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ActiWiz – optimizing your nuclide inventory at proton accelerators with a computer codeHelmut Vincke, Chris Theis CERN RSO committee – 1/3/2012

NBI workshop 20129/11/2012

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Contents

• Motivation for this project

• Introduction to “ActiWiz”

• Illustration of the Catalogue: “Radiological Hazard classification of Materials in CERN’s accelerator environments“

Motivation

Safety benefit

• Lower dose rates and committed doses

Operational benefit

• Reduced downtime due to faster access

• Less restrictions for manipulation & access

End of life-cycle benefit

• Smaller amount and less critical radioactive waste

• Smaller financial burden

3Project concerning the radiological classification of materials initiated by Dr. Myers (director of accelerators)

• Beside other aspects also the radiological consequences of the implementation of a material have to be considered

• Level of activation depends on the type of the material

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very strong dependence on radiation environment need for “CERN specific” assessment in contrast to experience from nuclear industry

Next to target:brass vs. iron equivalent

Outside:brass vs. iron significantly worse

Use-case

Using brass instead of iron as shielding @ COMPASS-2?

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Strategy to obtain radiological material guidelines

Categorization of radiation environment

Development of ActiWiz – code assessing radiation risks, dominant nuclides etc., for arbitrary materials

Radiological hazard catalogue for materials

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Radiological assessment of materials

Energy (machine) Position in accelerator

Radiological hazard assessmentfor a given material

Time of material present in accelerator

(irradiation time)

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Categorization of the radiation environments (energy)

FLUKA calculations of typical hadronic particle spectra (p, n, p+, p-) in CERN’s accelerators

LHC

SPS

PSLinac 4

+ Booster

160 MeV (Linac4), 1.4 GeV (Booster), 14 GeV/c (PS), 400 GeV/c (SPS), 7 TeV (LHC)

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Radiological assessment of materials

35 spectra * 5 irradiation periods * 13 cooling times FLUKA isotope calculations for 69 single components(63 chemical elements + 6 isotopes)

2400 single Monte Carlo simulations 157.000 nuclide inventories (10 GB of data) ~628.000 hazard factors

ActiWiz – software evaluate radiological hazard for arbitrary materials with a few mouse clicks

Close to tunnel wall

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

Energy (GeV)

E*dF

/dE

ProtonsPions+Pions-NeutronsClose to tunnel wall

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

Energy (GeV)

E*dF

/dE

ProtonsPions+Pions-Neutrons13 cm lateral to beam axis

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

Energy (GeV)

E*dF

/dE

ProtonsPions+Pions-Neutrons

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ActiWiz – program interface

1.) Select energy / location / irradiation times2.) Define material composition based on 69 fund. components

* Many thanks to R. Froeschl for providing activation data on Zinc

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Output of ActiWiz

Nuclide inventory & dominant isotopes

Safety relevant quantities(activity, H*(10), radiotoxicity)

Radiological hazard assessment• Hazard factors allowing to compare various materials

with each other

• Program provides so-called global hazard factors for• Operation (indicator of external dose to personnel)• Waste (indicator of risk generating radioactive waste)

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First example of an ActiWiz applicationComparison of ambient dose equivalent for various materials installed in a cable tray @ LHC, operating for 20 years– Copper – Aluminum – Iron – Steel 316L

Check nuclide inventory to understand results

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Further analysis with ActiWiz

“Why is stainless steel so much worse than pure iron?”

Co-60: 99% Fe-55: 86% Sc-44: 9%

Steel 316L Iron AluminumNa-22: 99% Co-60: 99%

Copper

Shielding requirements for equipment: defined by dominating energy of the radio-isotopes:

Co-60: 1.33 MeV 1.17 MeV

Fe-55: X-ray due to e Sc-44: 1.15 MeV

Steel 316L Iron AluminumNa-22: 1.27 MeV Co-60: 1.33 MeV

1.17 MeV

Copper

Required thickness of concrete shielding for an attenuation of a factor of 10:

Co-60: 31 cm Fe-55: /Sc-44: 30 cm

Steel 316L Iron AluminumNa-22: 31 cm Co-60: 31 cm

Copper

Main contributor to ambient dose equivalent for a cool down of 10 years:

Global hazard factors measure of the rad. hazard of material

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Nuclide inventory for each element(function of energy, location, irradiation & cooling period)

Convolution with * activity-to-dose coeff. (operational hazard factor)

* exemption limits (waste hazard factor)

Individual hazard factors for each element(function of energy, location, irradiation & cooling period)

Combine element hazards to compound hazards(function of energy, location, irradiation & cooling period)

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Global hazard factors

Dependence on cooling period should be transparent to user

Introduction of importance factors (empirical) contribution of the dose originating from interventions

after specific cooling periods to the collective annual dose

Integration over cooling periods incl. importance factors (1 hour – 20 years)

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Material catalogueproduced with ActiWiz

Material catalogue

Classification of most common materials by the use of global operational and waste hazard factors

Catalogue provides guidelines for selection of materials to be used in CERN’s accelerator environment

Authors: Robert Froeschl, Stefano Sgobba, Chris Theis, Francesco La Torre, Helmut Vincke and Nick WalterAcknowledgements: J. Gulley, D. Forkel-Wirth, S. Roesler, M. Silari and M. Magistris

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• Catalogue consists of three parts:

Catalogue for the radiological hazard classification of materials

Introduction

List of critical materials in terms of

handling & waste disposal*

Appendix with data

• Provides radiological guidelines via hazard values cannot replace Monte Carlo studies by a specialist for specific cases outside of the generic irradiation scenarios assumed

* Many thanks to Luisa Ulrici (DGS-RP-RW) for elaborating and providing the waste disposal guidelines

Catalogue structure

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160 MeV (Linac4), 1.4 GeV (Booster), 14 GeV/c (PS), 400 GeV/c (SPS), 7 TeV (LHC), energy independent

7 typical radiation fields in an accelerator

Various irradiation times

1 day, 1 week, 1 operational year, 20 years, irradiation time independent

Various energies/momenta

Materials not addressed by the catalogue can be assessed with the ActiWiz program

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Examples for using the catalogue

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Proton Beam

1 wt-% of hafnium shall be used as an additive to a copper cable. The cables are placed in cable trays attached to the concrete tunnel wall alongside to SPS magnets. Question arising: Is 1% of hafnium in terms of radiological consequences an acceptable choice?

Summary of situation:a) Foreseen location: concrete wall beside SPS magnetsb) Duration of its stay at this position: SPS life timec) Material choice: is 1% of hafnium acceptable?

Hazard factor comparison: Hazard factor comparison Hazard of elements per mass unit:Operational: 1.36 (copper) versus 976 (hafnium); Waste: 2.54 (copper) versus 51200 (hafnium) 1 wt-% of hafnium in the alloy causes an 7 times higher operational and a 200 times higher waste related radiological hazard than the remaining 99.0 wt-% of copper. find another additive for the cable

Example

Parameters to be chosen for retrieving the correct data:a. Irradiation energy + location: 400 GeV/c; activation occurring close to the concrete tunnel

wall (beam loss in bulky material)b. Irradiation time: 20 yearsc. Find hazard factor of hafnium in table listing elements per mass unit

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Web-based catalogue: ActiWeb http://actiweb.cern.ch

Interactive web-based catalogue in collaboration with software developer Fernando Leite Pereira (DGS/RP).

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Summary

ActiWiz software allows to quickly quantify radiological hazard of material implemented into CERN’s accelerator environment.

69 fundamental components and most common metals and construction materials were processed first version of a catalogue for CERN accelerators (LINAC4, BOOSTER, PS, SPS & LHC radiation environments)

Catalogue provides radiological guidelines supporting the user in the choice of materials to be implemented in the accelerator environment.

Currently we are in the process of promoting the catalogue & getting feedback from users.

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Thank you for your attention

christian.theis \at\ cern.ch

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FLUKA benchmarks

Fundamental quantity:calculation of radionuclide production with FLUKA

Very well benchmarked & documented:

M. Brugger, A. Ferrari, S. Roesler, L. Ulrici, Validation of the FLUKA Monte Carlo code for predicting induced radioactivity at high-energy accelerators, Proc. 7th Int. Conf. on Accelerator Applications - AccApp05, Nucl. Instrum. Meth. A562, 827-829, (2006).

M. Brugger, H. Khater, S. Mayer, A. Prinz, S. Roesler, L. Ulrici, Hz. Vincke, Benchmark studies of induced radioactivity produced in LHC materials, Part 1: specific activities, Proc. ICRS-10 (May 2004); Rad. Prot. Dosim. 116, 6-11, (2005).

S. Mallows. T. Otto, Measurements of the induced radioactivity at CTF-3, ARIA workshop 08 – PSI, (2008).

M. Brugger, D. Forkel-Wirth, S. Roesler, J. Vollaire, Studies of induced radioactivity and residual dose rates around beam absorbers of different materials, Proceedings of HB2010, Morschach, Switzerland, (2010).

J. Vollaire, M. Brugger, D. Forkel-Wirth, S. Roesler, P. Vojtyla, Calculation of water activation for the LHC, Nuclear Instruments and Methods in Physics Research A, Volume 562, Issue 2, p. 976-980, (2006).

M.Brugger, F.Cerutti, A.Ferrari Ferrari, E.Lebbos, S.Roesler, P.R.Sala,F.Sommerer, V. Vlachoudis, Calculation of Induced radioactivity with the FLUKA Monte Carlo code, ARIA workshop 08 – PSI, (2008).

non exhaustive list

G. Dissertori, P. Lecomte, D. Luckey, F. Nessi-Tedaldi, F. Pauss, T. Otto, S. Roesler, C. Urscheler,A study of high-energy proton induced damage in cerium fluoride in comparison with measurements in lead tungstate calorimeter crystals, Nuclear Instruments and Methods in Physics Research A, p. 41-48, Vol. 622, (2010).

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Categorization of the radiation environments (position)

beam impact area

within bulky material (e.g. magnet) surrounding the beam impact area

adjacent to bulky material surrounding the beam impact area

close to concrete tunnel wall (loss on bulky object)

behind massive concrete shielding

10 cm lateral distance to a target

close to concrete tunnel wall (loss on target)

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Concrete tunnel

7 TeV protons

Proton Beam

A support for a beam loss monitor foreseen to be installed close to LHC magnets has to be designed. A choice between Aluminium 5083 and Steel 316L in terms of materials to be used to build the support has to be made.

Summary of situation:a) Foreseen location: beside LHC magnetb) Duration of its stay at this position: LHC life timec) Material choice: either Aluminium 5083 or Steel 316L

Parameters to be chosen for retrieving the correct data:a. Irradiation energy + location: 7 TeV; activation occurring adjacent to bulky material (e.g. magnet)

surrounding the beam impact areab. Irradiation time: 20 yearsc. Compare hazard factors of compounds per unit volume

Example 1

Hazard factor comparison: Operational: 0.227 (Aluminium 5083) versus 2.36 (Steel 316L)Waste: 0.179 (Aluminium 5083) versus 7.18 (Steel 316L)

Aluminium 5083 provides a 10 times lower operational radiological hazard and a 40 times lower waste related hazard factor than Steel 316L.

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Concrete tunnel

7 TeV protons

Proton Beam

For a test lasting one year a container for an LHC collimator has to be built. It was proposed to build the container either of Steel 316L, Titanium Grade6 or Tungsten. What is in terms of radiological consequences the best choice?

Summary of situation:a) Foreseen location: locations close to a collimatorb) Duration of its stay at this position: 1 operational year (200 days)c) Material choice: Steel 316L, Titanium Grade6 or Tungsten ?

Parameters to be chosen for retrieving the correct data:a. Irradiation location: 7 TeV; activation occurring at 10 cm lateral distance to target b. Irradiation time: 200 daysc. Compare hazard factors of compounds (Steel 316L, Titanium Grade6) and elements (Tungsten) per

unit volume respectively.

Example 3/1

Hazard factor comparison: Operational hazard: 1.72 (Steel 316L) versus 1.06 (Titanium Grade6) versus 3.44 (Tungsten).Waste hazard: 0.819 (Steel 316L) versus 0.972 (Titanium Grade6) versus 2.75 (Tungsten).

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Example 3/2

Hazard factor comparison: Operational hazard: 1.72 (Steel 316L) versus 1.06 (Titanium Grade6) versus 3.44 (Tungsten).Waste hazard: 0.819 (Steel 316L) versus 0.972 (Titanium Grade6) versus 2.75 (Tungsten).

First conclusions• Tungsten can be excluded from the choice• Waste and operational hazard ratio inverted lower external exposure but higher risk of

producing radioactive waste

Titanium Grade6 should be taken as material to build the collimator container.

How to proceed in such a case:

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Concrete tunnel

7 TeV protons

Proton Beam

For a test lasting one year a container for an LHC collimator has to be built. It was proposed to build the container either of Steel 316L, Titanium TiNb or Tungsten. What is in terms of radiological consequences the best choice?

Summary of situation:a) Foreseen location: locations close to a collimatorb) Duration of its stay at this position: 1 operational year (200 days)c) Material choice: Steel 316L, Titanium TiNb or Tungsten ?

Parameters to be chosen for retrieving the correct data:a. Irradiation location: 7 TeV; activation occurring at 10 cm lateral distance to target b. Irradiation time: 200 daysc. Compare hazard factors of compounds (Steel 316L, Titanium TiNb) and elements (Tungsten) per

unit volume respectively.

Example 4/1

Hazard factor comparison: Operational hazard: 1.72 (Steel 316L) versus 1.63 (Titanium TiNb) versus 3.44 (Tungsten).Waste hazard: 0.819 (Steel 316L) versus 1.91 (Titanium TiNb) versus 2.75 (Tungsten).

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Example 4/2

Hazard factor comparison: Operational hazard: 1.72 (Steel 316L) versus 1.63 (Titanium TiNb) versus 3.44 (Tungsten).Waste hazard: 0.819 (Steel 316L) versus 1.91 (Titanium TiNb) versus 2.75 (Tungsten).

First conclusions• Tungsten can be excluded from the choice• Waste and operational hazard ratio inverted lower external exposure

Call RP for further advice in that matter.

How to proceed in such a case: