The use of ActiWiz in operational RP

1. SATIF 12 28-30 April 2014 FNAL The use of ActiWiz in operational RP Chris Theis, Helmut Vincke DGS/RP, CERN

2. Outline • Introduction to ActiWiz • The new features & their use in RP • build-up & decay engine • shielding module • Shielding benchmark

3. Introduction to ActiWiz • Code to assist in the selection of materials for high energy proton accelerators* • Specifically developed risk assessment model • Focus group: beam-line physicists, designers * H. Vincke, C. Theis, “ActiWiz – optimizing your nuclide inventory at proton accelerators with a computer code”, Proceedings of the ICRS12 conference, 2012, Nara, Japan, Progress in Nuclear Science and Technology, in print (2013).

4. Introduction to ActiWiz Sometimes more details related to activated material are of interest: e.g. electronics Courtesy of S. Damjanovic radiotoxicity& waste clearance, dominating isotopes, shielding …

5. Introduction to ActiWiz clearanceauthorization limits ActiWiz scenarios(based on FLUKA) g emission spectra decay engine • Nuclide inventory Monte Carlo dominating isotopes g spectroscopy isotope production sources* shielding module residual dose rate shielding * for ActiWiz scenarios only

6. Build-up & decay engine Nuclide production source term Build-up & decay engine for chains Full analysis ActiWiz gamma library Irradiation & cooling pattern Beam intensity can be defined via: GUI, formulas & variables Time

7. Build-up & decay engine Production & decay described via Bateman equations Nn … Number of isotope n Pn … Production rate of isotope n ln … Decay constant of isotope n bn … Branching ratio from isotope n-1 into n k … index of irradiation/cooling cycle Laplace transform (L) decay build-up can become indeterminate (e.g. stable nuclides l = 0)

8. Build-up & decay engine • decay description based on JEFF 3.1.1 • fully analytical solution • dedicated mathematical treatment of indeterminate cases • numerical issues: • double precision fails for 1kg of U-238 decaying for 100y(subtraction cancellation, exp. function, finite precision) • arbitrary precision arithmeticsimplemented with 512 bits • significand ~ 170 digits

9. The shielding module The gamma energies found in an activated electronic circuit board coming from the LHC (~60.000): • one clearly needs a numerical, iterative solution to find a shielding thickness for a complex nuclide mixture.

10. The shielding module • notintended for assessments of prompt radiation • shield residual activation, equipment which should be transported • very fast and works with nuclide inventories as an input: • nuclide inventories calculated with ActiWiz • nuclide production results calculated with FLUKA • ActiWiz exchange format for other sources (MARS, MCNP, Phits, …) • Canberra gamma spectroscopy reports (ASCII format)

11. The shielding module • works in relative units  relative attenuation factor (e.g. 1/10) • limited to photons • treats possible dose build-upin shielding via • interpolated factors (ANS geometric progression form) • comprises: concrete, iron, lead, tungsten, aluminium, tin, uranium, water • fast (deterministic): ~60.000 contributors take about 1 second to calculate this curve with 100 pointson a medium level PC

12. The shielding module - benchmark • Nucleonica*: suite of tools, well established in nuclear industry • both codes apply a deterministic approach • ActiWiz & Nucleonica show very good agreement • for Cs-137, Co-60 and nuclide mixture within a few % • small differences can be due to different nuclear libraries • that are being used & different algorithms * http://www.nucleonica.com

13. The shielding module - benchmark

14. Comparison with FLUKA Shielding thickness to attenuate Cs-137 to 1/10: deterministic methods are more conservative, proposing 0.4 cm more lead or 4.5 cm more concrete shielding

15. Comparison with FLUKA • deterministicmethods propose slightly thicker shielding (10-20%)  why? • dose build-up: shielding thickness& distances • stochastic solutions take geometry into account with high accuracy • deterministic approaches use conservative “one-size-fits-all” build-up function  approximation agreement within 10-20% can be considered as good

16. Summary & conclusions • ActiWiz: material optimization at high energy proton accelerators • extended for RP studies based on nuclide inventories(waste clearance, dominating isotopes, impact of impurities,…) • decay & build-up + shielding modules developed • code fully parallelized & comes with GUI • automatized analysis + reports and plots

17. Thanks for your attention

18. Primary output of ActiWiz Nuclide inventory & dominant isotopes Safety relevant quantities (activity, H*(10), radio-toxicity)

19. Example 1 – rad. hazard assessment 1 wt-% of hafnium shall be used as an additive to a copper cable. The cables are placed in cable trays attached to the concrete tunnel wall alongside to SPS magnets. Question arising: Is 1% of hafnium in terms of radiological consequences an acceptable choice? • Summary of situation: • Foreseen location: concrete wall beside SPS magnets • Duration of its stay at this position: SPS life time • Material choice: is 1% of hafnium acceptable? Things to be done in the ActiWiz program: Build your compounds (pure copper and copper +hafnium) and load them for comparison Choose Irradiation energy + location Things to be retrieved from the ActiWiz output file: Hazard factors for the two materials

20. Results – example 1 Ratio: ~2/1 ~100/1 * lower values = better The addition of 1 wt% of Hafnium considerably increases the dose (operational hazard) but its effect on the disposal of the material as radioactive waste is enormous.

21. Nuclide inventories – external sources • Nuclide production data obtained from FLUKA, MCNP(X), PHITS, • spectrum folding routines for air or water activation,…. • Initial nuclide concentrations can be treated as well (Ni > 0 for t = 0) • Optional definition of complex irradiation/cooling patterns

22. Nuclide inventories – external sources Format of external nuclide production source data: 1.) FLUKA residual nuclei ASCII outputs (FLUKA directly, usrsuw or usrsuwev utilities)

23. Nuclide inventories – external sources Format of external nuclide production source data: 2.) ActiWizexchange format: # --------------- D A T A ---------------- # Nuclide Nuc/primary H-3 2.16E-02 Be-7 5.49E-03 Be-10 4.81E-03 Ag-110m8.59E-03 <rel. error [0,1]> <Initial nuclide conc.> optional If no irradiation/cooling pattern is provided  user will be prompted for a simple one Complex patterns with several consecutive irradiation/cooling periods can be defined by: # --------------- EXAMPLARY IRRADIATION PROFILE ---------------- # tfBeamIntensity, IrradiationPeriod, CoolingPeriod define HalfHour3600.0 tf 1e10 / 2.0, 2 * day + 3/4 * HalfHour, 45 * min tf1e5, 1 * year + 2 * month, 0

24. Photon emission spectrum

25. Comparison with FLUKA FLUKA geometry setup: thickness d chosen based on ActiWiz/Nucleonica prediction & extrapolation to MC based 1/10 value using the obtained attenuation

26. ActiWiz – new features • ActiWiz is a proprietary development, currently distributed under an academic license (free of charge) to collaborators • desktop application running under Windows, core lib running under Windows, Linux & Mac, fully written in C++, parallelized code • Decay & buildup + shielding modules: proprietary development • decay data: JEFF-3.1.1 • gamma data: self-assembled library based on ENDF/B-VII.1, JEFF-3.1.1, JEF-2.2 & JENDL-FPDD2000 101539 lines • attenuation data: NIST • dose: M. Pelliccioni, Overview of Fluence-to-Effective Dose and Fluence-to-Ambient Dose Equivalent Conversion Coefficients for High Energy Radiation calculated using the FLUKA Code, RPD 88(4), pp 279 – 297, (2000)

27. Solution to Bateman equations Solution implemented in ActiWiz, including analytic treatment of indeterminate cases*: *Theis, Christian, Helmut Vincke, “Addendum to the build-up and decay engine in ActiWiz”, CERN Technical Note, CERN-RP-2014-017-REPORTS-TN, EDMS 1363771, (2014).