Fusion Neutronics Activity at JAERI from October 2000 to September 2001

1. Fusion Neutronics Activity at JAERI from October 2000 to September 2001 Peseted by Takeo NISHTANI IEA International Work Shop on Fusion Neutronics The Kongreshous Baden-Baden, Germany 18th October, 2001 (During 10th ICFRM Conference)

2. Fusion Neutronic Activity Items at FNS/JAERI • Breeding Blanket Experiments • Shielding benchmark experiments • Shutdown dose measurements • Double bent duct streaming experiment • Decay heat measurements • Activation Experiments for Sequential Charged Particle Reactions • Development of Neutron Measurement Technique • Development of Artificial Diamond Detector • Development of Micro Fission Chamber for ITER

3. Breeding Blanket Experiments OBJECTIVES One of our aim is to verify the nuclear performances of resent designed thermal blankets. IN THE PRESENT 2-dim F82H/6Li-enriched Li2TiO3/Beryllium mock-up - Tritium production performance for 6Li-enriched (40~95%) breeder - Verification of activation of a ferric steel (F82H) for fusion neutron fields FUTURE WORKS 3-dim F82H/Water/Breeder/Beryllium mock-up Pebbly mock-up

4. Present Blanket Assembly Detectors (NE213) FNS 80deg. D-T target A blanket assembly Shielding (Li2CO3) A schematic view of FNS blanket experiments

5. Measurement and Analysis Methods • Measurements • MeV-neutron f14-mm NE213 • Reaction rates Fission Chamber(U-235 and U-238) • HPGe (Nb, Al, In, Au and F82H sheet) • Liquid Scintillation Counter (Aloka-5500) Calculation Code MCNP-4B Nuclear data JENDLE-3.3 and JENDLE-FF

6. Results of Measurements Above spectra show the g-ray spectrum emitted from the irradiated F82H(Fe: balance, Cr: 8% and W: 2%) and b-ray spectrum emitted from the irradiated Li2TiO3 pellet. the reaction rates of the activities and tritium production can be obtained by the spectra. The g-ray spectrum emitted from the F82H The b--ray spectrum emitted from the Li2TiO3

7. Preliminary Result We have obtained the profile of reaction rates of the iron, chromium and tungsten in F82H and tritium production in 95-% Li2TiO3. C/E of the 95-% Li2TiO3 tritium production is closed to 1 with the error of plus and minas 10%. However, since experimental result of activities of Au foil in Be is significantly underestimated, The investigation of the cause is in progress. The profiles of reaction rates at the assembly

8. Shielding benchmark experiments for ITER (R&D Task T-426) • Shutdown dose measurements to evaluate accuracy of the new one step method • Double bent duct streaming experiment • Decay heat measurements for copper and type 316 stainless steel(presented at ICFRM-10)

9. 9.0 3.5 Reflector (SS316) Source Reflector (SS316) Shield (SS316/H20) 8.0 3.0 7.0 6.0 2.5 5.0 Shutdown dose rate（mSv/hr） 2.0 300 #a #b #c 800φ 4.0 1200φ 200 3.0 1.5 #A #B #C 356 2.0 1.0 1.0 0.0 0.5 1.0 3.0 5.0 7.0 9.0 11.0 13.0 15.0 D-T source Test region Cooling time (x 105sec) Shutdown dose measurements • Shutdown dose rates can be evaluated by the new one step method within experimental error (~10%) FENDL/2A FENDL/2 #A #a Cross sectional view of the assembly Comparison of shutdown dose rates

10. Auxiliary Shield 550 750 1200 Streaming Assembly #6 DT Source #1 #2 #3 Duct Opening (300 x 300) 1700 900 1000 #4 #5 800 150 565 765 Auxiliary Shield Iron Rack 335 1800 200 Double bent duct streaming experiment • Typical streaming effects can be reproduced by MCNP & FENDL/2 (~30%) Calculation #3 Experiment #4 #6 Neutron flux (n/cm2/source/lethargy) #5 Energy (MeV) Cross sectional view of the assembly Comparison of neutron spectrum

11. Activation Experiments for Sequential Charged Particle Reactions (SCPR) • For the safety design of future D-T reactors it becomes important to consider activations via SCPR. • Many protons are generated in coolant water, so sequential reactions will be enhanced around the surface of coolant pipes. → Fusion material foils (Cu, V, Ti, Fe, W, Pb) attached on a polyethylene board were irradiated by 14-MeV neutrons at FNS/JAERIand the sequential reaction rates were obtained for 5 positions.

12. Preliminary Results • The sequential reaction rate of 51V(p,n)51Cr for the foil-1 close to a polyethylene board is about 20 times larger than that for the foil-5 far from foil-1. Measured gamma-ray spectrum from V sample Reaction-rate distribution of 51V(p,n)51Cr

13. Development of Artificial Diamond Detector • Recently, we tried to use a chemical vapor deposition (CVD) diamond with single crystal. • The detector has an energy resolution of 0.4 % for 5.486 MeV  particles, which gives us a good prospect to the 14 MeV neutron spectrometer using a single crystalline CVD diamond. CVD diamond 5.486 MeV particles 0.4 % Polycrystalline Single crystalline

14. Fabricated micro-fission chamber Development of Micro-fission Chamber for ITER ■Micro-fission chamber was developed to be installed in ITER vacuum vessel for power monitor. ■Basic performances for radiation measurement under in-vessel condition were tested and confirmed to be excellent.

15. 10-3 Total Neutron Flux Calc. 10-5 >10MeV Neutron Flux Calc. Counts/sec/Source or n/cm2/sec/Source Reaction Rates Calc. 10-7 Count Rates Meas. 10-9 Chamber Location Comparison between Count Rates & Neutron Flux Arrangement of Shielding Experiment Main result of performance test ■Linearity between neutron source and detector response was confirmed. ■Response sensitivity for the neutron shielding turned out excellent. ■Gamma-ray background was estimated less than 0.1% the neutron flux. 1 2 3 4

16. Future Plan in Fusion Neutronic at FNS/JAERI • Extend of Breeding Blanket Experiments • Breeder and Beryllium pebbles • Activation Experiments for Sequential Charged Particle Reactions • Development of Neutron Measurement Technique • Development of Neutron Detector using Optical Fiber • Development of Artificial Diamond Detector