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/ 6 Li-enriched Li 2 TiO3/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. A schematic view of FNS blanket experiments FNS 80deg. D-T target A blanket assembly Detectors (NE213) Shielding (Li 2 CO 3 ) Present Blanket Assembly

5. Measurements MeV-neutron  14-mm NE213 Reaction ratesFission Chamber(U-235 and U-238) HPGe (Nb, Al, In, Au and F82H sheet) Liquid Scintillation Counter (Aloka-5500) Calculation Code MCNP-4B Nuclear dataJENDLE-3.3 and JENDLE-FF Measurement and Analysis Methods

6. Results of Measurements Above spectra show the  -ray spectrum emitted from the irradiated F82H(Fe: balance, Cr: 8% and W: 2%) and  -ray spectrum emitted from the irradiated Li 2 TiO 3 pellet. the reaction rates of the activities and tritium production can be obtained by the spectra. The  -ray spectrum emitted from the F82HThe   -ray spectrum emitted from the Li 2 TiO 3

7. Preliminary Result We have obtained the profile of reaction rates of the iron, chromium and tungsten in F82H and tritium production in 95-% Li 2 TiO 3. C/E of the 95-% Li 2 TiO 3 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. Shutdown dose measurements Cross sectional view of the assemblyComparison of shutdown dose rates Shutdown dose rates can be evaluated by the new one step method within experimental error (~10%) D-T source Test region Shield (SS316/H20) Source Reflector (SS316) 1200φ 300 200 800φ 356 #A#B#C #a#b#c Reflector (SS316) 1.0 Cooling time (x 10 5 sec) Shutdown dose rate （  Sv/hr ） 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 3.07.09.011.013.015.05.0 FENDL/2A FENDL/2 #A #a

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

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/JAERI and the sequential reaction rates were obtained for 5 positions.

12. Preliminary Results The sequential reaction rate of 51 V(p,n) 51 Cr 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 51 V(p,n) 51 Cr

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. 5.486 MeV  particles 0.4 % CVD diamond Single crystallinePolycrystalline

14. 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. Fabricated micro-fission chamber

15. 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. Counts/sec/Source or n/cm 2 /sec/Source Total Neutron Flux Calc. >10MeV Neutron Flux Calc. Reaction Rates Calc. Count Rates Meas. 10 -9 10 -7 10 -5 10 -3 Chamber Location Comparison between Count Rates & Neutron Flux Arrangement of Shielding Experiment 2 1 43

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