INDUCED RADIOACTIVITY IN ACCELERATOR MATERIALS AND …

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

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