PbLi/T database: status of the knowledge. I. Ricapito , ENEA CR Brasimone, FPN-FISING. OUTLINE. Solubility and Sieverts’ constant in PbLi Bulk diffusivity in PbLi Mass transfer PbLi-gas He in PbLi Possible developments. Solubility and Sieverts’constant.
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status of the knowledge
I. Ricapito, ENEA CR Brasimone, FPN-FISING
Impact of Sieverts’ constant on the tritium permeation rate for PPCS-HCLL
Sieverts’ law validity range /1
No deviation from Sieverst’s law (Reiter)
Deviation from Sieverts’ law (Wu)
Sieverts’ law validity range /2
From Polcaro (1983)
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).
Different values of Sieverts’ constant from different authors (and different techniques)
Sieverts’ constant: last results from SOLE campaign (2005), absorption technique
mol m-3 Pa-0.5 SOLE (A. Aiello)
mol m-3 Pa-0.5(Reiter)
Typical H2 pressure rise P(t) after saturation of the sample from gas phase and fast evacuation of the hydrogen atmosphere (desorption technique)
From Reiter, 1991
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 ×105Pa, tL=72h, m=250 g
Diffusion coefficient of hydrogen isotopes in LLE vs temperature
Comparison of the bulk diffusion coefficients obtained by Terai (1), Reiter (2),Shibuya (3), Fauvet (4)
(1) D=2.5 10‑7exp(‑27000/RT) m2s‑1
(2) D=4.03 10‑8 exp(‑19500/RT) m2s‑1
(3) D=2.62 10‑9 exp(‑6630/RT) m2s‑1
(4) D(450°C)= 1.5×10‑9 m2s‑1
Terai’s values are the highest, probably because determined in high hydrogen partial pressure, with reduced residual surface effects
Hydrogen transfer from LLE to gas phase: mechanisms related coefficients /1
Hydrogen transfer from LLE to gas phase: mechanisms related coefficients /2
mass transfer in the metal boundary layer hl
adsorption coefficient Ka
recombination coefficient Kr, with
Results from A. Viola* (1991)
*Results have been achieved assuming valid the D diffusivity and Sievert’s constant values as measured by Reiter
Effectivemass transfer coefficient: simplified description of the tritium desorption from LLE into a gas phase: J=KD(Cbulk ‑ Cinterface)
TERAI’s experiments (1991) on Tritium release from Pb16Li and influence of H2 partial pressure on it
PH= 1E3 Pa
KD[ms‑1]=2.510‑3 exp(‑30.7kJmol‑1/RT); T=600-1100K, PH2=1000 Pa
Formation of He bubbles and tritium trapping could have an important impact on the blanket operation
Henry’constant (from L. Sedano)