SAND2017-3179R Consensus on Intermediate Scale Salt Field Test Design Spent Fuel and Waste Disposition Prepared for US Department of Energy Spent Fuel and Waste Science and Technology Kristopher L. Kuhlman, Melissa M. Mills & Edward N. Matteo Sandia National Laboratories March 28, 2017 SFWD-SFWST-2017-000099 DISCLAIMER This information was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness, of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service by trade name, trade mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. Consensus on Intermediate Scale Salt Field Test Design March 2017 iii SUMMARY This report summarizes the first stage in a collaborative effort by Sandia, Los Alamos, and Lawrence Berkeley National Laboratories to design a small-diameter borehole heater test in salt at the Waste Isolation Pilot Plant (WIPP) for the US Department of Energy Office of Nuclear Energy (DOE-NE). The intention is to complete test design during the remainder of fiscal year 2017 (FY17), and the implementation of the test will begin in FY18. This document is the result of regular meetings between the three national labs and the DOE-NE, and is intended to represent a consensus of these meetings and discussions. The suite of tests is essentially modular, each test consisting of a central test borehole with water vapor collection and liquid brine sampling equipment, surrounded by satellite observation and instrumentation boreholes. Observation boreholes will be associated with temperature, electrical resistivity, and acoustic emission (AE) measurements. The first test of this modular design will be isothermal (no heating), and the second stage will be heated to a maximum borehole temperature of approximately 120°C. Later tests will be designed using information gathered from the first two boreholes, will be conducted at other temperatures, and may include other measurement types and test designs. The suite of field tests is focused on the objectives of quantifying brine availability, brine migration, and brine chemistry under heat-generating-waste relevant conditions in bedded salt. To accomplish the first two objectives, we will quantify the mass flowrate of water and conservative tracer into the borehole while circulating out humidity inside the central test borehole. Brine chemistry will be monitored through brine and gas sampling during the experiment. To interpret water inflow data, we will use thermal- hydrologic (TH), thermal-hydrologic-chemical (THC), and thermal-hydrologic-mechanical (THM) modeling to estimate formation properties, given the applied boundary conditions and observed inflow data. To interpret observed chemistry data, we will use thermal-chemical (TC) and THC models to interpret observed changes in the chemistry of inflowing brine, from observations of precipitating minerals and samples of brine composition while constantly removing water vapor from the borehole. Appendix A presents key components from historic heater tests in both bedded and domal salt. One motivation for this test is to “get back underground” and rebuild capabilities that have been lost with retiring staff since the bulk of in situ testing in salt was conducted in the 1980s. That being the case, this report presents key references and figures from previous tests as a first step in the design and implementation of the current suite of tests. ACKNOWLEDGEMENTS The SNL authors want to thank LANL and LBNL staff who actively participated in the development of the test design from the early stages, including Phil Stauffer, Hakim Boukhalfa, Doug Weaver, Brian Dozier, Shawn Otto, Jonny Rutqvist, and Yuxin Wu. We would like to thank those who reviewed and commented on aspects of the proposed experiment design and this report, including Pat Brady, Bob MacKinnon, Bill Spezialetti, Prasad Nair, Carlos Jové Colón, and Paul Domski. Special thanks to Michael Schuhen and Wes Deyonge for insightful comments and helpful advice on test design, to Paul Domski for providing WIPP brine chemistry data, and to Charles Bryan and Carlos Jové Colón for review and material related to brine chemistry and acid gas generation. Thanks to Ernie Hardin for technical and editorial review of the entire report; his suggestions improved the report and aspects of test design. Consensus on Intermediate Scale Salt Field Test Design iv March 2017 CONTENTS SUMMARY ................................................................................................................................................. iii ACKNOWLEDGEMENTS ......................................................................................................................... iii CONTENTS ................................................................................................................................................. iv ACRONYMS ............................................................................................................................................... ix 1. INTRODUCTION .............................................................................................................................. 1 1.1 Field Test Goals ....................................................................................................................... 1 1.2 Relevant History ...................................................................................................................... 3 1.3 Proposed Field Test in Context of Performance Assessment................................................... 4 2. FIELD EXPERIMENTAL PROCESS DESCRIPTION .................................................................... 5 2.1 Location and Design Strategy .................................................................................................. 5 2.1.1 Test Interval Location to Avoid Interbeds and DRZ .................................................. 6 2.1.1 Expected MU-0 Lithology .......................................................................................... 7 2.2 Heated Borehole Backfill Considerations .............................................................................. 10 2.3 Test Interval and Observation Boreholes ............................................................................... 11 2.4 Test Conditions and Features ................................................................................................. 12 2.4.1 Test Matrix ................................................................................................................ 12 2.4.2 Access Drift Monitoring ........................................................................................... 15 2.4.3 Salt Temperature Monitoring .................................................................................... 15 2.4.4 Vapor Collection and Gas Sampling ......................................................................... 15 2.4.5 Brine Composition Sampling .................................................................................... 18 2.4.6 Gas Flowrate Damage Testing .................................................................................. 18 2.4.7 Geomechanical Monitoring ....................................................................................... 19 2.4.8 Cement Exposure Test .............................................................................................. 20 2.4.9 Electrical Resistivity Surveys ................................................................................... 20 2.4.10 Deuterated Water Tracer ........................................................................................... 20 2.4.11 Acoustic Emission Monitoring ................................................................................. 21 2.5 Expected Test Conditions and Processes ............................................................................... 22 2.6 First Borehole Test Objectives ............................................................................................... 25 2.7 Second Borehole Test Objectives .......................................................................................... 27 2.8 Follow-on Borehole Test Objectives ..................................................................................... 28 2.8.1 Stepwise Heating....................................................................................................... 28 2.8.2 Sealed Borehole Test ................................................................................................ 28 2.8.3 Long-term Brine Availability .................................................................................... 29 2.8.4 Other Follow-on Measurement