Nuclear Waste: How much is produced, and what can be used

Transcription

1 Nuclear Waste: How much is produced, and what can be used Physics of Nuclear Reactors Faculty of Applied Sciences Delft University of Technology

2 Products from fission

3 Material balance in fuel cycle (1 GWe) Mining Milling Conversion Enrichment Fuel Fabrication Reactor Operation Spent Fuel 20,000 tonnes of 1% uranium ore 230 tonnes of uranium oxide concentrate (with 195 t U) 288 tonnes UF6 (with 195 t U) 35 tonnes UF6 (with 24 t enriched U)- balance is tails 27 tonnes UO2 (with 24 t enriched U) 7000 million kwh of electricity 27 tonnes containing 240 kg Pu, 23 t U (0.8% U-235), 720 kg FP

4 10 1 Spent fuel composition fission products Weight fraction (%) U-235 Pu-239 U-236 Pu-240 Pu-241 Pu-242 Pu Burnup (GWd/tU)

5 Fission product yields U-235

6 Fission product yields U LW R LMR 10 1 LW R U-235 Pu-239 Pu Yield (%) 10-1 Yield (%) Mass number A Mass number A

7 Fission product composition Weight fraction (%) Weight fraction (%) Atomic number Z Mass number A

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9 Fission product composition Xe-135 Gd-157 Weight fraction (%) Weight fraction (%) Atomic number Z Mass number A Cd-113 Sm-149

10 Fission product composition U LW R LMR 10 1 Xe-135 Gd-157 Yield (%) Weight fraction (%) Mass number A Mass number A Cd-113 Sm-149

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13 Radiotoxicity of spent fuel Actinides Fiss Prods Ore 10 7 Radiotoxicity (Sv) Storage time (a)

14 Radiotoxicity of fission products Radiotoxicity (Sv) Total Cs-137 Sr-90 Tc-99 Sn-126 I-129 Ore Storage time (a)

15 Radiotoxicity (%) Radiotoxicity of LLFP kg/thm Tc-99 I-129 Cs-135 Zr-93 Sn-126 Se Storage time (a)

16 Data on long-lived fission products Nuclide Half life (a) cross-sec (barn) Yield (%) a) Production (kg/a) b) Tc I Cs Zr Sn a) Cumulative yield U-235 b) For a 1 GWe PWR

17 Salt rise and subrosion

18 Nuclide Tc-99 I-129 Cs-135 Zr-93 Sn-126 Travel time from repository to environment Half life (a) T L 1 1 = t1+ R v1 cross-sec (barn) Retardation R Dose-conv (Sv/Bq)

19 Resultant dose rates for 100 GWae : 3 µsv/a Maximal 0.03 µsv/a Average

20 Reactor Type Transmutation of Tc-99 Configuration Inventory Transmutation Transmutation Tc-99 (kg) Rate a) Rate b) (kg/a) (kg/mwae) Half life (a) LMR Moderated SA inner core LMR Nonmoderated SA inner core CANDU Pin in moderator PWR- UO2 Pin in guide tube PWR- MOX Pin in guide tube a) Production equals 21 kg/a b) Production equals 0.02 kg/mwae

21 Other solutions T 1 = t + 1 L v 1 1 R Immobilizing nuclear waste (Cs-137, Sr-90, Cm-244) in synthetic rock, together with LLFP Near surface storage of synrock for few hundreds of years; geological disposal afterwards?

22 Spent fuel as a mine Sano et al, NucTech 148 (2004): Tc, Ru, Rh, Pd, Te valuable as catalysts

23 Rare earths in PWR spent fuel 3 Ru Mass (kg/thm) Tc Pd 0.5 Rh Te Atomic number Z

24 Specific activity of rare-earths Specific Activity (Bq/g) Tc Ru Rh Pd Te Am Ore Specific Radiotoxicity (Sv/g) Time (a) Time (a)

25 Radiotoxicity (Sv) Radiotoxicity of actinides Pu Am Cm U Np Ore Storage time (a)

26 Nuclear waste Uranium ore Nuclear waste contains mainly nuclides from: 4n+1 series (Cm-245, Pu-241, Am-241, Np-237, U-233, ) 4n+2 series (Cm-242, Pu-238, U-234, ) (soluble) fission products Uranium ore contains mainly nuclides from: 4n+2 series (U-238, ) 4n+3 series (U-235, )

27 10 3 Radiotoxicity of actinides 10 2 Radiotoxicity (%) Pu Am Cm U Np Storage time (a)

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29 Radiotoxicity of actinides

30 Yearly production of actinides Element PWR NL EU (kg/thm at 5a) (kg at EOC) (tonnes) Uranium Plutonium Neptunium Americium Curium

31 Plutonium Plutonium Hell no Versus Plutonium Hello

32 Plutonium recycling in PWRs

33 Plutonium recycling in PWRs 3x less Pu 3x more Am 4x more Cm

34 Advantage of a fast neutron spectrum Pu-239 Pu-240 Pu-241 Pu-242 α (σ fis /σ cap ) Energy (ev)

35 (kg/twhe) Pu in Pu out Pu Fast Burner Pu+MA MA in MA out Np in Np out Am in Am out Cm in Cm out

36 1% Am in PWR-UO2 2% Am in FR-MOX Alpha emission Beta emission Gamma emission Neutron emission Decay power 60,000 3,000 80,000 1,600 65,000 Fuel fabrication EOL + 5 years Alpha emission 14 Neutron emission Decay power

37 Recycling scheme

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39 Recycling scheme

40 10 8 Plutonium reduction 99 % 10 7 Radiotoxicity (Sv) Storage time (a)

41 10 8 Plutonium reduction 99 % 10 7 Americium reduction 95 % Radiotoxicity (Sv) Storage time (a)

42 10 8 Plutonium reduction 99 % 10 7 Americium reduction 95 % Curium reduction 90 % Radiotoxicity (Sv) Storage time (a)

43 Gain in radiotoxicity

44 Full transmutation would reduce Size of repository factor Peak dose rate factor 100

45 Costs of reprocessing

46 Historical Uranium price

47 Costs of electricity (COE) 0.1 cent

48 Full transmutation would reduce Size of repository factor Peak dose rate factor 100 Economical if spent fuel disposal would cost $3000/kgHM (10 times current estimates)

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50 Uranium Potassium Thorium

51 Uranium-238 ==> Uranium-234 ==> Radon-222 ==> Bismuth-214 ==> Bismuth-210 ==> Thorium-234 ==> Thorium-230 ==> Polonium-218 ==> Polonium-214 ==> Polonium-210 ==> Protactinium-234m => Radium-226 ==> Lead-214 ==> Lead-210 ==> Lead-206 ==> 40 MeV!!

52 1000 atoms U atoms U-235 (after 300 days) 1500 stable FP 1000 atoms Pb radioactive FP MeV 200 MeV

53 Energy release U-235 and FPR Fission products Power W) U-235 Power W) Time (a) Time (a) x 10 6

54 1000 atoms U atoms U atoms Pb MeV 1500 stable FP Energy Amplifier!!! (after 300 days) MeV 500 radioactive FP 200 MeV

55 Uranium: Don t leave it in the ground! (Nigel Holloway, Atom, June 1990) Uranium is a radioactive waste product from stellar fusion reactors It contributes to natural radioactivity that can harm the environment It contributes to geo-thermal energy that we cannot easily extract from the earths crust Fissioning Uranium reduces the total radioactivity Fissioning Uranium amplifies the geo-thermal energy originating from decay with a factor of five

56 Geo-thermal Energy Amplifier in Borssele (The Netherlands)

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