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FLUKA for accelerator radiation protection –Indian perspective. Sunil C Accelerator Radiation Safety Section Radiation Safety Systems Division , Bhabha Atomic Research Centre. Accelerator Radiation Safety Section. Operational radiation protection Associated R&D

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fluka for accelerator radiation protection indian perspective

FLUKA for accelerator radiation protection –Indian perspective

Sunil C

Accelerator Radiation Safety Section

Radiation Safety Systems Division,

Bhabha Atomic Research Centre

accelerator radiation safety section
Accelerator Radiation Safety Section
  • Operational radiation protection
  • Associated R&D
  • Heavy Ion Accelerators (TIFR Bombay and VECC, Calcutta
    • ~5-7 MeV/amu Pelletron
    • ~10 MeV/amu with a superconducting linac booster
    • ~100 MeV/amu superconducting cyclotron
  • Electron accelerators (RRCAT Indore)
    • 20 MeV Microtron to 2.5 GeV electron synchrotron
    • High current industrial accelerators
future plans
Future plans
  • ADSS
    • Proton accelerators
      • 20 MeV to 1 GeV
      • Swimming poll critical reactor that can also be operated in sub critical mode with 600 MeV protons incident on LBE
    • 14 MeV neutron generators
      • Bare
      • Injectors for sub critical assemblies
uses of fluka
Uses of FLUKA
  • Routine accelerator radiation protection
    • Source term calculations
    • Shielding
    • Induced activity
    • Synchrotron hutch shielding
    • Photoneutron estimation
  • ADSS
  • Proton accelerators
  • Secondary particle dose from heavy Ion reactions
  • Muon Transport and dose estimation
  • Spallation yields comparison with JQMD
heavy ion accelerators
Heavy Ion accelerators
  • Neutron source term calculations
    • EMPIRE, PACE (heavy ions) ALICE, PRECO (protons)
    • Transport using the source.f
  • BME!
    • 10 MeV/amu to 100 MeV/amu
    • Hauser-Feshbach for compound nucleus?
  • Induced activity calculations
  • Neutron spectrometry using passive techniques
  • ECR ion sources
    • Simulate electric fields?
electron accelerators
Electron Accelerators
  • Photon (Bremsstrahlung) spectrometry
    • High energy
  • Detector response studies
    • neutrons and photons
  • Photoneutron spectrometry and dosimetry
  • Synchrotron dosimetry
    • Low energy (< 10 keV)
photoneutrons
Photoneutrons
  • Contribution to the exposure in electron accelerators
  • A new technique to predict the neutron spectra using empirical relations
    • Spectra from FLUKA fitted to a Maxwellian
      • Temperature
      • Yield
    • Form a couple equation to predict the GDR part of the photoneutron spectrum
the procedure
The procedure

Sunil C, Sarkar P K, “Empirical estimation of photoneutron energy distribution in high energy electron accelerators”, Nuclear Instruments and Methods A 581, (2007), 844-849.

slide11

Independent FLUKA Calculation

Experiment

Our Calculation

neutrons 50 mev
Neutrons > 50 MeV
  • Experimental verification using Bi fission foils, track etch membranes shows higher values when compared to FLUKA calculations.
  • How much is photon induced fission?
  • The cross section is 1% of neutron fission (>200 MeV)
  • But at the experimental area, the photon fluence is expected to be several times higher than neutrons!
  • Calculate photon induced fission using FLUKA?
photon transmission
Photon Transmission
  • 30 cm diameter and 30 cm long cylindrical detector (approximating the upper trunk of a human body) is used to count the photons.
  • USRTRACK estimator tallies the photon fluence.
  • Deq99 (FLUSUW) subroutine used to fold the fluence with the dose conversion coefficients to obtain ambient dose equivalent
residual activity
Residual activity
  • 2.5 GeV electron incident on 10 X0 -1Xm targets.
  • DPMJET activated using PHYSICS
  • LAM-BIAS at 100
  • Photon transport cut off to 10 MeV
residual nuclei
Residual Nuclei
  • In SS, 51Cr was reported by Fasso with a higher neutron cutoff energy.
  • Swanson’s technique and present calculation agree within a factor of 2; for example 57Co in Ni target, 63, 65Cu from Cu target.
  • 59Fe in SS (58Fe(n,)) target in this calculation was found to be four orders less compared to that obtained by Sato and Fasso
  • Most of the important nuclides formed are in the range of 200 -500 MBqW-1.
synchrotron hutch shielding
Synchrotron Hutch Shielding
  • Hutch design in INDUS (2.5 GeV, 1 mA)
  • Bremsstrahlung mixed with SR
  • Experiments claim existence of SR
  • Transportation tough - low energy at the edge of FLUKA capabilities.
  • Can it be simulated using FLUKA?
heavy ion reactions
Heavy Ion reactions
  • Work done at PTB Germany
  • 200 MeV 12C ions on water phantom
  • Score neutron fluence and dose inside 5.7 cm spheres at different angles.
  • Compare with measurements done at GSI
    • Spectra from TOF (GSI measurements)
    • Dose using a TEPC (PTB measurements)
    • Dose using WENDI (GSI measurements)
neutron spectra
Neutron Spectra

200 MeV/amu 12C incident on 15 cm diameter cylindrical water phantom

charged particles
Charged particles

Apply coincidence measurements

response matrices
Response Matrices
  • Neutron attenuation through a target of finite thickness.
  • Response of Bonner sphere type passive techniques.
  • Response of liquid scintillators
  • Bismuth fission detectors
    • Neutron induced fission
    • Photon induced fission
slide29
ADSS
  • A sub critical assembly driven by 14 MeV neutrons
  • 256 nat.U rods inside water column, beam tube at center.
  • Analog mode
  • 36 hours for 106 histories !
  • And still large errors (10%-30%)
proton accelerators for adss
Proton accelerators for ADSS
  • Plans to couple a sub critical reactor to a proton accelerator
  • Source term for lateral shielding of the accelerator tunnel, reactor pool top
  • Residual activity in LBE loop
  • Activation of magnets concrete wall
  • LBE window rupture due to heat load
adss problems
ADSS problems
  • High beam current ;1-5 mA!
  • Proton energies varying from 100 MeV to 1GeV
  • Shielding calculations
    • Reduce dose by 9 orders:- ~7 meters!
  • Induced activity after several meters of water
    • Explicit Transport !? Or calculate neutrons at intermediate thicknesses?
  • Induced activity in magnets, concrete walls.
  • Induced activity in LBE after several combinations of irradiations.
shielding
Shielding
  • Attenuation length from IAEA 283
  • n/p ratio from FLUKA
  • Multiply end result by the n/p ratio to get the transmitted dose after shield
  • Biasing!
simplified view
Simplified view

concrete

7 m

water

Window

further work
Further work
  • Establish attenuation curves for different shield configurations.
    • Different types of concrete
  • Transport neutrons through several meters of water and calculate induced activity.
  • Irradiation profile, raddecay, dcytimes, usrbin