RD&D-Programme 2004 - SKB

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The size of the upswelling depends on the original densities of the buffer and the backfill and their associated expansion and compression properties, as well as the friction against the rock. Calculation models, both analytical and numerical, exist for analysis of this interaction. Conclusions in RD&D 2001 and its review SKI points out that SKB must make sure that the density of the buffer is not reduced too much when it swells up and displaces the backfill in the overlying tunnel (i.e. provide design premises for the backfill). In SKI’s view, studies of the buffer’s mechanical and rheological properties are of great importance, especially in view of the buffer-canister-rock interaction and the interaction with the backfill in the deposition tunnel. Newfound knowledge since RD&D 2001 The upswelling of the buffer against the backfill has been investigated for an alternative backfill material (Friedland clay). Calculations have been carried out using the same methodology as before and with new measurements of the compression properties of Friedland clay. The results show that with the low dry density of 1,400 kg/m 3 that was achieved in the field tests, the swelling is 0.3 m, which requires a cover of 2.7 m buffer above the canister (instead of 1.5 m, which is the current concept) so that the buffer around the canister will not lose in density /17-10/, see also Chapter 18. Programme The consequences of this interaction for other types of backfill will be studied in a similar manner as for Friedland clay. When the Prototype Repository is dismantled, the consequences will be able to be measured and comparisons made with calculations. 17.2.9 Mechanical interaction buffer/canister Mechanical interaction between buffer and canister is caused by the buffer’s clay matrix, which generates both compressive stresses and shear stresses, by the pore water, which generates only compressive stresses, and by gas in the buffer, which also generates only compressive stresses. Changes in these three variables take place during the water saturation process, and can also occur in response to external forces. The weight of the canister acts on the buffer, while the influence of the weight of the buffer on the canister is negligible. Rock movements that arise in the fracture plane, for example after earthquakes, give rise to stresses on the canister, which are transmitted from the rock through the buffer. The processes associated with the mechanical interaction between buffer and canister after water saturation are relatively well understood. The uncertainty mainly concerns the evenness of the wetting and the pressure build-up caused by possible gas formation. An important process is the movement of the canister in the buffer after water saturation. The weight of the canister results in a creep movement, caused mainly by shear stresses in the buffer. Extensive laboratory tests have been performed to study these creep movements. An established model for creep in clay has proved to work for the buffer, and calculations with this model show that the movement is only a few millimetres. An uncertainty in the model is the extrapolation to a long period of time. Conclusions in RD&D 2001 and its review In SKI’s view, studies of the buffer’s mechanical and rheological properties are of great importance, especially in view of the buffer-canister-rock interaction and the interaction with the backfill in the deposition tunnel. RD&D-Programme 2004 209
Newfound knowledge since RD&D 2001 Existing fractures that intersect deposition holes can be activated and sheared by a earthquake. The effect of such a rock shear has been investigated in a project that includes both laboratory tests and finite element calculations. /17-11, 17-12/. The buffer material in a deposition hole acts as a cushion between the canister and the rock, which reduces the effect of a rock shear substantially. The lower the density the softer the buffer and the less the effect on the canister. However, at the high densities proposed for the buffer in a deep repository, its stiffness is rather high. Stiffness is also a function of the rate of shear, which means that the canister can be damaged at very high shear rates. In order to investigate the stiffness and shear strength of the buffer material, a number of laboratory test series have been performed with shearing of water-saturated bentonite samples at different densities and shear rates. Based on these tests, a material model of the buffer that takes into account density and shear rate has been formulated. Tests have been carried out with shear rates of up to 6 m/s. The rock shear has been modelled and calculated with the finite element code Abaqus. A threedimensional finite element mesh that models the buffer and the canister has been created and a number of calculations that simulate different rock shears have been performed, see section 16.2.4. Figure 17-2 shows examples of calculation results. Programme There may be reason to further verify the modelled effect of a rock shear. The need for additional tests and possibilities for conducting such tests are being considered. Plastic strain +1.000e—01 +9.000e—02 +8.000e—02 +7.000e—02 +6.000e—02 +5.000e—02 +4.000e—02 +3.000e—02 +2.000e—02 +1.000e—02 +0.000e+00 Average stress (kPa) +4.416e+04 +4.000e+04 +3.600e+04 +3.200e+04 +2.800e+04 +2.400e+04 +2.000e+04 +1.600e+04 +1.200e+04 +8.000e+03 +4.000e+03 +0.000e+00 Figure 17-2. Examples of results from a calculation with 20 cm eccentric rock shear (density at water saturation 2,000 kg/m 3 and shear rate 1 m/s). Deformed structure (upper left), plastic strain in the cast iron insert (upper right), plastic strain in the buffer (lower left) and average stress (kPa) in the buffer (lower right). 210 RD&D-Programme 2004
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Technical Report TR-04-21 RD&D-Prog
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Preface SKB, Svensk Kärnbränsleha
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welding and nondestructive testing
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Alternative methods. SKB is followi
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5.5 Nondestructive testing of canis
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15 Fuel 163 15.1 Initial state in f
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18.1.10 Swelling pressure 229 18.1.
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Part I SKB’s programme and plan o
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Nuclear power plant Clab m/s Sigyn
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Figure 1-2. The Äspö HRL consists
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Figure 1-4. Interior from the Canis
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Siting SKB’s main alternative is
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Transport tunnel KBS-3V Deposition
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2.1 Nuclear fuel programme In Swede
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Encapsulation plant 2003 2004 2005
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2.2 LILW programme Parts of the sys
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environment. The barriers can also
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this cooperation entails that the o
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4 Overview - technology development
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4.7 Design of the deep repository T
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Diameter 1,050 Diameter 949 Diamete
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Conclusions in RD&D 2001 and its re
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Figure 5-3. Graphite shapes in cast
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Figure 5-5. Positions for test bars
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Programme The development project c
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Programme Trial fabrication of all
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The technology and procedures for c
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A method and equipment based on las
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Spacer plate Defect A Defect B Chan
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Newfound knowledge since RD&D 2001
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2004 2005 Process model welding met
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6.2.2 The welding process In parall
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Figure 6-9. Lid weld L028. Section
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Tensile test bars have been taken o
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6.3.3 The welding process The param
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A limitation in the evaluation of t
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Nondestructive testing methods such
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a b Through-transmission Reflection
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simulation program, and the body of
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SKB has devised a quality system fo
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8 Canister - encapsulation The desi
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Figure 8-2. Work stations in the en
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The filled canister transport casks
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Stages encapsulation plant 2003 200
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Figure 8-4. Possible location of a
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9 Transportation of encapsulated fu
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9.3 SKB’s transportation system -
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absorbs neutron radiation. The lid
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Applicable international and Swedis
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een specified yet. Since the size o
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• Methods exist for full-face dri
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Programme SKB keeps track of curren
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Judgement with regard to long-term
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Furthermore, it must not have an ad
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Studies of equipment will be conduc
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A third type of seal is intended to
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10.6.1 Requirements and premises In
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the long-term safety of the concept
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11.3 Execution - stepwise design Si
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Programme Design step D, which incl
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12 Deep repository - monitoring SKB
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• Trigger levels for action. •
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Part III Safety assessment and rese
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As a complement to the numerical mo
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Table 13-2. Research on the initial
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13.2.4 Backfill Together with Posiv
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Table 13-3. Projects and experiment
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spent nuclear fuel. It was neverthe
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concepts or whose descriptions requ
Page 149 and 150: 14.2.2 Radionuclide transport and d
Page 151 and 152: At present, the computational time
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Page 155 and 156: 15.1.2 Geometry The deep repository
Page 157 and 158: 7 6 BWR 55 MWd/tU PWR 42 MWd/tU PWR
Page 159 and 160: 15.1.11 Gas composition Conclusions
Page 161 and 162: 15.2.5 Heat transport Dealt with in
Page 163 and 164: simulating the repository environme
Page 165 and 166: 238 U 237 Np 239 Pu Concentration,
Page 167 and 168: The catalytic effect of uranium dio
Page 169 and 170: oxidant consumption in the bulk sol
Page 171 and 172: The influence of hydrogen peroxide
Page 173 and 174: A research programme to study cast
Page 175 and 176: Newfound knowledge since RD&D 2001
Page 177 and 178: 16.2.3 Heat transport No new knowle
Page 179 and 180: Programme The ongoing experiments w
Page 183 and 184: Programme Short-term tests aimed at
Page 185 and 186: Swelling properties The buffer must
Page 189 and 190: have been performed for some ten co
Page 191 and 192: 17.1.13 Impurity levels Bentonite i
Page 193 and 194: out when the buffer swells, but our
Page 195 and 196: These processes have been studied i
Page 199: • The gas injection phase will be
Page 203 and 204: Conclusions in RD&D 2001 and its re
Page 205 and 206: 19 9 D=205 d=175 D=172 d=170 D=168
Page 207 and 208: • Tests of the wetting process cl
Page 211 and 212: Figure 17-4. Natural redox front in
Page 213 and 214: These phenomena have been studied b
Page 215 and 216: 17.2.24 Radionuclide transport - ad
Page 217 and 218: Programme SKB does not consider sor
Page 219 and 220: 18.1.6 Smectite content SKB, togeth
Page 221 and 222: Programme See section 18.2.2. 18.1.
Page 223 and 224: The wetting of the backfill from th
Page 225 and 226: Conclusions in RD&D 2001 and its re
Page 227 and 228: ackfill must have a compression mod
Page 229 and 230: Programme See section 17.2.17. 18.2
Page 231 and 232: 18.2.23 Radionuclide transport - so
Page 233 and 234: 10 -5 I-129 Release rate (moles/yea
Page 235 and 236: and the rock matrix, is also crucia
Page 237 and 238: A thermal model will be constructed
Page 239 and 240: In a continuation of the super-regi
Page 241 and 242: A thorough overview has been done o
Page 243 and 244: The authorities are of the opinion
Page 247 and 248: 19.2.11 Advection/mixing - groundwa
Page 249 and 250: a so-called Markov-directed Random
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Diffusion measurements in the labor
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Uranium series analyses from clay-
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19.2.18 Microbial processes Conclus
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19.2.20 Colloid formation - colloid
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19.2.23 Methane ice formation Concl
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19.2.26 Integrated modelling - radi
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development that has taken place ha
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20.2 Review of RD&D 2001 Following
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work will continue, particularly in
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2 In Sea (mol) 3 Water Sea (mol/m 3
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The above work will be pursued in c
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certain substances, such as uranium
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In connection with the Safe project
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20.9 International work and dissemi
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the underlying material are current
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These reports describe dominant fun
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Glacial Permafrost Permafrost Borea
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Shoreline displacement has an isost
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The hydromechanical modellings that
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model that includes these factors a
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The salinity of the sea, inland sea
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• Public opinion and attitudes -
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Socioeconomic impact • Local deve
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Previously existing material is bei
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• The driving forces behind the d
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• Very effective methods for tran
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• A subcritical nuclear reactor w
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out in Cadarache, France. Hindas an
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Important results since 2001 includ
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Programme The goal of SKB’s resea
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Kasam says that disposal in Very De
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24 Decommissioning The facilities c
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SKB is responsible for management a
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25 Low- and intermediate-level wast
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25.2.1 Repository for short-lived L
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Programme Work on the design of the
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observation is that isosaccharinic
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stored so that the material can be
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6-4 Claesson S, 2004. Elektronstrå
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Chapter 14 14-1 SKB, 2004. Interim
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15-42 Ekeroth E, Jonsson M, 2003. O
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17-19 Le Bell J C, 1978. Colloid ch
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19-29 Hudson J (ed), 2002. Strategy
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19-77 Bath A, Milodowski A, Ruotsal
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20-19 Kautsky U (ed), 2001. The bio
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20-73 Blomqvist P, Jansson P-E, Esp
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20-119 Berggren J, Kyläkorpi L, 20
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23-10 NEA, 2002. Accelerator-driven
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SKB’s master plan Appendix A
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A1 Introduction A1.1 Background The
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generations unnecessarily. Another
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Encapsulation plant 2003 2004 2005
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facilitated by the fact that the re
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A2.3 System design A2.3.1 Fundament
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The system analyses will be largely
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Two safety reports will therefore b
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KBS-3H Basic Design Detailed engine
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Time horizon 2017 The current phase
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2003 2004 2005 2006 2007 2008 Phase
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In the subsequent phase, verificati
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The canister development work will
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Deep repository Year 2003 2004 2005
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A4.2 Site investigations Site inves
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Already in the feasibility study, l
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In step D2, the facility descriptio
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Table 4. Current situation and prel
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2003 2004 2005 2006 2007 2008 Desig
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Table 5. Continued. Technology issu
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A4.6.1 Siting factors Before priori
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A possible alternative scenario is
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of the NPPs starts, however, long-l
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Between now and 2008, an organizati
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Appendix B Abbreviations Abaqus ACL
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GIA Gis Goldsim Hindas HMC HPF HRL
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PMMA POD Posiva Prism Proper Protot
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ISSN 1404-0344 CM Digitaltryck AB,
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