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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OutlineOutline

• 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)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)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 FLUKAThe 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 Example of FLUKA benchmark

• T489 experiment in ESA in 2007 (28.5 GeV e- beam)

• 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) Example of FLUKA benchmark (2)

•Copper sample down beam of the target

Comparison of the calculated and measured residual activity

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Preliminary tests for BABAR activation (1)Preliminary tests for BABAR activation (1)

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Preliminary tests for BABAR activation (2)Preliminary tests for BABAR activation (2)

Need to be changed

• Quasi-Cylindrical symmetry of the system used• Concentric cylindrical layer with material homogenization

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Expected “Source term” of induced activityExpected “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)Use of B0B0 events as a test case (1)

• Known not to be a major source of radiations/activation• Used asymmetric distribution of particles (difference of

energy)

• Transported e+, e- , kaons, pions, neutrons…

All particle fluence

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Use of B0B0 events as a test case (2)Use of B0B0 events as a test case (2)

Neutrons fluence

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Use of B0B0 events as a test case (3)Use of B0B0 events as a test case (3)

Photons fluence

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Use of B0B0 events as a test case (4)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 (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 (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)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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ConclusionsConclusions

• 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&DCERN process for LEP and experiments D&D

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CERN process for LEP and experiments D&DCERN 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