Post on 21-Dec-2015
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
2
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
3
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
4
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
5
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
6
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
7
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
8
Preliminary tests for BABAR activation (1)Preliminary tests for BABAR activation (1)
9
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
10
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…)
11
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
12
Use of B0B0 events as a test case (2)Use of B0B0 events as a test case (2)
Neutrons fluence
13
Use of B0B0 events as a test case (3)Use of B0B0 events as a test case (3)
Photons fluence
14
Use of B0B0 events as a test case (4)Use of B0B0 events as a test case (4)
Pions and Kaons fluence
15
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
16
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
17
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)
18
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
19
CERN process for LEP and experiments D&DCERN process for LEP and experiments D&D
20
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