The Michigan International Copper Analogue (MICA) Project – Phase II

Introduction

The Michigan International Copper Analogue (MICA) Project focuses on the stability of native copper in the world’s largest native copper dominated deposits of the Keweenaw Peninsula, Michigan, U.S.A.

One of the key requirements for the deep geological disposal of high-level nuclear waste is the assessment of its long-term performance and safety for upwards of one million years. Observations made from the geological systems, i.e., natural analogues (NA), can be utilized in the safety case and can provide information on evolution of the disposal system.
NAs can also be used to support long-term predictions relevant for copper as part of high-level radioactive waste canisters. Copper is an important part of many disposal concepts, e.g., KBS-3 developed in Sweden and Finland and Mark II developed in Canada.

The goal of the MICA Project is to provide a unique data source to describe natural analogue processes governing long-term corrosion behaviour of the pure copper used in waste canisters. This information will support disposal safety cases as well as stakeholder communications.

During 2021-2023, in the MICA Phase I, geological description and overview to the potential analogues were produced, and feasibility of samples and evaluation of analogue types for assessed. Also, potential analytical methods were tested. MICA Phase I provided a context and a starting point to further work.

MICA Phase II, an independent continuation for work published by MICA Phase I, is an investigation project aiming to examine a selection of safety case relevant NA types that have not been previously investigated in sufficient detail to be used in the safety cases, including

1. bedrock copper NAs providing scientifically sound baseline results for copper stability NA as an example for expected evolution of the repository;

2. first assessment of the copper-in-clay NA providing potentially the most repository relevant analogue (engineered bentonite-based barriers used in many disposal concepts); and

3. copper sulfide NAs to expand the corrosion analogues to sulfur bearing environments (NA aiding process understanding)

Based on these, aim of the MICA Phase II is to provide NA result set for the repository context that can be used to support the safety case and stakeholder communications both regarding the expected evolution and potential changes caused by less likely or even extreme changes during the repository lifetime and beyond. Results will be presented in a technical report, scientific articles, and conference presentations.

Partners: MICA Phase II is an cooperation project. The work will be executed by executing partner GTK. Other partners in the MICA Phase II are Svensk Kärnbränslehantering AB (hereafter SKB) and Korea Atomic Energy Research Institute (KAERI).

The coordinator of the project: Geological Survey of Finland

Contact persons: Heini Reijonen (PM), Ismo Aaltonen (VPM)

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