Production of Pb-Li eutectic: cover gases or molten salts during melting?

Transcription

1 Production of Pb-Li eutectic: cover gases or molten salts during melting? Mª. I. Barrena, J. Mª. Gómez de Salazar, A. Soria, L. Matesanz Dpto. Ciencia Materiales e Ing. Metalúrgica. F. CC. Químicas. Universidad Complutense de Madrid. UCM, Spain M. Fernández and J. Quiñones CIEMAT. Avda. Complutense, Madrid, Spain

2 Outline Rationale of the activity Review of current production techniques Design proposals Conclusions and future

3 Rationale -1 Since early 70 s, Pb-Li eutectic (LLE, Pb15.7Li) represents today the most consolidate liquid breeder material. 6 Li enriched LLE should be manufactured for diverse ITER TBM (EU- HCLL, US-DCLL, IN-LLCB) according to nuclear material standards. Several tones of Pb15.7(2) 6 Li should prospectively to be procure by ITER parties LLE characteristics should be established according to nuclear material QA requirements ISO3131/- 1, /-5, Light Metals and light alloying metal: methods for processing and treatment Li chemical activity determine LLE activity: title has large impact on NFT. 3 H solubility in LLE would largely depends on Li-disproportioning by bad mixing or local aggregation. Other properties less modified 2 at% Li deviations are unacceptable from QA of LLE as Nuclear Material

4 Uncertainty in the eutectic composition ( T-soly) - overestimation depending on the experimental protocole for production and for its determination - W-T data for a total of 52 points {0 < x Li (at%) <22.2}, show to decrease smoothly from the melting point of pure Pb to the eutectic point (15.7(2) at% Li, 235(1) C, the hypereutectic increased towards the m.p. of the PbLi phase [P. Hubberstey et al, JNM (1992)], - a single liquid phase maintained over the composition range from 13.7 to 18.0 at% Li, Disproportioning by bad mixing ( T-soly) - not sistematically checked & driving potentially to incorrect overestimated solubility (in connection with Li-aggregation by clustering) - Mixing light Li with heavy Pb and large homogeneity is not an easy technical mater Ks Li ( LnK ) 1 ( at. Li. ( at. Li) spb Li eut ) 17 (3) eutectic disproportioning ( Ks) ( ) Figure 4. Deviation from theoretical eutectic composition [15.7(2)at%Li] at liquid phase and solubility impact with Li aggregation. Disproportioning effects can be like this eut

5 Rationale -2 Key QA aspects: 1. Material certified application database according with the material design functionalities [see., E. Mas de les Valls et al., JNM ] 2. Certified characterization techniques supporting database 3. QA demands to (LLE) characteristics: constitutive and compositional - QA constitutive specifications: & Li aggregation - Compositional specifications apply for Li title certification & impurity levels Production and material testing routes should be fixed according to QA standards In the EU, TBM Consortium of Associates (CIEMAT) is generating a procurement plan for 6 LLE according to nuclear standards

6 Roadmap for Pb - Li eutectic QA procurement Revision of set of ISO norms ISO3131/- 1, /-5, Light Metals and light alloying metal: methods for processing and treatment, in force for Nuclear Materials and IAEA Regulations. Fixing Material specification in terms of: maximum allowable impurity contents Li contents global deviations (ex. < ± 0.2 Li at%) Homogeneity criteria (ex. maximum size and distribution of Li and other Li-Pb phases aggregates Establishment of a production route (with specification of endorsing ISOs) according to previous material QA criteria. Establishment of set of certification tests for Material QA (fine calorimetry at eutectic, x-ray phase study, Atomic Absorptions Technique, ) Lack of database reproducibility for key FT properties can not even more potentially be justified in terms of material uncertainties

7 Programme goals In parallel to EU ITER/DA F4E activities (GRT-030) Spanish TECNO_FUS 2009/2012 Programme (CIEMAT, UCM) is facing production of 6 LLE according to ITER QA standards 6 LLE FUNCTIONAL (REPRODUCIBLE) DATABASE CERTIFIED CHARACTERISATION 6 LLE PRODUCTION ROUTES

8 Certified characterization Present EU Pb Li alloy specs. INGOTS A ±0.2%at Li Institute of Physics of the University of Latvia (IPUL) INGOTS B 18.8± ±3.5%at Li "Jost-Hinrich Stachov Metahandel", Germany MICROSTRUCTURE NEARLY EUTECTIC MICROSTRUCTURE HYPEREUTECTIC

9 Pb-Li binary diagram Y Ref. at.% Li Alloy origin T-control Analysis Uncertainties 88 [5] CEA, Li(99.5) and Pb(99.994) Figure 1: Phase diagram of Pb-Li system [Tegze and Hafner, 1989] 91 [6] Alloyed at home Poor detail N.S. 91 [3] laboratory, Li(99.4) from Metallgesellschaft with 0.5 Na, 0.01 K, 0.03 Ca, <0.01 Al, <0.03 Si and Pb(99.99) from Ventron 92 [7] 15.7 laboratory, use of an electromagnetic pump to ensure the homogeneity 05 [10] 15.8 laboratory, use of a three-phase MHD stirrer. Comparison with a sample from METEAUX-SPECIAUX (1993) and another from Jost-Hinrich Stachov Metallhandel (2003) 06 [11] laboratory, Li(99.8) and Pb(99.99) Thermal analysis (Ni- CrNithermocouple s) and thermal differential analysis with a Netzsch DTA measurement of electrical resistance as a function of T AAS -- X-ray phase study, AAS 0.01 wt.%, oxygen impurities were below the hot extraction method (0.01%) 1.3 at.% wt.%

10 Experimental Procedure Material Ingot A Ingot B

11 Previos work Temperature distribution Ingot A Homogeneous distribution Wall solidification Ingot B T f >> del ingot A High temperature areas y x y x Ingot A y x y x Ingot B

12 conc. Li / % at conc. Li / % at Previous work Chemical analysis Ingot A Ingot B Lingote A ThermoX ELAN Lingote B ThermoX ELAN 6 Li 6 Li 40 7 Li [Li] A = ± 0.50 % at 40 7 Li [Li] A = ± 1.38 % at Composición nominal fabricante Composición eutéctico Pb - Li Composición nominal fabricante Composición eutéctico Pb - Li muestra muestra

13 Y Y Y Y Previos work Li elemental analysis %at Li (distribution) A < B >> first solidification areas >> eutectic >> nominal composition Dependence with position Similar behaviour than T Ingot A1 X Ingot A Ingot B E X Ingot B int X X

14 Temperatura / 0 C Temperatura / 0 C Previous Work 320 ASM (up dated 1993) Hubberstey et al.; Este trabajo Lingote A Czochralski & Rassow; ; Lingote B Grube & Klaiber Pogodin & Schtilineshkii 320 ASM (up dated 1993) Hubberstey et al.; Grube & Klaiber Czochralski & Rassow; Pogodin & Schtilineshkii Este trabajo Lingote A: Tf c = ; Tf e = ; Lingote B: Tf c = ; Tf e Li / % at Li / % at Measurement T eut(m) C y T eut(s) C Ingot A shows the highest homogeneity

15 Basic scheme of our melting system A: Induction Furnace (8 kw) B: Reactor (Cr-Ni Alloy) C: Gases battery

16 Equipment designed Vacuum Thermocouple Gas Innlet Windows SiC crucible & Pb-Li ingots

17 Experimental description Material Pb(s) ultrapure Li(s) ultrapure Experimental condition Atmosphere N 2, Ar, molten salt,... Temperature C Time? Crucible C, CSi, SiO 2

18 Crucible material selection - Reactivity of the LLE

19 Experimental setup Group Ingot Temp ( C) time (min) Gas Crucible I PbLi PbLi N 2 (T) C PbLi SiC PbLi SiC II Ar PbLi SiO 2 III PbLi Ar (BIP) SiC IV PbLi PbLi PbLi PbLi V PbLi VI PbLi Ar (BIP) + eutectic LiCl/KCl Air + eutectic LiCl/KCl Ar (BIP) + eutectic LiCl/KCl C SiC SiC SiC

20 Results - Chemical characterization by ICP-MS Group Ingot %at Li PbLi I PbLi PbLi II PbLi 4 17 PbLi III PbLi PbLi IV PbLi PbLi PbLi V PbLi VI PbLi

21 Q (mw/mg) Results - Microstructure & DSC characterization 0,5 0,4 0,3 0,2 Eutectic Eutectic Pb-Li ingots 0,1 0,0-0,1-0,2-0,3-0,4-0,5-0,6-0,7-0,8-0,9 Eutectic T (ºC)

22 Q (mw/mg) Results - Microstructure & DSC characterization 0,4 0,3 0,2 0,1 Eutectic Solidification Hipoeutectic Pb-Li ingots 0,0-0,1-0,2 Melt -0,3-0,4-0,5-0,6-0,7 Eutectic T (ºC)

23 Q (mw/mg) Results - Microstructure & DSC characterization 0,3 0,2 Eutectic Solidification Hipereutectic Pb-Li ingots 0,1 0,0-0,1-0,2-0,3 oxidation Melt -0,4-0,5 Eutectic T (ºC) Intermetallic Pb-Li

24 XRD pattern of the oxidized phases Li3N and PbO

25 Results Melting points

26 Ongoing efforts Impurity control Optimization of the melting process Impurity control Design of the thermal treatment Reduce of oxidation process Li