HTS Tl-based coatings for FCC beam screens - Radiation Protection Aspects - Markus WIDORSKI, DGS-RP Information on ActiWiz: Courtesy of Chris Theis, DGS-RP FCC HTS beam-screen 13 Nov

Overview Activation of materials Optimisation during design Tool: ActiWiz HTS coating for beam screens – preliminary considerations FCC HTS beam-screen 13 Nov

Activation of materials Activation of the beam screen (in the arcs mainly) through radiation from beam-gas interactions Spallation and nuclear reactions lead to residual radioactivity Operational impact + Waste impact FCC HTS beam-screen 13 Nov

Optimisation during design Minimize production of critical isotopes or limit quantities Chose material with low activation properties to reduce residual dose rate and radioactivity Consider waste conditioning for compound materials  Reduce handling time Avoid materials for which no radioactive waste elimination pathway exists (e.g., highly flammable metallic activated waste) Chose radiation resistant materials FCC HTS beam-screen 13 Nov

An optimised design … Minimizes doses received by personnel during maintenance and repair Reduces downtime due to faster access and less restrictions for handling Limits handling for waste conditioning Reduces costs for waste disposal when able to clear a larger part of the material FCC HTS beam-screen 13 Nov

ActiWiz  Computer code based on a risk model using pre-calculated FLUKA (MC simulation) results, created by Ch. Theis & H. Vincke  Considers external exposure and radioactive waste disposal criteria  Provides radiological hazard assessment for arbitrary materials within a few seconds  Catalogue, produced with ActiWiz, listing pre-processed risk factors for typical accelerator construction materials as well as natural elements  Web-based catalogue (ActiWeb) allowing user friendly comparison of pre-processed materials  Check out: The tool to optimise during the design phase FCC HTS beam-screen 13 Nov

Current status – version 2.x assessment of radiological hazard for materials V 1.0 calculation of nuclide inventories - current version V 2.0 New generic generation of ActiWiz; under development (to be released in 2016) V 3.0 FCC HTS beam-screen 13 Nov

Workflow – material hazard factors Characterisation of radiation fields Calculation of nuclide production Time evaluation of nuclide inventory Post processing  raw hazard data Integration into ActiWiz risk model ActiWiz 2.x FLUKA INHOUSE ACTIWIZ CREATOR Characterisation of radiation fields ActiWiz 3 FLUKA Integration into ActiWiz risk model Calculation of nuclide production Time evaluation of nuclide inventory Post processing  raw hazard data FCC HTS beam-screen 13 Nov

ActiWiz output example Steel 316L Cast iron Main contributor: 54 Mn produced on Iron Main contributors: 60 Co (61%) produced on Cobalt 54 Mn (37%) produced on Iron 20 years irradiation 2 years cooling 10

LayerThickness est Total mass est FCC P5061 mm2 x ~ 73 t Cu0.3 mm2 x ~ 23 t Ag0.01 mm2 x ~ 0.9 t HTS*0.01 mm2 x ~ 0.6 t * (Tl,Pb,Bi) 1 (Ba,Sr) 2 Ca 2 Cu 3 (O,F) 8, est = 6.7 g/cm 3 FCC beam-screen and coating layers Silver and HTS quantities are ”small” at the FCC scale FCC HTS beam-screen 13 Nov

Relevant produced isotopes LayerIsotopes P506Mn-54, Fe-55, Co-60, Co-56 CuCo-60 AgAg-110m, Ag-108m Bi 1 (Ba,Sr) 2 C a 2 Cu 3 O 8 Po-208, Po-209, Po-210, Bi-207, Cs-134, Co-60, Cs-137, Ba Mn-54, Na-22 Pb 1 (Ba,Sr) 2 Ca 2 Cu 3 O 8 Cs-134, Co-60, Cs-137, Ba Mn-54, Na-22 Scenario: 20 y irradiation, 1 y cool down, waste elimination criteria, 7 TeV, activation within bulky material (e.g. magnet) surrounding the beam impact area FCC HTS beam-screen 13 Nov

ActiWiz output: stainless steel, operational hazard FCC HTS beam-screen 13 Nov

ActiWiz output: stainless steel, waste hazard FCC HTS beam-screen 13 Nov For equal mass !

ActiWiz output: HTS, waste hazard FCC HTS beam-screen 13 Nov For equal mass !

ActiWiz output: beam screen, waste hazard FCC HTS beam-screen 13 Nov For equal mass !

Some conclusions Silver is considered as highly critical element due to its radiotoxicity and should be avoided – but quantities matter. Alternatives ? Bismuth is a critical element and will lead to the production of long- lived alpha emitters; should be avoided Lead is a critical element, where restrictions may apply for radioactive waste elimination, again quantities and chemical form matters Thallium, no conclusion can be given for now; as it is the lightest of the three heavy elements, it might be the least problematic one  ActiWiz 3 Replacing Barium by Strontium is recommended Replacing Fluor by Oxygen is recommended Chemical toxicity matters as well for waste handling ! FCC HTS beam-screen 13 Nov

Next … With ActiWiz 3... Re-evaluation for beam-gas interaction spectrum at FCC parameters Include Thallium Whatever compounds may be considered, the comparison of the radiological impact will be simple with ActiWiz 3. And further … Evaluation of activity concentration values Waste conditioning requirements and elimination pathway  Coating removal at elimination ? FCC HTS beam-screen 13 Nov