Excavation Damage Zone in the Experimental Deposition Holes at Äspö and Comparison to Existing Data

2003 ◽  
Vol 807 ◽  
Author(s):  
Jorma Autio ◽  
Hanna Malmlund ◽  
Thomas Hjerpe ◽  
Maarit Kelokaski ◽  
Marja Siitari-Kauppi
Keyword(s):  
Hard Rock ◽  
Damage Zone ◽  
High Level Waste ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Crushed Zone ◽  
High Level ◽  
Excavation Damage ◽  
The Impact ◽  
Clear Increase

ABSTRACTDisposal in deep, stable bedrock is currently one concept for isolating high-level wastes from the environment. Repository for high-level waste in rock excavated using different drilling techniques is surrounded by an excavation damaged zone (EDZ) which properties have been changed. The micro fracturing of samples taken from the experimental deposition holes in the underground Hard Rock Laboratory at Äspö were investigated by the 14C polymethylmetha-crylate (14C-PMMA) method and scanning electron microscopy (SEM) to evaluate the impact of EDZ on migration. The porosity of the damaged rock zone is clearly higher than the porosity of undisturbed rock. The thickness of the crushed zone with significantly higher porosity is a few millimetres and the average depth of the damaged zone (i.e. a clear increase in porosity found) is from 5 to 20 mm from the hole wall. The apertures of the inter- and intragranular fractures in the crushed zone varied from 5 to 30 μm according to SEM examination. Earlier results of porosity, diffusivity and permeability measurements in granites were compiled and the results of the porosity values of Äspö diorite were compared to the porosity values measured in other types of granites. The results were compiled in permeability-diffusivity-porosity space and were found to form a plane that could be used to estimate the range of diffusivity and permeability of the Äspö diorite.

scholarly journals The Method of Determining Excavation Damaged Zone by Acoustic Test and the Application in Engineering Cases

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qian-Cheng Sun ◽  
Hao-Sen Guo ◽  
Zhi-Hua Xu ◽  
Yue Liu ◽  
Xiao Xu
Keyword(s):  
Rock Mass ◽  
Damage Evolution ◽  
Hard Rock ◽  
Damage Zone ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Columnar Jointed Rock Mass

It is very important to accurately determine the depth of excavation damaged zone for underground engineering excavation and surrounding rock stability evaluation, and it can be measured by acoustic test, but there is no quantitative method for analysis of the results, and it relies heavily on the experience of engineers, which leads to the low reliability of the results and also limits the application of the acoustic method. According to substantial field test data and the feedback of surrounding rock support parameters, the boundary method is proposed to determine the depth of excavation damaged zone in surrounding rock based on the relation between the ultrasonic velocity of measured point and the background wave velocity of rock mass. When the method is applied to the columnar jointed rock mass of Baihetan and the deep-buried hard rock of Jinping, the excavation damaged zone was well judged. The results in the Baihetan project show that the proposed method of determining excavation damage zone by the acoustic test can well demonstrate the anisotropy characteristics of the columnar jointed rock mass, and the damage evolution characteristics of jointed rock mass at the same position can also be obtained accurately. Moreover, the method also can accurately reveal the damage evolution process of the deep-buried hard rock under the condition of high ground stress, which proved the applicability of this method in jointed or nonjointed rock masses.

The Effect of EDZ on the Migration of Radionuclides in a KBS-3 Type Repository

2003 ◽  
Vol 807 ◽  
Author(s):  
Jorma Autio ◽  
Thomas Hjerpe ◽  
Marja Siitari-Kauppi
Keyword(s):  
Spent Nuclear Fuel ◽  
Hard Rock ◽  
State Of The Art ◽  
Migration Route ◽  
Excavation Damaged Zone ◽  
Tunnel Floor ◽  
Damaged Zone ◽  
Hydraulic Gradients ◽  
Drill And Blast

ABSTRACTThe role of excavation damaged zone (EDZ) in a KBS-3 type repository for spent nuclear fuel depends significantly on the design of the engineered barrier systems such as tunnel backfill since one obvious function of the backfill is to prevent the growth of EDZ. Main results of EDZ studies based on using 14C-PMMA method carried out at Äspö Hard Rock Laboratory in Sweden, and at Research Tunnel at Olkiluoto in Finland by Posiva and SKB in co-operation are presented. The significance of the results is evaluated quantitatively and qualitatively. The EDZ around the deposition hole on migration of radionuclides diffusing out of a waste canister was found unlikely to be a significant migration route in the absence of large hydraulic gradients. According to the study the EDZ caused by state-of-the-art drill and blast excavation adjacent to walls and roof of deposition tunnels was found negligible, however the EDZ adjacent to deposition tunnel floor is evidently more extensive and more significant.

scholarly journals Development of a ceramic waste form for high-level waste disposal

1999 ◽  
Vol 556 ◽  
Author(s):  
D. W. Esh ◽  
K. M. Goff ◽  
K. T. Hirsche ◽  
T. J. Battisti ◽  
M. F. Simpson ◽  
...  
Keyword(s):  
Spent Nuclear Fuel ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Fission Products ◽  
Waste Form ◽  
High Level Waste ◽  
Durability Test ◽  
Ceramic Waste ◽  
High Level ◽  
The Impact

AbstractA ceramic waste form is being developed by Argonne National Laboratory* (ANL) as part of the demonstration of the electrometallurgical treatment of spent nuclear fuel [1]. The halide, alkaline earth, alkali, transuranic, and rare earth fission products are stabilized in zeolite which is combined with glass and processed in a hot isostatic press (HIP) to form a ceramic composite. The mineral sodalite is formed in the HIP from the zeolite precursor. The process, from starting materials to final product, is relatively simple. An overview of the processing operations is given. The metrics that have been developed to measure the success or completion of processing operations are developed and discussed. The impact of variability in processing metrics on the durability of the final product is presented. The process is demonstrated to be robust for the type and range of operation metrics considered and the performance metric (PCT durability test) against which the operation metrics are evaluated.

Impact of Advanced Fuel Cycles on Geological Disposal

2009 ◽  
Vol 1193 ◽  
Author(s):  
Jan Marivoet ◽  
Eef Weetjens
Keyword(s):  
Radioactive Waste ◽  
Cooling Time ◽  
High Level Waste ◽  
Waste Streams ◽  
Geological Disposal ◽  
Fuel Cycles ◽  
Thermal Output ◽  
Advanced Fuel ◽  
High Level ◽  
The Impact

AbstractIn recent years the increasing oil prices and the need for carbon-free energy to limit global warming have resulted in a revival of interests in nuclear energy. Advanced nuclear fuel cycles are being studied worldwide. They aim at making more efficient use of the available resources, reducing the risk of proliferation of nuclear weapons, and facilitating the management of the resulting radioactive waste. Recently, the Red-Impact project has investigated the impact of a number of representative advanced fuel cycles on radioactive waste management, and more specific on geological disposal. The thermal output of the high-level waste arising from advanced fuel cycles in which all the actinides are recycled is reduced with a factor 3 for a 50 years cooling time and with a factor 5 for a 100 years cooling time in comparison with the spent fuel arising from the once-through fuel cycle. This reduction of the thermal output allows for a significant reduction of the length of the disposal galleries and of the size of the repository. Separation of Cs and Sr drastically reduces further the thermal output of the high-level waste, but it requires a long-term management of those heat generating separated waste streams, which contain the very long-lived 135Cs. Recycling all the actinides strongly reduces the radiotoxicity in the waste, resulting in significantly lower doses to an intruder in the case of a human intrusion into the repository. However, the reduction of radiotoxicity has little impact on the main safety indicator of a geological repository, i.e. the effective dose in the case of the expected evolution scenario; for disposal in clay formations, this dose is essentially due to mobile fission and activation products. The deployment of advanced fuel cycles will necessitate the development of low activation materials for the new nuclear facilities and fuels and of specific waste matrices to condition the high-level and medium-level waste streams that will arise from the advanced reprocessing plants.

Spinel Settling in HLW Melters

2001 ◽  
Author(s):  
Josef Matyáš ◽  
Jaroslav Kloužek ◽  
Lubomír Němec ◽  
Miroslav Trochta
Keyword(s):  
Liquidus Temperature ◽  
Linear Growth ◽  
Critical Level ◽  
High Level Waste ◽  
Input Concentration ◽  
Average Temperature ◽  
Input Size ◽  
Waste Loading ◽  
High Level ◽  
The Impact

Abstract The efficiency of high-level waste (HLW) melters is limited by spinel settling and accumulation on the melter bottom if the waste loading is increased above a certain limit at which spinel crystallizes from the melt. Spinel accumulation interferes with melter operation and shortens melter lifetime. The mathematical modeling of spinel settling in a HLW melter was applied to define the critical level of spinel deposition during the lifetime of the melter and the corresponding increase in waste loading. In this study, spinel settled on the bottom, slant melter walls, and in the output pipe with a linear growth of spinel-sludge thickness after its concentration stabilized inside the melter. The calculations provided a higher concentration of spinel crystals in the melter regions where the temperature was lower then the liquidus temperature, i.e., T<TL. The effects of the following parameters on sludge-layer thickness were examined: 1) the impact of input concentration of spinel crystals of the same size, 2) the impact of different input size of spinel crystals of the same concentration entering from cold cap (melting batch on the melt surface), and 3) the influence of the average temperature (Tavg) inside of the melting space. The calculations showed that higher a concentration and bigger crystals caused thicker sludge layers in the melter, either because of a higher settling density of crystals or because of their higher settling rate. The nucleation of spinel crystals plays a more important role with decreasing of average temperature inside of the melter, and the thicker layer was formed at lower average temperatures.

scholarly journals Optimization of the Solidification Method of High-Level Waste for Increasing the Thermal Stability of the Magnesium Potassium Phosphate Compound

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3789
Author(s):  
Svetlana A. Kulikova ◽  
Sergey S. Danilov ◽  
Kseniya Yu. Belova ◽  
Anastasiya A. Rodionova ◽  
Sergey E. Vinokurov
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Compressive Strength ◽  
Potassium Phosphate ◽  
Treatment Temperature ◽  
High Level Waste ◽  
Leaching Rate ◽  
High Level ◽  
The Impact ◽  
Thermal Stability Of

The key task in the solidification of high-level waste (HLW) into a magnesium potassium phosphate (MPP) compound is the immobilization of mobile cesium isotopes, the activity of which provides the main contribution to the total HLW activity. In addition, the obtained compound containing heat-generating radionuclides can be significantly heated, which increases the necessity of its thermal stability. The current work is aimed at assessing the impact of various methodological approaches to HLW solidification on the thermal stability of the MPP compound, which is evaluated by the mechanical strength of the compound and its resistance to cesium leaching. High-salt surrogate HLW solution (S-HLW) used in the investigation was prepared for solidification by adding sorbents of various types binding at least 93% of 137Cs: ferrocyanide K-Ni (FKN), natural zeolite (NZ), synthetic zeolite Na-mordenite (MOR), and silicotungstic acid (STA). Prepared S-HLW was solidified into the MPP compound. Wollastonite (W) and NZ as fillers were added to the compound composition in the case of using FKN and STA, respectively. It was found that heat treatment up to 450 °C of the compound containing FKN and W (MPP-FKN-W) almost did not affect its compressive strength (about 12–19 МPa), and it led to a decrease of high compressive strength (40–50 MPa) of the compounds containing NZ, MOR, and STA (MPP-NZ, MPP-MOR, and MPP-STA-NZ, respectively) by an average of 2–3 times. It was shown that the differential leaching rate of 137Cs on the 28th day from MPP-FKN-W after heating to 250 °C was 5.3 × 10−6 g/(cm2∙day), however, at a higher temperature, it increased by 20 and more times. The differential leaching rate of 137Cs from MPP-NZ, MPP-MOR, and MPP-STA-NZ had values of (2.9–11) × 10−5 g/(cm2∙day), while the dependence on the heat treatment temperature of the compound was negligible.

Estimation of Horizontal-Well Productivity Loss Caused by Formation Damage on the Basis of Numerical Modeling and Laboratory-Testing Data

SPE Journal ◽  
2018 ◽  
Vol 24 (01) ◽  
pp. 44-59 ◽  
Author(s):  
Dmitry D. Vodorezov
Keyword(s):  
Analytical Solutions ◽  
Laboratory Testing ◽  
Horizontal Well ◽  
Damage Zone ◽  
Formation Damage ◽  
Well Productivity ◽  
Skin Factor ◽  
Damaged Zone ◽  
Variable Distribution ◽  
The Impact

Summary This paper presents a new numerical model of inflow to a well with a zone of damaged permeability. It is built on the principle of dividing the wellbore and damaged permeability zone into numerous segments. Simultaneous work of the segments is modeled with the method of velocity-potential theory. The model is applicable for wellbores of different trajectories including horizontal and multilateral wells. The model is focused on the extended application of results obtained during laboratory core testing that include a return-permeability (RP) profile of the core and cleanup parameters. The developed solution includes the effects of anisotropy, reservoir-boundary conditions, and a nonuniform distribution of formation damage in both radial and axial directions. The paper presents the new approach to include depth-variable distribution of damage in skin-factor models. The approach provides for the evaluation of pressure drop in a depth-variable damage zone by the resulting permeability that is defined by flow regime. Laboratory-obtained overall core permeability is associated with a linear flow, and when applied to a zone near the wellbore with radial or elliptic flow, it causes an error because of the depth-variable distribution of damage. The provided numerical simulations show that the impact of this factor on horizontal-well productivity is significant. The developed model is compared with existing analytical solutions of Furui et al. (2002) (FZH) and Frick and Economides (1993) (FE) for the case of a horizontal well with a cone-shaped damaged zone. The results show that a skin-factor transformation originally proposed by Renard and Dupuy (1991) for a case of a uniformly damaged well can be used successfully for the referred-to analytical solutions, which makes them applicable for wells with an elliptic drainage area. In this paper, we also suggest an approach whereby we relate the characteristics of the cleanup of the region near the wellbore to laboratory-testing conditions.

scholarly journals Directional Blasting Technology of Slit Charge for Geological Disposal of High-Level Radioactive Waste

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ke Man ◽  
Xiaoli Liu ◽  
Ju Wang ◽  
Xiyong Wang
Keyword(s):  
Radioactive Waste ◽  
Dynamic Stress Intensity Factor ◽  
Dynamic Fracture Toughness ◽  
Dynamic Tensile Strength ◽  
Tunnel Face ◽  
Geological Disposal ◽  
High Level Radioactive Waste ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
High Level

Based on the slit charge technology, the blasting progress and the blasting theory have been studied in detail. Combined with the high-level radioactive waste geological disposal, in which the excavation damaged zone of the surrounding rock is required as small as possible, the testing of the Beishan exploration tunnel (BET) has been studied, and the blasting parameters have been designed using the slit charge technology. Theoretically, the rock failure criterion has been proposed, which adopted the dynamic mechanical parameters, such as the dynamic compress strength, dynamic tensile strength, dynamic modulus, dynamic passion ratio, dynamic fracture toughness, and dynamic stress intensity factor. Furthermore, the blasting test has been carried out under the same tunnel face with left and right sides simultaneously, and it can be found that the blasting effect with the slit charge technology is better than another side, which verified the useful and scientific meaning of this technology. It should be noticed that the blasting method includes numerous blasting parameters, which interact with each other. Those blasting parameters obtained just limited the slit charge, and the result and the theoretical knowledge could be applied to the blasting and excavation of the deep geoengineering and HLW geodisposal.

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