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)

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

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

A schematic view of FNS blanket experiments

FNS 80deg. D-T target

A blanket assembly

Detectors (NE213)

Shielding (Li2CO3)

Present Blanket Assembly

Measurements

MeV-neutron 14-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

Measurement and Analysis Methods

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 Li2TiO3 pellet. the reaction rates of the activities and tritium production can be obtained by the spectra.

The -ray spectrum emitted from the F82H The -ray spectrum emitted from the Li2TiO3

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

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)

Shutdown dose measurements

Cross sectional view of the assembly Comparison 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)

1200

φ300

20080

0φ

356#A#B #C

#a #b #c

Reflector(SS316)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

1.0E+05 3.0E+05 5.0E+05 7.0E+05 9.0E+05 1.1E+06 1.3E+06 1.5E+060.5

1.0

1.5

2.0

2.5

3.0

3.5

1.0

Cooling time (x 105sec)

Shut

dow

n do

se ra

te（

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

0.53.0 7.0 9.0 11.0 13.0 15.05.0

FENDL/2AFENDL/2

#A

#a

Double bent duct streaming experiment

Typical streaming effects can be reproduced by MCNP & FENDL/2 (~30%)

Cross sectional view of the assembly Comparison of neutron spectrum

Iron Rack

Auxiliary Shield

Streaming Assembly

Auxiliary Shield

1800200

800

1000 900 Duct Opening

(300 x 300)

DT Source

1700

1200

550750

765

335

565150

#1 #2 #3

#4 #5

#6

1.0E-12

1.0E-11

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E+00 1.0E+01 1.0E+02

Energy (MeV)

Neu

tron

flux

(n/c

m2 /s

ourc

e/le

thar

gy)

Calculation

Experiment #3

#4

#5

#6

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.

n p A(p,n)C

A(n,x)Brecoi led

Coolant

Coolant(H2O)

14-MeVneutrons

Pipes Polyethylene(3mmt)

14-MeVneutrons

Niobium Foi l

Fusion Material Foi l s (100Å 2̀50É mt)

Experiment

1 2 3 4 5

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

Development of Artificial Diamond Detector Recently, we tried to use a chemical vapor deposition (CVD) dia

mond 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.

1.0 mm(a) 1.0 mm(b)

0

100

200

300

400

500

750 775 800 825 850Channel number

5.486 MeV particles

0.4 %

CVD diamond

Single crystallinePolycrystalline

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

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.

0 1 2 3 4 5Co

unts

/sec

/Sou

rce

or

n/c

m2 /

sec/

Sour

ce

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

21 43

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