Minor Actinides Transmutation: ADS and Power Fast Reactors

Transcription

1 Nuclear 2011 Piteşti May 25-27, 2011 Minor Actinides Transmutation: ADS and Power Fast Reactors Carlo Artioli

2 Outline - Wastes and Minor Actines - EFIT, the ADS of EU EUROTRANS Project (Lead coolant) concept and performances - Interdependency among main EFIT parameters - A way for avoiding Minor Actinides net production (Gen IV) - Close cycle and adiabatic core (LEADER project) - Dynamic equilibrium composition - Material Balances - Core designing sequence (2NP Design) -Adiabatic core used as MA burner - Conclusions

3 Wastes and Minor Actines TRUs, Minor Actinides(MA) and Pu, are the major contributors to the long lived wastes Considering and using Pu as a fuel, an important work must be devoted to solve the MA problem As far as the MA legacy, both present and to be built up, is concerned: -their incineration, meantime producing energy, is a promising solution While for the future could rely on: -a close cycle, without any MA net production Sketches of both are presented in the frame of the Lead cooled systems: -An ADS (Accelerator Driven System) for an intensive burning of the MA legacy, -A so called adiabatic ELSY-Type for achieving a theoretical zero net production of MA

4 EFIT, the ADS of EU EUROTRANS Project Within the EUROTRANS Project (EU 6 th FW) the EFIT ADS (European Facility for Industrial Transmutation) has been designed Features: -Lead coolant the EFIT ADS -Power 400 MWth -Fuel: Pu+MA oxide in inert matrix (MgO or Mo) -Accelerator: 800 MeV protons, i<20 ma In the EUROTRANS Project (EU 6 FW) (European Facility for Industrial Transmutation) has been designed Features: -Lead coolant -Power 400 MWth -Fuel: Pu+MA in inert matrix (MgO or Mo) -Accelerator: 800 MeV protons, i<20 ma

5 42-0 concept and performances Transmutation MA FUEL High enrich. Low MA transmutation MA decreases slightly or Pueven increases (Pu burner) Transmutation fission fission High MA transmutation MA decreases strongly but not only by fission (Pu breeder) MA Low enrich. Transmutation Pu Transmutation fission

6 e = Pu / (Pu+ MA) Carlo Artioli Nuclear 2011 Pitesti 26 May 2011 Transmutations MA mass balance Kg/TWh Pu mass Balance Pu breeder Pu burner 42-0 concept and performances FUEL Approximation: No effect on the spectrum by the variation of the matrix fraction (in the range) Ex. - 60, MA Pu Fission product Total balance 42 kg / Twhth Ex. - 30, ( %fuel ) %MgO

7 MA mass balance Kg/TWh Pu mass Balance Pu breeder Pu burner 42-0 concept and performances In EFIT we want: - No new Pu production (what would be contradictory with the inert matrix choice) - No Pu burning (what would be economically disadvantageus) therefore a Pu balance = 0, that implies a MA balance = -42 Ex. - 60, +18 MA X kg/twh of net Transmutations Pu FP, 42 kg/twh Ex. - 30, -12 Suitable e = Pu / (Pu+ MA)

8 Verification and optimization INPUT to be supplied Pu and MA vectors DESIGN Main statement: 42-0 OUTPUT Pu, MA dioxyde stoichiometry and density; Matrix, density and fraction Gas releases = f (T, BU) Max linear power, TH (T max, conductivity law) K eff required Search of suited Pu/ (Pu+MA) Pellet composition Pin geometry definition (diameter and other by guess) Fuel element definition Core definition Definition of enrich. Pu/ (Pu+MA) Fuel density power Core density power Core size and power

9 42-0 concept and performances

10 42-0 concept and performances Hom. Power density at midplane (calculations: M. Sarotto) Maximum allowed, corresponding to linear power rating 207 and 180 W/cm

11 [ kg ] Carlo Artioli Nuclear 2011 Pitesti 26 May concept and performances 3000 MA and Pu balances Tot Pu Tot MA DMA / MA (BOC) -13,9% DPu / Pu (BOC) -0,7% With the definitive right enrichment we have the balances: MA: 41.9 kg/twhth Pu: 0 kg/twhth 3 years but [ years ] BU = 78,28 MWd / kg (HM) BU -40,17 kg (MA) / TWh Total E = 10,0915 TWh th -1,74 kg (Pu) / TWh

12 [ kg ] [ % ] [ % ] 42-0 concept and performances 3000 Pu, MA vectors evolutions MA and Pu balances Behaviour of Pu isotopes Tot Pu Tot MA Tot Pu Pu238 Pu239 Pu Behaviour of MA isotopes Tot MA Am241 Am243 Cm242 Cm Carlo Artioli Nuclear 2011 Pitesti 26 May DMA / MA (BOC) -13,9% Years years 2500 The Pu and MA vectors evolve in the time toward 2400 equilibrium configurations; this implies: 3 years DPu / Pu (BOC) -0,7% 0 1 [ years ] Calculation of the final enrichment with the equilibrium vectors Total E = 10,0915 TWh - Enrichment resetting in the transitory phase BU = 78,28 MWd / kg (HM) BU -40,17 kg (MA) / TWh -1,74 kg (Pu) / TWh

13 42-0 concept and performances 42-0 approach - ONE fission corresponds ONE MA atom fissioned, either directly or indirectly (Pu acts as catalyzer ) -the MA burning efficiency is 41.9 kg/twhth, i.e. about 120 kg of MA/y (400 MWth, load factor 0.8) - meantine there is a net power production of about 100 MWe

14 Interdependency among main EFIT parameters Carlo Artioli Nuclear 2011 Pitesti 26 May 2011

15 A way for avoiding Minor Actinides net production (Gen IV) Carlo Artioli Nuclear 2011 Pitesti 26 May 2011 No net production of Pu and MA via close cycle

16 Close cycle and adiabatic core For operating in a close cycle the reactor (core) must be an adiabatic one, which means able not to exchange significant materials with the environment. Both on the front and back end

17 Dynamic equilibrium composition Reaction channels C. Artioli, G. Grasso and C. Petrovich A new paradigm for core design aimed at the sustainability of nuclear energy: the solution of the extended equilibrium state. Ann. of Nucl. En. 37: (2010). Two different mathematical approaches have been developed for the solution of the equilibrium vector (recursive and matricial) The results have been validated by 2 codes: MCNPX and FISPACT

18 Dynamic equilibrium composition Recursive Integration Method Every isotope can be expressed as: j N ( t) a e with r j j j i j ij -r t The coefficients a ij are found integrating recursively the Bateman equations with the requirement that the amount of every isotope does not change after some irradiation time (e.g. 5 years) and cooling time (e.g. 4 years) On the ELSY-Type spectrum U 82.1% Pu 17.0% MA 0.9% total 100% 238 Pu 2.1% 239 Pu 57.3% 240 Pu 34.0% 241 Pu 3.3% 242 Pu 3.3% 243 Pu 0.0% 100%

19 ELSY [LFR, 1500 MW th ] mass (grams) Carlo Artioli Nuclear 2011 Pitesti 26 May 2011 Dynamic equilibrium composition 2.6E E+05 Cooling time Pu238 - MCNPX 2.2E E E E E+05 U 82.1% Pu 17.0% MA 0.9% total 100% 238 Pu 2.1% 239 Pu 57.3% 240 Pu 34.0% 241 Pu 3.3% 242 Pu 3.3% 243 Pu 0.0% 100% Pu242 - MCNPX Pu241 - MCNPX Am241 - MCNPX 1.2E E years

20 Material Balances Theoretical equilibrium fuel cycle for 1500 MW th LFR (ELSY-type) Considering 0.5% losses in the reprocessing: - in the waste there are also: 25 kg/y U, 6 kg/y Pu, 0.3 kg/ MA; - fed U must be 580 kg/y

21 Material Balances Theoretical equilibrium fuel cycle for 1500 MW th LFR (ELSYtype) Despite the fact that the Adiabatic LFR acts as a pure U fissioner, fission reactions occurs on all the component, i.e. U, Pu and MA MA rate of actual fissioning (1g/Gwhe) is rather low: infact the greatest part (4 g/gwhe) of their disappearing rate (5 g/gwhe) occurs by fissioning indirectly via Pu ; This accounts for a smooth sensitivity of beff to the MA content.

22 Material Balances Theoretical equilibrium fuel cycle for 1500 MW th LFR (ELSYtype) Such a core can be operated as adiabatic (i.e. removing from the waste only Fission Product and adding in fabrication equal amount of U) even when the equilibrium composition is not reached yet. The natural evolution toward the equilibrium implies for ELSY a variation of reactivity of some 600 pcm, to be compensated with 2-3% of fuel elements or devoted absorbers. How to deal with the reactor not at equilibrium?

23 feedback Core designing sequence (2 NP Design) U/Pu/MA equilibrium (guess spectrum) feedback ADIABATIC CORE DEFINED SIZE AND POWER - Thermal conductivity - Max allowed Temperature (T c ) Linear power Admitted (P lin ) Once criticality reached PRELIMINARY CORE (preliminary spectrum) Thermo-hydraulics constraints: - Max cladding temperature - Coolant outlet temperature (T out ) Possible to design critical facility by gathering as many cells are required to reach k eff =1 Thermo-hydraulics constraints: - Inlet-outlet temperature (T in, T out ) - Pin diameter No viable solution for adiabatic or Rearrange volume fractions keeping the fuel composition YES - Coolant Volume Fraction NO K inf > 1? Elementary Cell Defined (guess spectrum) Carlo Artioli Nuclear 2011 Pitesti 26 May 2011

24 Adiabatic core used as MA burner MA Introduction of new MA in the fuel, other than the equilibrium ones induces their net burning (by fission either directly or via Pu). Evolution is roughly exponential toward their equilibrium concentration. Rate of burning is depending on their overload over the equilibrium

25 Increasing difficulties on reprocessing and fabrication Carlo Artioli Nuclear 2011 Pitesti 26 May 2011 Adiabatic core used as MA burner MA Pu % C i =8 C 5y =7 C 0 =5 C i,initial concentration, must be optimized τ = 12 y τ (depending on both flux intensity and spectrum) Data: ELSY [LFR, 1500 MW th ] MA 5% Pu P&P Code C 0 equilibrium ratio (depending on the spectrum and not on the flux intensity) EOL=5y (BU peak = 100 MWD/kg) t

26 Increasing difficulties on reprocessing and fabrication Carlo Artioli Nuclear 2011 Pitesti 26 May 2011 Adiabatic core used as MA burner MA % Pu MA Pu EOL=5y (BU peak = 100 MWD/kg) % C i =8 C 5y =7 C 0 =5 Balance (example) τ (depending on both flux intensity C i = 8 % MA loaded (as hypothesis) and spectrum) 480 kg C 0 = 5 % MA equilibrium concentration C 5y = 7 % unloaded MA EOL=5y Burnt MAs amount (5y) (BU peak = 100 MWD/kg) MA quantity to be reprocessed = 7 % C i,initial concentration, must be optimized MA losses in reprocessing = 0.5 % of 420 kg Actual Losses (Losses/Burnt) = 2kg/60kg t MA 5% Pu τ = 12 y Data: ELSY [LFR, 1500 MW th ] 420 kg t 420 kg MA 5% Pu C 0 equilibrium ratio (depending on the spectrum and not on the flux intensity) 300 kg 60 kg (12 kg/y) 2 kg P&P Code 3 % (the same for EFIT)

27 Adiabatic core used as MA burner MA % Pu MA 5% Pu EOL=5y (BU peak = 100 MWD/kg) t Performance improving (example) Performances can be improved by both: -Increasing the MA overloading (reprocessing & fabrication problem!) -Increasing the BU (modest effect) For example: -Increasing the BU by 50% (!), the MA burning rate increases by 13% from 12 to 13.5 kg/y - increasing the allowed MA concentration by 50% (from 8 to 12%), the MA burning rate increases by 140%, from 12 to 29 kg/y

28 Conclusions 1 / 2 (legacy) 1) MA produced by present and short term future reactors, as significant contributors to the waste loads, can be fissioned (either directly or indirectly) in ADS systems. 2) Maximum real efficiency is reached in the 42-0 concept and is about 42 kg/twh th ; higher figures mean that the exceeding part has been transmuted in new Pu and not fissioned. 3) EFIT (EU 400 MWth ADS, lead cooled, oxide in inert matrix) has been predesigned within the EU 6 th FW. 4) Main challenges are about the accelerator (800 MeV proton, i=16 ma) and fabrication/reprocessing of such a fuel.

29 Conclusions 2 / 2 (future) 1) Implementing a close cycle, waste would content only Fission Products (and U, Pu, MA lost in reprocessing). 2) Gen IV Adiabatic reactor keeps constant the amount of TRUs, so acting as a pure U fissioner. 3) To obtain this goal the appropriate composition of fuel, equilibrium fuel, has to be calculate as first step and kept in the core design. 4) In any case the available fuel will evolve toward the equilibrium composition. 5) Evolution from the initial fuel toward the equilibrium one can be hosted in the same core (removing 2-3% of fuel elements or adding absorbers). 6) Capacity of burning MA legacy, even not huge, is not negligible. 7) Main challenges are in the fabrication and reprocessing of such a fuel (U 82%, Pu 17%, MA 1% with important quantity of Cm).

30 Some references Artioli, C., A-BAQUS; a multi-entry graph assisting the neutronic design of an ADS. Case study: EFIT. In Fifth International Workshop on the Utilisation and Reliability of High Power Proton Accelerator (HPPA 5), Mol, Belgium, May 6-9. Artioli, C., Chen, X., Gabrielli, F., Glinatsis, G., Liu, P., Maschek, W., Petrovich, C., Rineiski, A., Sarotto, M., Schikorr, M., Minor actinide transmutation in ADS: the EFIT core design. In International Conference on the Physics of Reactors (PHYSOR 2008), Interlaken, Switzerland, September Artioli, C., Grasso, G., Sarotto, M., Monti, S., Malambu, E., European Lead-cooled SYstem core design: an approach towards sustainability. In International Conference on Fast Reactors and Related Fuel Cycles: Challenges and Opportunities (FR09), Kyoto, Japan, December Bateman, H., Solution of a system of differential equations occurring in the theory of radioactive transformations. Proc. Cambridge Philos. Soc. 15, Cinotti, L., Smith, C.F., Sienicki, J.J., AÃ t Abderrahim, H., Benamati, G., Locatelli, G., Monti, S., Wider, H., Struwe, D., Orden, A., The potential of the LFR and the ELSY Project. In 2007 International Congress on Advances in Nuclear Power Plants (ICAPP â 07), Nice Acropolis, France, May DOE-GIF, A Technology Roadmap for Generation IV Nuclear Energy Systems. Technical Report GIF , GIF. Fensin, M., Hendricks, J., Anghaie, S., MCNPX 2.6 depletion method enhancements and testing. In International Conference on the Physics of Reactors (PHYSOR 2008), Interlaken, Switzerland, September Forrest, R.A., FISPACT-2001: User manual. Technical Report, EURATOM/UKAEA Fusion Association. Grasso, G., Artioli, C., Monti, S., Rocchi, F., Sumini, M., On the effectiveness of the ELSY concept with respect to Minor Actinides transmutation capabilities. In Tenth Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (IEMPT10), Mito, Japan, October Carlo Artioli Nuclear 2011 Pitesti 26 May 2011

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