Results from pre-tests on liquid metal embrittlement

Research output: Book/ReportReportProfessional

Abstract

The possible risk for liquid metal embrittlement (LME), solid metal induced embrittlement (SMIE) and liquid metal corrosion (LMC) caused by lead metals on nuclear materials was raised due to an event at a power plant where radiation shields were unintentionally left on the outer surface of the primary circuit for one operation period (-1 year). The shields were removed at the following outage and the surfaces were cleaned and the cleanliness was evaluated by analysing the outer surface using a portable x-ray analyser. The compositions and melting points of the radiation shields were also determined and found to be below the temperature of the primary circuit outer surface. Based on the literature review evidence of lead causing embrittlement on steel was found, with the pre-requisite that a wetting is achieved and the steel is free from an oxide layer. Before performing LME investigations on nuclear materials, test set-up verification was performed, repeating tests found in the literature, consisting of a series of high temperature tensile tests with and without exposure to lead. The reduction of area was almost similar on exposed and non-exposed tests, while the literature reported a clear reduction. The reason for the difference may be the flux. However, further tests on nuclear materials are not feasible using this test set-up, but would require more extensive studies. The results from the tests performed and reported here as well as from parts of the literature, together with the cleaning procedures performed at the plant, the shielding effect of the oxide layer, and the expected low stresses at the outer surface, indicate a very low risk for lead induced embrittlement on the outer surface of the primary piping with temperature below the melting point of the lead shield.
Original languageEnglish
PublisherVTT Technical Research Centre of Finland
Number of pages26
Publication statusPublished - 2015
MoE publication typeD4 Published development or research report or study

Publication series

NameResearch Reports
PublisherVTT
VolumeVTT-R-00308-15

Fingerprint

Embrittlement
Liquid metals
Lead
Melting point
Radiation
Oxides
Steel
Networks (circuits)
Metals
Outages
Shielding
Temperature
Wetting
Cleaning
Power plants
Corrosion
Fluxes
X rays
Chemical analysis

Keywords

  • LME
  • steel
  • tensile tests

Cite this

Autio, J-M., & Ehrnsten, U. (2015). Results from pre-tests on liquid metal embrittlement. VTT Technical Research Centre of Finland. Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, Vol.. VTT-R-00308-15
Autio, Juha-Matti ; Ehrnsten, Ulla. / Results from pre-tests on liquid metal embrittlement. VTT Technical Research Centre of Finland, 2015. 26 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, Vol. VTT-R-00308-15).
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Autio, J-M & Ehrnsten, U 2015, Results from pre-tests on liquid metal embrittlement. Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, vol. VTT-R-00308-15, VTT Technical Research Centre of Finland.

Results from pre-tests on liquid metal embrittlement. / Autio, Juha-Matti; Ehrnsten, Ulla.

VTT Technical Research Centre of Finland, 2015. 26 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, Vol. VTT-R-00308-15).

Research output: Book/ReportReportProfessional

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N2 - The possible risk for liquid metal embrittlement (LME), solid metal induced embrittlement (SMIE) and liquid metal corrosion (LMC) caused by lead metals on nuclear materials was raised due to an event at a power plant where radiation shields were unintentionally left on the outer surface of the primary circuit for one operation period (-1 year). The shields were removed at the following outage and the surfaces were cleaned and the cleanliness was evaluated by analysing the outer surface using a portable x-ray analyser. The compositions and melting points of the radiation shields were also determined and found to be below the temperature of the primary circuit outer surface. Based on the literature review evidence of lead causing embrittlement on steel was found, with the pre-requisite that a wetting is achieved and the steel is free from an oxide layer. Before performing LME investigations on nuclear materials, test set-up verification was performed, repeating tests found in the literature, consisting of a series of high temperature tensile tests with and without exposure to lead. The reduction of area was almost similar on exposed and non-exposed tests, while the literature reported a clear reduction. The reason for the difference may be the flux. However, further tests on nuclear materials are not feasible using this test set-up, but would require more extensive studies. The results from the tests performed and reported here as well as from parts of the literature, together with the cleaning procedures performed at the plant, the shielding effect of the oxide layer, and the expected low stresses at the outer surface, indicate a very low risk for lead induced embrittlement on the outer surface of the primary piping with temperature below the melting point of the lead shield.

AB - The possible risk for liquid metal embrittlement (LME), solid metal induced embrittlement (SMIE) and liquid metal corrosion (LMC) caused by lead metals on nuclear materials was raised due to an event at a power plant where radiation shields were unintentionally left on the outer surface of the primary circuit for one operation period (-1 year). The shields were removed at the following outage and the surfaces were cleaned and the cleanliness was evaluated by analysing the outer surface using a portable x-ray analyser. The compositions and melting points of the radiation shields were also determined and found to be below the temperature of the primary circuit outer surface. Based on the literature review evidence of lead causing embrittlement on steel was found, with the pre-requisite that a wetting is achieved and the steel is free from an oxide layer. Before performing LME investigations on nuclear materials, test set-up verification was performed, repeating tests found in the literature, consisting of a series of high temperature tensile tests with and without exposure to lead. The reduction of area was almost similar on exposed and non-exposed tests, while the literature reported a clear reduction. The reason for the difference may be the flux. However, further tests on nuclear materials are not feasible using this test set-up, but would require more extensive studies. The results from the tests performed and reported here as well as from parts of the literature, together with the cleaning procedures performed at the plant, the shielding effect of the oxide layer, and the expected low stresses at the outer surface, indicate a very low risk for lead induced embrittlement on the outer surface of the primary piping with temperature below the melting point of the lead shield.

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Autio J-M, Ehrnsten U. Results from pre-tests on liquid metal embrittlement. VTT Technical Research Centre of Finland, 2015. 26 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, Vol. VTT-R-00308-15).