Applying laboratory methods for durability assessment of vitrified material to archaeological samples

Lorena Nava-Farias,Carolyn I Pearce,Claire L Corkhill,David K Peeler,Clare L Thorpe,Rossane C Delapp,Rolf Sjöblom,José Marcial,David S Kosson,Russell J Hand,James J Neeway,Albert A Kruger,Sam A Walling,John S Mccloy,Nathan L Canfield,Michael J Schweiger,Edward P Vicenzi

doi:10.1038/s41529-021-00204-2

Abstract

Laboratory testing used to assess the long-term chemical durability of nuclear waste forms may not be applicable to disposal because the accelerated conditions may not represent disposal conditions. To address this, we examine the corrosion of vitrified archeological materials excavated from the near surface of a ~1500-year old Iron Age Swedish hillfort, Broborg, as an analog for the disposal of vitrified nuclear waste. We compare characterized site samples with corrosion characteristics generated by standard laboratory durability test methods including the product consistency test (PCT), the vapor hydration test (VHT), and the EPA Method 1313 test. Results show that the surficial layer of the Broborg samples resulting from VHT displays some similarities to the morphology of the surficial layer formed over longer timescales in the environment. This work provides improved understanding of long-term glass corrosion behavior in terms of the thickness, morphology, and chemistry of the surficial features that are formed.

Highlights

Public acceptance is a critical part of the regulatory framework associated with the disposal of nuclear waste glass
One of our aims was to see if laboratory-made samples with identical compositions to those found in the field could be used as a replacement for samples excavated at the site
The study of vitreous archeological samples altered in the natural environment, including vitrified archeological samples produced by pre-Vikings at the Broborg hillfort ~1500 years ago, is an important part of the overall strategy for predicting the behavior npj Materials Degradation (2021) 57

Summary

Introduction

Public acceptance is a critical part of the regulatory framework associated with the disposal of nuclear waste glass. To show that glass is chemically stable for long time periods and that the dominant corrosion mechanisms are well understood, waste glasses are subjected to short-term, accelerated laboratory tests. Vitreous archeological materials have long been considered as analogues that can be used to assess the corrosion behavior of nuclear waste glasses that will be disposed in subsurface geological repositories[1,2,3,4]. Archeological samples can be used to assess the impacts of the near-field environment and to study how the corrosion layers on the archeological samples may have formed. The use of vitreous archeological samples as analogues for nuclear waste glasses is limited, because the precise corrosion environment (e.g., temperature, hydraulic saturation, etc.) is unknown and archeological samples differ in comparison to modern day industrial compositions. There remains an opportunity to compare results obtained from short-term laboratory tests to the surface characteristics of archeological samples

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Results

Conclusion