Model Development for Thermal-Hydrology Simulations of a Full-Scale Heater Experiment in Opalinus Clay

Abstract

Disposal of commercial spent nuclear fuel in a geologic repository is studied. In situ heater experiments in underground research laboratories provide a realistic representation of subsurface behavior under disposal conditions. This study describes process model development and modeling analysis for a full-scale heater experiment in opalinus clay host rock. The results of thermal-hydrology simulation, solving coupled nonisothermal multiphase flow, and comparison with experimental data are presented. The modeling results closely match the experimental data.

Keywords:

• Nuclear waste disposal
• opalinus clay
• thermal hydrology
• in situ heater experiments

Acknowledgments

DECOVALEX is an international research project comprising participants from industry, government, and academia, focusing on development of understanding, models, and codes in complex coupled problems in subsurface geological and engineering applications. DECOVALEX-2023 is the current phase of the project. The authors appreciate and thank the DECOVALEX-2023 Funding Organizations for their financial and technical support of the work described in this paper—Andra: National Radioactive Waste Management Agency, France; BASE: Federal Office for the Safety of Nuclear Waste Management, Germany; BGE: Federal Company for Radioactive Waste Disposal, Germany; BGR: Federal Institute for Geosciences and Natural Resources, Germany; CAS: State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, China; CNSC: Canadian Nuclear Safety Commission, Canada; COVRA: Centrale Organisatie Voor Radioactief Afval, Netherlands; DOE: U.S. Department of Energy, United States; ENRESA: Empresa Nacional de Residuos Radiactivos, Spain; ENSI: Swiss Federal Nuclear Safety Inspectorate, Switzerland; JAEA: Japan Atomic Energy Agency, Japan; KAERI: Korea Atomic Energy Research Institute, Korea; NWMO: Nuclear Waste Management Organization, Canada; NWS: Nuclear Waste Services, Great Britain; SSM: Swedish Radiation Safety Authority, Sweden; SURAO: Radioactive Waste Repository Authority, Czech Republic; Taipower: Taiwan Power Company, Taiwan. The statements made in the paper are, however, solely those of the authors and do not necessarily reflect those of the funding organizations.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Disclosure Statement

No potential conflicts of interest are reported by the authors(s).

Additional information

Funding

This work was supported by the U.S. Department of Energy Nuclear Energy.