LA-UR-15-21114 Approved for public release; distribution is unlimited. Proceedings of the Third International Workshop on Actinide and Brine Chemistry in a Salt-Based Repository (ABC-Salt III) WIPP Facility and Stratigraphic Sequence The funding for this document is provided by the U.S. Department of Energy, Carlsbad Field Office. Cover illustration: WIPP TRU Repository Los Alamos National Laboratory, an affirmative action/ equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396. This report was prepared as an account of work sponsored by an agency of the U.S. Government. 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Los Alamos National Laboratory strongly supports academic freedom and a researcher’s right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. Los Alamos Report LA-UR-15-21114 Issued: February 2015 Proceedings of the Third International Workshop on Actinide and Brine Chemistry in a Salt-Based Repository (ABC-Salt III) * April 15-17, 2013 Santa Fe, NM, USA. Edited by: Donald Reed Actinide Chemistry and Repository Science Team Repository Science & Operations Program Los Alamos National Laboratory Carlsbad, NM, USA Marcus Altmaier Karlsruhe Institute for Technology Institute for Nuclear Waste Disposal Karlsruhe, Germany *ABC-Salt (III) was co-organized by D. Reed and M. Altmaier as an activity of the NEA Salt Club (http://www.oecd-nea.org/rwm/saltclub) ii This page intentionally left blank. iii iv This page intentionally left blank. v Table of Contents Joe Franco (DOE) Foreword ……………….....……………..………..…. iv Proceedings Summary …………………………..………………….…….. viii Acknowledgements ……………………………………………..………….. xvi Workshop Attendees Picture …………………………….………..……… xviii Workshop Title Page and Program Overview ………..…..………………. 1 Workshop Detailed Program ……………………..…………..…...……… 3 ABC-Salt III Workshop Abstracts ………………………………..……… 7 List of Abstracts …………………………………………………………... 9 Monday, April 15th Presentation Abstracts …….………………..…… 13 Monday, April 15th Poster Abstracts ………………......................………. 41 Tuesday, April 16th Presentation Abstracts ……………………………… 69 Wednesday, April 17th Presentation Abstracts …………..……………… 105 List of Attendees …………………………………………………………… 123 vi This page intentionally left blank. vii Actinide and Brine Chemistry in a Salt-Based Repository (ABC-Salt III) Workshop Proceedings Summary Historical Perspective and Importance ABC-Salt Workshop Series This is the third international workshop in the ABC-Salt series and was held at the La Fonda Hotel in the Santa Fe, New Mexico (USA) downtown Plaza area on April 15-17, 2013. The goals of this workshop series, organized as an activity of the Nuclear Energy Agency (NEA) Salt Club, has been to status the state-of-the-art of actinide and brine chemistry experimental and modeling results and continue an international dialog to coordinate and prioritize research in this field. This workshop series evolved out of a collaborative dialog between the Los Alamos Actinide Chemistry and Repository Science Program (ACRSP) team investigating actinide/brine chemistry for the U.S. Waste Isolation Pilot Plant (WIPP) and the German Karlsruhe Institute for Technology Institute for Nuclear Waste Disposal (KIT/INE) researchers who were also investigating potential applications of a salt repository concept for nuclear waste. The ABC-Salt III workshop was comprised of forty six presentations and sixteen posters on the topics of international program updates, brine chemistry, microbial effects, actinide chemistry in brine, and the modeling of high ionic-strength solutions. There were over fifty attendees (twenty one of which were international) representing seven countries (United States, Germany, Canada, United Kingdom, France, Australia and Spain). The majority of the participants, as expected, were from Germany and the United States as these are the two countries that are most active in research to support salt repository concepts. The abstracts for many of these presentations and posters (see list of abstracts on page 9) are provided in this proceedings report. In all there was a very good international dialog established in this workshop and this key aspect of the ABC-Salt workshop series was well met. The first ABC-Salt workshop was held in Carlsbad New Mexico (USA) on September 8 and 9, 2010. This was well attended with forty five scientists from four countries, but mostly from the United States and German repository programs. The technical agenda, extended abstracts, and attendees list can be found in the published workshop proceedings [Proceedings of the International Workshop on Actinide and Brine Chemistry in a Salt –Based Repository (ABC- Salt), Donald Reed and Marcus Altmaier (Eds.), Los Alamos Report LAUR-14-28463, Los Alamos, NM, USA]. A tour of the WIPP facility was also given to the international visitors and was an important feature of the workshop. viii The second workshop was held in Karlsruhe Germany on November 7 and 8, 2011 and was hosted by the KIT/INE. This was again a well-attended workshop with over 80 participants from several countries and was coupled to a workshop on High Temperature Aqueous Chemistry (HITAC 2011). The abstracts and summary of these workshops are published in the proceedings [Proceedings of the Interantional Workshops ABC-Salt (II) and HiTAC 2011, Marcus Altmaier, Christiane Bube, Bernhard Kienzler, Volker Metz, Donald Reed (Eds.), KIT Scientific Reports 7625, KIT Scientific Publishing]. Further workshops are planned and the ABC-Salt IV workshop will be held on the 14th and 15th of April 2015 in Heidelberg, Germany. Importance of High Ionic-Strength Actinide Chemistry to the Salt Repository Safety Case The safety case for the use of a bedded salt or salt dome for the permanent geologic isolation of nuclear waste is centered on the self-sealing properties of salt that lead to geologic isolation. This, under ideal conditions, will lead to a “dry” site that can geologically isolate the nuclear waste for millions of years. The salt formations being considered or used for geologic isolation are hundreds of millions of years old and have remained unsaturated with no interconnected groundwater for much of this time. In many respects this disposal concept is somewhat independent of the nature of the wasteform since it relies on geologic isolation and not on container material and wasteform properties under the expected repository conditions. There are also significant cost advantages to a salt repository approach since the technology for the mining of salt is well established and we have a 12-year operational history and experience at the WIPP site, which is the best working example and application of this repository concept. It is critically important that a repository concept, and its associated safety case, has a sound scientific basis to assure the public that the repository will perform as predicted. For a salt-based nuclear repository, although primary safety reliance is on the self-sealing of its geology, there are low probability scenarios where brine intrusion can solubilize actinides/ radionuclides in high ionic-strength brines leading to their subsequent release to the accessible environment. It is this low-probability scenario that justifies the actinide and brine chemistry research that is the subject of this workshop. In this context, it is critical to show that even if the worse-case scenario of brine intrusion and release occurs, the repository will still perform and regulatory release limits are not exceeded. The dissolved actinide/ radionuclide concentration, in this low-probability scenario, is defined by the multitude of subsurface processes that impact actinide/radionuclide speciation and the associated modeling of actinide chemistry in high ionic- strength brine systems. ix Summary of Key ABC-Salt III Workshop Results A general summary of each of the key presentation areas is given in the following sections. In all, this workshop provided a very comprehensive discussion of the programmatic and technical issues that pertain to brine and actinide chemistry in a salt repository. International Program Updates Detailed program updates from the United States and German salt repository programs were provided. For the German programs, an overview of German repository activities was provided along with results of a recently completed preliminary safety assessment of the Gorleben site (VSG). The preliminary safety assessment was favorable and confirmed that salt is a viable option as the host rock for a high-level waste (HLW)