FLUKA radioprotection calculations Maria – Ana Popovici Politehnica University of Bucharest

Dose Legal Limits in Romania ProfessionalPublic Efective dose rate (CNCAN, NSR- 06) 20 mSv /year 55 μSv/day 2.3 μSv/h 1 mSv/year ≈ 2.7μSv/day ≈ 0.11 μSv/h NSR-01 Monitorul Oficial al Romaniei Partea I nr. 404 bis / Fundamental Norms for Radiological Safety

Overview FLUKA simulations of ELI-NP facility “hot spots” (from a radioprotection point of view) were performed for: Gamma Source a) 600 MeV electron beam dump b) 19.5 MeV gamma beam dump (E7, E8 in the general layout) 10 PW Laser (E1)

ELI-NP Facility Layout

FLUKA Settings – Defaults Precisio EMF on Rayleigh scattering and inelastic form factor corrections to Compton scattering activated Detailed photoelectric edge treatment and fluorescence photons activated Low energy neutron transport on down to thermal energies included, (high energy neutron threshold at 20 MeV) Fully analogue absorption for low-energy neutrons Particle transport threshold set at 100 keV Multiple scattering threshold at minimum allowed energy, for both primary and secondary charged particles

FLUKA Settings Delta ray production on with threshold 100 keV Heavy particle e+/e- pair production activated with full explicit production (with the minimum threshold = 2m_e) Heavy particle bremsstrahlung activated with explicit photon production above 300 keV Muon photonuclear interactions activated with explicit generation of secondaries Heavy fragment transport activated

Materials (FLUKA input) Normal concrete (walls)  Normal concrete, used at ELBE(FZD); density 2.6 g/cm3 Composition (mass fraction): HYDROGEN ; OXYGEN ; SILICON ; SODIUM ; MAGNESIU ; ALUMINUM ; IRON ; POTASSIU ; CALCIUM ; TITANIUM ; FLUORINE ; SULFUR ; PHOSPHO ; CHLORINE Heavy concrete (beamdumps)  MPQ Concrete; densiy g/cm3 Composition (mass fraction): HYDROGEN – ; BORON CARBON – ; OXYGEN – ; FLUORINE – E-4; SODIUM E-4 ; MAGNESIU – ; ALUMINUM – ; SILICON – ; PHOSPHO – ; SULFUR – E-4; POTASSIUM – E-4; CALCIUM – ; TITANIUM E-5; MANGANES – ; IRON – ; STRONTIU E-4

Materials (FLUKA input)  Stainless steel (electron pipeline, laser beamdump – as an alternative) AISI316LN; density 7.8 g/cm3 Composition (mass fraction): IRON – ; CHROMIUM ; NICKEL ; MANGANES ; SILICON ; PHOSPHO - 4.5E-4; SULFUR - 3.E-4; CARBON - 3.E-4  Borated polyethylene (beamdump); density g/cm3 Composition (mass fraction): CARBON – ; HYDROGEN – ; OXYGEN – ; BORON-11 – ; BORON-10 –  Wet air (air with moisture); density g/cm3 Composition (mass fraction): NITROGEN ; OXYGEN ; CARBON ; ARGON ; HYDROGEN

Source terms (FLUKA input) Gamma Source ( ELI-NP White Book) a) Electrons: 600 MeV electron beam, 250 pC/pulse, 12kHz, Div = 0.1 mrad, Gaussian, FWHM = 6 MeV b) Photons: 19.5 MeV gamma beam, 8.0E+08 g/pulse, Div = 0.1 mrad, Gaussian, FWHM = MeV

Source terms (FLUKA input) 10 PW Laser (I = 1.0E+22) - (ELI-PP White Book - draft) Hz, 300 J pulse-1 a) Photons 3 thermal components with CUTOFF energy at 4 MeV, isotropic T1 = MeV, N1 = 1.1E+14 sr-1 pulse-1 T2 = 0.58 MeV, N2 = 1.0E+14 sr-1 pulse-1 T3 = 8.8 MeV, N3 = 9.0E+11 sr-1 pulse-1 b) Electrons 38 GeV Gaussian beam, FWHM = 1MeV, CUTOFF energy at 38 GeV, N = 9.0E+13 sr-1 pulse-1, Div = 1o

Source terms (FLUKA input) c1) Protons 1 thermal component with CUTOFF energy at 2 GeV, isotropic T = 20 MeV, N = 1.0E+07 sr-1 pulse-1 c2) Protons uniform energy distribution between 0 and 2 GeV, isotropic T = 20 MeV, N = 1.0E+07 sr -1 MeV -1 pulse PW Laser (I = 1.0E+23) – ELI-PP estimations concerning only protons First estimation 1 thermal component with CUTOFF at 100 MeV, Div = 40 o T = 20 MeV, N = 5.0E+13 sr -1 pulse -1 Second estimation uniform energy distribution between 0 and 100 MeV, Div = 40 o N = 5.0E+13 sr-1 MeV -1 pulse -1

Gamma Source Electron Beamdump - Geometry  Cave dimensions: 19m x 5m x 11m  Lateral walls, roof, floor – thickness = 1m Exception: lateral wall for beamline admitance 1.5 m  Beamline: diameter = 2cm, 2mm thick, in AISI316LN, 1mm thick Al cap

Gamma Source Electron Beamdump - Geometry Beamdump: 6m x 4.5m x 8m in MPQ concrete (Martin Gross design) Beamdump core: graphite (cone, diameter = 10cm, height = 50cm), Al (cylinder, diameter = 10cm, height = 30cm)

Gamma Source Electron Beamdump – FLUKA Simulation

Gamma Source Gamma cave + Beamdump Geometry Cave E7: 8m x 5m x 8m Cave E8: 8m x 5m x 5m Walls – 1.5 m thick Wall opposite to the admitance of the beamline is 2m thick

Gamma Source Gamma cave + Beamdump Geometry Beamdump dimensions: 3m x 3m x 4m Beamdump in normal concrete Central hole in beamdump: 30 cm diameter, 1m length Beamline in stainless steel, diameter 2 cm, 2 mm thick walls, 1 mm thick exit cap in Al.

Gamma Source Gamma cave – FLUKA Simulation

10 PW Laser Laser Cave & Reaction Chamber Geometry Cave dimensions: 5m x 5m x 10m Lateral walls, roof, floor – thickness = 1.5 m Reaction chamber dimensions 1.3m x 1.5m x 2.85m Wall thickness – 6 cm Pipe: diameter = 40 cm, 2cm thick, 2 m length in Al, 2mm thick Al cap

10 PW Laser First Beamdump Geometry & Materials 3m x 3m x 7.5m MPQconcrete BD 50 cm Bor_Poly inside cave Lead core 1.3m x 1.3m x 3m Central hole: 2m long cylinder (diameter = 15cm) + 50 cm height cone

10 PW Laser Second Beamdump Geometry & Materials 3m x 3m x 7.5m AISI316LN stainless steel BD 1m Bor_Poly inside cave 1m Bor_Poly outside the external region of BD Graphite core 1m long cylinder (diameter = 20cm) + 50 cm height cone Central hole: 1m long cylinder (diameter = 20cm)

10 PW Laser Electrons – FLUKA Simulation

10 PW Laser Photons – FLUKA Simulation

10 PW Laser Protons – FLUKA Simulation

10 PW Laser - 1.0E+22 W cm -2 Protons 1 thermal component with CUTOFF energy at 2 GeV, isotropic T = 20 MeV, N = 1.0E+07 sr-1 pulse-1 Protons uniform energy distribution between 0 and 2 GeV, isotropic N = 1.0E+07 sr-1 MeV-1 pulse-1

10 PW Laser - 1.0E+22 W cm -2 Protons (thermal) – FLUKA Simulation

10 PW Laser - 1.0E+22 W cm -2 Protons (uniform) – FLUKA Simulation

10 PW Laser - 1.0E+23 W cm-2 Protons (thermal) – FLUKA Simulation

10 PW Laser - 1.0E+23 W cm-2 ELI-PP estimations concerning only protons 1 thermal component with CUTOFF at 100 MeV, Div = 40 o, T = 20 MeV, N = 5.0E+13 sr-1 pulse-1, uniform energy distribution between 0 and 100 MeV, Div = 40 o, N = 5.0E+13 sr-1 MeV-1 pulse-1

10 PW Laser - 1.0E+23 W cm-2 Protons (uniform) – FLUKA Simulation

Conclusions All the radiation sources at the ELI-NP facility are shieldable in the present simplified layout, even in an uninterrupted 0.1 Hz working regime. An important exception: protons with a rectangular energy distribution. If this source term definition will prove to be valid, then a limitation of the number of shots per day will become necessary. In order to avoid such unwanted limitations, more realistic source definitions would be very helpful.

Conclusions The present calculations are schematic and changes in these results are naturally expected once building and experimental setup details are taken into account. Shielding calculations with FLUKA transport code can and need to be refined, but this requires the cooperation of members of the experimental groups, who need to provide detailed description of their setups. Also, the problem of the source term definition should find a realistic solution for each type of experiment which is to be performed.