Gonzalez de Vicente, S.M.

Möslang, A.

Stieglitz, R.

English

Gonzalez de Vicente, S. M.

KITopen

Impact of coolant choice on design and performance of a fast neutronsystemR. Stieglitz, S.M. Gonzalez de Vicente, A. MöslangVienna, Austria5 ‐ 7 July 2017 1st Workshop on Challenges for Coolant in Fast Spectrum Systems: Chemistry and MaterialsContent Environment of fast spectrum applications Coolant functions in fast (neutron) spectrum application Thermo‐physical aspects Neutron‐physical considerations Consequences on licensing frame and time scales Example‐Fast reactors Impact of coolant choice on reactor design –power conversion options Coolant poising/conditioning/handling Coolant confing structures and material degradation Safety analyses Example‐Accelerator applications Coolant choice consequence on integral facility design Objectives to be met by the workshop Vision/Measures for future cross fertilizing exploitation04/07/2017 2Environment of fast spectrumapplicationsTypes of utilization fundamental sciences & technologiesAccelerator Applications nuclear energy conversion Fission & FusionBoundary conditionsI. volumetric high efficiency (particle yields, fuel utilization, thermal efficiency)II. improved safety (all three lines: accidental safety/operational safety/disposal)III. enhanced lifetimeConsequencesI. enlarged coolant/material damageII. dedicated constructive/operational/handling measuresIII. long extensive licensing procedures demanding data bases ageing/fatigue aspects lifetime management component qualification,  code & standards04/07/2017 3Coolant functions in fast (neutron) spectrum applicationsthermo‐physical considerationsCOOLING FUNCTIONFUNDAMENTALS OF KINETICS & ENERGY TRANSFERInputs  heat source type (e.g. charged particles, neutrons, photons ) coolant (thermophysical properties ) coolant confining material (thermo‐physical properties and thermo‐mechanical properties ) Design to match functionality geometry (wall thickness, flow‐configuration,..)RESULT = KINETICS 04/07/2017 4 heat conductivity , W  T  material, fluid limits thermal inertia (.cp)  time  operational grace time, removable power temperature threshold  T  phase change (safety),removable power, design provisions (auxiliary heating, boiling detection thermal expansion    passive heat removal capability (safety), pumping power (Balance of Plant)  kinematic vicosity (.) )  p  pressure loss, wall shear stress (erosion, corrosion)Coolant functions in fast (neutron) spectrum applicationsthermo‐physical considerations some typical soolants considered in fast spectrum applications(thermo‐physical data) there is not optimal coolant from thermo‐physical point of view !!04/07/2017 5H2O[300°C,15MPa]Li[500°C]Na[500°C]Hg[20°C]Pb[500°C]Pb45Bi55[500°C]SaltNaCl‐KCl‐MgCl2[600°C] He[500°C,6MPa]CO2[500°C2MPa] [kg/m3] 725 475 857 13534 10724 9660 1800 3.7 13.5cp [J/(kgK)] 5475 4169 1262 140 145 145 1004 5190 1170( cp)[MJ/(m3.K)]3.97 1.98 1.081 1.895 1.555 1.401 1.807 0.19 0.158 [W/(mK)] 0.561 49.7 66.3 8.3 15 11 0.39 0.303 0.056 [(m2/s). 10‐7] 1.2 7.16 2.6 1.1 1.5 1.1 0.138 0.9 0.25Tmelt [°C] ‐0.4 180 98 ‐39 327 126 396 ‐ ‐58Tboiling [°C] 334 1317 883 356 1737 1533 2500 ‐ ‐78not desirable advantageousCoolant functions in fast (neutron) spectrum applicationsNeutron‐physical considerationsCOOLANT NEUTRONIC FUNCTION neutron (charged particle) interaction with matter high particle fluxes (e.g. charged particles, neutrons, photons ) high incident particle energies dedicated material (fuel/target compositions secondary reactions ) Design to match functionality geometry (wall thickness, reduced leakage,..) high volumetric power densities04/07/2017 6Constraints to coolant if possible transparent to incident particles no (or short lived ) immobile activation products no temporal degradation by neutronicinteraction (destruction of coolant chemistry, radiolytic decomposition ) all safety & economic parameters ………..Coolant functions in fast (neutron) spectrum applicationsNeutron‐physical considerationsNeutronics Moderation s(logarithmic energy decrement per collision smacroscopic scattering cross‐section hardly moderation in Pb , He moderate performance of Na design challenges for H2O04/07/2017 7 11ln2112AAAA(.s) [cm‐1]Zr 0.00046Fe 0.0023Na 0.0027Pb 0.00013H2O 1.36He 0.00024C 0.06O 0.0058 Nuclear cross‐sections (tot) high hydrogen cross section throughout E‐range Large values for Pb and Pb‐alloys in but no broad band resoncances as Na  almost no interference using He except for He each other coolant posesneutron physics challengesENDF,20017Coolant functions in fast (neutron) spectrum applicationsNeutron-physical considerationsCoolant treatment requires consideration of coolant/functional materials.  Structure material also affected by  nuclei matter interaction  nuclear reactions f (E) and time,  operational temperature,  the design of the component  swelling, formation of transmutation products within the material, hardening and a set of other phenomena (all dynamic).  Additionally, at fluid‐structure interface mass transport processes (bi‐directional) due to scalar gradients (T, c, p) corrosion, stress‐corrosion cracking, embrittlement enforced/assisted by  irradiation.  Nuclear and conventional islandinterlinked via coolant coolant choice affecting nuclear system architecture.04/07/2017 8Coolant functions in fast (neutron) spectrum applicationsConsequences on licensing frame and time scalesSystematic Safety Analysis (SSA) ‐ Success criteria normal operation dose to worker on site < limit accidental analysis :   worst dose to public (MEI)    < limit consequences: mobility in long term storage < limit (what ?) all to be met04/07/2017antipcipatedplant operation+materialINPUTnormal operation(mainly governed by radio protection)accidental analysisinevitable consequences(radiation protection, societal contract)PST=Process Source Term,  MEI=Most Exposed IndivudualCoolant functions in fast (neutron) spectrum applicationsConsequences on licensing frame and time scalesNuclear licensing requiresinput at the begin of processtracking plant for decadestaking responsibility for centuriesMandatory pre‐requisites @ tstartreliable, broad data basevalidated code/standards/procedures04/07/2017 10 TOPICS  Coolant characteristics under irradiation  Coolant confining structures  Interfaces and Safety and operational aspects.Workshop objective synthesize knowledge on coolant behaviour in fast spectrum systemselucidate potential knowledge gaps Formulation of  required efforts to overcome present shortcommingsExample‐Fast reactorsImpact of coolant choice on reactor design –power conversion optionsIn Gen‐IV  4 of 6 reactors fast reactors Sodium Fast Reactor (SFR) Gas cooled Fast Reactor (GFR) Lead cooled Fast Reactor (LFR) Molten Salt Reactor (MSR)04/07/2017 11Selection criteriaSustainability (fuel utilization/ transmutation/ waste reductionEconomy (long cycles, life >60y, compactness) Safety (increased safety/operational reliability /low probability of core accidents/elimination for off‐site emergency response Proliferation resistance Conventional PWR loop type SFR GFR LFRExample‐Fast reactorsImpact of coolant choice on reactor design –power conversion optionsSome FR characteristicshigh material allocation in coremax. utilization of neutronssmall coolant channels (as e.g. fusion) decay heat managementhigher f /a ration and more d breeding/transmutation options high n‐leakagelarger n‐capture higher fuel enrichmenthigh volumetric power densities (>100MW/m3) power management coolant voiding reactivtiy management high n‐Energy challenging to coolant (fuel, structure) material (fuel, structure) coolant material interaction04/07/2017 12PWR GFRSFRLFRExample-Fast reactorscoolant poisoning/conditioning/handlingCoolant activation nuclear reaction with nradioisotope formation reuse of Na after 50‐60years feasiblePbBi will be classified waste (almost forever)04/07/2017 13isotope formation channel T1/2 [a]22Na 23Na(n,2n)22Na 2.624Na 23Na(n,g)24Na 1.7.10‐3205Pb 204Pb(n,g)205Pb 1.5.10‐7208Bi 209Bi(n,2n)208Bi 3.7.105210Bi 209Bi(n, )210Bi 3.6.106210Po 210Bi ()210Po 0.3810-2 10-1 100 10110110210310410510654Fe Gas Production Cross Section, barnNeutron Flux, 1010  n/(cm2  s)/MeVNeutron Energy, MeV DEMO HCPB-FW BOR60-D23 HFR-F8 HFIR-target10-810-710-61x10-51x10-410-310-210-11004HeDH Transmutation in structures n‐energies exceeding Eth gas production in structure (fuel)‐such as H, D, T, He 2 effects diffusion of gas into coolant necessitating diffusion barriers or partial pressures on sec./ternary side permanent gas formation in structure (damage‐He) Example‐Fast reactorsCoolant poisoning/conditioning/handlingOperational consequencespermanent coolant conditioning (physico‐chemistry) Na:  O, H –management via cold, traps, fire, explosion measures in bypass He:  H (but esp. T) extraction by coolant purification techniques (getters) Pb:  active oxigen control to prevent steel corrosion, coolant oxidation f=(T, t,cO, u0, dpa)oxygen sensor developmentbarrier developmentprocess technologymaterial validation04/07/2017 14Austenitic steeldissolution of  alloying elements (Ni); rate up to 1 µm/hF/M steel huge oxidation rate F/M‐9Cr‐steels oxide spallation by growth stress weak heat removal capabilityWeisenburger et al., 2011, J. Nuc.MatExample-Fast reactorscoolant confining structuresand material degradation irradiation causes constraints to material performance. Physicsradiation induced growth atom segregation in lattice (diffusion controlled)radiation induced growth f =(T, dpa, E, dose rate, , composition, He)radiation damage affects the mech. properties  hardening & localized deformation,  fracture behavior  embrittlement and  irradiation creepFive evils for radiation damage in metal based materials (G.Was, 2014):radiation hardening & embrittlement (<0.4TM, >0.1 dpa)phase instabilities from rad.‐induced precipitation (0.3‐0.6 TM, >10 dpa)high temp. He embrittlement (>0.5 TM, >10 dpa)vol. swelling from void formation (0.3‐0.6 TM, >10 dpa) irradiation creep (<0.45 TM, >10 dpa)04/07/2017 15© S. Zinkle, ORNLExample‐Fast reactorscoolant confining structuresand material degradationMost relevant for radiation damage He/dpa ratiostrongly depending on applicationHelium generated in material 04/07/2017 16SpallationFission reactorTtest  Tirr = 450°CSpallation irradiation yields higher strength irrthan fission reactor irradiations due to He© Dai,2009, workshop PSI Does this impact other quantities as well?Example‐Fast reactorscoolant confining structuresand material degradationYES sensitivity of He to mech. Properties as  fracture toughness (Charpy tests)04/07/2017 170 10 20 30 40 50 60 70050100150200250 F82H, F82H-mod (Tirr=300°C-337°C) EUROFER97 (Tirr=300°C-335°C) EUROFER97 HT (Tirr=250°C-335°C)EUROFER, <10 appm Hedamage dose [dpa]DBTT[°C]0 100 200 300 400 5000100200300400ARBOR2SPICESPICEARBOR1Tirr = 250-350°CEUROFER, 10-500 appm HeSpallationY. Dai, PSI©  Gaganidze et al., J. Nucl. Mater. 417 (2011)93‐98additional He [appm]extra DBTT[°C] without He saturation of  Ductile Brittle Transition Temperature (DBTT) for  50dpa  with He additional significant DBTT increase significantly limiting the lower operation temperature05101520253035400 0.2 0.4 0.6 0.8 1 1.2Axial Fuel Expansion (mm)Transient Time (s)LT2 testAST‐IKEAST‐IRSNSAS‐SFRClad ExpansionHodoscopeExample‐Fast reactorssafety aspectsAccidental safety analysismodel improvementApproach  identification of modelling deficits by code-to-code comparisioncomplemented by experimental dataSome Results gap heat transfer model validated  fission gas model contains many parameters  sensitivity analysis of some parameters axial fuel expansion overestimated  visco-plasticity model now in ASTEC-Na V2.0 But major deficit lack of experimental datagap heat  transfer (coolant temp.)fission gas release axial fuel exp. fuel meltingExample‐Fast reactorssafety aspects each FR type exhibits safety limiting scenarios (worst case) GFR:  decay heat removal (DHR) in depressurized conditions. SFR:  sodium fires, positive void effect (for unprotected loss of flow/ loss of heat sink), DHR.  LFR:  degradation core materials, formation Po, seismic stability of containment, DHR.  Completely different to PWR  (loss of coolant accident (LOCA), reactivity‐initiated accident (RIA)) Passive DHR strategy adopted for most FR developments General ideas  Heat transfer cascade via media separation buoyancy driven  accident tolerant design04/07/2017 19GFR SFR LFRExample‐Spallation neutron sourcesdesign optionsTarget:  generation of high quantities of neutrons Means:  interaction of matter in a thick target ‐ target material selection high current, high energy accelerator  internuclear cascade dominant  higher amount of neutron production number of  n/p depend on target material  high Z‐materials (Pb, Hg, W)Consequences heat deposition in target  activation of target (&and coolant)How many neutrons can we get ? saturation of  generated n/p @ 2.5GeV04/07/2017 20averagen‐multiplicityper incidentper ptarget thickness [cm]target thickness [1023/cm2]A. Letourneau et al.,  Nucl. Instr. and Meth. in Phys. Res. B 170 (2000) 299© Phil Fergusson SNSExample‐Spallation neutron sourcesdesign optionsTarget design options:  homogeneous – coolant spallation source & target (Hg, Pb, PbBi) heterogeneous – inert coolant + solid target (He/W)ESS‐ Target Selection exercise Option 1: liquid PbBi gravity (pump support) 04/07/2017 21 despite high power no boiling  surface temperature & damageok simple set‐up, low power, no confinement penetration  gravity drain (safety), marginal spaceMajor decision criteria: Small & separated development risks spallation products easy to confine nuclear waste foot print timely realizationExample‐Spallation neutron sourcesdesign optionsESS‐ Target Selection exercise Option 2: rotating helium cooled tungsten target04/07/2017 22 moderate wall & W temperatures manageable manufacturingo challenging wheel design complex integration & safety demonstration Summary &Workshop objectivesSUMMARY neutronics, thermo‐physics and thermo‐chemistry of both coolant(s) and its  confining structures are strongly interconnected validated data, approved modelling means are of key importance to establishcode/standards/procedures and to allow for an integral enveloping safety assessment………………….04/07/2017 23Hard Objectives descpription of state‐of the art knowledge in your individual expert field formulation of fundamental physics based limitations, constraints identification of knowledge gaps and means/suggestions/proposals to overcomepresent deficits (experimental, instruments, modeling, data)  R&D needs adressing interfaces to adjacent fields and methods for overarching topicssuch as safety/design Workshop objectives& PerspectiveSoft Workshop objectives interdisciplinary information exchange  cross‐fertilization of different communities identification of collaborations (use of infrastructures, common R&D projects, development of codes) 04/07/2017 24Vision on continuation regular meeting of experts as side meeting to community conferences (Fast reactor conference, ISFNT and accelerator applicationsFormation of sub‐groups necessesary ?…..

Impact of coolant choice on design and performance of a fast neutron system

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Impact of coolant choice on design and performance of a fast neutron system

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