The Underground as a Storage Facility. Modelling of Nuclear Waste Repositories and Aquifer Thermal Energy Stores
(1998) Abstract (Swedish)
 Popular Abstract in Swedish
Denna skrift behandlar marklagring av värme, kyla och kärnavfall.  Abstract
 The underground is a vast region, which is, too a large extent, unused by man. It has a large potential as a storage facility due to its vastness and availability.
This thesis, which consists of eleven papers and reports, deals with nuclear waste repositories in solid rock and with aquifer thermal energy storage systems. All these storage systems induce multidimensional, timevariable thermohydroelastic processes in the ground in and around the storage region. The partial differential equations that govern the physical processes are solved analytically in some cases, and in other cases numerical models are developed. Many methods of classical mathematical physics are employed for the solution. The analytical approach... (More)  The underground is a vast region, which is, too a large extent, unused by man. It has a large potential as a storage facility due to its vastness and availability.
This thesis, which consists of eleven papers and reports, deals with nuclear waste repositories in solid rock and with aquifer thermal energy storage systems. All these storage systems induce multidimensional, timevariable thermohydroelastic processes in the ground in and around the storage region. The partial differential equations that govern the physical processes are solved analytically in some cases, and in other cases numerical models are developed. Many methods of classical mathematical physics are employed for the solution. The analytical approach provides a deeper physical understanding of the processes and their interactions.
At large depths, the salinity of groundwater, and hence its density, often increases downwards. In the first study, the upward buoyancy flow of groundwater in fracture planes due to heat release from the nuclear waste is studied considering the added effect of a salt gradient. The aim of the study is to determine the natural barrier effect caused by the salt. A simple formula for the largest upward displacement from the repository is derived. There may be a strong natural barrier, which is independent of fracture permeabilities.
In two papers, the temperature field in rock due to a large rectangular grid of heatreleasing canisters containing nuclear waste is studied. The solution is by superposition divided into different parts. There is a global temperature field due to the large rectangular canister area, while a local field accounts for the remaining heat source problem. A complete analytical solution is presented
In the next set of papers, the thermoelastic response from the rectangular field of nuclear waste is analysed. An analytical solution for any rectangular heat source in a semiinfinite medium is derived. The thermoelastic problem for the rectangular heat source in an infinite surrounding is solved exactly. An important step is the introduction of socalled quadrantal heat sources. The solution for the rectangle is obtained from four quadrantal solutions. The condition of zero normal and shear stresses at the ground surface is fulfilled by using a mirror heat source and a boundary solution. The boundary solution accounts for the residual normal stress at the ground surface. Using a Hertzian potential, a surprisingly simple solution is obtained. The analytical solution is applied for the Swedish KBS3 concept to determine the complete threedimensional stress and strain fields at any time during the first thousand years. Regions of largest tensile stress are identified.
Another study concerns the use of heat as a tracer to investigate flow in a fracture plane. One result is that a commonly used twodimensional, analytical solution cannot describe the complete process in the fracture plane and surrounding rock.
Two papers deal with the thermohydraulic evaluations of two aquifer heat storage projects in Southern Sweden. Both plants have been successfully simulated using models based on conformal flow and entropy conservation techniques. In the last paper, the conformal flow technique is presented together with the very useful thermal front tracking model. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/38804
 author
 Probert, Thomas ^{LU}
 opponent

 Tsang, ChinFu, Lawrence Berkeley National Laboratory, Nuclear Waste Department, Berkeley, USA.
 organization
 publishing date
 1998
 type
 Thesis
 publication status
 published
 subject
 keywords
 exponential decay, modelling, fractured rock, classical mechanics, quantum mechanics, Mathematical and general theoretical physics, relativity, statistical physics, thermodynamics, Matematisk och allmän teoretisk fysik, klassisk mekanik, relativitet, kvantmekanik, gravitation, statistisk fysik, termodynamik, Environmental technology, pollution control, kontroll av utsläpp, Miljöteknik, conformal flow, heat as a tracer, KBS3, stress field, temperature field, analytical solution, salt buoyancy, groundwater flow, nuclear waste repository, aquifer thermal energy storage, Fysicumarkivet A:1998:Probert
 pages
 402 pages
 publisher
 Division of Mathematical Physics, Sölveg. 14A, Box 118, SE221 00 Lund, Sweden,
 defense location
 Lecture Hall A, Fysicum
 defense date
 19980611 10:15
 external identifiers

 other:LundMPh98/02
 ISBN
 9162830511
 language
 English
 LU publication?
 yes
 id
 8178b3495bcf4fb6aa2252d2d2b6d5cf (old id 38804)
 date added to LUP
 20071001 09:17:43
 date last changed
 20160919 08:45:13
@phdthesis{8178b3495bcf4fb6aa2252d2d2b6d5cf, abstract = {The underground is a vast region, which is, too a large extent, unused by man. It has a large potential as a storage facility due to its vastness and availability.<br/><br> <br/><br> This thesis, which consists of eleven papers and reports, deals with nuclear waste repositories in solid rock and with aquifer thermal energy storage systems. All these storage systems induce multidimensional, timevariable thermohydroelastic processes in the ground in and around the storage region. The partial differential equations that govern the physical processes are solved analytically in some cases, and in other cases numerical models are developed. Many methods of classical mathematical physics are employed for the solution. The analytical approach provides a deeper physical understanding of the processes and their interactions.<br/><br> <br/><br> At large depths, the salinity of groundwater, and hence its density, often increases downwards. In the first study, the upward buoyancy flow of groundwater in fracture planes due to heat release from the nuclear waste is studied considering the added effect of a salt gradient. The aim of the study is to determine the natural barrier effect caused by the salt. A simple formula for the largest upward displacement from the repository is derived. There may be a strong natural barrier, which is independent of fracture permeabilities.<br/><br> <br/><br> In two papers, the temperature field in rock due to a large rectangular grid of heatreleasing canisters containing nuclear waste is studied. The solution is by superposition divided into different parts. There is a global temperature field due to the large rectangular canister area, while a local field accounts for the remaining heat source problem. A complete analytical solution is presented<br/><br> <br/><br> In the next set of papers, the thermoelastic response from the rectangular field of nuclear waste is analysed. An analytical solution for any rectangular heat source in a semiinfinite medium is derived. The thermoelastic problem for the rectangular heat source in an infinite surrounding is solved exactly. An important step is the introduction of socalled quadrantal heat sources. The solution for the rectangle is obtained from four quadrantal solutions. The condition of zero normal and shear stresses at the ground surface is fulfilled by using a mirror heat source and a boundary solution. The boundary solution accounts for the residual normal stress at the ground surface. Using a Hertzian potential, a surprisingly simple solution is obtained. The analytical solution is applied for the Swedish KBS3 concept to determine the complete threedimensional stress and strain fields at any time during the first thousand years. Regions of largest tensile stress are identified.<br/><br> <br/><br> Another study concerns the use of heat as a tracer to investigate flow in a fracture plane. One result is that a commonly used twodimensional, analytical solution cannot describe the complete process in the fracture plane and surrounding rock.<br/><br> <br/><br> Two papers deal with the thermohydraulic evaluations of two aquifer heat storage projects in Southern Sweden. Both plants have been successfully simulated using models based on conformal flow and entropy conservation techniques. In the last paper, the conformal flow technique is presented together with the very useful thermal front tracking model.}, author = {Probert, Thomas}, isbn = {9162830511}, keyword = {exponential decay,modelling,fractured rock,classical mechanics,quantum mechanics,Mathematical and general theoretical physics,relativity,statistical physics,thermodynamics,Matematisk och allmän teoretisk fysik,klassisk mekanik,relativitet,kvantmekanik,gravitation,statistisk fysik,termodynamik,Environmental technology,pollution control,kontroll av utsläpp,Miljöteknik,conformal flow,heat as a tracer,KBS3,stress field,temperature field,analytical solution,salt buoyancy,groundwater flow,nuclear waste repository,aquifer thermal energy storage,Fysicumarkivet A:1998:Probert}, language = {eng}, pages = {402}, publisher = {Division of Mathematical Physics, Sölveg. 14A, Box 118, SE221 00 Lund, Sweden,}, school = {Lund University}, title = {The Underground as a Storage Facility. Modelling of Nuclear Waste Repositories and Aquifer Thermal Energy Stores}, year = {1998}, }