Impedance spectroscopy characterization of neutron irradiated thermoelectric modules for space nuclear power

Ramy Mesalam; Hugo R. Williams; Richard M. Ambrosi; Daniel P. Kramer; Chadwick D. Barklay; Jorge García-Cañadas; Keith Stephenson; David P. Weston

doi:10.1063/1.5095619

Impedance spectroscopy characterization of neutron irradiated thermoelectric modules for space nuclear power

Ramy Mesalam, Hugo R. Williams, Richard M. Ambrosi, Daniel P. Kramer, Chadwick D. Barklay, Jorge García-Cañadas, Keith Stephenson, David P. Weston

Metallurgy and Materials

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

Abstract

The European Space Agency is currently supporting the research and development of advanced radioisotope power systems utilising thermoelectric modules. The performance of thermoelectric modules following exposure to neutron radiation is of significant interest due to the likely application of radioisotope thermoelectric generators in deep space exploration or planetary landers requiring prolonged periods of operation. This study utilises impedance spectroscopy to characterise the effects of neutron irradiation on the performance of complete thermoelectric modules, as opposed to standalone material. For a 50 W_e americium-241 radioisotope thermoelectric generator design, it is estimated that the TE modules could be exposed to a total integrated flux of approximately 5 × 10¹³ neutrons cm^-2 (>1 MeV). In this study, an equivalent neutron dose was simulated experimentally via an acute 2-hour exposure in a research pool reactor. Bi₂Te₃-based thermoelectric modules with different leg aspect ratios and microstructures were investigated. Gamma-ray spectroscopy was initially used to identify activated radionuclides and hence quantify irradiation induced transmutation doping. To evaluate the thermoelectric properties pre- and post-irradiation, impedance spectroscopy characterization was employed. Isochronal thermal annealing of defects imparted by the irradiation process, revealed that polycrystalline based modules required significantly higher temperature than those with a monolithic microstructure. Whilst this may indicate a greater susceptibility to neutron irradiation, all tested modules demonstrated sufficient radiation hardness for use within an americium-241 radioisotope thermoelectric generator. Furthermore, the work reported demonstrates that impedance spectroscopy is a highly capably diagnostic tool for characterising the in-service degradation of complete thermoelectric devices.

Original language	English
Article number	055006
Journal	AIP Advances
Volume	9
Issue number	5
DOIs	https://doi.org/10.1063/1.5095619
Publication status	Published - 1 May 2019

Bibliographical note

Funding Information:
Funding for RM was provided in part via EPSRC grants EP/L505006/1, EP/M506564/1 and EP/M508081/1. JGC acknowledge financial support from the Spanish Agencia Estatal de Inves-tigación under the Ramón y Cajal program (RYC-2013-13970) and from the Universitat Jaume I under the project UJI-A2016-08. The authors gratefully acknowledge the assistance provided by, the Ohio State University Research Reactor team, the European Space Agency and the role of the EPSRC TE Network in fostering the collaboration.

Publisher Copyright:
© 2019 Author(s).

ASJC Scopus subject areas

General Physics and Astronomy

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10.1063/1.5095619

Cite this

@article{9d2eb29cfc71431ea986a04d203667bf,

title = "Impedance spectroscopy characterization of neutron irradiated thermoelectric modules for space nuclear power",

abstract = "The European Space Agency is currently supporting the research and development of advanced radioisotope power systems utilising thermoelectric modules. The performance of thermoelectric modules following exposure to neutron radiation is of significant interest due to the likely application of radioisotope thermoelectric generators in deep space exploration or planetary landers requiring prolonged periods of operation. This study utilises impedance spectroscopy to characterise the effects of neutron irradiation on the performance of complete thermoelectric modules, as opposed to standalone material. For a 50 We americium-241 radioisotope thermoelectric generator design, it is estimated that the TE modules could be exposed to a total integrated flux of approximately 5 × 1013 neutrons cm-2 (>1 MeV). In this study, an equivalent neutron dose was simulated experimentally via an acute 2-hour exposure in a research pool reactor. Bi2Te3-based thermoelectric modules with different leg aspect ratios and microstructures were investigated. Gamma-ray spectroscopy was initially used to identify activated radionuclides and hence quantify irradiation induced transmutation doping. To evaluate the thermoelectric properties pre- and post-irradiation, impedance spectroscopy characterization was employed. Isochronal thermal annealing of defects imparted by the irradiation process, revealed that polycrystalline based modules required significantly higher temperature than those with a monolithic microstructure. Whilst this may indicate a greater susceptibility to neutron irradiation, all tested modules demonstrated sufficient radiation hardness for use within an americium-241 radioisotope thermoelectric generator. Furthermore, the work reported demonstrates that impedance spectroscopy is a highly capably diagnostic tool for characterising the in-service degradation of complete thermoelectric devices.",

author = "Ramy Mesalam and Williams, {Hugo R.} and Ambrosi, {Richard M.} and Kramer, {Daniel P.} and Barklay, {Chadwick D.} and Jorge Garc{\'i}a-Ca{\~n}adas and Keith Stephenson and Weston, {David P.}",

note = "Funding Information: Funding for RM was provided in part via EPSRC grants EP/L505006/1, EP/M506564/1 and EP/M508081/1. JGC acknowledge financial support from the Spanish Agencia Estatal de Inves-tigaci{\'o}n under the Ram{\'o}n y Cajal program (RYC-2013-13970) and from the Universitat Jaume I under the project UJI-A2016-08. The authors gratefully acknowledge the assistance provided by, the Ohio State University Research Reactor team, the European Space Agency and the role of the EPSRC TE Network in fostering the collaboration. Publisher Copyright: {\textcopyright} 2019 Author(s).",

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AU - Mesalam, Ramy

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AU - Barklay, Chadwick D.

AU - García-Cañadas, Jorge

AU - Stephenson, Keith

AU - Weston, David P.

N1 - Funding Information: Funding for RM was provided in part via EPSRC grants EP/L505006/1, EP/M506564/1 and EP/M508081/1. JGC acknowledge financial support from the Spanish Agencia Estatal de Inves-tigación under the Ramón y Cajal program (RYC-2013-13970) and from the Universitat Jaume I under the project UJI-A2016-08. The authors gratefully acknowledge the assistance provided by, the Ohio State University Research Reactor team, the European Space Agency and the role of the EPSRC TE Network in fostering the collaboration. Publisher Copyright: © 2019 Author(s).

PY - 2019/5/1

Y1 - 2019/5/1

N2 - The European Space Agency is currently supporting the research and development of advanced radioisotope power systems utilising thermoelectric modules. The performance of thermoelectric modules following exposure to neutron radiation is of significant interest due to the likely application of radioisotope thermoelectric generators in deep space exploration or planetary landers requiring prolonged periods of operation. This study utilises impedance spectroscopy to characterise the effects of neutron irradiation on the performance of complete thermoelectric modules, as opposed to standalone material. For a 50 We americium-241 radioisotope thermoelectric generator design, it is estimated that the TE modules could be exposed to a total integrated flux of approximately 5 × 1013 neutrons cm-2 (>1 MeV). In this study, an equivalent neutron dose was simulated experimentally via an acute 2-hour exposure in a research pool reactor. Bi2Te3-based thermoelectric modules with different leg aspect ratios and microstructures were investigated. Gamma-ray spectroscopy was initially used to identify activated radionuclides and hence quantify irradiation induced transmutation doping. To evaluate the thermoelectric properties pre- and post-irradiation, impedance spectroscopy characterization was employed. Isochronal thermal annealing of defects imparted by the irradiation process, revealed that polycrystalline based modules required significantly higher temperature than those with a monolithic microstructure. Whilst this may indicate a greater susceptibility to neutron irradiation, all tested modules demonstrated sufficient radiation hardness for use within an americium-241 radioisotope thermoelectric generator. Furthermore, the work reported demonstrates that impedance spectroscopy is a highly capably diagnostic tool for characterising the in-service degradation of complete thermoelectric devices.

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Impedance spectroscopy characterization of neutron irradiated thermoelectric modules for space nuclear power

Abstract

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