Molten Salt Reactor related research in Switzerland

Transcription

1 Wir schaffen Wissen heute für morgen Molten Salt Reactor related research in Switzerland Jiri Krepel, Boris Hombourger, Carlo Fiorina, Sergii Nichenko, Jarmo Kalilainen, Arnoldo Badillo, Peter Burgherr, Dmitrii Kulik, Andreas Pautz, Horst-Michael Prasser, Martin A. Zimmermann ThEC5 BARC Mumbai PS, 9. Oktober 25

2 Launching MSR research at PS: justification MSR technology bears many innovative and multidisciplinary features that could be used in the frame of the department-level project and provide framework for PhDs and PostDocs projects and for funding from alternative financial sources, e.g. SNF, KT. MSR may be acceptable for public: high resources utilization, low waste production, and risk reduction and/or exclusion of severe accidents. n long term it can have a potential to be cheaper that current technology. MSR with fluoride salts enables cooperation with international partners. Status of MSR Research at Nuclear Energy Department of PS: 4 accomplished, 2 ongoing, and 5 proposed MSc theses. 2 ongoing PhD theses financed by SNF at PS and EPFL Lausanne. 2 accomplished and 2 ongoing PhD theses in cooperation with PS. 2 Scientist and 3 PostDoc working partly on MSR. 5 financed and 2 finished projects related to MSR. Seite 2

3 MSR relevant recent projects: finished & ongoing ACSEPT EU FP7 project, predecessor of SACSESS. o Heracles database creation (AHL: N. Shcherbina). SACSESS EU FP7 project: Safety of ACtinide Separation processes. o PS contribution of 2MM in 3 years project from 3/23. o Behaviour of: ) Mo and MgO in LiKCl, 2) AcF in LiF-AlF3. o AHL: M. Streit and S. Nichenko. Two Swiss National Science Foundation (SNF) PhD grants one dedicated to Small Modular Molten Salt Reactor Designing for Low Waste Production. o 36MM in 3 years PhD project from 4/24 for B. Hombourger LRS. swisselectric & PS financed research project (PSEL) Feasibility and plausibility of innovative reactor concepts in an European electricity supply environment. o 2 years project from 5/25 with 23.25MM (HTR) + 9.5MM (MSR). o LTH: H.M. Prasser, T. Lind, LRS: A. Pautz, J. Krepel, LEA: S. Hirsberg, P. Burgherr. EVOL EU FP7 project, predecessor of Samofar project. o PS as observer; MSR spectral study used as PS deliverable (LRS: J. Krepel). Samofar UE Horizon 22 project: A Paradigm Shift in Nuclear Reactor Safety with the Molten Salt Fast Reactor. o 4 years project from 8/25 dedicated to very innovative safety. o Aim is technological readiness level increase: TRL ->3 or 2->3. o PS contribution of 38.5MM has 2 parts: ) Reactor physics simulation 8MM and 2) Fission products chemical behaviour 2MM. o LTH: T. Lind, LRS: J. Krepel, LEA: P. Burgherr, AHL: M. Streit and S. Nichenko. Seite 3

4 Combining all activities into internal project 4 working packages are proposed for the project to group similar research topics. WP: core designing is ongoing in the frame of SNF PhD, but it should not be the main priority of the project at this stage. WP4: safety of MSR should be the main long term aim of the project. However, knowledge from WP-3 will be necessary for WP4 and only selected task can be done independently. WP2 and WP3 represent design-independent topics. Especially WP2 has the potential to involve all PS/NES laboratories. Seite 4

5 WP: MSR core design and fuel cycle WP should not be the main priority of the project at the initial stage. Design decision Nr. : studies will be based on fluoride salts MSR. f needed for WP2-4 salts from MSFR (as the reference concept ), MSBR, or MSRE should be used for design-independent studies. Main applied tools are EQLD and EQL3D developed at PS:. EQL3D - ERANOS based procedure for core level simulation. 2. EQLD v MATLAB-ERANOS ECCO, reaction rates based, cell level. 3. EQLD v2 MATLAB-SERPENT, reaction rates based, cell or core level. 4. EQLD2 v3 MATLAB-SERPENT, adopts the SERPENT burn-up matrix, cell or core level, includes fission products (v and v2 not). WP: MSR designing Parametric spectral study Design option evaluation Optimal design identification ts detailed NK & TH analisis Evaluation of inovative ideas PSEL - fuel cycle simplification Pool type MSR with cold jet V MSc - B. Hombourger PhD - B. Hombourger V 25 V 26 V 27 PhD - B. Hombourger PhD - B. Hombourger J. Krepel ) Křepel, J. et al., 23. Fuel Cycle Advantages and Dynamics Features of Liquid Fueled MSR. Annals of Nuclear Energy. vol. 64, pp J. Krepel MSc proposal 2) Hombourger, B. et al., 25. Parametric Lattice Study of a Graphite-Moderated Molten Salt Reactor. Journal of Nuclear Engineering and Radiation Science. Vol., JANUARY 25. Seite 5

6 WP: EQLD v3 routine Burn-up matrix for MATLAB is adopted from SERPENT inclusive fission products. Chebyshev Rational Approximation Method (CRAM) as in SERPENT. Multi-medial coupled burn-up. Composition and e.g. decay heat is traced in off-gas system and online reprocessing. = PS, = ( ) ( ) ( ) ( ) ( ) ( ) () ( ) ( ) Seite 6

7 WP: EQL3D and EQLD equilibrium cycle analysis - cell level - EQL3D Graphite EQLD Salt X % = Salt volumetric share in the core. % 7 cm Salt channel radius (cm) MSR equilibrium closed cycle was simulated by EQLD procedure on a cell level. And by EQL3D on the cell and core levels. 9 EQLD study 8 EQL3D study % 7% 2% 6% 5% 5% % 4% Salt chann el radiu s 8% 5% nverted channel layout 8% 7% 6% 5% Salt share in the core (%) 9 EQL3D core level 3 cm 4% cm 3% 2% 5% % Classical channel layout PS, % 8% Salt 5% Salt Salt share Seite 7

8 WP: EQLXD results: infinite equilibrium reactivity The moderation as well as the heterogeneity effect is strong. EQL3D results seems to be arbitrary line on EQLD surface. Krepel, J. at. al., HYBRD SPECTRUM MOLTEN SALT REACTOR. Physor 24 Kyoto Seite 8

9 WP: Hybrid spectrum core Flux distribution not-moderated 2 Graphite moderated. Equilibrium cycle: keff =.797 Critical share for initial fuel: A) 233U:.9% of Ac B) LWR Pu: 25.% of Ac 2. Equilibrium cycle: keff =.28 Critical share for initial fuel: A) 233U: 5.72% of Ac B) LWR Pu : 25.5% of Ac 3. Equilibrium cycle: keff =.8869 Critical share for initial fuel: A) 233U: 2.5% of Ac B) LWR Pu : 3.4% of Ac Main conclusions: Graphite does not provide strong reduction of the fluence on the core wall, ZrH does. 3 ZrH is applicable for the initial, but not for the equilibrium cycle. ZrH moderated 9. Oktober 25 Krepel, J. at. al., HYBRD SPECTRUM MOLTEN SALT REACTOR. Physor 24 Kyoto Seite 9

10 WP: EQL3D results, reactivity break-down Krepel, J. at. al., Molten Salt Reactor with Simplified Fuel Recycling and Delayed Carrier Salt Cleaning. CONE 24 Prague Two main families of salts were investigated: chlorides and fluorides. (other halides are not considered) Chlorides were studied in 7-ties also at PS (ER-332). Chlorides are relevant for fast U-Pu cycle. Majority of international research focus on fluorides. Th-U fluorides 25 Th-U equilibrium cycle, LiF carrier salt Thermal Epithermal Fast spectra 2 233U 5 4 Fast Spectrum Max. theoretical reactivity 5 Pu Max. realistic reactivity Th-U equilibrium cycle, NaCl carrier salt 24-2Pu Am MA Salt+graphite Nat. Cl Enr. Cl Salt to graphite ratio, salt share in the core (%) Salt share % 27 and 29 October 24 Fast Spectrum 24Pu Reactivity (pcm) 5 Max. theoretical reactivity 239 chlorides U Pu MA Salt Graphite U-Pu equilibrium cycle, LiF carrier salt Thermal Epithermal Fast spectra 3 234U Reactivity (pcm) chlorides U-Pu fluorides Seminar for ETH and EPFL students Max. realistic reactivity U-Pu equilibrium cycle, NaCl carrier salt Nat. Cl Enr. Cl Salt to graphite ratio, salt share in the core (%) Salt share % Seite

11 WP: MSRs in Breed-and-Burn (B&B) mode Assumptions: 3 Net neutrons produced per FMA [-] No reprocessing: discharged fuel is «lost». Feed is fertile: No fissile support. High breeding maintains criticality & compensates losses during refueling. Solid fuel B&B limited essentially by max. cladding fluence, no issue in MSRs. Single-fluid MSR very simply refueled. Computation of Neutron Excess (NE, see fig.) gives min. and max. burn-up for a given fuel. 2 NaCl-ThCl4 (-) NaCl-UCl3 (Nat) NaCl-UCl3 (-) LiF-ThF4 LiF-UF Main conclusions:. Works with Chlorides, but necessitates high levels of enrichment (in 37Cl). 2. Possibility of keeping the necessary amount of FPs in solution uncertain. 3. Chlorides are transparent, big cores necessary for leakage reduction. 2 Min. burn-up Burn-up [% FMA] 6 7 Max. burn-up (for a single-fluid MSR) Hombourger, B. et. al., Fuel cycle analysis of a molten salt reactor for breed-and-burn mode, CAPP 25, Nice Seite 8

12 WP: Comparison of recycling strategies for MSR Assumptions: Reprocessing unit capacity 25 l/day. The volume for reprocessing is taken from core (cases 6 and 7) or from temporary storage tank (cases -5). Strategy Nr Main conclusions: 3. Reactivity swing is positive and proportional to the reprocessing time. 2. Continuous Th refilling can be used as reactivity control, independently off the selected salt clean up treatment. 3. The strategy with longest reprocessing time has lowest average FPs content. (it has also highest breeding gain) 4. ts disadvantage is the biggest salt volume (initial load) necessary for reactor operation. 9. Oktober 25 Th refilling each 24M each 2M each 6M each 3M each M each day each M Min. salt volume for operation 36 m3 27 m m m m3 8 m3 8 m3 8l each 24M 9l each 2M 45l each 6M 225l each 3M 75l each M 25l each day cont., Th refill each M Reactivity (PCM) (decreasing Th mass = +2.2 PCM/kg; increasing FPs mass = -2. PCM/kg) Salt clean-up from FPS 8l each 24M 9l each 2M 45l each 6M 225l each 3M 75l each M 25l each day continuous Time (EFPM) Reactivity swing for 7 recycling strategies Krepel, J. at. al., Comparison of Several Recycling Strategies and Relevant Fuel Cycles for Molten Salt Reactor. CAPP 25Seite Nice 2

13 WP: Simplified fuel recycling using volatilization Recycling NP237 Pu238 (U234) Pu239 Other Ac Sum Assumptions: sobreeding MSR initialized by 233U. Salt reprocessing every 2 months. Reactor power of 2.6GWth = ton of burned fuel per year. Only volatilization method is used for simplified fuel recycling; 3 scenarios:.e+2 Main conclusions:. f only U is recycled, the cumulative Ac waste after EFPY will be dominated by 237Np - 37 kg and 238Pu - 45 kg. 2. The waste radiotoxicity for simplified recycling will be just slightly higher. 9. Oktober 25 Radiotoxicity of cumuated Ac (Sv) (U(%)+Np(99%)+Pu(99%)+.).U only (% efficiency) recycling. U+Np (29) Only U (36) Cumulative Ac mass in kg in the waste produced during EFPY of operation.. All Ac recycling (not simplified). U(%)+Np(99%) recycling. All Ac (4) All Ac recycling Only U recycling U+Np recycling.e+ % losses for all Ac (except U).E+.E+9.E+8.E+7.E+6 Time (years) Radiotoxicity of cumulated Ac mass. Krepel, J. at. al., Molten Salt Reactor with Simplified Fuel Recycling and Delayed Carrier Salt Cleaning. CONE 24 Prague Seite 3

14 WP2: Fuel behavior at nominal and accidental conditions Chemistry is the main MSR challenge. t influences all other WPs. (fuel cycle, safety, thermal-hydraulics, material behavior) PS has a competence in thermo-dynamics and MD simulations. n house code GEMS (Gibbs Energy Minimization Software for Thermodynamics Modelling) is unique open source alternative to the commercial FactSage code. The respective database HERACLES needs modification and extensions. Cooperation with TU (experimental data) may be crucial. WP2: GEMS dev. & app. 25 V 26 V 27 V 28 2MM AHL AcF behavior in LiF-AlF3 EU Sacsess project 2MM LES (phase diagrams) new proposal PostDoc 2MM AHL (Heracles database) new proposal PostDoc PhD LES & AHL GEMS: salt chemistry new proposal Phd PhD LTH GEMS: vaporization & solid. new proposal Phd MSc LTH GEMS: vaporization & solid. MSc proposal 6MM AHL MD of PuF3 in fluoride salts EU project Samofar 6MM LTH Aerosols formation EU project Samofar MSc AHL & LRS FPs chemical behavior in MSR (GEMS) MSc proposal Seite 4

15 WP2: Fuel behavior at nominal and accidental conditions 3 tasks in WP2 are already financed (Sacsess and Samofar). The work on HERACLES database has already started. Kulik D.A., Dmytrieva S.V., Wagner T., Kosakowski G., Thoenen T, Berner U., et al. (24-24): Gibbs Energy Minimization Software (GEMS) homepage ( Seite 5

16 WP3: MSR thermal-hydraulics and DHR system MSR thermal-hydraulics is specific. (distributed decay heat = volumetrically heated liquid; moderator, if applied, cooled by fuel; delayed neutron drift; etc.) Study related to volumetric heated liquid can be crucial in this WP. WP3 aim: thermal-hydraulics design of the core and DHR system, transient system behavior (Trace-point kinetics or Trace-PARCS), transient core behavior (GeN-Foam). 24 WP3: Thermal-hydraulics V LRS: Heat exchanger analysis MSc LRS: MSR decay heat evaluation LRS: Trace-PARCS MSR modification LRS: GeN-Foam development PostDoc C. Fiorina LRS: 2MM Multiphysics simul. of transient PhD LTH: Nusselt for vol. heated salts LTH: MSR instability Trace application LTH: MSR turbulence modeling LTH & ETH: salt instrumentation 25 V 26 V 27 V 28 MSc MSc EU project Samofar new proposal 3 PhD MSc proposal 2 MSc proposals visitng PosDoc at ETH Seite 6

17 WP3: 3 recently finished MSc topics at PS/EPFL MSRE Reactor outlet Reactor inlet Rod position (cm).7 Upper rod limit 2 Control rod thimble (typical).9 Fraction of graphite matrix (66.4 cm total) Fraction of effective core (2.7 cm total) FAST system code (TRACE or TRACE-PARCS) System analysis tool modelling primary, intermediate and secondary circuits. ndividuation and preliminary assessment of major accidental transients or optimization of the design. Assessment of primary heat exchanger (TRACE) Choice and preliminary design of the primary heat exchanger (shell and tube or printed circuit). Analysis of the proposed HX in steady state and accidental conditions Decay heat evaluation with EQLD Fuel salt - decay heat off off--gas system Core formed by graphite stringers Driven rod & scrammed rod lower limit -. Horizontal graphite.. Anti-swirl vanes Vessel drain line.5. Radius of core (7.2 cm total) Printed circuit heat exchanger Seite 7

18 WP3: Multi-physics simulation at PS Gen-Foam 2D or 3D transient analysis of full core (and primary loop) Solves for: Neutronics (Multi-group time dependent diffusion), Coarse (porous media)/fine (CFD) mesh thermal hydraulics Subscale fuel temperature field (coarse mesh) Thermal mechanics (Mesh deformation) mplicitly coupled Three independent unstructured meshes Adaptive time step fvm::ddt(v,flux[energy])fvm::laplacian(d,flux[energy])fvm::sp(nusigmafis[energy]/keff* (.-Beta)*chiPrompt)sigmaDisapp,flux[energy])delayedNeutroSource*chiDelayedscatteringSource fvm::ddt(rho, U) + (/porosity)*fvm::div(phi, U) + turb.divdevrhoreff(u) - porousmedium. semimplicitmomentumsource(u) fvm::d2dt2(disp) == fvm::laplacian(2*mu + lambda, Disp, "laplacian(dd,d)")+ divsigmaexp Fiorina C. at al., 25. GeN-Foam: a novel OpenFOAM based multi-physics solver for 2D/3D transient analysis of nuclear reactors. Nuclear Engineering and Design, Volume 294, December 25, Pages Seite 8

19 WP4: MSR safety, fuel stream, and relevant limits Evaluation of MSR safety should be the main long-term aim of the New NES projects. t strongly depends on the results from WP-3. Thus only selected task can be addressed in the initial phase. There are no proposals from the labs for this working package. (2 MSc topics have been proposed by LEA). Material research for MSR may deserve additional WP. Since there are no proposals, it is mentioned in WP4 at the moment. (e.g. structural integrity of Hastelloy at accidental conditions) 25 WP4: MSR safety 8MM LEA Simplified PSA level 3 MSc LEA dentification of DBA & BDBA MSc LEA Risk information in MSR designing 26 V EU project Samofar MSc proposal MSc proposal V 27 V 28 Seite 9