INDUCED RADIOACTIVITY IN ACCELERATOR MATERIALS AND …
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INDUCED RADIOACTIVITY IN
ACCELERATOR MATERIALS
AND SOIL-SHIELD SAMPLES
F.P. La Torre and M. Silari SATIF-12
Material activation
Radioactive waste study
Estimation of the radioactivity induced in materials
invested by stray radiation generated by beam losses
High-energy proton accelerators
Goals:
Conversion coefficients from unit lost beam power to
induced specific activity at saturation
Radionuclide production in soil with 3H and 22Na
leaching study
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.2
SATIF-12
Material samples
About 30 different types and grades of accelerator materials were selected
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.3
SATIF-12
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.4
SATIF-12
Steel Aluminium
14 grades L485, P355,
P506, B500B,
Phynox, G-steel,
IBA, YUS130S,
MAGNETIL,
304L, 316L,
316LN, INVAR,
MuMETAL
3 grades Al (99.99%)
AW-5083,
AW-6082
Copper Concrete
1 grade Cu-OFE
(CW00XA)
2 types Standard,
Barite
Lead Soil
1 grade Pb (99.993%) 1 type Molasse
Titanium Mix
1 grade W (99.98%) 5 types Bus Bars,
Superconducting
cable, LHC coils,
UCT1S cable,
ZCT1 cable
LHC material samples
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.5
SATIF-12
Iron yoke - MAGNETIL
(Low-carbon magnetic steel)
Collars - YUS130S
(non-magnetic
austenitic steel)
Bus Bars - CW009A
(Cu-OFE) + AgSn alloy
Dipole coils
NbTi superconducting
cables + Cu wedges
• The irradiation facility at CERN
H4 beam line
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.7
SATIF-12
H4IRRAD uses secondary or
attenuated beam from the SPS
impinging on a dedicated and
design-optimized copper target to
create a radiation field. It is
placed in the H4 beam line of the
CERN North Experimental Area
SPS
PS
Irradiation @ H4IRRAD
SPS attenuated primary beam at 400 GeV/c
Average intensity of ~ 3x109 protons per pulse (45 s)
Irradiation time: 20 days
0.0 2.0x105
4.0x105
6.0x105
8.0x105
1.0x106
1.2x106
1.4x106
1.6x106
0.0
5.0x108
1.0x109
1.5x109
2.0x109
2.5x109
3.0x109
3.5x109
4.0x109
4.5x109
Time [s]B
eam
in
ten
sity [p
roto
ns/s
pill
]
0
1x1013
2x1013
3x1013
4x1013
5x1013
6x1013
7x1013
8x1013
A
ccum
ula
ted
be
am
pa
rtic
les
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.8
SATIF-12
FLUKA simulations
Proton
beam
10-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
10-6
10-5
10-4
10-3
10-2
10-1
100
E x
d
/ dE
[cm
-2]
E [GeV]
neutrons
protons
pions+
pions-
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.9
SATIF-12
Sample measurement
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.10
SATIF-12
Extended Range Coaxial Ge detector
(XtRa Canberra, 2 keV FWHM at 1.33 MeV,
relative efficiency ≥ 40%)
Safety and Environmental
Protection Unit
Liquid Scintillation Analizer
Packard Tri-Carb TR-LSC
• Results and conversion coefficients
Steel AISI 316L
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.12
SATIF-12
Element Fe Cr Ni Mo Mn Si Co N C P S
(g/100g) Balance 16 – 18.5 11 - 14 2 – 2.5 2 1 < 0.2 0.05 0.03 < 0.03 < 0.01
the 316L is a Molybdenum-containing stainless steel
Mo enhances corrosion resistance and austenitic
stability
this grade is used in LHC interconnections and for
vacuum applications
Steel AISI 316L
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.13
SATIF-12
Nuclide 𝒕𝟏 𝟐 Experiment
(Bq/g)
H4IRRAD
As (Bq/g/W)
LEP*
As (Bq/g/W)
Ratio
H4/LEP
22Na 2.6 y 0.34 ± 0.07 8.53E+03 8.80E-02 9.70E+04
46Sc 83.8 d 65.5 ± 6.5 1.99E+05 3.90E-01 5.11E+05
54Mn 312 d 229 ± 23 2.04E+06 1.03E+01 1.98E+05
56Co 77.3 d 62.0 ± 5 1.79E+05 1.4E+00 1.28E+05
57Co 272 d 77.4 ± 9 6.09E+05 8.3E+00 7.34E+04
58Co 70.9 d 262 ± 26 7.15E+05 7.7E+00 9.29E+04
60Co 5.27 y 1.39 ± 0.13 7.06E+04 5.80E-01 1.22E+05
88Y 107 d 6.32 ± 0.63 2.29E+04 3.40E-02 6.73E+05
88Zr 83.4 d 4.18 ± 0.67 1.27E+04 3.10E-02 4.09E+05
*M. Silari and L. Ulrici, Nuc. Instr. Meth. Phys. Res. A 526 (2004) 510–536
• Soil-shield activation study
Soil-shield activation
Accelerators and experiment
facilities sited underground:
earth as a shield
Hazard: 3H and 22Na
• soluble chemical form
• long half-life
•3H is 𝛽−emitter
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.15
SATIF-12
ECN3
Activation of soil-shield samples
ECN3
Activation of soil-shield samples
ECN3
Activation of soil-shield samples
Chemical analysis of the soil
Chemical analysis performed by the EMPA laboratory
X-ray fluorescence spectrometry (WD-XRF)
The moisture was measured at the CERN Environmental laboratory by drying a known amount of earth.
The water content measured in the soil specimen was 5% by weight
Element O Si Ca Al C Fe Mg K Na Ti
(g/100g) 38.8* 24 16 6.8 5* 4 2 1.9 0.7 0.42
Element Mn Ba P Sr Zn Cr Zr Eu Ni S
(g/100g) 0.11 0.06 0.06 0.05 0.03 0.02 0.02 0.01 0.01 0.01
*Extrapolated value. Not quantifiable by XRF analysis.
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.19
SATIF-12
Nuclide 𝒕𝒕𝟏𝟏 𝟐𝟐⁄ Experiment (Bq/g)
FLUKA (Bq/g)
Exp/ FLUKA
3H 12.32 y / 14.1 ± 0.3 /
7Be 53.1 d 425 ± 32 257 ± 4 1.65
22Na 2.6 y 12.5 ± 0.8 10.2 ± 0.2 1.22
46Sc 83.8 d 3.02 ± 0.19 2.99 ± 0.35 1.01
48V 16 d 9.33 ± 0.50 12.3 ± 1.1 0.76
51Cr 27.7 d 25.0 ± 2.3 27.2 ± 1.4 0.92
52Mn 5.59 d 6.01 ± 0.43 6.95 ± 0.49 0.86
54Mn 312 d 6.02 ± 0.42 5.74 ± 0.23 1.05
56Co 77.3 d 0.40 ± 0.04 0.86 ± 0.09 0.46
58Co 70.9 d 0.22 ± 0.05 0.35 ± 0.05 0.63
Comparison Experiment/FLUKA
Soil Nuclide 𝒕𝒕𝟏𝟏 𝟐𝟐⁄ Experim.
(Bq/g) FLUKA (Bq/g)
Exp/ FLU
3H 12.32 y 28.9 ± 2.6 27.6 ± 0.5 1.05
7Be 53.1 d 523 ± 48 480 ± 12 1.09
Water
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.20
SATIF-12
Leaching procedures
Ground water
stagnation in the soil
Ground water percolation
through the soil
Mixing system Flowing system
Two possibilities were investigated to emulate
natural conditions
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.21
SATIF-12
Mixing system
Soil
(100 g)
Millipore
filter
(0.45 µm)
Cloudy water
Gamma
spectrometry Liquid
scintillation
Water
(1 liter)
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.22
SATIF-12
Data Analysis (Mixing)
After
decay
corrections
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.23
SATIF-12
Flowing system
Water
(1 liter)
Soil
(100 g)
Millipore
filter
(0.45 µm)
Gamma
spectrometry Liquid
scintillation
Flowing water
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.24
SATIF-12
Data Analysis (Flowing)
After
decay
corrections
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.25
SATIF-12
Leachable fraction of 3H and 22Na
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.26
SATIF-12
Literature data
1) T.B. Borak et al., «The underground migration of radionuclides produced in soil
near high energy proton accelerators», Health Physics 23 (1972), 679 – 687.
2) S. I. Baker et al., «Leaching of accelerator-produced radionuclides»,
Health Physics 73 (1997), 912 – 918.
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.27
SATIF-12
Leachable fraction (%)
3H 22Na
Borak et at. (1) 100 10 - 20
Baker et al. (2) 66 -100 7 - 32
This work 28 - 38 11 - 12
Assumption:
All the 3H produced in the sample that could be leachable is
transferred to the water and comes out in the distillation process
Fraction of tritium leached out
Activity (Bq) 3H (mix) 3H (flow)
Soil bulk (FLUKA) 1265 ± 105 1265 ± 105
Soil moisture (5 g) 145 ± 13 145 ± 13
Leach water 542 ± 33 391 ± 41
Leachable fraction of 3H in moisture
100% 100%
Leachable fraction of 3H in bulk
31.4% 19.4%
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.28
SATIF-12
Conclusions
Selection and activation of about 30 different type and grades of accelerator materials
Conversion coefficients from unit lost beam power to induced specific activity and comparison with LEP data (when available)
Activation of soil-shield samples:
1. Measurement of 3H and 22Na leachable fraction
2. Estimation of 3H leached out from soil bulk and soil moisture
F.P. La Torre – Induced radioactivity in accelerator materials and soil-shield samples – 28 Apr 2014 – p.29
SATIF-12
THANK YOU
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