TY - JOUR
T1 - Kinetics and transport of hydrogen in graphite at high temperature and the effects of oxidation, irradiation and isotopics
AU - Vergari, Lorenzo
AU - Scarlat, Raluca O.
N1 - Funding Information:
This research is being performed using funding received from the Department of Energy, Office of Nuclear Energy, Nuclear Energy University Program, project IRP-20-22026. Lorenzo Vergari acknowledges the University of California, Berkeley for its Graduate Fellowship.
Publisher Copyright:
© 2021
PY - 2022/1
Y1 - 2022/1
N2 - The kinetics of uptake and desorption impact the performance of graphite as a vector for tritium in high-temperature fission reactors and in the blanket of fusion reactors. Graphite components in these reactors are exposed to temperatures > 500 °C and H2 partial pressures of few Pa and desorption temperatures are limited to < 1600 °C; limited data is available at these conditions. We review the mechanisms for uptake in, transport and desorption of hydrogen from graphite at high temperature, compiling data on uptake rates, diffusion coefficients and activation energies and providing a discussion of the impact of irradiation, pre-oxidation and isotope. At FHR conditions, trapping impacts uptake rates, leading to a reduction in apparent diffusivity by 35 to 80% compared to higher partial-pressure uptake. Timelines for desorption are not clearly defined; extrapolating from available data, at 1150 °C desorbing 80% of tritium uptaken at FHR conditions may take from 100 to 10,000 h.
AB - The kinetics of uptake and desorption impact the performance of graphite as a vector for tritium in high-temperature fission reactors and in the blanket of fusion reactors. Graphite components in these reactors are exposed to temperatures > 500 °C and H2 partial pressures of few Pa and desorption temperatures are limited to < 1600 °C; limited data is available at these conditions. We review the mechanisms for uptake in, transport and desorption of hydrogen from graphite at high temperature, compiling data on uptake rates, diffusion coefficients and activation energies and providing a discussion of the impact of irradiation, pre-oxidation and isotope. At FHR conditions, trapping impacts uptake rates, leading to a reduction in apparent diffusivity by 35 to 80% compared to higher partial-pressure uptake. Timelines for desorption are not clearly defined; extrapolating from available data, at 1150 °C desorbing 80% of tritium uptaken at FHR conditions may take from 100 to 10,000 h.
KW - Graphite matrix and nuclear graphite
KW - Hydrogen absorption kinetics
KW - Hydrogen thermal desorption
KW - Molten salt
KW - MSR and FHR
KW - Tritium management
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U2 - 10.1016/j.jnucmat.2021.153142
DO - 10.1016/j.jnucmat.2021.153142
M3 - Review article
AN - SCOPUS:85112210541
SN - 0022-3115
VL - 558
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
M1 - 153142
ER -