Spent Fuel Reprocessing Optimisation H. Druenne

Transcription

1 Spent Fuel Reprocessing Optimisation H. Druenne CHOOSE EXPERTS, FIND PARTNERS 12-13/07/10 2 Outline Nuclear in Belgium : a long story Optimisation of the stored spent fuel for recycling

2 12-13/07/10 3 HISTORY OF THE GDF SUEZ GROUP ELECTROBEL TRACTIONEL COMPAGNIE UNIVERSELLE DU CANAL MARITIME DE SUEZ LYONNAISE DES EAUX ET DE L'ECLAIRAGE 12-13/07/10 4 GDF SUEZ A world leader in the utilities sector providing electricity, gas, energy services and environmental services - Turnover of 80 billion in employees

3 12-13/07/10 5 GDF SUEZ, A balanced electricity generation mix with nuclear MW of installed generating capacities A competitive electricity generation portfolio Flexible, efficient and low CO2 generation facilities Safe and reliable nuclear power plants. 11% 52% 3% 1% 1% 16% 16% Nuclear Hydro Natural Gas Coal Biomass and biogas Wind Other non renewables 12-13/07/10 6 GDF SUEZ > A STREAMLINED ORGANISATION

4 12-13/07/10 7 KEY FIGURES 2009 Turnover of Tractebel Engineering : 460 M INDUSTRY 2% GDF SUEZ 47% NUCLEAR 26% POWER 42% Sector Client GAS 7% INFRASTRUCTURE 23% THIRD PARTY 53% /07/10 STAFF Resources : highly skilled people present in > 20 countries 27% WOMEN 71% ENGINEERS 23% BRAZIL 7% INDIA-ASIA 13% REST OF EUROPE 2% MIDDLE EAST 73% MEN 29% OTHERS 55% BELGIUM & FRANCE

5 12-13/07/10 9 A long story but with many reversals 12-13/07/ : U mine of Shinkolobwe (in Belgian Congo) - Union Minière du Haut Katanga : the richest mine in the world at that time - First exploited for Radium (for therapeutical uses)

6 12-13/07/ : U mine ok Shinkolobwe (in Belgian Congo) : African Metal : Manhattan project : tripartite agreement between GB USA and Belgium to guarantee the total U production to the US in return for the participation of Belgium in future civil nuclear development. But - Most of the Belgo-Congolese U was used for military objectives : decision of US senator Mc Mahon to forbid any exchange of the US civil nuclear technology 12-13/07/10 12 In the 50 ies, everything seems possible with nuclear 1952 : creation of SCK/CEN one of the most famous hot labs in the world = still active:many international programs Atomium : Universal Exhibition Brussels, 1958

7 12-13/07/ : BR-1 : after GB and France, Belgium (although small) is the 3rd country in Western Europe to get a core critical - Graphite-gas cooled reactor with natural U = still in operation (research and education) 12-13/07/ : BR-2 : research reactor = still operational (research on materials)

8 12-13/07/ : BR-3 : first PWR in Europe now being dismantled = full size dismantling technique development Removal of the RPV Cutting with plasma torch 12-13/07/ : founding of IRE (Institute for Radioelements) - Mission : to contribute to public health and environmental protection Production of radionuclides for nuclear medecine > Worldwide leader Major producer of I-131 First producer of Mo-99 for Europe 95% of exportation Management of radioactive waste Radiological monitoring of the environment (TRANSRAD) Consultancy projects : founding of IRE ELIT

9 12-13/07/10 17 Reprocessing and recycling are the reference policy 1957 : Belgonucléaire : Development of the MIMAS (now applied in MELOX plant in F) : 12 MOX fuel rods in BR3 for electricity production: a world first : 660 thm = 40 ton Pu Japan Belgium But shut down in Germany Switzerland France Year 12-13/07/ : founding of FBFC : first PWR fuel assembly in Europe / first MOX assembly in the world : first BWR fuel assembly in Europe (RBU/AEG) : start up of Gad fuel fabrication / 1991 : first PWR MOX for France / Germany / 1998 : first BWR MOX for Germany / Japan = still in operation

10 12-13/07/ : EUROCHEMIC - pilot plant for reprocessing - built in MOL with contribution of 14 OECD countries - before industrial scale in France and GB But extension abandoned and shutdown in 1974 > the large countries had their own capacities and were no longer interested /07/ : CHOOZ A a French-Belgian project largest PWR in the world at that time Shutdown in : DOEL and TIHANGE First power stations : reprocessing as design basis small pools reprocessing contracts with La Hague

11 12-13/07/ : launch of a research program for underground repository underground laboratory HADES = still on going 12-13/07/10 22 UNIT In operation since NSSS Number of assemblies Assembly lattice Fissile height Thermal power Power uprate programs DOEL ICFM LHGR MOL - DESSEL [ft] [MW] [W/cm] [ C] FDH Doel W * > 1311 (+10% ) PU+SGR in m Doel W * > 1311 (+10% ) PU+SGR in m Doel FRA * > 3054 (+10% ) PU+SGR in m (end of MOX) TIHANGE Doel W * SGR in m 165 ² Tihange FRA * > 2865 (+8% ) PU+SGR in m Tihange FRA * > 2895 (+4.3% ) PUCE in > 3054 (+10% tot) PU+SGR in m Tihange W * SGR in m 165 ² PU = power uprating SGR= steam generator replacement PUCE = Power Uprate and Cycle Extension 2 Typical value as for EPR Core outlet temperatures Hot spot

12 12-13/07/ /07/10 24 But US decision to not reprocess TMI in Tchernobyl in 1986 Anti nuclear movement >> Lack of information => wrong perception of the public : - Nuclear waste - Danger of incidents : small probability but unmanageable in densely populated Belgium - Risk of proliferation (dirty bomb)

13 12-13/07/10 25 Pu is demonized! BNS Conference - 26 March /07/10 26 But Strong reduction of U price => economic profit questionable

14 12-13/07/10 27 But 1993 : Parliament decision to suspend reprocessing 1998 : Government decision to cancel reprocessing contract concluded in 1991, but authorized 66 ton HM coming from former reprocessing to be recycled as MOX in 2 units (Tihange 2 and Doel 3) and ERU in Doel 1 Since then : - no more reprocessing and fuel stored in interim storage on site - reprocessing and direct disposal of spent fuel are put on equal footing 12-13/07/10 28 Things are changing

15 12-13/07/ : MYRRHA = go! - A flexible fast spectrum research reactor, is conceived as an accelerator driven system (ADS), able to operate in sub-critical and critical modes. It contains a proton accelerator, a spallation target and a multiplying medium with MOX fuel, cooled by liquid lead-bismuth (Pb-Bi). - Funds voted in march /07/10 30 In most countries, the final back end solution is not defined nor decided yet saturation of the storage capacities To face the storage capacities saturation, and according to the Government resolution, 2 solutions are studied in parallel : build new capacities and reprocess the spent fuel

16 12-13/07/10 31 Situation on QUANTITY OF SPENT NUCLEAR FUEL (1) definitively unloaded since 1976 (2) reprocessed in UP2 plant (3) reprocessed in UP3 plant (4) currently stored at NPPs = (1) - (2) - (3) (5) to be unloaded up to the end of the 40 years ton HM (6) to be disposed if no reprocessing = (4) + (5) recyclable plutonium in (6) with 55% fissile recyclable uranium in (6) with 1% U /07/10 32 Average discharge burnup [MWd/ /t] REPROCESS THE SPENT FUEL The storage capacities contain large ranges of burnup enrichment cooling time Should the reprocessing be chosen as back end solution, then how to define the best strategy? Ideal enrichment -average discharge burnup dependance in annual cycle Feed enrichment [%]

17 12-13/07/10 33 REPROCESS THE SPENT FUEL Physics : evolution of MOX and ERU characteristics versus burnup enrichment cooling time Do they meet the technical constraints? Illustrative application : comparison of 2 strategies on a specific spent fuel inventory Conclusion 12-13/07/10 34 Curso s de veran o 2010 MANY TRANSMUTATIONS Yield of U-232, U-234 and U-236 during irradiation U232 decay after reprocessing U-234 and U-236 stable (half-life resp. 2.4 E+05 and 2.3 E+07 years)

18 DRH /07/10 35 Curso s de veran o 2010 MANY TRANSMUTATIONS Main source of various Pu isotopes Pu 238 Pu 239 Pu 240 Pu 241 Slide 35 DRH1 Voir les sections 4 slides plus loin : fissions / capture = un peu moins de 2 tant pour U5 que pour Pu9 U-235 : Sur 6 neutrons absorbés, 5 fissions et 1 capture Pu-239 : sur 4 neutrons absorbés, 3 fisisons + 1 capture Allure des courbes d'évolution (au moins en début d'irradiation (hors disparition par fission) Pu 239 : Evolution linéaire car production continue par absorption dans U8 Pu240 : intégrale de l'évolution du Pu239 => fonction du second degré Pu241 : intégrale de l'évlution du Pu240 => 1 degré en plus de la précédente druenne; 09/02/2010

19 12-13/07/10 36 IMPACT OF BU ON PU AND REPU QUALITY Higher burnups => lower Pu and U quality U235 and U236 in [%] Residual enrichment depending on depletion U235 U236 Pu236 U232 U Assembly burnup [MWd/t] Pu236 and U232 in [ppb] or U234 in [ / 00] Pu content [%] - Am241 [ 0 /00] Residual Pu versus U depletion before reprocessing Initial ENU enrichment : Burnup UO2 [MWd/t] [%] U238 content [ PU 238 PU 239 PU 240 PU 241 PU 242 Am 241 U /07/10 37 EQUIVALENCE PRINCIPLE No change in cycle energy when some ENU replaced by MOX and/or ERU If same k inf at EOC core average burnup Simple approach and very good approximation (based on full core calculations)

20 12-13/07/10 38 CONSTRAINTS Neutronics : MOX fraction is chosen accordingly Storage capacities => minimum reprocessing rate Pu max content in MOX MOX equivalence MOX fabrication & transport MOX assembly decay heat ERU maximum enrichment ERU equivalence ERU fabrication U-232 limit in ERU 12-13/07/10 39 MOX CHARACTERISTICS During source ENU cooling time: Pu-241 decay Pu quality loss higher [Pu] in MOX Average Pu content [%] Total Pu average content in MOX equivalent to 4.3% UOX 4.5% => 51 GWd/t 3.8% => 41 GWd/t Feed enrichment -discharge burnup dependance forannual cycle Storage duration before reprocessing (years) The shorter the source ENU cooling time: the better the Pu quality => [Pu] For long storage times : stabilisation Equivalence limit due to [Pu] limit

21 12-13/07/10 40 MOX CHARACTERISTICS During source ENU cooling time: Pu-241 decay Pu quantity losses more ENU to be reprocessed for 1 MOX assemblies Number of Number of ENU assemblies to be reprocessed to get 1 MOX (equivalent to 4.3 UOX) Feed enrichment -discharge burnup dependance forannual cycle Storage duration before reprocessing (years) The shorter the source ENU cooling time: the lesser ENU to be reprocessed 12-13/07/10 41 MOX CHARACTERISTICS During source ENU cooling time: Pu-238 decay Lower PuO 2 powder residual heat But MOX residual heat depends also on [Pu] Decay heat [W W/assembly] Fresh MOX decay heat of 1 MOX ass. equivalent to 4.3% UOX Feed enrichment -discharge burnup dependance forannual cycle Storage duration before reprocessing (years) Maximum decay heat at 15 y source ENU cooling time Small variation but : best as short as possible or wait as long as necessary

22 12-13/07/10 42 ERU CHARACTERISTICS Reprocessed U quality : U-235 (fissile) / U-236 (neutron absorber) Impact of initial URT quality and ERU (@ 5%) equivalence enrichment 4.5 and burnup 4.4 But rather stable isotopes => not impacted by cooling time U-235 / U Feed enrichment - discharge burnup dependance for annual cycle Source assembly burnup [MWd/t] Achievable equivalence with 5% ERU ERU enrichment limit : limited available equivalence : 4.4 to 4.25% impact on ICFM 12-13/07/10 43 ERU CHARACTERISTICS During source ENU storage time U-232 = parent product of Tl-208 = strong gamma emitter Pu-236 decay before separation U-232 decay after separation U-232 [ppb] U-232 content in ERU 45 35% U-232 decay 40 30% 35 25% 30 ERU enrichment : 5% 25 20% 20 15% 15 10% % 0 0% Accumulation MWd/t from 5 Pu_ MWd/t decay Delay before reprocessing [years] MWd/t Relative Pu-236 conte ent ERU U-232 best for short storage times or much longer But margins versus future limit 37 ppb

23 12-13/07/10 44 ILLUSTRATIVE APPLICATION Typical spent fuel stock - Belgian stock taken as an example Note that reprocessing in Belgium is currently not possible without formal Government authorization => explorative analysis - Huge dispersion in burnups, enrichments and cooling times Burnup [MWd/t] Feed initial enrichment [%] 12-13/07/10 ILLUSTRATIVE APPLICATION Comparison of 2 scenarios : - Hot first : the assemblies are sent to reprocessing as soon as they have cooled enough (the older ones remains in the storage) - Cold first : the oldest assemblies are first reprocessed Burnup [MWd/t] Same equivalence objective and same MOX fraction Feed initial enrichment [%]

24 12-13/07/10 46 SPENT FUEL MANAGEMENT For older assemblies more ENU to get 1 MOX - Cold first scenario leads to a faster reduction of the storage inventory - Hot first scenario strong reduction of reprocessing needs Number of assemblies to be stored Storage management "Hot first" scenario "Cold first" scenario Reprocessing year from T /07/10 47 MOX EQUIVALENCE The shorter the source ENU cooling time the better the Pu quality - Hot first scenario gives better Pu => better equivalence 4.8 Available equivalence [UOX %] MOX equivalence MOX average Pu content [%] Reprocessing year from T0

25 12-13/07/10 48 MOX DECAY HEAT Maximum decay heat at 15 y cooling time: best as short as possible or wait as long as necessary - Hot first hotter MOX assemblies still compatible with transport capacities (1100 W/ass) MOX assembly heat (W)/ass) MOX decay heat Reprocessing year from T /07/10 49 ERU EQUIVALENCE Limited available equivalence : 4.4 to 4.25% Not dependant on source ENU cooling time But source ENU enrich & BU => more residual U-235 for more recent ENU Hot first more ERU assemblies Available equivalence [UOX %] ERU equivalence ERU enrichment [%] Reprocessing year from T0

26 12-13/07/10 50 ERU - RADIOPROTECTION Best for short storage times or much longer - The scenarios are before or after the U-232 peak => limited impact U-232 [ppb] ERU U-232 content Reprocessing year from T /07/10 51 CONCLUSION For this specific case, the best choice is the hot first scenario - The amount of ENU to reprocess hot first = - 18%! - The gains on Natural U : hot first + 3% and SWU : hot first +20% (resulting from ENU assemblies replacement by ERU and MOX) Very attractive to think about and optimize it! To be done for each specific case as results depend on: storage constraints ICFM equivalence objectives acceptable MOX fraction