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

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

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

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

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-2011-067-RP-TN, EDMS 1161816, (2011)

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)

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)

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

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

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)

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

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

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 used @ 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

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

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).

Examples for using the catalogue

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: 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. 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, …)

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: 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 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: 200 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: 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).

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 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.

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: 200 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: 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).

Example 4/2 Call RP for further advice in that matter. 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 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.

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

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.

Thank you for your attention www.cern.ch/actiwiz