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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 PbLi/T database: status of the knowledge I. Ricapito, ENEA CR Brasimone, FPN-FISING

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 - Solubility and Sieverts constant in PbLi - Bulk diffusivity in PbLi - Mass transfer PbLi-gas - He in PbLi - Possible developments OUTLINE

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Solubility and Sievertsconstant The knowledge of the function linking the tritium concentration solubilized in LLE with the corresponding tritium partial pressure at equilibrium, C T =f(P T ), is of basic importance for the LLE breeder blanket concept because of the strong impact on: tritium permeation rate from the blanket into HCS; requested capacity of the Coolant Purification System for a given value of allowed T partial pressure in HCS

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Solubility and Sievertsconstant Impact of Sieverts constant on the tritium permeation rate for PPCS-HCLL

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Solubility and Sievertsconstant Sieverts law validity range /1 No deviation from Sieversts law (Reiter) Deviation from Sieverts law (Wu)

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Absorbed hydrogen weight (sample weight = 172 mg) as a function of time of absorption (in min.) is shown at various hydrogen pressures: 1. PH2=20.87 kPa. 2. PH2=30.80 kPa. 3. PH2=47.01 kPa. 4. PH2=53.30 kPa. 5. PH2=77.41 kPa. 6. PH2=86.63 kPa. 7. PH2=100.11 kPa. One can see that the 5 fold increase in pressure (from plot 1 to 7) gives rise to about 7 fold increase of solubility (reviewed by A. Pisarev). Solubility and Sievertsconstant Sieverts law validity range /2 From Polcaro (1983)

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Different values of Sieverts constant from different authors (and different techniques) Solubility and Sievertsconstant Absorption technique Desorption technique Aiello

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Sieverts constant: last results from SOLE campaign (2005), absorption technique Solubility and Sievertsconstant mol m -3 Pa -0.5 SOLE (A. Aiello) mol m -3 Pa -0.5 (Reiter)

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Bulk Diffusivity Typical H 2 pressure rise P(t) after saturation of the sample from gas phase and fast evacuation of the hydrogen atmosphere (desorption technique) Curve (a) is desorption from the sample, container and vacuum walls. Curve (b) is a control run without the sample. Curve (c) is the difference giving desorption from the sample. Parameters of the experiment: T=591K, P=1.01 ×10 5 Pa, t L =72h, m=250 g From Reiter, 1991

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Bulk Diffusivity Diffusion coefficient of hydrogen isotopes in LLE vs temperature Reiter, 1991

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Bulk Diffusivity Comparison of the bulk diffusion coefficients obtained by Terai (1), Reiter (2), Shibuya (3), Fauvet (4) (2) D=4.03 10 8 exp( 19500/RT) m 2 s 1 (4) D(450°C)= 1.5×10 9 m 2 s 1 (3) D=2.62 10 9 exp( 6630/RT) m 2 s 1 (1) D=2.5 10 7 exp( 27000/RT) m 2 s 1 Terais values are the highest, probably because determined in high hydrogen partial pressure, with reduced residual surface effects

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Mass transfer PbLi-gas Hydrogen transfer from LLE to gas phase: mechanisms related coefficients /1

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Mass transfer PbLi-gas mass transfer in the metal boundary layer h l adsorption coefficient K a recombination coefficient K r, with Results from A. Viola* (1991) *Results have been achieved assuming valid the D diffusivity and Sieverts constant values as measured by Reiter Hydrogen transfer from LLE to gas phase: mechanisms related coefficients /2

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Mass transfer PbLi-gas Effective mass transfer coefficient: simplified description of the tritium desorption from LLE into a gas phase: J=K D (C bulk C interface ) P H = 1E3 Pa TERAIs experiments (1991) on Tritium release from Pb16Li and influence of H2 partial pressure on it K D [ms 1 ]=2.510 3 exp( 30.7kJmol 1 /RT); T=600-1100K, P H2 =1000 Pa

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 He in PbLi Formation of He bubbles and tritium trapping could have an important impact on the blanket operation Henryconstant (from L. Sedano) Diffusivity (from L.Sedano)

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Fusione, Tecnologie e Presidio Nucleare Sezione Ingegneria Sperimentale IEA Workshop on PbLi-T Idaho Falls, 11-12/06/2007 Possible developments Uncertainty remains about the range of validity of the Sieverts law. On the other hand, there isnt consensus on the Sieverts constant values. Taking into account the big impact of such issues on the LLE based blanket, there is the urgent need to find reliable and agreed data. A new task is presently open in EU for a further experimental activity. Anyway, an international collaborations should be of outstanding importance in this field. Reference Tritium diffusivity values in bulk LLE (Terai and Reiter) are spread in less than one order of magnitude. A sensitivity analysis should be done in order to evaluate the impact of the different diffusivity values on the tritium permeation rate into HCS: need of modelling implementation. Only few data on T/LLE-gas mass transfer coefficients are available. A new set of data should be extracted from TRIEX experimental campaigns, planned in the next two years. To do it, the implementation and validation of mathematical models in this ambit appears as a priority.

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