Induced Activity Calculations in Support of D&D Activities at SLAC Joachim Vollaire, Radiation Protection Department

2 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

3 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) 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 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 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) Copper sample down beam of the target Comparison of the calculated and measured residual activity

8 Preliminary tests for BABAR activation (1)

9 Preliminary tests for BABAR activation (2) Need to bechanged Quasi-Cylindrical symmetry of the system used Concentric cylindrical layer with material homogenization

10 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…)

11 Use of B 0 B 0 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 B 0 B 0 events as a test case (2) Neutrons fluence

13 Use of B 0 B 0 events as a test case (3) Photons fluence

14 Use of B 0 B 0 events as a test case (4) Pions and Kaons fluence

15 Total Induced Activity (from B 0 B 0 events) (1) Total induced activity after 10 years of irradiation and 1 year of cooling

16 Total Induced Activity (from B 0 B 0 events) (2) Total induced activity after 10 years of irradiation and 5 years of cooling

17 Induced Activity (from B 0 B 0 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 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

19 CERN process for LEP and experiments D&D

20 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