Simulation of photon-nuclear interaction in production of medical isotopes and transmutation of nuclear waste

Transcription

1 Simulation of photon-nuclear interaction in production of medical isotopes and transmutation of nuclear waste Barbara Szpunar Collaboration with Prof. Chary Rangacharyulu Available on: October 7 th, 2010, Eucera 1 st Advanced FLUKA Workshop B.Szpunar@usask.ca

2 Content Purpose of this work and introduction Details on FLUKA input file Photon induced artificial transmutation Medical isotope production Photofission Treatment of long-lived isotopes in nuclear waste Summary and conclusions

3 Purpose of this work and introduction Shortage of medical isotopes call for alternative production methods Most widely used Mo -> m Tc (~35 common radiopharmaceuticals) m Tc -> Tc + γ Each diagnostic uses few GBq (1GBq = Ci) EPAC 2000 Vienna, world uses: 150,000 Ci/year Proton cyclotrons located close to hospital can supply average usage: e.g. at CHUS, Sherbrooke 10 Ci/week of m Tc m Tc is short-lived (T 1/2 = h) therefore Mo (T 1/2 = h) needed for remote, small hospitals

4 Mo and other medical and industrial usage isotopes can be produced using photons at Giant Dipole Resonance energies E Giant Dipole Resonance 80 Energy / Width [MeV] Energy Width 20 77*A -1/3 23*A -1/ Atomic mass

5 April 2010, Canadian Light Source, workshop CLS equipped with a CO 2 laser back scatter system to test the feasibility of application of photo-nuclear transmutations Discussion and collaboration with international community (Japan (JAEA), USA) Achievable at CLS maximum photon energy: 15 MeV for 2.9 GeV electron beam energy (0 degree incident angle) Supportive FLUKA simulation: design of experiment, evaluation

6 FLUKA; input file GLOBAL DEFAULTS PRECISIO PHYSICS 1. COALESCE PHYSICS 3. EVAPORAT BEAM PHOTON BEAMPOS GEOBEGIN COMBNAME. GEOEND PHOTONUC Mo100 Mo100 LAM-BIAS Mo100 PHOTON 0.0 LOW-MAT LEAD PB.. USRBIN 10. ENERGY EneDep USRBIN & RESNUCLE TARGET 1.0Target USRTRACK -1. PHOTON -71. TARGET photon USRTRACK 1. 1D-12 & USRTRACK -1. PROTON -71. TARGET proton USRTRACK 1.0 1D-12 & USRTRACK -1. NEUTRON -71. TARGET neutron USRTRACK D-12 &

7 Photonuclear reaction; biasing 193 Ir of cylindrical shape (0.01 m diameter, 0.04 m height) in spherical lead container (0.3 m radius) Produced Isotope (reaction) Yield [per one photon/cm 3 ] Error [%] (n,γ) 194 Ir 1.36x (γ,e + e - ) 193 atomic Ir 1.28x (γ,n) 192 Ir 2.04x (γ,2n) 191 Ir 9.00x Produced Isotope (reaction) Yield [per one photon/cm 3 ] Error [%] (n,γ) 194 Ir 1.33x (γ,e + e - ) 193 atomic Ir 1.28x (γ,n) 192 Ir 2.04x (γ,2n) 191 Ir 9.16x (γ,p) 192 Os 1.97x No biasing Hadronic interaction length reduced by a factor 0.02 Proceedings, CNS 31st Annual Conference, Montreal, May 24-27, 2010

8 I: FLUKA hybrid simulations Five runs (each 10 6 particles, GDR energy) Energy deposition, equivalent dose Fluence (n = L particle / V target dn/dlne): neutron, photon, proton Residual nuclei (R n - per particle) No time dependence Time dependence Calculate induced activity for a given beam intensity (I) N( t t i ) R (1 e t / dn( t ti) ti i R(1 e ) e dt ) / ( t t ) / R = I * R n t i irradiation time τ mean life Activity N (t) = N(t) Activity atom

9 II: FLUKA induced activity simulations Time dependence Set irradiation and cooling time, beam intensity Perform five runs using FLUKA s exact analytical implementation of Bateman equations for induced activity calculations Total activity Yield FLUKA ASCI files processed using Fortran routines with csv format to create directly EXCEL files for easy plotting

10 FLUKA; Proton versus photon 100 Mo transmutation; Geometry (target: 1.2 cm (d) x 3.6 cm (h)), energy deposition (p,2n) 22 MeV 14.8 MeV (γ,n) Natural Mo: 9.63% 100 Mo, 24.13% 98 Mo

11 FLUKA; Proton versus photon 100 Mo transmutation; Equivalent dose (p,2n) (γ,n) W n : 10 (2-20 MeV), 5 (above) and 20 (below this energy)

12 Produced Isotope (reaction) FLUKA; Proton versus photon 100 Mo Yield [per one proton/cm 3 ] 100 Mo target Pb container transmutation Error [%] (p,n) 100 Tc 5.44x Produced Isotope (reaction) Yield [per one photon/cm 3 ] 100 Mo target Pb container Error [%] (n,γ) 101 Mo # 3.65 x (p,2n) Tc 4.14x10-3 (~ 2x10-3 m Tc) 1 (γ,e + e - ) atomic 100 Mo 7.85 x (p,3n) 98 Tc 7.23x (γ,n) Mo 1.31 x (n,γ) 101 Mo # 1.00x (γ,2n) 98 Mo 6.06 x (p,p) 100 Mo 2.09x (p,n&p) Mo 9.42x (γ,3n) 97 Mo 9.27 x (γ,4n) 96 Mo 1.04 x #Secondary neutron capture; * 98 Mo Natural Mo: 9.63% 100 Mo, 24.13% 98 Mo

13 FLUKA hybrid versus FLUKA calculations 6 x atoms in 1g of Mo NRU produces (in reactor) per year : ~3.65 x Mo atoms ~24 g Mo with 25% Mo Burns 6 g of 10% Mo: 2,887,3 of 10 kg HEU Ci (decay) (90%,-> Al) ~ 60,000 uranium Ci Waste: 9kg HEU EPAC 2000 Vienna, used per year: 150,000 Ci N(t) = Activity g (t)/activity atom Target s weight: 41.6 g Target Irradiation Mo Mo m Tc m T 100 Mo Time [hrs] Activity [Ci] Specific Activity [Ci/g] Activity [Ci] Specific Activity [Ci/g] Mo, T 1/ h m Tc, T 1/ h

14 FLUKA; Photon induced activity Mo T 1/2 = h m Tc T 1/2 = h Target s weight: 41.6 g

15 Photofission versus GDR transmutation Photons (16 MeV) Fission yield per one photon [Nuclei/cm 3 ] (May be heavily underestimated by the FLUKA currently!) β - yield Target Mo(42) Kr(36) Rb(37) Sr (38) Y(39) Zr(40) Nb(41) Mo(42) 238 U 1.17x x x x x x x x10-4 Errors (%) Produced Isotope (reaction) Yield [per one photon/cm 3 ] Error [%] (n,γ) 101 Mo # 3.65 x (γ,e + e - ) 100 atomic Mo 7.85 x (γ,n) Mo 1.31 x (γ,2n) 98 Mo 6.06 x #Secondary neutron capture

16 Fission in FLUKA (geometry, target: 12 cm (d) x 6 cm (h))

17 Photofission versus subcritical thermal and fast neutron s fission

18 Mo production in photofission Photons (12.5 MeV) Subcritical fission yield per one particle [nuclei/cm 3 ] May be heavily underestimated by FLUKA currently! β - yield* Target Mo(42) Kr(36) Rb(37) Sr (38) Y(39) Zr(40) Nb(41) Mo(42) 238 U 2.75x x x x x x x x10-5 Errors (%) U 1.35x x x x x x x x10-3 Errors (%) U 5.54x x x x x x x x10-3 Errors (%) Th 4.00x x x x x x x x10-6 Errors (%)

19 Thermal neutrons Mo production comparison Target 0.12 m diameter and 0.06 m height Fission (subcritical) yield per one neutron [nuclei/cm 3 ] β - yield* Total Target Mo(42) Rb(37) Sr (38) Y(39) Zr(40) Nb(41) Mo(42) Mo(42) 235 U 7.01 x x Errors (%) GDR Produced Isotope (reaction) Yield [per one photon/cm 3 ] Error [%] (n,γ) 101 Mo # 6.88 x (γ,e + e - ) 100 atomic Mo 7.69 x (γ,n) Mo 1.58 x (γ,2n) 98 Mo 8.47 x (γ,3n) 97 Mo 9.71 x (γ,4n) 96 Mo 1.11 x (γ,5n) 95 Mo 1.75 x

20 GDR, photofission versus thermal neutrons fission (subcritical); Energy deposition

21 Photofission versus thermal neutrons fission (subcritical); Fluence No protons

22 Waste management Nuclear waste consists of 0.74% fission products and.26% actinides, with 98.81% uranium and 0.45% longlived transuranic actinides (Ottensmeyer, CNS 2010) Treatment of long-lived isotopes: 79 Se, 93 Zr, 107 Pd, 126 Sn, 129 I and 135 Cs; radio-toxic >10 5 years needed GDR transmutation to short-lived isotopes ( Tc is not transformed to short-lived isotope) 1.57 x10 7 years half-life time of 129 I to 24. min 128 I or h 130 I (secondary neutron capture)

23 Photons versus neutrons I (,n) 128 I 129 I(n, ) 130 I Cross Sections [barns] e-8 1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 Incident Energy [MeV]

24 Long lived waste transmutation; energy deposition & equivalent dose Wn: 10 (2-20 MeV), 5 (above), 20 (below this energy)

25 129 I transmutation by GDR (15.24 MeV ) Produced Isotope (reaction) Yield [per one photon/cm 3 ] Error [%] (n,γ) 130 I # 9.22 x (γ,e + e - ) atomic 129 I 6.15 x (γ,n) 128 I 2.88 x (γ,2n) 127 I 9.88 x (γ,p) 128 Te 3.20 x Be container #Secondary neutron capture 1.57 x10 7 years half-life time of 129 I 24. min 128 I or h 130 I (secondary neutron capture) Produced Isotope (reaction) Be/Pb container Yield [per one photon/cm 3 ] Error [%] (n,γ) 130 I # 7.91 x (γ,e + e - ) atomic 129 I 6.17 x (γ,n) 128 I 2.90 x (γ,2n) 127 I 9.87 x (γ,p) 128 Te 5.60 x Produced Isotope (reaction) Yield [per one photon/cm 3 ] Pb container Error [%] (n,γ) 130 I # 1.08 x (γ,e + e - ) atomic 129 I 6.81 x (γ,n) 128 I 2.88 x (γ,2n) 127 I 1.00 x (γ,p) 128 Te 2.80 x

26 Long lived waste transmutation; fluence

27 Summary and conclusion FLUKA simulations show that the production of the desired isotopes via GDR (photon) are orders of magnitude higher than the other isotopes, indicating this technique to be promising method for artificial transmutations Applications Production of medical and industrial isotopes Transmutation of long lived isotopes to short lived Induced transmutation & photofission as a source of neutrons Comment: Currently γ beams have too low intensity for some applications. While it is expected that the intensity will be increased sufficiently for a production of medical isotopes, the total transmutation of nuclear waste requires intensities that will be probably not possible to achieve in the near future.

28 Acknowledgement Access to FLUKA code FLUKA developers and support group (especially Francesco Cerutti) V. Vlachoudis for FLAIR graphic interface with FLUKA C. Cederstrand for technical support Science and Engineering division for start up funding and support