Transcript Induced Activity Calculations in Support of D&D Activities at SLAC

Induced Activity Calculations
in Support of D&D Activities at
SLAC
Joachim Vollaire, Radiation Protection Department
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Outline
• Calculations of the induced activity
– Overview of the MC code FLUKA
– Example : (very) preliminary BABAR
activation calculations
• Similarities with CERN process for LEP
accelerator and experiments D&D
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Calculation of the induced activity (1)
• First step of the proposed process for the
relief of the suspension on unrestricted
release of metal from Radiological Areas
• Due to the nature of the activation
mechanisms (volumetric activation), the
geometry, number and complexity of the
components systematic and very detailed
measurements are not possible of all
components
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Calculation of the induced activity (2)
• Goal of the calculations will be to identify
areas with induced activity above the MDA
• Calculations will be confirmed using
detailed measurements (gamma
spectrometry) / dose measurement during
operation
• Calculation tool proposed for this analysis
is the MC code FLUKA
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The Monte-Carlo code FLUKA
• FLUKA handles the whole joint electromagnetic
and hadronic cascade simulation in complex 3D
geometries
• Possibility to score residual nuclei production
following the particle interactions within the
materials (Nuclei de-excitation)
• Residual activity calculations (and residual dose
rate) performed for complex irradiation patterns
(takes activity buildup/decay, decay chains into
account)
• FLUKA predictions confronted to experimental
results in several dedicated benchmark
experiment
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Example of FLUKA benchmark
• T489 experiment in ESA in 2007 (28.5 GeV ebeam)
• Copper target surrounded by materials typically
found in accelerators structure (Al, Cu, SS, Ti …)
•Irradiation
•gamma spectrometry
• dose rate measurements,
•comparison with calculations
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Example of FLUKA benchmark (2)
Comparison of the calculated and measured residual activity
•Copper sample
down beam of the
target
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Preliminary tests for BABAR activation (1)
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Preliminary tests for BABAR activation (2)
Need to be
changed
• Quasi-Cylindrical symmetry of the system used
• Concentric cylindrical layer with material homogenization
Expected “Source term” of induced activity
• All hadrons and gamma with sufficient
energy to induce nuclear reactions
• Need to be worked out with detector /
accelerator physicists
– e+e- collisions
– e+e- induced photon-photon interactions
– elastic scattering e+e- (Bhabba)
– Particles coming from PEP (collimators…)
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Use of B0B0 events as a test case (1)
All particle fluence
• Known not to be a major source of radiations/activation
• Used asymmetric distribution of particles (difference of
energy)
• Transported e+, e- , kaons, pions, neutrons…
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Use of B0B0 events as a test case (2)
Neutrons fluence
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Use of B0B0 events as a test case (3)
Photons fluence
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Use of B0B0 events as a test case (4)
Pions and Kaons fluence
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Total Induced Activity (from B0B0 events) (1)
• Total induced activity after 10 years of irradiation
and 1 year of cooling
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Total Induced Activity (from B0B0 events) (2)
• Total induced activity after 10 years of irradiation
and 5 years of cooling
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Induced Activity (from B0B0 events)
• Known not to be the dominant source of induced activity
• Induced activity inside the forward IFR plug (steel)
• 10 years of irradiation (1,2 and 5 y of Cooling time)
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Conclusions
• FLUKA is the suitable tool for the analysis
• Significant amount of work has to be put in
the determination of the “source term”
• Experience from LEP/detectors
dismantling for LHC installation is very
useful
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CERN process for LEP and experiments D&D
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CERN process for LEP and experiments D&D
• Waste management in France based on
“Zoning” approach:
– calculation based process to identify areas
with non negligible amount of radioactivity and
define a boundary between :
• Areas with conventional items
• Areas with radioactive items
– No clearance level
• FLUKA was used for LEP waste study