Oct.18, 2001 1

Neutron Field and Induced Radioactivity in IFMIF Environment

M. Sugimoto(JAERI)

IEA International Work Shop on Fusion Neutronics The Kongreshous Baden-Baden, Germany

Oct.18, 2001 2

Contents

1. IFMIF Overview

2. Issues Related to Neutronics and Radiation Safety

3. Source Neutron Characteristics

4. Deuteron Induced Radioactivity

5. Requirements for Neutron Nuclear Data

6. Summary

Oct.18, 2001 3

Test specime

ns

Deuteron beam

Li target

D+7Li→ ｎ＋８ Be or ｎ＋ｐ＋ 7Li etc.

Ｄ - Ｌｉ neutron ~14MeV peakＤ - Ｌｉ neutron ~14MeV peak

IFMIF Overview

Neutron Irradiation Fieldfor Fusion Materials

Post Irradiation ExaminationTest Facilities

DeuteronAccelerators

Li-TargetLoops

Li-TargetAssembly

Ed: 40 or 32MeV, Id: 250mA (=10MW max) Flux-volume: 500 cm3 (@> 1014 n/cm2/s)

Oct.18, 2001 4

Issues Related to Neutronics and Radiation Safety

• Li+d source neutron characteristics(not only TTY for 40 and 32 MeV, DDY is preferable)

• Materials+d source neutron characteristics(due to beam loss along accelerator and beam line)

• Deuteron induced radio-activities (Ed<40MeV)

• Neutron induced radio-activities (Ed<50~60MeV)

• Neutron shielding and streaming from Test Cell• Handling of radioactive materials during operation

(lithium, irradiation sample, target assembly, etc.)

Oct.18, 2001 5

Source Neutron Characteristics (1)

Oct.18, 2001 6

Source Neutron Characteristics (2)

0 10 20 30 401012

1013

1014

1015

1016

1017

Present Ed=25MeV 4deg

M.A.Lone et al. Ed=23MeV 0deg

Neu

tron

Yie

ld [M

eV-1・

sr-1・

C-1

]

Neutron Energy [MeV]

0 10 20 30 40 501012

1013

1014

1015

1016

1017

0 10 20 30 40 501012

1013

1014

1015

1016

1017

Neu

tro

n Y

ield

[M

eV-1

·sr-1

·C-1

]

Present 25MeVSugimoto 32MeV

10-deg

Neu

tro

n Y

ield

[M

eV-1

·sr-1

·C-1

]

Neutron energy [MeV] Neutron energy [MeV]

0 10 20 30 40 501012

1013

1014

1015

1016

1017

Neutron energy [MeV] Neutron energy [MeV]

Neu

tro

n Y

ield

[M

eV-1

·sr-1

·C-1

]

Neu

tro

n Y

ield

[M

eV-1

·sr-1

·C-1

]

20-deg

0 10 20 30 40 501012

1013

1014

1015

1016

1017

40-deg

Extend to Lower Energy Part & at Higher Deuteron Energy up to 40 MeV

Recent Measurement at CYRIC (Tohoku Univ., 2000)

Oct.18, 2001 7

Thick Target Yield: Li+d at Ed=35 MeV (J ohnson 78)

0.001

0.01

0.1

1

10

100

0 10 20 30 40 50

Neutron Energy [MeV]

Yie

ld [

1e1

5 n

/MeV

/sr/

C]

041220304570105150

Source Neutron Characteristics (3)

Thick Target Yield of d+7Li at Ed=8 MeV

1.E+06

1.E+07

1.E+08

1.E+09

0 5 10 15 20 25

Neutron Energy [MeV]

Yie

ld [

n/M

eV/m

C/s

r]

0510152030405060708090100

Thick Target Yield of Li+d at Ed=24 MeV (Sugimoto 1990)

1.0E+06

1.0E+07

1.0E+08

1.0E+09

1.0E+10

1.0E+11

0 5 10 15 20 25 30 35 40Neutron Energy [MeV]

Yie

ld [

n/M

eV

/μC

/sr]

0510152030405060708090100110120130140

Thick Target Yield from d+Li at Ed=16 MeV (Sugimoto)

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

0 5 10 15 20 25 30 35 40

Neutron Energy [MeV]

Yie

ld [

n/M

eV

/μC

/sr]

0510152030405060708090100110120130140

Oct.18, 2001 8

Source Neutron Characteristics (4)Energy Integrated Neutron Yield from Thick Li Target

1.E+09

1.E+10

1.E+11

1.E+12

0 30 60 90 120 150 180angle [deg]

Yie

ld [

n/s

r/mC

]

7.8MeV (Sugimoto)

15.9MeV (sugimoto)

23.9MeV (Sugimoto)

31.9MeV (Sugimoto)

40MeV (Saltmarsh)

8 MeV (Nelson)

12 MeV (Nelson)

15 MeV (Nelson)

14.8MeV (Lone)

18MeV (Lone)

23MeV (Lone)

Oct.18, 2001 9

Deuteron Induced Radioactivity (1)

0 10 20 30 40104

105

106

107

Ed (MeV)

dps/

(μA

·hou

r)natLi(d,2n)7Be TTY

Present1Present2U.Von Möllendorff et al.S.Mukhammedo et al.P.P.Dmitriev et al.IRACM calculation

Recent Measurement at CYRIC (Tohoku Univ., 2000)

D.L.Johnson et al.

Oct.18, 2001 10

Deuteron Induced Radioactivity (2)6Li(d,n)7Be

0.01

0.1

1

10

100

1000

0.01 0.1 1 10 100Deuteron Energy (meV)

Cro

os S

ectio

ns (m

b) A0174 Cecil+1982 (TT diff Ex=0.43)

A0081 Guzhovskij+1980

A0619 Vysotskij+1990

A1359 Hirst+1954

B0137 Szabo+1977

F0024 Guzhovskij+1984 (Ex=0.43)

B0177 Elwyn+1977

B0177 Elwyn+1977 (Ex=0.43)

F0034 Holland+1979

Oct.18, 2001 11

Deuteron Induced Radioactivity (3)

3H and 7Be production

0.1

1

10

100

1 10 100

Deuteron Energy (MeV)

Diff

. Yie

ld (

10

^-2

7 c

m^

3/M

eV

)

6Li(d,n)7Be7Li(d,2n)7Be7Li(d,t)6Li

Relative Importance of D-induced radio-activities in Li

Oct.18, 2001 12

Requirements for Neutron Nuclear Data

Spectrum Calculation• Neutron DDX (especially at low energy and larger scattering angles)

Nuclear Heating Calculation• Photon production• Charged particle production

Activation Calculation• Long-lived residual production• Sequential multi-step reaction process

UNIVERSAL REQUESTSIN USE FOR IFMIF NEUTRONICSPROBLEMS

e.g. (n,2n), (n,3n) and (n,Xn) (where X=charged particle) processes are important in some calculations

(Neutron cross sections up to 50~60 MeV)

Oct.18, 2001 13

Status of Neutron Nuclear Data(n,2n) : Generally good situation except for Be, candidate of multiplier material.(n,3n) : Generally worse. Heavily relied on model calculations.

Experimental consistency check is recommended.(n,pn) : Situation is better. Systematic measurement to separate (n,d) process

is lacked.(n,n) : Comparatively worse. No systematic study is found.

Partial DDX information for each channel is necessary to establish the clear systematic understanding about channel branching, though its measurement is extremely difficult. Theoretical support calculation which excludes the excessive model parameters is inevitable.

Continued systematical measurements of the above reaction cross sections at JAERI/FNS and the other facilities (esp. at higher than 14 MeV) is strongly desired and the results are much useful.

Oct.18, 2001 14

Summary

1. Neutron source characteristics are relatively well-known.2. Detailed analyses to deduce Double-Differential Yields

for mono-energetic deuterons based on the correct theoretical interpretation are needed.

3. Deuteron induced activities might be measured at each laboratory, however, these data are not available in a systematical form.

4. Neutron induced activities are