Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz The use of the GDT based neutron source as driver in a sub-critical burner of minor actinides K. Noack Research Center Rossendorf (Germany) Budker Institute of Nuclear Physics, September 26, 2006, Novosibirsk, Russia

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Content Part I:Transmutation of nuclear waste – a short overview on the actual state Part II:The GDT as neutron source in a sub-critical system for transmutation? (~ Presentation at OS`2006, Tsukuba, Japan)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz  To become a long-term sustainable option for the worlds energy supply fission reactor technology must:  maximally use nuclear fuel (uranium) and  minimize its high level waste (HLW)!

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz  :Partitioning & Transmutation Main problem on long-time scale.  HLW repository problem ! Goal: To transmute radio-isotopes in short-lived or stable isotopes by neutron reactions! France, Japan, USA Uranium U-235: 3-5% U-238: 95-97% Burn-up Spent nuclear fuel U:95.5% + TRU isotopes Pu:0.9% MA (Np, Am, Cm):0.1% + Rad. FP isotopes:0.4% + Stable isotopes:3.2% 3-4 years # In today´s Light Water Reactors (LWRs): Problem on short-time scale. 1 LWR (~1.3 GW el. ) produces per year (kg): Pu: ~ 270 Am: ~ 13.5 Np: ~ 13 Cm: ~ 2 FPs: ~ 1000

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz (B. Frois) Classic glass MA + FP Pu + MA + FP FP Light glass # Radiotoxicity for various options of waste disposal:

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz From: M. Salvatores, FZR-presentation (2005) FPs ~3x10 2 years Total >10 5 years Pu & decay products ~10 4 years MAs & decay products Uranium ore Tc-99, I Years after discharge Radiotoxicity

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Geological Disposal Direct Disposal Spent Fuel from LWRs # Partitioning & Transmutation of TRUs and FPs: From: M. Salvatores, FZR-presentation (2005) Dedicated Fuel Fabrication Pu MA Partitioning & Transmutation (TRUs and FPs) Partitioning Transmutation Geological Disposal Dedicated Fuel Reprocessing FP Pu, MA FP Partitioning

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Neutron reactions for transmutation: Is the only option for FPs. However: secondary nuclei can be also long-lived. Thermal or intermediate (E n : ~ eV-10 keV) neutrons are necessary. Minor actinides are fissionable! Fission is the preferable reaction for transmuting MAs  :- substantially shorter life-times, - possibility of „fast systems”. „Fast“ neutrons with E n > 0.5 MeV are necessary. Capture Fission  :„Fast systems” should be a suitable tool for transmuting MAs!  :Only low transmutation rates of FPs achievable! M. Salvatores: The problem is not yet solved!

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz A „fast system“ with high neutron flux inside an acceptable large volume! Fission Technology offers two options: # An efficient burning of Pu and MA isotopes demands: „Driven sub-critical system“ „Fast reactor“ – Main class: ADS = Accelerator Driven System : What is the most important physical difference ? & What is the advantage of an ADS compared to FR ?

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Neutron field in a reactor: Solution of the Static Reactor Equation = eigenvalue equation Neutron field  power distribution in the reactor Eigenvalue = k eff - “effective multiplication factor” > 1 - super-critical reactor, P: k eff = 1 - critical reactor, P: < 1 - sub-critical reactor P:  A minimum on fission reactor physics:  Important phenomenon: „Delayed“ fission neutrons with a relative portion:  eff  6.5x10 -3 !  It makes possible to control a fission reactor !

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz „delayed“ super-critical state „prompt“ super-critical state critical state  constant power 1+  eff   eff super-critical state sub-critical state k eff  : T  s !!!  : T  100 s ! „driven sub-critical systems“ ~0.95 ? What is the impact of a power increase on k eff ? (“reactivity effects”)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Fast reactors: -  eff should be large! -Positive total reactivity effects (k eff ↗ ) should not appear!  : What is the impact of MAs on these demands?  Reactor safety considerations: Driven sub-critical systems:keff ≤ 0.98 !  : „They offer much higher flexibility for burning Pu and MAs than Fast Reactors“ !  In Fast Reactors the maximum allowable fraction of MAs in the fuel is ~ 5 % only !

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Time Waste  Strategic role of Driven Sub-critical Sytems in the future of Nuclear (Fission) Energy in US  : The use of the GDT neutron source as driver in a Driven System for transmutation of nuclear waste could be an additional goal for further Research & Development ! M. Cappiello, „The potential role of Accelerator Driven Systems in the US“, ICRS-10 (2004) Use of ADS

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz A D D C C B Act. Mineurs Chargés (%) Variation (%) B A: Na-void effect (k eff ↗ ) B: Doppler-effect ( k eff ↘ ) C: Burn-up D:  eff Increase of Na-void effect ! Decrease of  eff ! Decrease of Doppler effect ! # Effect of MA introduction on reactivity coefficients in a Na-cooled Fast Reactor: Bad effects by MAs: Decrease of burn-up Good effect: From: M. Salvatores, FZR-presentation (2005)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz THE GDT AS NEUTRON SOURCE IN A SUB-CRITICAL SYSTEM FOR TRANSMUTATION? K. Noack Research Center Rossendorf (Germany) A. Rogov Joint Institute of Nuclear Research Dubna (Russia) A.A. Ivanov, E.P. Kruglyakov Budker Institute of Nuclear Physics Novosibirsk (Russia) Open Systems´2006, July 17-21, 2006, Tsukuba, Japan (With modifications for BINP-presentation)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz 2  Fission reactor technology must  recycle spent nuclear fuel and  minimize its high level waste (HLW) ! Introduction (1/3)  :Partitioning & Transmutation ! Main problem on long time scale.  HLW repository problem ! Goal: To transmutate radio-isotopes in short-lived or stable isotopes by neutron reactions. Japan (JAEA): „OMEGA“ Uranium U-235: 3-5% U-238: 95-97% Burn-up Spent nuclear fuel U:95.5% + TRU isotopes Pu:0.9% MA (Np, Am, Cm):0.1% + Rad. FP isotopes:0.4% + Stable isotopes:3.2% 3-4 years

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz (B. Frois) Classic glass MA + FP Pu + MA + FP FP Light glass

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Introduction (2/3) 3  Two efficient ways for transmutation of TRU´s by neutron reactions: 1) Fast reactors (“effective multiplication factor”: k eff =1) 2) Sub-critical systems (keff= ) that are driven by an “outer” neutron source Advantage:More flexibility because of less stringent safety requirements ! Requirement: Powerful neutron source ! – „Accelerator Driven Systems“ (ADS) - Spallation neutron source „ADS“ # Suitability of the GDT n-source for a driven system? # How does it compare with the ADS? :

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Introduction (3/3) 4  The idea of a GDT-DS for transmutation: GDT experimental device (BINP, Novosibirsk)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz ADS GDT (“basic variant”) The Neutron Sources 5  Comparison of near-term projects: 2) Energetic efficiencies  P Accel. = 20 MW el  P NBI = 60 MW el (!)  price [W/(n/s)]:  p ADS = 1.6x  p GDT = 8.7x (!) # Peculiarity of the GDT-source:  S GDT = 2 x (1/2) ! 1) Total intensities  p-beam: 1 GeV x 10 mA = 10 MW  Y n = 20 n/p (at Pb)  :  S ADS = 12.5x10 17 n/s  n-power: P n =1.56 MW DT fusion neutrons  S GDT =6.9x10 17 n/s Factor ~ 1.8 Factor ~ 5 ! # SNS (ORNL): 1 GeV x 1.4 mA, 60 Hz pulsed, – first neutrons ! P n  0.25 MW

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Spallation reaction: neutron yield per proton (Pb, Pb/Bi): K. van der Meer et al., Nucl. Instr. and Meth. in Phys. Res. B 217 (2004)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz (From Yu. Tsidulko)  : P n =  : P inp = (el. Power) Power losses should be reduced or recovered!

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Features Calculation Models (1/2) 6 p Core Reflector Height z (cm) Target Buffer Void Radius r (cm) #OECD-NEA Calculation Benchmark (1999) for an accelerator-driven MA-burner with nominal power = 377 MW. (Developed from ALMR/PRISM) # ADS principles Dedicated core:Pu & MA Fe, Pb-Bi Coolant: Pb-Bi eutectic Reflector: Steel, Pb-Bi Target: Pb-Bi Buffer: Pb-Bi 32%, 68%!!!

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz C z r B z r Calculation Models (2/2) 7 A # Geometric systems: „ADS“ „GDT-DS“ „GDT-DS+B“ # “External” neutron sources: Spallation spectrum in „GDT-DS“ „MIXED“ z r Spallation source DT fusion source – cylinder: Radius: 10 cm Height: 50 cm

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Neutron Transport Calculations (1/5) 8 Neutron transport code: MCNP-4C2 Nuclear data from: JENDL-3.3 (NDC of JAEA)  Tools:  Two types of transport calculations: Reactor criticality calculation (without external source)  k eff With external sources

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Neutron Transport Calculations (2/5) 9 Geometry system ´Reactor´Driven Systems k eff M eff MSMS h fis / MeVr n,2n A ADS B GDT-DS C GDT-DS+B  Calculated integral parameters (per source neutron): Spall. Sp Effective multiplicity: M eff =k eff /(1-k eff ) # Positive feature of 14 MeV neutrons: High probability of n,2n reactions at Pb and Bi ! But: No effect at Na ! # 0.95 < k eff < 0.96 ! (1999) B z r

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz total n,2n n,3n n,  10 MeV

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Neutron Transport Calculations (3/5) 10  Flux distributions (per source neutron): Total Flux: Radial dependence in core

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Neutron Transport Calculations (4/5) 11  Flux distributions (per source neutron): Power peak factor over height at r=21 cm

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Neutron Transport Calculations (5/5) 12  Flux distributions (per source neutron): Spectra of energy group fluxes at r=21 cm

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz The MA-burners (1/2) 13  Calculated integral parameters: ParameterADSGDT-DS/2*GDT-DS+B/2* S (10 17 n/s) P fis (MW) Nominal Power 377 MW: 1) S´ (10 17 n/s) ) k´ eff * One MA-burner on each side ! x ~1.5! Today: 0.96 < k eff < 0.98 ! Q=5.2 Q= k eff : ! 2.5~ x

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz The MA-burners (2/2) 14  Radial flux distribution (at nominal power):

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Tritium breeding 14a T-breeding module # T-breeding module: – ITER inboard module, – He cooled pebble bed (Be and breeder pebble beds, breeder: Li 4 SiO 4 with 40% Li-6) – FZKA 6763 (FZ Karlsruhe, 2003) – 6 Li + n  4 He + 3 H MeV  Result: g tritium / f.p. year ! („basic variant“, sum of both sides)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Conclusions (1/2) 15 (1) Energetic price of the neutron emission intensities: p GDT  5 x p ADS  !!! (2) ADS and GDT neutron source projects do not supply sufficiently high source intensities to operate the MA- burner at nominal power. For that are necessary: S ADS : x ~1.5  S GDT : x ~2.5 (for 2 burners !) (3) Alternatively, one has to redesign the MA-burner so that for ADS: k eff  0.97  for GDT: k eff   !!! (4) Fusion source neutrons generate a substantially higher fission power in the core by n,2n reactions at the nuclei of the Pb-Bi coolant!

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Conclusions (2/2) 16 (5) The power multiplication factor Q of the driven MA- burners: Q ADS  2.6 x Q GDT-DS ! (6) For the same power of the driven MA-burners one can expect: [MA-burning rate] ADS  [MA-burning rate] GDT-DS

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz 1) Energetic efficiency must be increased! # The Q-factor must be comparable with that of ADS! # Increase of T e is the key issue: T e = 0.75 keV  T e  2.25 keV ! 2) „Next Step“ with a modified MA-burner: Project „ π “ # MA-burner*:k* eff =0.98,P* th =500 MW  GDT-NS*:S*=10.8x10 17 n/s (P* n =2.5 MW) instead of: S= 6.9x10 17 n/s (P n =1.56 MW) by:T e =0.75 keV  T* e  1.25 keV !  As goal for the GDT neutron source project: ~60%

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # P inj =60 MW (el.), E inj =65 keV „Basic variant“ + 2 burners == ~ x 500-MW-burners*, k* eff =0.98 Q 5.2 ~ x 377-MW-burners Diagram from Yu. Tsidulko

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz Thank you!

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz 1) Source strength (neutron power): # MA-burner:k eff =0.98,P th =500 MW  GDT-NS:S=10.8x10 17 n/s (P n =2.5 MW) instead of: S= 6.9x10 17 n/s (P n =1.56 MW)  As goal for the GDT neutron source project: 2) Energetic efficiency: # The Q-factor must be comparable with that of ADS! # Increase of the electron temperature is the key issue: T e =0.75 keV  T e =2.25 keV ! ~60%

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Transmutation of 99 Tc using neutron capture: R. Klapisch, Europhysics News, Vol. 31 No. 6 (2000); (Proposed by C. Rubbia) „Adiabatic resonance crossing“

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Flux spectra of the MA-burner and of FR PHENIX: [10 4 4x10 6 ] Fast Neutron spectrum (Na cooled) From: G. Alberti et al., NSE 146, (2004) „Fast systems“

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz  :At high neutron energies (E n >0.5 MeV) fission dominates over capture ! FR # σ c and σ fis for important TRUs: E (eV) From: D. Westlen, RIT Stockholm (2001)

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz α – probability of capture # Advantage of fast neutron spectra for MA-burning: Originally from C. Rubbia

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz „Energy amplifier“ proposed by C. Rubbia (1993): Accelerator ↓ particle beam ↓ Target ↓ neutrons ↓ Sub-critical system (arrangement of nuclear fuel) ↓  Strong neutron field inside the whole volume of the fuel system by means of fissions ! Release of nuclear energy Transmutation of nuclear waste ! (protons) (heavy metal) (spallation) # Principles of an ADS:

Institute of Safety Research Member Institution of the Scientific Association Gottfried Wilhelm Leibniz # Schematic view of a lead- cooled Fast Reactor (pool-type): Core without external neutron source Power control by absorber rods Is one of 3 Fast Reactors among 6 reactor types considered in the GENERATION IV - International - Forum.