Isotope Effects on Tritium Mass Transfer in Li 17 Pb 83 Liquid Blanket

Transcription

1 CJWS-3 Kunming, China, Jun 0-3, 010 Isotope Effects on Tritium Mass Transfer in Li 17 Pb 83 Liquid Blanket S. Fukada, *Y. Edao, H. Okitsu and M. Okada Department Of Advanced Energy Engineering Science Interdisciplinary Graduate School of Engineering science Kyushu University

2 Contents 1 Background Our purpose & research 3 Experiment & Discussion 4 Conclusion 1

3 Background Necessary conditions of Tritium breeding blanket Self-sufficient tritium cycle High temperature heat recovery Inertial fusion reactor, KOYO-Fast Li 17 Pb 83 eutectic alloy ITER-TBM High tritium-breeding simplified blanket structure DCLL HCLL

4 Tritium recovery and leakage Inertial fusion reactor, KOYO-fast Furnace chamber LiPb flow 300 o C,.7m 3 /s leak Circulation pump 1GWt fusion reactor T generation rate : 1.5MCi/day Overall tritium leak : 10Ci/day T transfer 500 o C Tritium recovery Heat system exchanger Tritium recovery ratio of % is demanded!! leak Fueling system T recovery rate Power generator 3

5 Solubility [1 / Pa 0.5 ] Purpose & Recent research Temperature [ Design of tritium recovery system and evaluation of o C] tritium leakage F.Reiter(H) Chan and Veleckis(H) Katuta(H) C.H.Wu(D) In order to clarify the difference 10-8 Large difference /T [1/K] Estimation of property for tritium mass transfer in LiPb Wettability at interface between LiPb and wall materials Isotope effects in hydrogen isotope solubility Impurity effects Li composition change Experiment of H or D permeating through Li-Pb 4

6 Experiment of H, D permeating through Li-Pb A schematic diagram of the experimental apparatus Mass flow meter Glove-box Gas purification exhaust Experimental conditions H or Ar Li-Pb Temperature K H partial pressure D measurement purge Pure Fe H or D Electric furnance GC D partial pressure 10 5 H, D flow rate 5ccm Ar flow rate 5ccm Permeability, diffusivity and solubility of hydrogen isotopes in LiPb were determined by means of a permeation methd 5

7 Permeated H concentration in Ar purge gas [ppm] H permeation rate through LiPb+Fe system 10 5 Fe-H permeation Good agreement in the wide range Fe+Li 17 Pb 83 -H permeation Experiment LiPb Temp. = 873K LiPb+Fe system Fe 10 (transient-state permeation) (steady-state permeation) Time [hour] The overall hydrogen permeation rate is around 100 times higher than the LiPb and Fe dual layer system. The rate-determining step is in the diffusion in the LiPb layer 6

8 Permeation flux of H [mol/m s] H permeation flux in Li-Pb Dependence of H permeation flux, J LiPb-H, on upstream pressure PLiPbH J LiPb H ( ph,, ) upstream p P H downstream LiPb H KLiPb H DLiPb d Downstream-side Ar H K J H =1.6x p H 873K J H =1.4x p H 773K J H =1.x p H 673K J H =1.4x p H Upstream H pressure [Pa] recombination LiPb Diffusion of atom H Fe dissociation The hydrogen solubility obeys the Sieverts law H Upstream-side 7

9 Permeated H concentration in Ar purge gas [ppm] Wettability of Li-Pb with metal surfaces IF less wettability Possibility in some void generating between liquid and solid The apparent solubility is increased The follows equation is not valid when a certain amount of mirobubbles is present at the interface between LiPb and Fe 10 5 P K D Fe-H permeation Fe+Li 17 Pb 83 -H permeation (transient-state permeation) Experiment LiPb Temp. = 873K LiPb+Fe system Fe (steady-state permeation) Time [hour] LiPb H LiPb H Liquid Li-Pb Solid metal LiPb H Micro bubble Micro-bubble gives no effect on the values of P LiPb-H, D LiPb-H, K LiPb-H determined in the present permeation cell Our experimental permeation rate determined by the permeation method is in good agreement with the numerical one under the condition of no micro-bubble formation. 8

10 Diffusivity of H and D [m /s] Solubility of H and D [1 / Pa 0.5 ] Diffusivity & Solubility of H and D Diffusivity Temperature [ o C] Solubility Temperature [ o C] H permeation experiment D permeation experiment F.Reiter(H) T.Terai(T) Okamoto(T) H permeation experiment D permeation experiment Chan and Veleckis(H) F.Reiter(H) Katuta(H) C.H.Wu(D) /T [1/K] /T [1/K] There is no isotopic difference between H and D diffusivity in Li-Pb Solubility of D in Li-Pb is larger than H in Li-Pb 9

11 Isotope effects of solubility The isotope effects are correlated in terms of the harmonic oscillation model Hydrogen solubility is described by the difference in energy between the gaseous phase and the liquid metal phase. The Gibbs free-energy of each hydrogen gas under the standard condition, G k,0, is correlated to the following equation. (By R. Lasser) G k,0 R T g LkT ln 1 e 3.5 J k / T R g D k,0 B k,0 3 H-H LiPb-H k = H, HD, D, DT, T Gas phase Li-Pb phase 10

12 Isotope effects of solubility When H atoms dissolved in Li17Pb83 interstitials are assumed to vibrate in a three-dimensional isotropic harmonic oscillation mode, the vibration energy is described in terms of the zero-point energy, H,0, and the energy of excited state. Isotope effect calculated by harmonic oscillation model for H or D solution in Li-Pb ln K H K D sinh h D,0 k 3ln B T sinh h G G H,0 D,0 R H,0 g T k B T H,0 D,0 Isotope effect can be correlated by H (=h H,0 /k B T) The isotope effects are correlated in terms of the harmonic oscillation model 11

13 Tritium permeation rate through LiPb Tritium permeation rate through heat exchanger wall of a laser fusion reactor Furnace chamber LiPb flow Circulation pump 300 o C,.7m 3 /s leak T transfer 500 o C Tritium recovery Heat system exchanger leak Fueling system T recovery rate Power generator T concentration in LiPb, x T =10-8 (T/LiPb) R T >100Ci/day Necessary to develop high tritium recovery and high efficient permeation barrier 1

14 Conclusion Our recent activities on Li-Pb blanket material are introduced in the present paper. We continue the experiment and design activity for fusion reactor systems 1 3 The solubility obeys the Sieverts law regardless of various pressures. The wettability is estimated and micro-bubble gives no effect on the values of permeability, diffusivity and solubility determined in the present experiment. Solubility of D in Li-Pb is larger than H in Li-Pb. There is no isotopic difference between H and D diffusivity in Li-Pb. The isotope effects are correlated in terms of the harmonic oscillation model. Tritium permeation rate through heat exchanger wall of the laser fusion reactor are estimated and it is larger than 10Ci/day 13

15 CJWS-3

16 Effects of impurities and composition changes Decrease of electro-resistivity of Li-Pb with reaction of oxygen impurity 4Li (in Li-Pb)+O =Li O F. Barbier, FED (1997) Previous researches pointed out that some impurities affect solubility and diffusivity

17 Repeated measurement of Li17Pb melting point Melting point We checked melting point of Li-Pb several times, and we made sure that the melting temperature did not change after several hydrogenatingdehydrogenating operation of Li-Pb

18 Li and H activity of Li X Pb 1-X -H eutectic alloy system Pure Li Pb Pb H - Li+ Pb Li + Pb H - Li-Pb can constitute eutectic alloy system. 0.5 a HinLi a H x HinLi p H When x Li >0.5, electric charge of Li + is not shielded by Pb atoms, and Li + -H - ionic binding is major in Li X Pb 1-X eutectic alloy. Activity of Li is higher. When x Li <0.5, electric charge of Li + is shielded by Pb atoms, and Li + and H - ions may not be combined directly. Activity of Li is the lowest. 18

19 Properties of liquid blanket materials Li Li 0.17 Pb 0.83 FliBe vaporn pressure(800k).1pa 0.37Pa 0.011Pa latent heat 140kJ/mol 180kJ/mol 05kJ/mol viscosity 3.6x10-5 kgs/m.0x10-4 kgs/m 1.5x10-3 kgs/m density 0.48g/cm 3 9.5g/cm 3.0g/cm 3

20 Appendix 1 : Analytical equation One-dimensional diffusion equation The determining-step is diffusion in Li-Pb I.C. t=0, c=0 : B.C. t>0, x=0: t>0, x=l: W W up down P H P P c t, H 0 ", up P down 0 D LiPbH AD AD x LiPb c c x LiPbH x0 c x, c xl up, c down K s K s p H, p up H, down c LiPb D LiPbH K S L 9L JL L 4Dt 4Dt 4 e e e p H up p D H down LiPbHt 5L Dt

21 Appendix The diffusion equation in Li-Pb+pure-Fe system is as follows : 0 x Fe Fe x c, t Fe H, Fe LiPb D H, Fe c, t H, Fe The initial and boundary conditions are as follows: t 0, c H Fe 0, ch,, LiPb 0 H, LiPb c x D H, LiPb x0 c H, LiPb x ph, up ADH, Fe c H, Fe x 0, Wup, ch, Fe c p x x x Fe c 0 H, LiPb, i Fe, clipb K H, LiPb LiPb c H, Fe, i c Fe K H, Fe Fe K H, Fe, ph, down ADH, LiPb ch LiPb j, H Wdown, ch, LiPb c p x 0 x Fe LiPb p H, up LiPb K H, LiPb p H, down

22 Tritium recovery method from Li-Pb blanket Gas-liquid counter-current extraction tower using a packed column Furnace chamber LiPb flow Circulation pump T/He out 300 o C,.7m 3 /s leak leak T transfer 500 o C Tritium recovery Heat system exchanger Fueling system Power generator T recovery rate T/LiPb in He in Li-Pb Raschig ring T He C T Tritium p T,i LiPb out p T C T,i Liquid phase Gas phase Interface Ldc T k L a v kgav ( ct ct i) dz ( pt, R T G dp p, i T T g t p ) dz

23 Ratio of T permeation rate to the total T generation rate Tritium recovery ratio (E recovery )[%] Tritium recovery & permeation T concentration profiles in a packed-column and the rate of permeation T to the total T d=m d=1m d=0.5m E recovery < 99.9% Caluculation (1-c T, LiPb out /c T, LiPb in )x100(= E recovery ) Temperature 500 o C LiPb flow rate 3.5m 3 /s Flow velosity 1m/s Height of extraction column [m] 10-5 Tube diameter, d=0.1m Li-Pb flow rate [m 3 /s]

24 Calculation of packed column h The differential mass balance equation in the height direction of tower under steady-state Ldc T k L a v kgav ( ct ct i) dz ( pt, R T ) dz c T and p T are integrated to determine the column height H L N L L k a L v c c T, in c G p, i T T g t dct c HETP of gas side, H G, and liquid side, H L, for 1 inch raschig ring H G N G p GR T T, in dp T. out T T, i G v t pt, out T i T, k a g p p p dp T p H G 3.07 G0.3 L 0.51 G G D G 3 H L 1 L 430 L 0. L L D L 0.5