Development of High Heat Flux Components in JAERI

Transcription

1 US-Japan Workshop on Fusion High Power Density Device and Design, UCLA, February, 16-19, 1999 Development of High Heat Flux Components in JAERI K. Ezato, NBI Heating Lab., Dept. Of Fusion Engineering, JAERI

2 High Heat Flux Components of ITER Divertor 2m Vertical Target Dome Liner 5m 1m ITER Divertor Cassette Major design parameters Normal operation Steady-State Heat Load : 5 MW/m 2 Transient Heat Load : 20 MW/m 2, 10s Incident Ion Flux : < ions/m 2 /sec Neutron Load : MW/m 2 Plasma Disruption Disruption Heat Load : 100 MJ/m 2 Duration : ms Cooling condition Coolant : Water Inlet Pressure : 4 MPa Inlet Temperature : 140 o C Materials Plasma Facing Material : CFC, W Structural Material : Cu alloy, SS

3 Vertical Target Heat sink (Cu or Cu-alloy) High Ion Flux Region(W) CFC or W Swirl Tube Stainless steel Support structure High Heat Load Region (CFC) Divertor Vertical Target To deal with the high heat flux; Refractory material. Metallurgical joining between W/Cu and CFC/Cu. High performance cooling.

4 Recent Progress of Development on ITER Divertor High Heat Flux Components Particle beam engineering facility (PBEF) was upgraded for heating test on large components using a large ion source. Lower vertical target mock-up with full scale length was fabricated, and thermal cycle tests were carried out. It is confirmed for the mock-up to satisfy the ITER heat load conditions; 5 MW/m 2, 30 sec for 3,000 cycles, and 20 MW/m 2, 10 sec for 1,000 cycles.

5 Lower Vertical Target Mock-up With Full-scale Length Was Fabricated. Vertical Target with monoblock CFC CFC ~0.9 m The mock-up was fabricated and tested to verify: productivity, and durability in HHF condition.

6 Descriptions of Lower Vertical Target Mock-up Cooling tube 425mm 900mm D-CFC monoblock (30 blocks) Unit:mm Thermocouples (11 flow paths) Braze Armor Tiles : 2D-CFC (30mm l x 33mm w x 60mm t ) (To reduce thermal stress) Brazing : Silver-Free braze (Cu-Ti) (To decrease the induced radioactivity) Cooling tube : DSCu swirl tube (To obtain strength in high temperature)

7 Particle Beam Engineering Facility (PBEF) Was Upgraded to Heat Large Components. PBEF Power supply 4m 7m Large Ion Source Hydrogen Ion Beam 90cm 3.5m Mock-up and Beam Dump 5 MWm 2, 30 sec Heating source : Hydrogen ion beam from a new large ion source. Heating conditions; (1) 5 MW/m 2, 30 sec ITER steady-state heat load condition, and (2) 20 MW/m 2, 10 sec ITER transient heat load condition.

8 The Mock-up Withstood the ITER Steady-state Heat Load Condition of 5 MW/m 2, 30 Sec for 3000 Cycles. Heat load : 5MW/m 2, 30sec SP2 Hot Spot tile SP1 At 3000th cycle IR Image of surface temperature at 3000th cycle. Temperature [oc] SP2 Steady-state surface temp. obtained by FEM analysis 800 SP Heating cycle number Temperature evolutions of surface through 3000 thermal cycles. Surface temperatures of hot spots did not change through the heating test. These hot spots were due to initial failure of joining.

9 Ultrasonic NDT Is the Effective Method for an Inspection of Joining Between the Cooling Tube and the Armor Tile. 70 o (13mm) X=0 Ultrasonic Probe (20MHz) X θ θ Schematics of ultrasonic NDT Scanning direction X[mm] Cross-sectional view of the hot spot tile after 3000 cycles Joining flaw or crack Traces of swirl tape o 70 o Angle,θ [deg] Intensity of reflected wave [db] 10 deg = 1.8 mm (at OD of cooling tube) Ultrasonic NDT was carried out in collaboration with Austria Research Center.

10 The Mock-up Withstood the ITER Transient Heat Load Conditions of 20 MW/m 2, 10 Sec, and 1000 Cycles. Heat load : 20 MW/m 2, 10 sec SP2 SP1 Initial surface Erosion Enlargement At 1000th cycle IR Image of surface temperature at 1000th cycle. T surf is more than 2800 o C. Cooling tube Cross-sectional view of mock-up after 1000 cycles The armor tiles suffered the erosion of 1cm depth through the heat load of 20 MW/m 2, 10 sec for 1000 cycles. There was no detachment of tiles.

11 Temperature [oc] Surface Erosion Caused Variation of Temperatures at Surface and Joint Interface During Heating Cycle mm Surface temperature (depth of erosion) 8mm (measured value) SP1 SP2 FEM Analysis 10mm Heating cycle number Temperature of joint interface of cooling tube and CFC armor (measured value) mm 8mm 400 0mm 350 TC1 300 TC2 FEM Analysis Heating cycle number Surface Temp. decreases because a distance from the surface to the cooling tube becomes short. Temp. of the joint interface increases because decreasing of re-radiation at the surface leads an effective heat flux at the interface to become 1.25 times as large as the initial value. 500

12 Summary Vertical target mock-up with full-scale length was fabricated; Armor tile : 2D-CFC monoblock, Cooling tube : DSCu swirl tube, Braze : Silver-free filler (Cu-Ti). Heating tests were performed in the PBEF facility. The mock-up satisfied the ITER divertor heat load conditions; 5 MW/m 2, 30 sec for 3000 cycles, and 20 MW/m 2, 10 sec for 1000 cycles. (In this case,erosion of the armor is about 1 cm.)

13 Summary (continued) Ultrasonic NDT with 20MHz is the effective method for an inspection of joining between the cooling tube and the armor tile. Detection limit is about 2 mm of the joint flaw. Effective heat flux to the joint interface between the armor and the cooling tube is increased due to the coupled effect of the erosion and variation of the surface temperature. Results of FEM analysis considering re-radiation at the surface are good agreement with the experimental results.

14 Thermal Response of Surface Temperature and Thermocouple at Top of Cooling Tube Heat Load : 20MW/m 2, 10sec Cooling conditions: 10 m/sec, 2MPa, RT Temperature [oc] Surface temperature 1st 100th 500th 1000th Time [sec] Temperature [oc] Temperature of joint interface of cooling tube and CFC armor st 100th 500th 1000th Time [sec]

15 Comparison of Surface Temperature Predicted Supposing Distribution of Joint Flaw With the Experimental Results Numerical prediction of surface temperature supposing distribution of joint flaw Surface Temp. Rise,DT, [oc] 1200 DT: oc Prediction DT:240 oc Distribution of joint flaw [deg] It is necessary to develop a method to estimate distribution the joint flow from variation of surface temperature in the heating test.

16 Relation among Erosion Depth, Surface Temp. and Heat flux at Surface and Cooling Tube Temperature [oc] Radiation HF from surface (Emiss=0.9) Surface Temperature Erosion Depth [mm] Heat flux [MW/m2] Temperature [oc] HF at interface Tmp. at Interface Erosion Depth [mm] Heat flux [MW/m2] Surface temp. and Radiation HF VS Erosion Depth Temp. and HF at joint interface VS Erosion Depth