eurisol ds project task#2: multi-mw target design

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EURISOL DS Progress Meeting T2-03, CEA Saclay, France 27 – 28 October, 2005

EURISOL DS PROJECT

Task#2: MULTI-MW TARGET DESIGN

Adonai Herrera-Martínez & Yacine Kadion behalf of T2

European Organization for Nuclear Research, CERNCH-1211 Geneva 23, [email protected]

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Overview

1. Baseline Parameters

2. Baseline Design (BLD) vs. Hg Jet (Hg-J) → Intermediate Solution (IS)

3. Comparison of the FLUKA Simulation Results

– Primary Particle Flux → Proton Escapes

– Neutron Flux and Energy Spectra

– Fission Densities → Isotopic Yields

– Energy Deposition → Temperature Increase

4. Conclusions

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Sensitivity Study

http://eurisol-hg-target.web.cern.ch/eurisol-hg-target/

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Baseline Parameters of the MMW Hg Target

Parameter Symbol Units Nval Range

Converter Target material Zconv - Hg (liquid) LBE

Secondary Target material Ztarg - UCx, BeO

Beam particles Zbeam - Proton Deuteron

Beam particle energy Ebeam GeV 1 2

Beam current Ibeam mA 4 2 – 5

Beam time structure - - dc ac50Hz 1ms pulse

Gaussian beam geometry sbeam mm 15 25, parabolic

Beam power Pbeam MW 4 5

Converter length lconv cm 45 85

Converter radius (cylinder) rconv cm 15 8 – 20

Hg temperature Tconv ºC 150 (tbc) < 357

Hg flow rate Qconv kg/s 200 (tbc) < 3000

Hg speed Vconv m/s 2 (tbc) < 30

Hg pressure drop ΔP1 bar tbc << 100

Hg overpressure Δ P2 bar tbc << 100

UCx temperature Ttarg ºC 2000 500 – 2500

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MMW Hg Target Configuration

• BLD: Shape of Hg target optimised for neutron production (neutron balance)

• 15 mm sigma proton beam, fully contained in the Hg target

• Possibility of further reduction in Hg target dimensions → Intermediate solution (IS)

Hg Target

Reflector

Reflector

Target container

UCx/BeO Target

Protons

73 cm

30 cmProtons

Reflector

Reflector

Hg Jet

UCx/BeO Target

UCx/BeO Target

40 cm

4 cm

• Hg-J: designed for high-energy neutron fluxes in the UnatC3 (3 g/cm3) fission target

• 4 mm sigma proton beam, mostly contained in the 4 cm diameter Hg Jet

• Use of reflector to improve neutron economy and to shield HE particles

Hg Target

Reflector

Reflector

Target container

UCx/BeO Target

Protons

68 cm

16 cm

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Primary Proton Flux Distribution

Primary flux (prim/cm2/s/MW of beam)• 1GeV proton range ~ 46 cm

• BLD: Beam fully contained inside

• Hg-J: Important HE primary escapes (~1013 prim/cm2/s/MW of beam), mostly at small polar angles (up to 25% losses)→ Beam dump

• IS: Some primary escapes through the endcap, mostly contained by the reflector

• BLD and IS: Beam window suffering ~100 μA/cm2/MW (radiation damage limit)

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Neutron Flux Distribution

Neutron flux (n/cm2/s/MW of beam)

• Neutron fluxes in the fission target ~1014 n/cm2/s/MW of beam

• BDL and IS: Partial containment by the reflector of the escaping neutron flux

• Hg-J: Higher neutron flux in the fission target (~2×1014 n/cm2/s/MW of beam)

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238U Fission Cross Section

0

0.5

1

1.5

2

2.5

5 15 25 35 45 55 65 75 85 95 105

Energy (MeV)

Sigm

a (B

arn)

neutron

proton

deuteron

• Significantly harder spectrum for the Hg-J, with a peak neutron energy between 1 − 2 MeV, compared to 300 keV for BLD and 700 keV for IS

• Very low fission cross-section in 238U below 2 MeV (~10-4 barns). Optimum energy: 35 MeV

• Use of natural uranium: f in 235U (0.7% wt.): at least 2 barns

• Further gain if neutron flux is reflected (e.g. BeO)

Neutron Energy Spectrum vs Fission Cross-Section in Uranium

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Fission Density Distribution in UnatC3

Fission density (fissions/cm3/s/MW of beam)• High-energy fissions in Hg → Radioactive isotopes in Hg

•BLD: 1011 fiss/cm3/s/MW, homogenously distributed

• Hg-J: High and anisotropic fission density (~4×1011 fiss/cm3/s/MW)

• IS: 2×1011 fiss/cm3/s/MW, homogenously distributed → ~1015 fissions/s for 4 MW of beam and a 1 litre UnatC3 (3 g/cm3) fission target

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HE Fission Density Distribution in UnatC3

•Non-homogenous HE fissions in all cases

• BLD: ~10% of the fissions are HE (>20 MeV), compared to ~20% in IS and ~40% in Hg-J

HE fission density (fissions[>20 MeV]/cm3/s/MW of beam)

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LE Fission Density Distribution in UnatC3

LE fission density (fissions[<20 MeV]/cm3/s/MW of beam)

• BLD: LE fissions account for 90% of the radial fissions

• BDL and IS: Important effect of the reflector ← More LE fissions in the outside surface of the fission target

• Hg-J: Stronger anisotropy in the LE fissions and lack of containment for LE neutrons

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• Maximum energy deposition in the first 10 cm beyond the interaction point, in Hg

• BLD and IS, maximum power density in Hg: ~2 kW/cm3/MW of beam

• Hg-J, maximum power density in Hg: ~22 kW/cm3/MW of beam!

• Power density in the UnatC3

target: ~3 W/cm3/MW of beam in the BLD and ~5 W/cm3/MW the IS, homogenously distributed in both

• ~20 W/cm3/MW of beam UnatC3

target for the Hg-J, following the fission density distribution → Strongly anisotropic

Power Densities (1)

Power density (W/cm3/MW of beam)

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Power Densities (2)

Hg

Bea

m W

indo

w

• More than one order of magnitude difference between the free surface Hg-J (~22 kW/cm3/MW) and the confined Hg targets (BLD, ~2 kW/cm3/MW)

• BDL and IS: Beam window suffering important power densities (~1 kW/cm3/MW → extra cooling plus radiation resistant material needed)

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Power Densities (3)

• Increasing beam from 15

to 25 mm or taking

parabolic beam of at

least 45 mm radius →

reduce T in Hg by a

factor 2 - 2.5

• Doubling the flow rate

(~2 m/s) will reduce T

by factor 2

• → T ~ 130 - 150 ºC

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Radioisotope Yields in UnatC3 Target (1)

Harder neutron spectrum for the Hg Jet → more high-energy neutron induced fissions → large increase in the symmetrical fission products

Small differences in terms of asymmetrical (low energy) fission fragments

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Radioisotope Yields in the UnatC3 (1)

28-Ni (A) Baseline design Intermediate solution Hg Jet

70 1.7E+05 2.9E+06 0.9 1.6E+05 17.3

71 2.0E+05 2.3E+06 1.9 3.9E+05 11.4

72 3.4E+05 2.9E+06 2.1 7.1E+05 8.5

Ni isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

31-Ga (A) Baseline design Intermediate solution Hg Jet

73 3.7E+05 9.8E+06 1.3 4.7E+05 26.4

75 1.2E+06 2.1E+07 2.3 2.8E+06 17.3

76 2.6E+06 2.8E+07 2.4 6.2E+06 10.5

77 7.1E+06 5.1E+07 2.1 1.5E+07 7.3

78 1.2E+07 6.2E+07 1.9 2.4E+07 5.0

79 2.0E+07 1.0E+08 2.0 4.0E+07 5.1

80 1.6E+07 7.4E+07 1.5 2.5E+07 4.6

81 1.4E+07 7.7E+07 1.7 2.3E+07 5.5

Ga isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

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Ga isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

31-Ga(A) Baseline design Intermediate solution Hg Jet

82 7.4E+06 3.1E+07 1.8 1.3E+07 4.1

83 1.9E+06 1.6E+07 2.0 3.9E+06 8.1

84 7.3E+06 8.9E+06 1.4 1.0E+07 1.2

85 2.0E+05 2.3E+06 1.9 3.9E+05 11.2

36-Kr (A) Baseline design Intermediate solution Hg Jet

84 1.9E+06 5.4E+06 2.9 6.3E+07 33.9

85 2.1E+07 3.5E+07 1.7 9.6E+07 4.6

86 7.1E+07 1.2E+08 1.7 2.8E+08 3.9

87 3.2E+08 4.8E+08 1.5 5.0E+08 1.6

88 1.2E+09 1.8E+09 1.5 1.7E+09 1.4

89 2.3E+09 3.4E+09 1.5 2.8E+09 1.2

90 3.2E+09 4.8E+09 1.5 4.6E+09 1.5

91 2.5E+09 3.8E+09 1.5 4.6E+09 1.9

92 1.5E+09 2.4E+09 1.6 3.8E+09 2.5

Kr isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

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Kr isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

36-Kr (A) Baseline design Intermediate solution Hg Jet

93 5.5E+08 9.6E+08 1.7 1.8E+09 3.3

94 2.0E+08 3.8E+08 1.9 9.8E+08 5.0

95 3.4E+07 6.6E+07 1.9 2.1E+08 6.2

96 3.5E+07 5.3E+07 1.5 1.0E+08 2.9

97 1.8E+06 2.0E+06 1.2 1.2E+07 6.6

98 2.2E+06 4.0E+06 1.8 7.7E+06 3.4

100 6.8E+04 7.9E+04 1.2 2.8E+05 4.1

Sn isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

50-Sn (A) Baseline design Intermediate solution Hg Jet

117 1.53E+09 5.82E+09 3.8 7.71E+10 50.4

118 4.21E+09 1.54E+10 3.6 1.70E+11 40.5

119 6.07E+09 2.28E+10 3.8 2.08E+11 34.2

120 1.78E+10 5.44E+10 3.1 4.63E+11 26.0

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Sn isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD50-Sn (A) Baseline design Intermediate solution Hg Jet

121 2.38E+10 6.24E+10 2.6 4.75E+11 16.3

122 5.37E+10 1.36E+11 2.5 8.74E+11 14.3

123 5.44E+10 1.37E+11 2.5 7.77E+11 12.4

124 9.74E+10 2.35E+11 2.4 1.21E+12 10.2

125 8.99E+10 1.90E+11 2.1 9.21E+11 8.3

126 1.42E+11 2.95E+11 2.1 1.18E+12 5.8

127 1.60E+11 3.07E+11 1.9 9.33E+11 3.8

128 3.36E+11 5.67E+11 1.7 1.29E+12 3.2

129 4.79E+11 7.93E+11 1.7 1.54E+12 2.4

130 9.92E+11 1.62E+12 1.6 2.42E+12 2.8

131 9.24E+11 1.55E+12 1.7 2.56E+12 2.9

132 6.43E+11 1.09E+12 1.7 1.87E+12 3.4

133 1.84E+11 3.20E+11 1.7 6.30E+11 4.3

134 3.77E+10 6.80E+10 1.8 1.61E+11 4.8

135 3.40E+09 6.99E+09 2.1 1.64E+10 6.0

136 2.03E+08 1.57E+08 0.8 1.22E+09 6.0

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Conceptual Design of the MMW Hg Target

Conclusions

• The Intermediate Solution brings us closer to the ideal performance of a Hg Jet in terms of fission density and relevant isotopic yields, additionally reducing the particle escapes and power densities in Hg

• The Hg Jet presents important technical issues regarding Hg cooling, radiation damage to the nearby structures and radiation shielding

• Need to clearly establish the beam requirements (i.e. CW vs. pulsed, beam frequency and beam shape) and fission target configuration

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The End (... or The Beginning)

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• 3 times more fissions with UnatC compared to UnatC3 (proportional to density)

• With 238UC less isotropic distribution and fission yield reduced by factor 3

Fission Density Distribution: UnatC vs 238UC

UnatC

238UC

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At high masses it is characterized by the presence of three peaks corresponding to(i) the initial target nuclei, (ii) those obtained after evaporation below and (iii) those obtained after acivation above (A+1)

Three very narrow peaks corresponding to the evaporation of light nuclei such as (deuterons, tritons, 3He and a)

An intermediate zone corresponding to nuclei produced by high-energy fissions (symmetric distr.)

At higher proton energy nuclei from evaporation and multi-fragmentation (ligth nuclei) are more abundant

Residual Nuclei Distributions in Hg

1x105

1x106

1x107

1x108

1x109

1x1010

1x1011

1x1012

1x1013

0 50 100 150 200

A, mass number

1 GeV impact point

2 GeV impact point

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At high masses it is characterized by the presence of acivation products (Pu239 !!) ==> dominates over fission !!

Three very narrow peaks corresponding to the evaporation of light nuclei such as (deuterons, tritons, 3He and ) ==> very few

An intermediate zone represented double humped distribution corresponding to nuclei produced by low-energy fissions

twice as much fission in radial position

Radioisotope yields in UCx targets

1x104

1x105

1x106

1x107

1x108

1x109

1x1010

1x1011

1x1012

1x1013

0 50 100 150 200 250

A, mass number

UnatC Radial

UnatC End cap

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5 times less fissions with U238 overall but…

equal amount of high-energy neutron induced fissions (sym. distribution)

Radioisotope yields in UCx targets (2)

1x104

1x105

1x106

1x107

1x108

1x109

1x1010

1x1011

1x1012

1x1013

0 50 100 150 200 250

A, mass number

U238C End cap

UnatC End cap

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Radioisotope yields in UCx targets (3)

harder neutron spectrum along the beam axis with 2 GeV protons ==> more high-energy neutron induced fissions and few evaporations

no differences radially

1x104

1x105

1x106

1x107

1x108

1x109

1x1010

1x1011

1x1012

0 50 100 150 200 250

A, mass number

1 GeV radial

2 GeV radial

1x104

1x105

1x106

1x107

1x108

1x109

1x1010

1x1011

1x1012

0 50 100 150 200 250

A, mass number

1 GeV end cap

2 GeV end cap

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He-3 He-4 He-6 C-12 C-13 N-151x109

1x1010

1x1011

1x1012

Radioisotope yields in BeO target

aim for 2x1013 6He at/s

eurisol ds project task#2: multi-mw target design

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