GIF Reactor System Development Status: Molten Salt Reactor

Transcription

1 10 th GIF -INPRO IAEA Interface Meeting, Vienna, Austria, 11 April, 2016 GIF Reactor System Development Status: Molten Salt Reactor Presented by Victor Ignatiev NRC Kurchatov Institute, Moscow, RF

2 There were two people at the [Manhattan Project] metallurgical laboratory, Harold Urey, the isotope chemist, and Eugene Wigner, the designer of Hanford, both Nobel Prize winners who always argued that we ought to investigate whether chain reactors, engineering devices that produced energy from the chain reaction, ought to be basically mechanical engineering devices or chemical engineering devices. And Wigner and Urey insisted that we ought to be looking at chemical devices that means devices in which fuel elements were replaced by liquids. Mechanical engineering device presumes that the fuel (solid) has to be used in a max condensed form that excludes reprocessing and has advantage of technical simplicity while reactor operating. Chemical engineering device has not only possibilities of general benefits such as unlimited burn-up, easy and relatively low cost of purifying and reconstituting the fuel (fluid), but also there are some more specific potential gains. 2

3 Molten salts fluorides were developed originally at US ORNL for MSR in 1970s to reflect Gen II, but not Gen IV objectives. Gen II Th-U MSRs had mainly graphite moderated cores Design MSBR DMSR Reactor thermal power, MW Overall plant efficiency, % Fuel salt inlet/outlet, C 566 / / 704 Coolant salt inlet/outlet, C 454 / / 621 Steam conditions, MPa/ C 24.3/ / 538 Core height/diameter, m 4.0 / 4.3 8,3 / 8,3 Salt volume fraction in core, % 13 /37 20 Average core power density, MW /m Estimated core graphite life, years 4 30 Total fuel salt volume, m Thorium / Fissile inventory, t 68 / / 2.37 Breeding ratio ,85 (0,8)

4 Different reactor concepts using molten salt are discussed an GIF MSR pssc meetings Molten Salt Fuelled Reactors (the circulating salt is the fuel + coolant)» MSRMOUSignatoriesFranceEUandSwitzerlandworkonTh- U MSFR (Molten Salt Fast Reactor). Switzerland joined MOU in 2015.» Russian Federation works on MOSART (Molten Salt Actinide Recycler & Transmuter) with and without Th-U support. RF joinedthemouin2013» China, Japan and South Korea work on Th-U TMSR with graphite moderator Molten Salt Cooled Reactors(solid fuelled)» USA and China work on FHR (fluoride-salt-cooled hightemperature reactor) concepts and are Observers to the PSSC» Australia works with China on materials development for MSRandFHR AustraliaisjoiningtheMOUin2016 4

5 Fluoride-salt-cooled high-temperature reactors combine three technologies Fuel: high-temperature coated-particle fuel developed for high-temperature gascooled reactors (HTGRs) with failure temperatures >1650C Coolant: high-temperature, low-pressure liquid-salt coolant ( 7 Li 2 BeF 4 ) with freezing point of 460 C and boiling point >1400C (transparent Power Cycle: nuclear air-brayton combined power cycle with GE 7FB compressor Candidate FHR Demonstration (ORNL) Mk1 PB-FHR flow schematic (UCB) 5

6 DOE s Focused Investment in FHRs is Through University Research University lead integrated research projects ($5 M each) focused on addressing technical issues for FHRs initiated from 2015 till to 2018 Purpose for CRADA is to Accelerate Development of FHRs CRADA supports and is funded by SINAP s thorium MSR program CRADA is limited to solid fueled MSRs MIT, UC-Berkeley, U-Wisconsin, and U-New Mexico form one team Georgia Tech, Texas A&M, and Ohio State form other team US-Czech collaboration on F 7 LiBe reactivity worth measurement is under development U.S. and China Have Begun Cooperating R&D on FHR (CRADA) Nearly all technology developed will be applicable to MSRs CAS is providing the entirety of CRADA funding, with an estimated $5 million a year. The collaborations under the new agreement are authorized for 10 yrs. 6

7 CAS has initiated a TMSR development program with similar to prior US graphite moderated cores and has provided resources for R&D, design and construction of MSR test reactor in China. This initial test reactor will have a power of 10MWt. A second, 100MWt test reactor is also planned. Both test reactors will use low-enrichment U fuel. The near-term Goal of TMSRs project: 2MW Molten Salt Reactor with liquid fuel( 2022) TMSR Reactor Site Source: Zimin Dai (SINAP) 2015

8 Europe focused on liquid fuel and no solid moderator inside the core possibility to reach specific power higher than in a solid fuel strong negative feedback coefficients good breeding ratio no problem of graphite life-span relatively high initial loading Fuel circuit MOSART (RF) MSFR(EU) Fast Spectrum Configuration Fuel salt, mole% LiF-BeF 2 +1TRUF 3 LiF-BeF 2 +5ThF 4 +1UF LiF-12.9ThF 4 3.5UF 4- -5TRUF LiF-6.6ThF UF 4-3.6TRUF 3 MSFR Temperature, о С Core radius / height, m 1.4 / / 2.26 Core specific power, W/cm 3 Container material in fuel circuit Removal time for soluble FPs, yrs Ni-Mo alloy HN80MTY Ni-W alloy ЕМ MOSART

9 In the Li,Be/F MOSART core without U-Th support it is possible to burn TRUs from used LWR fuel with MA/TRU ratio from 0.1 up to 0.45 within solubility limit Single fluid 2.4GWt core with the rare earth removal time 1 yr containing as initialloading2mole%ofthf 4 and1.2mole%oftruf 3,after12yrs canoperate withouttruf 3 makeupbasingonlyonthsupport At equilibrium molar fraction of fertile material in the fuel salt is near 6 mole % anditisenoughtosupportthesystemwithcr=1

10 MOSART Fuel Clean up: Reductive extraction of An s from molten salt into liquid bismuth with their subsequent re-extraction into purified salt flowisthemostacceptablewayofanrecycling Component Cycle Removal times operation Kr, Xe 50 sec He Sparging Zn,Ga,Ge,As,Se,Nb, Mo,Cd,InSn,Sb,Te,Ru, Rh,Tc Zr Ni,Fe,Cr Np,Pu,Am,Cm Y,La,Ce,Pr,Nd, Pm,Gd,Tb,Dy, Ho,Er,Sm,Eu Sr,Ba,Rb,Cs 2.4hr 1-3 yrs >30yr Plating out on surfaces + To off gas ystem Reductive extraction, Oxide precipitation, Electrodeposition Li, Be, Na Salt discard 10

11 Collaborations: Europe SAMOFAR Project (Started 08/2015: 4 years, Euro 5M) A paradigm Shift in Nuclear Reactor Safety with Molten Salt Reactor EU Partners: TU-Delft, CNRS, JRC, CIRTEN, IRSN, AREVA, CEA, EDF, KIT, PSI, CINVESTAV Non EU partners: SINAP (China), Univ. of New Mexico (USA)and KI (Russia) The grand objective of SAMOFAR is: prove the innovative safety concepts of MSFR, deliver breakthrough in nuclear safety and waste management create a consortium of stakeholders to demonstrate MSFR beyond SAMOFAR Main results will be: experimental proof of concept safety assessment of the MSFR update of the conceptual MSFR design roadmap and momentum among stakeholders Technical work-packages: Integral safety assessment Safety related data Experimental validation Numerical assessment Materials compatibility Salt chemistry control Fuel salt processing

12 Company Spectrum Feed Processing Notes Terrestrial Energy Thermal LEU Gas stripping and mechanical filtering ThorCon Power Thermal LEU Gas stripping and mechanical filtering Transatomic MSRs Are Currently Being Developed Under Both Commercial Private and Government Sponsorship Thermal & Epithermal LWR TRU or Th Canadian company DMSR -Replace vessel with salt every seven years DMSR -Replace vessel with salt every seven years ZrH moderator would require significant advances in cladding. Not apparent that version from white paper can maintain criticality. FLiBe Energy Thermal Th Two Fluid MSBR Close analogy to historic MSR program Terra Power Fast No enrichment after startup Polishing only Chloride salt Hatch Thermal Canadian company Waterfall design Moltex Fast Polishing only UK company; Chloride salt

13 MCFR Commercial Development Roadmap Has Three Phases Early validation Completed by 2019 Supported jointly by U.S. Government and Southern Nuclear Services led consortium Heat exchanger Neutron reflectors Main fuel salt inventory Critical test reactor Mid 2020s Vessel Commercial prototype By 2035 RIAR Contract Radiochemical is still under negotiation. Division Image courtesy of TerraPower The MCFR core is composed of the reactor vessel, fuel salt, neutron reflectors, and primary heat exchangers.

14 MSRs Have Several Remaining Technology Challenges Ni-based alloys embrittle under high neutron fluxes at high temperature Refractory alloys and structural ceramic composites remain at a low technology readiness levels High power density reactors challenge heat exchanger material mechanical performance and reflector/shield material temperatures Minimizing ex-core fuel volume necessitates high performance heat exchangers Strengthening alloy microstructures dissipate over time at temperature Proper chemistry control is imperative Alkali halide salts can be highly corrosive Ratio of U 4+ / U 3+ is key to maintaining low corrosivity Molten salts can generate substantial amounts of tritium Especially lithium bearing salts Fast spectrum MSR s operate near solubility limits for actinide trifluorides to maintain criticality 14

15 MSR Commercial Deployment Depends Upon Resolving Multiple Materials Issues Max temperature of fuel salt in the primary circuit made of Alloy N is mainly limited by Te IGC under strain depending on salt Redox potential 15

16 Metallic Materials for Fuel Circuit Element Hasteloy N US Hasteloy NM US HN80М-VI Russia HN80МTY Russia HN80МTW Russia MONICR Czech Rep EM-721 France Ni base base base 68.8 Cr 7,52 7,3 7,61 6,81 7 6, Mo 16,28 13,6 12,2 13, , Ti 0,26 0,5 2,0 0,001 0, , Fe 3,97 < 0,1 0,28 0,15 2, Mn 0,52 0,14 0,22 0,013 0, Nb - - 1,48 0,01 < 0,01 - Si 0,5 < 0,01 0,040 0,040 0, Al 0,26-0,038 1,12 0, W 0,06-0,21 0, ,

17 Alloy N Compatibility With Fuel Salts Strongly Depends on Redox Potential Li,Be,Th,U/F HN80МT-VI HN80МTY [U(IV)]/[U(III)] 500 without loading at 735 o C K =3360pc µm/cm; l =166µm K=1660pc µm/cm; l=68µm [U(IV)]/[U(III)] 500 Loading 25MPa 750 o C [U(IV)]/[U(III)] 100 Loading 25MPa 750 o C K =8300pc µm/cm; l =180µm no K = 1850pc µm/cm ; l=80µm no Source: Ignatiev (KI) 2013

18 Te Corrosion in LiF-BeF 2 -UF 4 U(IV)/(UIII) 30 without loading at 760 o C Alloy N enlargement 160 no HN80МTY enlargement 160 no 60 without loading at 760 o C K = 3500pc μm/cm; l = 69μm no 90 without loading at 800 o C K = 4490pc μm/cm; l = 148μm K = 530pc μm/cm; l = 26μm Source: Ignatiev (KI) 2013

19 Tritium Control is Necessary for MSR Acceptability Trapping tritium at the primary to intermediate heat exchanger preserves separation of nuclear and non-nuclear portions of plant At MSR temperatures tritium diffuses through structural alloys Primary heat exchanger is a significant escape path Tritium release potential features prominently in the WASH report An Evaluation of the MSBR, USAEC, 1972 Main strategies for mitigation include: advanced materials for the piping and heat exchangers, inert gas sparging, additional coolant lines and metal hydride addition or chemical removal. Refinement of geometric configuration of the intermediate heat exchangers, minimizing tritium flux, including double wall designs Additional development of permeation-resistant coatings, e.g. W-Si, aluminades, etc. Ultrasonic degassing to facilitate removal of tritium, reducing required total bubble volume for gas sparging Discovery of reusable solvents for direct tritium removal from molten salt The chemistry of sodium fluoroborate and the tritium trapping process Tritium uptake on graphite 19

20 Min temperature of the fuel salt is determining not only its melting point, but also the solubility for AnF 3 in the solvent for this particular temperature А Р Г О Н local γ-spectrometry, isothermal saturation and reflectance spectroscopy 2 Растворимость PuF 3, мольн. % 5 4,75 4,5 4,25 4 3,75 3,5 3,25 3 2,75 2,5 2,25 2 1,75 1,5 1,25 6 y = 0,0206x - 10,2 R² = 0, LiF-27BeF 2 +PuF Температура, 0 С lgs, мол. % 1,5 1 0,5 0-0,5 (1) 45LiF-12NaF-43KF (2) 78LiF-22ThF 4 (3) 75LiF-5BeF 2-20ThF 4 (4) 58NaF-17LiF-25BeF 2 (5) 66LiF-34BeF PuF 3 Растворимость AmF3, мольн. % 5,5 5 4,5 4 3,5 3 2,5 2 1,5 y = 0,0264x - 13,25 R 2 = 0, LiF-27BeF 2 +AmF 3-1 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,25 1, /Т, K Температура, 0 С

21 An and Ln Trifluorides Solubility Up to 873K joint solubility PuF 3 +UF 4 in Li-NaF-KF eutectics is much less compared to individual ones for PuF 3 and UF 4 Temperature, K Individual Solubility, mol.% Joint Solubility, mol. % LiF-NaF-KF PuF 3 UF 4 PuF 3 UF ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±1.1 Near the melting point for 78LiF-7ThF 4-15UF 4 and 72.5LiF- 7ThF UF 4 salts,thecef 3 significantlydisplacepuf 3 Temperature, K 72,5LiF-7ThF 4-20,5UF 4 78LiF-7ThF 4-15UF 4 PuF 3 CeF 3 PuF 3 CeF ,35±0,02 1,5±0,1 1,45±0,7 2,6±0, ,5±0,2 2,5±0,1 5,6±0,3 3,6±0, ,4±0,4 3,7±0,2 9,5±0,5 4,8±0, ,4±0,5 3,9±0,2 10,5±0,6 5,0±0,3

22 Proliferation Resistance Has Become A Dominant Concern For All Fuel Cycles MSRs can be highly proliferation resistant or vulnerable depending on the plant design MSR designs until the mid-1970s did not consider proliferation issues Several current MSR design variants do not include separation of actinide materials Liquid fuel changes the barriers to materials diversion Lack of discrete fuel elements prevents simple accounting Homogenized fuel results in an undesirable isotopic ratio a few months following initial startup (no short cycling) Extreme radiation environment near fuel makes changes to plant configuration necessary for fuel diversion very difficult High salt melting temperature makes ad hoc salt removal technically difficult Low excess reactivity prevents covert fuel diversion 22

23 Summary MSR has flexiblefuel cycle and can operate in different modes: - MSCRs build upon prior MSR heritage - MSFRs avoid requirement for future uranium enrichment - TRU fuel utilizes amount of existing long lived TRU s Liquid fuel inherently intimately interconnects the fuel cycle with the reactor MSR fuel cycles can be highly proliferation resistant or have substantial proliferation vulnerabilities Basic elements of MSR fuel cycles have been identified and demonstrated with varying degrees of sophistication Significant research, development, and demonstration remains to enable any MSR Historic MSR program and successful MSRE operation provides foundational technology and proof-of-concept for future MSRs

24 Another perspective. Our problem is not that our idea is a poor one rather it is different from the main line, and has too chemical a flavor to be fully appreciated by non-chemists. -- Alvin Weinberg 24