Thermal Evolution near Heat-Generating Nuclear Waste Canisters Disposed in Horizontal Drillholes

We consider the disposal of spent nuclear fuel and high-level radioactive waste in horizontal holes drilled into deep, low-permeable geologic formations using directional drilling technology. Residual decay heat emanating from these waste forms leads to temperature increases within the drillhole and the surrounding host rock. The spacing of waste canisters and the configuration of the various barrier components within the horizontal drillhole can be designed such that the maximum temperatures remain below limits that are set for each element of the engineered and natural repository system. We present design calculations that examine the thermal evolution around heat-generating waste for a wide range of material properties and disposal configurations. Moreover, we evaluate alternative layouts of a monitoring system to be part of an in situ heater test that helps determine the thermal properties of the as-built repository system. A data-worth analysis is performed to ensure that sufficient information will be collected during the heater test so that subsequent model predictions of the thermal evolution around horizontal deposition holes will reliably estimate the maximum temperatures in the drillhole. The simulations demonstrate that the proposed drillhole disposal strategy can be flexibly designed to ensure dissipation of the heat generated by decaying nuclear waste. Moreover, an in situ heater test can provide the relevant data needed to develop a reliable prediction model of repository performance under as-built conditions.

[1]  Antonio Gens,et al.  THM analysis of a large‐scale heating test incorporating material fabric changes , 2012 .

[2]  T. S. Nguyena,et al.  Modelling the FEBEX THM experiment using a state surface approach , 2005 .

[3]  David W. Shoesmith,et al.  Fuel corrosion processes under waste disposal conditions , 2000 .

[4]  Max D. Morris,et al.  Factorial sampling plans for preliminary computational experiments , 1991 .

[5]  G. Kamei,et al.  Kinetics of long-term illitization of montmorillonite—a natural analogue of thermal alteration of bentonite in the radioactive waste disposal system , 2005 .

[6]  Eckart Hurtig,et al.  Fibre-optic temperature measurements in shallow boreholes: experimental application for fluid logging , 1994 .

[7]  J. T. Birkholzer,et al.  Modeling the thermal‐hydrologic processes in a large‐scale underground heater test in partially saturated fractured tuff , 2000 .

[8]  Saltelli Andrea,et al.  Global Sensitivity Analysis: The Primer , 2008 .

[9]  W. Wagner,et al.  The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use , 2002 .

[10]  D. W. Shoesmith,et al.  Assessing the Corrosion Performance of High-Level Nuclear Waste Containers , 2006 .

[11]  T A Buscheck,et al.  Validation of the multiscale thermohydrologic model used for analysis of a proposed repository at Yucca Mountain. , 2003, Journal of contaminant hydrology.

[12]  Sebastià Olivella,et al.  Analysis of a full scale in situ test simulating repository conditions , 1998 .

[13]  F. Gera,et al.  Disposal of high-level radioactive waste in argillaceous formations: In situ and laboratory heating experiments , 1986 .

[14]  Olaf Kolditz,et al.  Results from an International Simulation Study on Coupled Thermal, Hydrological, and Mechanical Processes near Geological Nuclear Waste Repositories , 2008 .

[15]  F. King,et al.  The effect of the evolution of environmental conditions on the corrosion evolutionary path in a repository for spent fuel and high-level waste in Opalinus Clay , 2008 .

[16]  K. Travis,et al.  A model for heat flow in deep borehole disposals of high‐level nuclear waste , 2008 .

[17]  Thomas A. Buscheck,et al.  Thermohydrologic behavior at an underground nuclear waste repository , 2002 .

[18]  George Shu Heng Pau,et al.  iTOUGH2: A multiphysics simulation-optimization framework for analyzing subsurface systems , 2017, Comput. Geosci..

[19]  Antonio Gens,et al.  Coupled thermal-hydrological-mechanical analyses of the Yucca Mountain Drift Scale Test - Comparison of field measurements to predictions of four different numerical models , 2004 .

[20]  Rodney C. Ewing,et al.  Chemical corrosion of highly radioactive borosilicate nuclear waste glass under simulated repository conditions , 1990 .

[21]  Liange Zheng,et al.  A coupled THMC model of a heating and hydration laboratory experiment in unsaturated compacted FEBEX bentonite , 2010 .

[22]  H. Vosteen,et al.  Influence of temperature on thermal conductivity, thermal capacity and thermal diffusivity for different types of rock , 2003 .

[23]  Ernest Hardin,et al.  Deep Borehole Field Test Conceptual Design Report , 2016 .

[24]  Yi‐Feng Chen,et al.  Modeling coupled THM processes of geological porous media with multiphase flow: Theory and validation against laboratory and field scale experiments , 2009 .

[25]  Peter N. Swift,et al.  Deep Borehole Disposal of High-Level Radioactive Waste. , 2009 .

[26]  Stefan Finsterle,et al.  Practical notes on local data‐worth analysis , 2015 .

[27]  K. Pruess,et al.  TOUGH2 User's Guide Version 2 , 1999 .

[28]  Long-term effects of an iron heater and Äspö groundwater on smectite clays: Chemical and hydromechanical results from the in situ alternative buffer material (ABM) test package 2 , 2016, Clay Minerals.

[29]  G. Siemens,et al.  Thermal properties of engineered barriers for a Canadian deep geological repository , 2018, Canadian Geotechnical Journal.

[30]  Barry Freifeld,et al.  Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber‐optic distributed thermal perturbation sensor , 2008 .

[31]  S. Horseman,et al.  Thermal constraints on disposal of heat-emitting waste in argillaceous rocks , 1996 .

[32]  Sandra Dalvit Dunn,et al.  Thermally induced natural convection effects in Yucca Mountain drifts. , 2003, Journal of contaminant hydrology.

[33]  P. Lichtner,et al.  Joule–Thomson Effects on the Flow of Liquid Water , 2014, Transport in Porous Media.

[34]  Charles W. Forsberg,et al.  Rethinking High-Level Waste Disposal: Separate Disposal of High-Heat Radionuclides (90Sr and 137Cs) , 2000 .

[35]  R. Pusch,et al.  Aspects on the Illitization of the Kinnekulle Bentonites , 1995 .

[36]  Jens T. Birkholzer,et al.  Predictions and observations of the thermal-hydrological conditions in the Single Heater Test , 1999 .

[37]  C. Turick,et al.  Review of concrete biodeterioration in relation to nuclear waste. , 2016, Journal of environmental radioactivity.

[38]  Yu-Shu Wu,et al.  Modeling thermal-hydrological response of the unsaturated zone at Yucca Mountain, Nevada, to thermal load at a potential repository. , 2003, Journal of contaminant hydrology.

[39]  D. Jaeggi,et al.  Experiments on thermo-hydro-mechanical behaviour of Opalinus Clay at Mont Terri rock laboratory, Switzerland , 2017 .

[40]  Antonio Gens,et al.  A full-scale in situ heating test for high-level nuclear waste disposal: observations, analysis and interpretation , 2009 .

[41]  R. Askari,et al.  Thermal conductivity of granular porous media: A pore scale modeling approach , 2015 .

[42]  Liange Zheng,et al.  On the impact of temperatures up to 200 °C in clay repositories with bentonite engineer barrier systems: A study with coupled thermal, hydrological, chemical, and mechanical modeling , 2015 .

[43]  K. Travis,et al.  Modeling Temperature Distribution Around Very Deep Borehole Disposals of HLW , 2008 .