1. CATIA users meeting
07/06/2012
Material guidelines project – radiological hazard classification Helmut Vincke, Chris Theis on behalf of DGS/RP
RSO committee – 1/3/2012

2. Contents
Motivation for this project
Introduction to “ActiWiz”
Illustration of the Catalogue: “Radiological Hazard classification of Materials in CERN’s accelerator environments“

3. End of life-cycle benefit
Motivation
Beside other aspects also the radiological consequences of the implementation of a material have to be considered
Material being placed in an accelerator environment can become significantly radioactive  undesirable
The activation depends on the type of the material
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
S. Myers initiated the project concerning the radiological classification of materials

4. Using brass instead of iron as shielding @ COMPASS-2?
Use-case
Using brass instead of iron as COMPASS-2?
Outside:
brass vs. iron  significantly worse
Next to target:
brass vs. iron  equivalent
 very strong dependence on radiation environment
 need for “CERN specific” assessment in contrast to experience from nuclear industry

5. 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
* Helmut Vincke & Chris Theis, ActiWiz – a computer code to model and assess radiological hazards of activated material, CERN-DGS RP-TN, EDMS , (2011)

6. Categorization of the radiation environments (energy)
FLUKA calculations of typical hadronic particle spectra (p, n, p+, p-) in CERN’s accelerators
LHC
SPS
Linac 4 + Booster PS
160 MeV (Linac4), 1.4 GeV (Booster), 14 GeV/c (PS), 400 GeV/c (SPS), 7 TeV (LHC)

7. 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)

8. Radiological assessment of materials
Time of material present in accelerator (irradiation time)
Energy (machine)
Position in accelerator
Radiological hazard assessment for a given materials
ActiWiz – software evaluate radiological hazard for arbitrary materials with a few mouse clicks

9. ActiWiz – program interface
1.) Select energy / location / irradiation times
2.) Define material composition based on 69 chemical elements
* Many thanks to R. Froeschl for providing activation data on Zinc

10. Radiological hazard assessment
Output of ActiWiz
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)
Program flags materials with significant hazard if incorporated (destructive work)

11. Material catalogue 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

12. Catalogue for the radiological hazard classification of materials
Catalogue consists of three parts:
Introduction
List of critical materials in terms of handling & waste disposal*
Appendix with data
* Many thanks to Luisa Ulrici (DGS-RP-RW) for elaborating and providing the waste disposal guidelines
Provides radiological guidelines via hazard values  cannot replace Monte Carlo studies by a specialist for specific cases outside of the generic irradiation scenarios assumed

13. Catalogue for the radiological hazard classification of materials
Implementation & processing
of material list with ActiWiz
Assessment of results and compilation in a catalogue to be used by beam-line physicists, designers, etc.
Research most common materials CERN
Authors of this catalogue: Robert Froeschl, S. Sgobba, Chris Theis, Francesco La Torre, Helmut Vincke and Nick Walter
We would like to thank for their contribution & discussions:
J. Gulley, D. Forkel-Wirth, S. Roesler, M. Silari and M. Magistris

14. Catalogue structure Various energies/momenta
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
Materials not addressed by the catalogue can be assessed with the ActiWiz program

15. Two hazard factor types are available
Hazard factor per volume unit
Hazard factor per mass unit
MAIN APPLICATION
Applications for “hazard factors per volume unit”:
Choosing material for non-bulky objects (the thickness of the object for which the material is chosen should be less than 10 cm iron equivalent).
For choosing material for massive objects (thickness of more than 10 cm iron equivalent) if the density variation between the different materials is < 2.
Applications for “hazard factors per mass unit”:
Evaluation of the influence of chemical elements on the hazard factor of a compound (e.g.: change of hazard factor of a compound when x wt% of element A is added).
Massive objects of a thickness of more than 10 cm iron equivalent if the density variation between the different materials is > 2  (ActiWiz program has to be used).

16. Examples for using the catalogue

17. Example 1
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:
Foreseen location: beside LHC magnet
Duration of its stay at this position: LHC life time
Material choice: either Aluminium 5083 or Steel 316L
Parameters to be chosen for retrieving the correct data:
Irradiation energy + location: 7 TeV; activation occurring adjacent to bulky material (e.g. magnet) surrounding the beam impact area
Irradiation time: 20 years
Compare hazard factors of compounds per unit volume
Hazard factor comparison: Operational: (Aluminium 5083) versus 2.36 (Steel 316L)
Waste: (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.
Concrete tunnel
7 TeV protons
Proton Beam
In case only steel desired (e.g.: mechanical reasons) Very good choice: Steel PSI02* Hazard factors: operational: 1.41, waste: 1.39  better than Steel 316L
*Note: this example refers solely to radiological properties. The chosen materials might differ strongly in terms of other aspects (corrosion stability, elasticity, …)

18. Example 2
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:
Foreseen location: concrete wall beside SPS magnets
Duration of its stay at this position: SPS life time
Material choice: is 1% of hafnium acceptable?
Parameters to be chosen for retrieving the correct data:
Irradiation energy + location: 400 GeV/c; activation occurring close to the concrete tunnel wall (beam loss in bulky material)
Irradiation time: 20 years
Find hazard factor of hafnium in table listing elements per mass unit
Proton Beam
Hazard factor comparison: Hazard factor comparison Hazard of elements per mass unit:
Operational: (copper) versus 976 (hafnium);
Waste: (copper) versus (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

19. Example 3/1
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:
Foreseen location: locations close to a collimator
Duration of its stay at this position: 1 operational year (200 days)
Material choice: Steel 316L, Titanium Grade6 or Tungsten ?
Parameters to be chosen for retrieving the correct data:
Irradiation location: 7 TeV; activation occurring at 10 cm lateral distance to target
Irradiation time: days
Compare hazard factors of compounds (Steel 316L, Titanium Grade6) and elements (Tungsten) per unit volume respectively.
Concrete tunnel
7 TeV protons
Proton Beam
Hazard factor comparison:
Operational hazard: (Steel 316L) versus 1.06 (Titanium Grade6) versus 3.44 (Tungsten).
Waste hazard: (Steel 316L) versus (Titanium Grade6) versus 2.75 (Tungsten).

20. Example 3/2 Hazard factor comparison:
Operational hazard: (Steel 316L) versus 1.06 (Titanium Grade6) versus 3.44 (Tungsten).
Waste hazard: (Steel 316L) versus (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
How to proceed in such a case: If the ratio between the two waste factors (higher/smaller) is less than two times higher than the ratio between the two operational factors (higher/smaller) the material with the smaller operational factor shall be chosen.
Titanium Grade6 should be taken as material to build the collimator container.

21. Example 4/1
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:
Foreseen location: locations close to a collimator
Duration of its stay at this position: 1 operational year (200 days)
Material choice: Steel 316L, Titanium TiNb or Tungsten ?
Parameters to be chosen for retrieving the correct data:
Irradiation location: 7 TeV; activation occurring at 10 cm lateral distance to target
Irradiation time: days
Compare hazard factors of compounds (Steel 316L, Titanium TiNb) and elements (Tungsten) per unit volume respectively.
Concrete tunnel
7 TeV protons
Proton Beam
Hazard factor comparison:
Operational hazard: (Steel 316L) versus 1.63 (Titanium TiNb) versus 3.44 (Tungsten).
Waste hazard: (Steel 316L) versus 1.91 (Titanium TiNb) versus 2.75 (Tungsten).

22. Example 4/2 Call RP for further advice in that matter.
Hazard factor comparison:
Operational hazard: (Steel 316L) versus 1.63 (Titanium TiNb) versus 3.44 (Tungsten).
Waste hazard: (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
How to proceed in such a case: If the ratio between the two waste factors (higher/smaller) is more than two times higher than the ratio between the two operational factors (higher/smaller) RP has to be called for further advice.
Call RP for further advice in that matter.

23. Web-based catalogue: ActiWeb http://actiweb.cern.ch
Interactive web-based catalogue in collaboration with software developer Fernando Leite Pereira (DGS/RP).

24. Summary
ActiWiz software  allows to quickly quantify radiological hazard of material implemented into CERN’s accelerator environment.
69 elements and most common metals and construction materials were processed  first version of a catalogue is now available (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.

25. Thank you for your attention