1. IP EUROTRANS WP 1.5 Safety Meeting KTH - Stockholm, May 22 nd – 23 rd 2007 Neutronic Design of the three zone EFIT-MgO/Pb core (Task 1.2.4: ANSALDO, ENEA, FZK, CEA, CRS4, Framatome ANP, NNC) C. Artioli, V. Peluso, C. Petrovich, M. Sarotto ENEA, Italian Agency for new Technologies, Energy and Environment, FPN-FISNUC Advanced Physics Technology Division, Via Martiri di Monte Sole, 4, 40100, Bologna, Italy

2. KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto Summary  The 395 MW th EFIT/MgO-Pb two zone model (Lyon Oct. 2006, WP1.5 meeting) shows high ff rad in the outer zone 3 zones to respect the limit on the clad T (avoiding  orificing in the same fuel zone)  Neutronic design performed by means of: 1) ERANOS ver. 2.0 deterministic code - ERALIB1(JEF2.2 updating) library (JEFF3.1 not yet available) - 3D Hexagonal model 2) MCNPX ver. 2.6.c code with ENDF/B-VI & JEFF3.1 libraries  EFIT/MgO-Pb three zone core will be described in the rev. 1 of the Deliverable D1.6 (in progress) 2

3. 3 Main Design Requirements & Choices  Lead coolant (v  1 [m s -1 ]): T Inlet 400 °C – T Outlet 480 °C  U-free CERCER Fuel (PuO 2, MAO 2 from MOX spent fuel) in a MgO matrix  To flat the PD profile  3 Radial zones  Max Linear power f(MgO VF & Conductivity): - with 50%* MgO VF (Fuel Intermediate & Outer)  Max P L  180 [W cm -1 ] - with 57% MgO VF (Fuel Inner)  Max P L  200 [W cm -1 ] *Lowest MgO technological content  Max Fuel operating T maxfuel = 1380 °C & Max clad T (SS, SA213T91) T maxclad = 550 °C: since T OUT Pb is 480 °C  Limited radial form factors (ff rad )  Residence time = 3 years: Pb corrosion is the most restricting condition (in comparison to BU max, DPA max )  Requires high fuel PD KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

4. 4 Transmutation Performances: “42-0” approach  Avoid Pu Burning (expensive in sub-critical reactors)  Avoid Pu Build Up (aim of the U-free choice; also for public acceptability)  Since physically is always  42 kg (HM) fissioned per TWh the approach is: -42 kg (MA) / TWh 0 kg (Pu) / TWh f (fuel E = 45,7%) It does not depend on P th (plant size), PD … The core design for this goal has to be compatible with: Limited k eff (t) variations ( f (fuel E) ) during the cycle  Limited Proton Current Range The proton accelerator performances (800 MeV, 20 mA) E = Pu / ( MA + Pu ) MA: (Np, Am, Cm) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

5. 5 Core Design Requirements (1/2)  P th  300-400 MW th but the size optimization criteria should be: Min cost per kg of fissioned MAsMin cost per MW deployed cost / MW deployed = f (core size, accelerator size) Because the present lack of data about the unitary costs, we assume the following semplified criterion: Decreases by increasing P th Could increase by increasing P th (also for the loose of φ*) 42-0 approach The largest size core acceptable within the spallation module already designed (ANSALDO) able to evacuate  11-12 MW The corresponding proton accelerator is: 800 MeV-20 mA KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

6. 6 Core Design Requirements (2/2)  Spallation module size (19 central FAs) fixes the FA dimension (double apothem = 191 mm)  Spallation module size, max I (20 mA - 800 MeV), k eff & Max P L P th (plant size is an output data) To obtain high PD (& max allowable P th ) in each fuel zone: - PD profiles have to reach its PD max - ff rad as low as possible PD max,homFA = VF Pellet * MaxP L /  R pellet 2 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto Inner IntermOuter 106 [W cm -3 ] 96 [W cm -3 ] “Desirable Performances” “PD max,homFA obtained with ERANOS” 200 [W cm -1 ] 180 [W cm -1 ]

7. 7 Radial Flattening KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto The subdivision in radial zones has two main goals not correlated: 1) Neutronic: to flat the Flux & PD distributions (Since the fuel E is fixed by the 42-0 approach variation of the VF HM ) 2) Thermo-hydraulic: to allow a proper different tuning of the coolant flow (v Pb  1,02 – 0,96 – 0,99 in the inner, intermediate & outer zones, respectively)  Assuming as reference the intermediate zone with 50% MgO VF (minimum) and suitable pin & pitch, the fuel VF HM has been varied : - in the inner zone increasing the MgO content (up to 57%); - in the outer zone increasing the pin diameter (maintaining the 50% MgO). because using only one flattening strategy (either pin diameter or MgO VF) we do not achieve the same level of both flattening and PD max values

8. 8 Inner, Intermediate & Outer FA Design KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto Inner and Intermediate: Outer: Same pin & pitch;  MgO VF (57%, 50%) > Pin  - Same MgO VF (50%)

9. 8.a Inner, Intermediate FA Design (by ANSALDO) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

10. 8.b Outer FA Design (by ANSALDO) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

11. 9 Deterministic Calculations (for the overall core design w/o the P th distribution in the FA pins) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto  ERANOS ver. 2.0 – ERALIB1 library - Cell calculations by the ECCO code with 1968 energy groups (heterogeneous geometry description for the fuel cells) - Spatial calculations by the VNM-VARIANT TGV Hexagonal 3D code - Burn Up calculations by 75 Solid FPs  Spatial & Energy distribution of the external source (n < 20 MeV) given by MCNPX 2.5.b calculations  By fixing: 1) fuel E (for the 42-0 approach) 2) Spallation Target:  R t = 43,7 cm (19 FAs) 3) AH = 90 cm (to limit the pressure drop) 4) FA geometries we obtain: 180 FAs to get k eff (t) ≤ 0,97 during the fuel cycle 42 / 66 / 72 FAs to exploit PD max1,2,3 (inner / intermediate / outer zones)

12. 10 384 MW th core: H3D model & cylindrised vertical section KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto 42 66 72

13. 11 384 MW th core performances KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto (*) 5 MW are dissipated in the other structural zones (proton beam excluded) (**) ff rad is defined as the P th ratio between the hot and the averaged FA (*) (**) AvePD HomCore  70,7 [W cm -3 ]

14. 11a 384 MW th core radial flattening (equivalent cylindrical model) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

15. 12 k eff (t) behaviour (384 MW th, E Pu = 45,7%): 200 pcm/y k eff (t) depends also on the 75 solid FPs model adopted: the gas FPs have been neglected (for their migration in the plenum). Their contribute is however of about 100 pcm. BOLBOCEOC KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto 200 pcm / y FA EOL Proton Current = f (k eff (t),  *, P th )  13,5 mA (almost constant)

16. 13 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto Burn Up Performaces (384 MW th, E Pu = 45,7%)  Pu / Pu (BOC)  -0,7%  MA / MA (BOC)  -13,9% 3 years BU = 78,28 MWd / kg (HM) BU -40,17 kg (MA) / TWh Total E = 10,0915 TWh th -1,74 kg (Pu) / TWh

17. 14 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto k eff increases by  200 pcm/year (in spite of the Pu 239 decrease) mainly for the Am 241 disappearence (by capture   -,  decay  Pu 238 ) Pu, MA vectors Evolutions

18. 15 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto 15 AveE  0,5 MeV  Captures exceed Fissions [barn]

19. 16 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto BOC Monte Carlo Calculations (for the overall core design with the P th distributions in the FA pins) k eff 0.97403  0.00023 Neutron source (S) (neutrons/proton) 23.02  0.08 M = all fission neutrons / S 19.45  0.25 k S = M / (M+1) 0.95111  0.00059 0.52 Proton current13.2 mA BOC condition - ERANOS results: k eff = 0.97094 k s = 0.95328  * = 0.61 I = 13.5 mA (ERALIB1) Reference values for P th deposition calculations at BOC (800 MeV p+): - LA150h proton library when E p+ < 150 MeV - CEM03 physics model when E p+ > 150 MeV - CEM03 physics model when E n > 20 MeV (e.g. fuel) or E n > 200 MeV (Pb) - JEFF 3.1 library (Pb, MgO, SS) when E n < 20 MeV (e.g. fuel) or E n < 200 MeV (Pb) - ENDF/B-VI library (fuel) when E n < 20 MeV p+ n

20. 17 BOC: comparison between ERANOS & MCNP results KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto ERANOSMCNPX 2.6.c ERALIB1JEF2.2 JEFF3.1 with URR* JEFF3.1** no URR JEFF3.1 + ENDF/B-VI for fuel JEFF3.1 + LA150h for Pb k eff 0.9709 0.96330.96200.9616 0.9740 0.9646 kSkS 0.9533 0.94130.93200.9297 0.9511 0.9349 * * 0.61 0.540.53 0.52 0.53 I [mA] 13.5 17.2 wrong URR tables 19.2 13.2 P thmax / FA (inner zone) 2.57 2.79 wrong URR tables 2.86 2.46 * URR = Unresolved Resonance Region If we assume a k eff reference value of 0.97: - MCNPX with JEFF3.1 (Pb, SS, Pb) + ENDF/B-VI (for fuel) - ERANOS with ERALIB1 represent our “best estimate” for the P th deposition I = f (k eff,  *, P th ) with k eff = 0.96 gives not correct P th values in the inner hot pins ** Missing  transport for some HMs

21. 18 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto 1) The core has been designed by a deterministic code 2) The P th distribution has been obtained with MCNP: heterogeneous description (pin detail), geometry dilatation and n libraries at working T 3) The different libraries influence the k eff values and, as a second order effect, the P th distributions 4) Independently from the calculation code and library, the “real” k eff level is 0.97 (at the moment) 5) For a realistic estimation of the max P L (near the external source) the MCNP P th distribution results has to be obtained at k eff = 0.97 in order to correctly evaluate the contribution of: - the external source - the sub-critical core 6) The “best estimate” of the max P L is obtained by a Monte Carlo code and library that gives k eff  0.97 (on the core defined with deterministic methods) Chosen procedure

22. 19 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto P th at BOC [MW th ]MCNPX (*) Inner zone (42 FA) 94 Intermediate zone (66 FA) 140 Outer zone (72 FA) 141 Out of the FA10 Total384 (*) By excluding the spallation module and beam pipe zones (**) By including the n contribute on spallation module and beam pipe zones (  0,7 [MW]) ERANOS (**) 96 142 140 5 384 P th deposition Comparison between ERANOS & MCNP results

23. 20 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto OUTER ZONE MCNP analysis of P th deposition in all the FAs

24. 21 KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto OUTER ZONE Possible improvements of the P th distribution - Possible improvements of the radial P th flattening by re-arranging the interface between the different zones (closer to a “circular” shape) 2 nd zone FA 3 rd zone FA 2 nd zone FA

25. 22 MCNP analysis of the average FA P th in the 3 zones (  < 1.8%) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto Average P th in FA [MW] Average P th in fuel pellets [MW] Axial form factor in the average FA Inner zone2.232.061.14 Interm. zone2.121.981.17 Outer zone1.961.841.17 Pb level No-symmetry around the core mid-plane (z=0) because of the external source

26. 23 MCNP analysis of the hottest FA in the 3 zones (  < 2.5%) KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto Pb level (about 6-8% of the P th is outside of the fuel pellets) Max P th in FA [MW] Max P th in the fuel pellets [MW] Hottest pin in hot FA (pellet) [kW] Axial form factor in the hot FA Hottest pin / average pin (hot FA) Max linear power in pin [W/cm] Inner zone2.462.2816.41.131.21203 Interm. zone2.352.1913.71.181.05177 Outer zone2.432.2915.01.201.10197 In ERANOS the limit of 180 [W cm -1 ] is respected (because of the homogeneous FA description w/o the pin details)

27. 24 Concluding Remarks  42-0 approach for MAs transmutation (without Pu burning and production) by a  400 MW th Pb cooled ADS is a viable strategy: - the lowest k eff during the fuel cycle is compatible with the 20 mA current limit - the k eff (t) swing is 200 pcm / y Limited proton current range  The calculated performances (k eff, proton I, P L peak, etc…) depend “strongly” on the adopted nuclear data libraries (JEF2.2, ERALIB1, JEFF3.1, ENDF-B.VI)  The limits on the clad T seem to be respected by the subdivision in 3 radial zones (w/o  orificing in the same zone)  The P L results (hottest pins) are very close to the design constraints (mainly in the outer part). Eventually the problem could be faced by re-arranging the interface between the different fuel zones and the core size (to maintain the same k eff )  In the revision 1 of the deliverable D1.6 (in progress): - the analysed design of the EFIT/MgO-Pb core will be addressed as reference; - the possible improvements (P th distribution) will be indicated. KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

28. Supplementary

29. S1 Pu & MA Isotopic Compositions MOX spent Fuel after 30 years’ cooling ( CEA ) Pu Vector KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

30. S2 After the first 3 years:  Before refuelling the average residence t is 2 years  After refuelling the average residence t is 1 year We consider: - the k eff behaviour, core performances… between 1 (BOC) and 2 (EOC) years - the BU results (without refuelling) at the 3 rd year We have approximated: the “actual situation” that gives an average residence t of x years with an entire core that has burnt for x years without refuelling Fuel cycle hyphotesis For Pb corrosion (strongest requirement):  3 years as max residence time  Refuelling of 1/3 core each year KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

31. S3  Two radial fuel zones Radial Flattening Technique Fuel_Inner Fuel_Outer R1R1 R2R2 Target RtRt Different MgO matrix contents (fabrication more expensive for supplementary line cleaning) Different Pin diameters (less efficient because in the outer zone the max coolant outlet T is reached before reaching the max allowed linear power & PD) StructuralC o o l a n t F u e l Pu+MA Matrix StructuralC o o l a n t F u e l Pu+MA Matrix MgO VF OUT = 50% MgO VF IN = 57% BREST Style KTH Stockholm, 22 nd – 23 rd May 2007, IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

32. S4 Kg/TWh MA Pu - 42 0 Pu Burner Pu Breeder 0  k e (pcm/y) (%) %MgO 50 54 I (mA, 800 MeV) 10 32 50 -36 -6 E=50% R (cm) P 200 20 E=27% E=50% -65 +23 E=27%  K swing E=45.7% 1900 27 E=45.7% 400 optimization 13 16 57/50/50 200