding units outlet manifold (T=500oC)
Edge-on breeding units inlet manifold (1 of 2 alternative paths) T=353oC
Edge-on breeding units outlet manifold (1/2) T=500oC
Mass flow rate
In: 0.9 kg/s
Out: 0.82 kg/s
By-pass: 0.08 kg/s

3. Thermo-mechanics tests unit cell
Volumetric heat is generated in the unit cell by neutron capture in the breeder, multiplier and structural materials
Tmax < 850C
to ensure pebble bed integrity
Average nuclear heating rates from 2-D calculations by Youssef, Sawan, Ying:
Structure (55% F82H) = 1.24 W/cm3
Breeder (Li4SiO4, 75% Li6, single size, 60% packing fraction) = 3.24 W/cm3
Beryllium (single size, 60% packing fraction) = 1.24 W/cm3
FEM thermal analysis
Inlet 300 C
Volumetric ratio for TM units:
Structure = 20%
Breeder = 35%
Beryllium = 45%
Outlet 500 C

4. Thermo-mechanics tests unit cell
Independent mass flow control and manifold design allow to choose optimal temperature distribution.
Breeder bed front toroidal dimension: 18 mm
Back to front ratio = 1.7
Operational windows of different ceramic breeders will be tested. Variable temperature distribution in each unit cell is desirable
Single pass configuration, parallel flow:
32 channels
6.5 mm pitch
channel length = 2.5 m
5 mm
Unit cell mass flow = 31.8 g/s
He flow velocity = 10 m/s
h = 1400 W/m2 K
Channel Dp = 6000 Pa
3.5 mm
6.5 mm

5. Thermo-mechanics tests unit cell
Double pass configuration, upper half and lower half counter flow:
16 channels
6.5 mm pitch
channel length = 5 m
Unit cell mass flow = 31.8 g/s
He flow velocity = 20 m/s
h = 2400 W/m2 K
Channel Dp = Pa
Single pass configuration, counter flow:
32 channels
6.5 mm pitch
channel length = 2.5 m
Unit cell mass flow = 31.8 g/s
He flow velocity = 10 m/s
h = 1400 W/m2 K
Channel Dp = 6000 Pa

6. Neutronics and tritium production tests unit cell
Simplest, low cost design is considered for NT unit cells. Temperature limit is ensured by overestimating mass flux. Temperature gradient within the 4 sections is not an issue.
Tmax < 350C
to inhibit T release
Unit cells are exposed only to a few irradiation pulses during D-D and early D-T phases
Inlet 100 C
Volumetric ratio for NT units:
Structure = 26%
Breeder = 26%
Beryllium = 48%
Outlet 250 C

7. Summary Thermal-hydraulic analysis of unit cells has been performed
Independent He cooling circuit allows wide operational window
For neutronic tests unit cells the simplest configuration is chosen, and the outlet He temperature limited to 250 C to ensure T trapping inside breeder material at all locations
For thermo-mechanics tests unit cells a combination of flow rate and manifold design optimization will allow to test operational windows of different ceramic breeder materials
Flow parameter optimization will be finalize with 3-D thermal analysis