ENEA Experience in PbLi Technologies

ENEA Experience in PbLi Technologies DCLL WORKSHOP- Tritium extraction technologies for EU DCLL M. Utili (ENEA) marco.utili@enea.it 14-15 November 2014

DCLL BB: Tritium extraction from Pb-16Li Tritium Extraction System (TES), scope: to extract tritium from the flowing lithium lead alloy in a dedicated sub-system called Tritium Extraction Unit (TEU), to remove it from the resulting gas stream by Tritium Removal System (TRS) to route it to the Tritium Plant for final processing. Development and Design of Tritium Extraction System, key factors: SAFETY-WASTE: Tritium release, Inventory Tritium/Hydrogen INTEGRATION: Physical size, complexity, synergy with tritium measurement and accountancy system, volume of gas to be treated PERFORMANCE: efficiency OPERATION: Maintainability, Flexibility, Reliability ECONOMICS: Cost (R&D, capital, operation) D. Demage, BB Project KoM Tritium Extraction Technology & Tritium Control

DCLL status 1995-2012 PbLi Loops 1995 PbLi Loops 2013 Heat exchanger 1st EU-US DCLL Workshop

Preliminary PFD PbLi loop DCLL Breeder Blanket 425 C 46.000kg/s TES 425 C Heat exchanger H2O PMP pump 275 C 25% of mass flow rate CPS H2O He Line Operative Conditions: T production 360 g/day 16 toroidal segment: 3 OB per sector, 2 IB per sector n. recirculation x day: 100 Total PbLi mass fow rate: ~ 46.000kg/s N. PbLi loop: 16 PbLi mass flow rate x Segment: ~ 2875kg/s Storage D2tank The issue of corrosion products precipitation in cold legs or near megntic fields. Picture from OECD NEA Handbook of HLM V 1.0, Chap 6, in publishing. 1. Solution 2. Diffusion 3. Transport of dissolved metal 4. Nucleation 5. Transport of crystallites 6. Crystal growth and sintering (plug formation)

Tritium extraction from Pb-16Li Tritium Extraction System Technologies: Gas Liquid Contactor: Vacuum Permeator: Liquid Regenerable Gas Gas getters: - Bubble columns - Packed columns - Spray tower A gas and a liquid phase are brought into contact for the purpose of a diffusion interchange between them. Facilities: Melodie loop (CEA), TRIEX (ENEA) Liquid Contactors ifferent typologies: ss Transport J C T,l C T,l * K s (P T2,i ) 0.5 RT T,l Boundary Layer h (c l T,l c * T, l ) IF *2 J packed columns bubble columns droplet spray columns Boundary Layer P T 2 Droplets tower: Bulk k ( P P 2) T, g g T 2, i T Gas Liquid Contactors Liquid Bulk Tritium fluxes in the different liquid and gas regions based on the phenomenon of tritium permeation through a membrane C T,l,in PbLi, T Different typologies: Mass Transport J C T,l C T,l * K s (P T2,i ) 0.5 RT T,l Liquid Boundary Layer h (c Net Tritium flow-rate from PbLi into gas T av hl [c Vacuum phase per Permeators unit volume permeable membrane l IF J Gas Boundary Layer P T 2 Gas Bulk k ( P P 2) * T,l c T, l ) T, g g T 2, i T *2 J T, r kr ct ka PT 2, i T,l 1 1 ( 2 4 packed columns bubble columns droplet spray columns 2 c T,l 2 S k P T2 ) 0.5 ] = k r /h l T PROS and CONS for Gas Liquid Contactors 2 Permeated side Need to have low typologies: value of γ tube&shell (high h l ) and high value of a v : this last point is very difficult C T,l,out T PbLi [ C] 475 to be achieved by bubble helicoidal columns tube and droplet stray column. With packed columns PbLi, a reasonable T value of a v is assured by the packing itself GLCs need ac downstream * T,M process M for PbLi tritium [kg/s] concentration 1.000 3.000 in He before routing tritium to the further tritium processing systems upstream the refuelling stage Mass Transport Packed columns are large systems especially when large liquid flow-rates have to be processed and high extraction efficiency is required making small droplets in the vacuum, C tritium is released and T,l collected by vacuum line. Kyoto University Robust technology with much industrial experience This technology uses a tritium gettering Liquid Boundary Layer bed of metal in which the solubility of Tritium fluxes in the different * J h (c c ) tritium is higher than T in,l lead l T,l lithium T, l liquid and solid regions η= c H PbLi Already tested at CEA (F) on Melodie loop, with 30% of extraction efficiency achieved C * T,l C * T,g Membrane Gas Boundary Layer J T,g Parameters T production [g/day] k c r * 2 T, g in Value 360 out c H PbLi in c H PbLi 5

PAV: Permeators Against Vacuum PAV technologies is based on the phenomenon of tritium permeation through a membrane in contact with Pb-15.7Li toward a secondary side where vacuum or a carrier gas is present. PAV is a first choice process candidate due to its simplicity and reliability. 2 2 2 11 P 2 1 (upstream) (2.14) p ads des m 1 p abs dsb 1 1 (upstream) (2.15) 1 1 1 1 C D C C 1 2 (bulk) (2.16) p d x C 2 2 2 2 1 (downstream) (2.17) p dsb abs 2 2 p des 2 (downstream) (2.18) 2 2 I. Ricapitoa, A. Ciampichetti, R. Lässer, Y. Poitevin, M. Utili, FUSION SCIENCE AND TECHNOLOGY VOL. 60 OCT. 2011 KS,M and KS,LM are the Sieverts constants of tritium in the membrane and liquid metal the pipe length is strongly depending on the tritium mass transfer coefficient through LBL

y d C T,l,in PbLi, T permeable membrane C T,l,out Fuskite loop (CIEMAT): New size of the test section C Scale testing of permeation * T,l against vacuum Liquid Boundary Layer Tritium fluxes in the different J Perform measurements T,l h l (c T,l c ) liquid and solid regions of T, permeation h in correlation gas-phase for the mass transfer and coefficient flowing the liquid PbLi ld T 2 Mass Transport Permeated side PbLi, T Membrane Gas Boundary Layer Analyze permeation under a number of controlled variables (T, P, velocity, species) C T,l boundary taken from literature for fluids different from PbLi * l typologies: tube&shell helicoidal tube C * T,M D C * T,g J tube T,g T,Pb17Li PROS and CONS for Vacuum Permeators k c r * 2 T, g 0.0096 Re High compactness, especially in the helicoidal tube configuration Being the overall tritium mass transfer strongly sensitive to h l, the tritium mass transfer coefficient in the liquid boundary layer, its value needs to be experimentally determined under relevant conditions. Present data from 0.913 Sc 0.346 [A. Ibarra, 1st EU US DCLL Workshop Fuskite PbLi loop Karlsruhe, April 23-24th 2013] literature refer to fluids different from PbLi drawback when using Nb/pure iron is that at high temperature it has a strong tendency to The metallic membrane needs to have significant tritium permeability and high oxidation, compatibility with PbLi requiring underrelevant a operating very conditions high vacuum during operation and/or a surface layer of Pd The metallic membrane needs to be resistant to oxidation in case of incidental which reduction is or loss more of vacuum oxidation (killing issue foresistant. Nb). Possible need This of ais coating a point of great importance, strongly impacting layer (Pd?) on the vacuum side to keep the membrane oxidation under control PAV design. g o y preliminary sizing of a tube and shell PAV in niobium was carried out in the frame of the design of the DCLL (Dual Coolant Lithium Lead) BB for Aries-CS reactor, having a tritium generation rate of 340 g/d. Vacuum Permeators Never experimentally tested, even atsmall scale

GLC: Packed Columns The packed columns are vertical columns filled with packing or other device providing a large interfacial surface between liquid and gas phase in both counter-current and cocurrent flow. Liquid in L in, x in Gas out G out, y out Packed Column Liquid out L out, x out Gas in G in, y in There are two groups of packing: the random packing like rings the regular or structured packing like layered sheets J T = K D c T,l c T,eq The main characteristics of packed columns are: Advantages: reliable injection system, because it is not necessary to inject small size bubbles reliability of the functional answer because of the kinetics of mass transfer the packing material could be manufactured with high corrosion resistance materials to Pb-15.7Li the Packed columns, used as tritium extraction from lead lithium, have been tested extensively in the past in Melodie loop at CEA

GLC: Packed Columns experimental results on Melodie loop - 800 mm height, 54 mm diameter, packing area: 750 m 2 /m 3, T:673 K Test n. LM flow-rate Ar flow-rate P H2,in (%) (lh -1 ) (N lh -1 ) (Pa) 10 70-90 6 1200-1350 20-22 11 30-50 6 1000-1100 29-31 L/G =7 12 30-50 30 975-1000 29-31 13 30-50 6 450-475 23-25 14 30-50 6 220-230 23-25 Disadvantages: Lower rate size/η (tritium extraction efficiency for one column is 25-30%) than permeators. In any case the size of the columns is a consequence of its efficiency, and the design of the columns can be optimised.

GLC Packed column The extractor column, used for the stripping of the hydrogen contained in the eutectic alloy Pb 16Li, is of the filled type, in counter flow. The liquid phase, represented by the Pb 16Li alloy, enters in the column from the top, passing through the filler, in hydrogen saturated conditions. The real hydrogen content is read by a hydrogen sensor in liquid metal. The gaseous phase, represented by pure argon, is injected in the column from the bottom through an appropriate system of distribution that has the function to uniform and fragment the gas bubbles. Extractor: B B C C D D L.S. L.T. L.S. L.T. Barelli B1 350 Material AISI 304 Tipe B1-350 Spec. surface [m 2 /m 3 ] 350 Loading specific volumetric 250 flow[m 3 /m 2 h)]

11:50:00 10:15:00 08:40:00 07:05:00 05:30:00 03:55:00 02:20:00 00:45:00 23:10:00 21:35:00 20:00:00 18:25:00 16:50:00 15:15:00 13:40:00 12:05:00 10:30:00 08:55:00 07:20:00 05:45:00 04:10:00 02:35:00 Extraction efficiency [%] Hydrogen partial pressure [bar] GLC: Packed Columns Determination of the efficiency with the partial pressures: c H = k S P H η = k S P in k S P out k S P in = P in P out P in η = L vol 1 1 1 SK + D 2G mol VM Ar 40 35 30 0,16 0,14 0,12 25 20 15 10 5 0 0,1 0,08 0,06 0,04 0,02 0 Efficiency Theoretical Efficiency

Droplets and Gas-liquid counter-current extraction tower or vacuum sieve tray By making small droplets in the vacuum, tritium released from droplets is collected by vacuum pumping system. Fusion Engineering and Design (2012), 87(7-8): 1014-1018 tritium release from LiPb is governed by diffusion-limited process A recent study at Kyoto University indicated interesting results on the vacuum sieve tray approach

Droplets and Gas-liquid counter-current extraction tower or vacuum sieve tray Parameters Value Temperature [ C] 400 P H2 [Pa] 2.5x10 4 Nozle radius [mm] 1 Extraction environment Vacuum Droplet radius Rd Experimentally obtained values: Rd = 0.9mm l0 = ~20mm One - stage Mass Flow rate: 0,724 m3/s (6.440kg/s) Diameter: 2,1m h= 1m Efficiency: 45% Multi-stage Mass Flow rate: 0,724 m3/s (6.440kg/s) Diameter: 4,6m h= 6-7 m Efficiency: 90% Fusion Engineering and Design (2012), 87(7-8): 1014-1018

GLC Packed Tower PAV GLC- Droples SAFETY-WASTE INTEGRATION Volume of gas to be treated, physical size Physical size PERFORMANCE 30% 69%-90% 45-90% OPERATION Reliability Maintainability Flexibility: floading loading condition Reliability Maintainability Flexibility Reliability Maintainability Flexibility ECONOMICS SAFETY-WASTE: Tritium release, Inventory Tritium/Hydrogen INTEGRATION: Physical size, complexity, synergy with tritium measurement and accountancy system, volume of gas to be treated PERFORMANCE: efficiency OPERATION: Maintainability, Flexibility, Reliability ECONOMICS: Cost (R&D, capital, operation, power required)