Low-level Radioactive Waste Disposal Research Articles

The spatial politics of siting a radioactive waste facility in Korea: A mixed methods approach

Low-level radioactive waste disposal facilities represent one of the most controversial Locally Unwanted Land-Uses (LULUs). In Korea in 2005, one of these disposal facilities was assigned to be placed in Gyeongju city after a competitive local referendum amongst four candidate cities took place. Many conflicts occurred between the residents living within and near the Gyeongju city following the decision. In this paper, we explore the spatial issues in the referendum system and aim to discover the reason behind these conflicts. To do so, we analyzed the spatial distribution of the acceptance rate in each ward of the four cities using several spatial statistical methods, Getis-Ord G and Gi*, and several types of interviews. We found that the referendum system has a problem with spatial inequity within and across its jurisdiction. Furthermore, the causes of the spatial outliers in the acceptance rate were verified by interviews. The results suggest that spatial matters should be considered to increase the local acceptance of LULUs.

Discussion on Very Low-Level Radioactive Waste near Surface Disposal

Radioactive waste disposal is one of the most sensitive environmental problems. As the arriving of decommissioning of early period nuclear facilities in China, large amounts of very low-level radioactive waste will be produced inevitably. The domestic and abroad definitions about very low-level radioactive waste and its disposal were introduced, and then siting principles of near surface disposal of very low-level radioactive waste were discussed. The near surface disposal sites’ natural barriers were analyzed from the crustal structure and the radionuclide adsorption characteristics of natural barriers. The near surface disposal sites’ engineering barriers were analyzed from the repository design and the repository barrier materials selection. Finally, the improving direction of very low-level radioactive waste disposal was proposed, which would promote the study of very low-level radioactive waste disposal in China.

Modelling of calcium leaching and its influence on radionuclide migration across the concrete engineered barrier in a NSDF

A multi barrier concept of disposal is adopted for both low and intermediate level radioactive waste disposal to prevent the spread of radionuclides into the human environment. Concrete engineered barrier is a part of multi barrier system for radioactive waste disposal. As long as the concrete barrier is intact, the containment of radioactive waste within the disposal facility is assured. However, every concrete structure has a finite lifetime. Concrete barriers degrade with time with lifetime dependent on type of concrete, external and internal environmental factors. This degradation allows the free moment of the radionuclides out of the concrete barrier. Hence an attempt was made to model the Calcium (Ca) leaching from side wall of a concrete engineered barrier in a Near Surface Disposal Facility (NSDF) and its influence on radionuclide migration across the concrete barrier, limited to conditions specified in the paper. The conceptual model assumes that rain water seeps into the engineered barrier through the top cover and dissolves radionuclides from the nuclear waste matrix. The modelling was attempted with Finite Difference analysis and validated with the results available in literature. The influence of Ca leaching on radionuclide migration in concrete barrier has been discussed for eight different radionuclides (Cs-137, Sr-90, I-129, H-3, Pu-239, Am-241, Co-60 and Tc-99).

Durability Analysis on Reactive Powder Concrete as Barrier Materials for Low-Level Radioactive Waste Disposal

Reactive powder concrete (RPC) has been proposed as barrier materials for the construction of engineered barrier in a low-level radioactive waste disposal site. The durability characteristics of RPC in such applications become paramount for the success of the containment of the wastes. The adverse environmental conditions at the disposal site could attack concrete barrier material and result in degradation of the material. Laboratory tests were conducted on RPC with various compositions to investigate the physical and durability properties of RPC. The effects of the addition of cement, silica fume, quartz powder, silica sand, steel fiber, and 2 levels of water-to-binder ratio (W/B = 0.25 and 0.30) on the properties of RPC specimens were investigated. Experimental results indicate that the long-term durability of RPC is significantly improved with the hydration of pozzolanic materials, which produces a very dense structure and thus exhibiting improved durability. The coefficient of permeability of RPC matrix determined using gas permeability apparatus demonstrated that RPC has much lower permeability than that of ordinary concrete. Heat-treating of concrete at 80°C accelerates the hydration process of RPC and shows enhanced physical and durable characteristics, as demonstrated by the chloride penetration test results.

Twenty Years’ Operation of Low-Level Radioactive Waste Disposal and Challenges for the Next Project

Twenty Years’ Operation of Low-Level Radioactive Waste Disposal and Challenges for the Next Project Rokkasho Low-level Radioactive Waste Disposal Center (the Center) has been operating as the only commercial waste disposal site in Japan for 20 years. It receives low level radioactive waste (LLW) generated at Japanese nuclear power plants (NPPs). The planned capacity is up to 600,000 m3 (3,000,000 drums) and the Center has been already approved for 80,000 m3 (400,000 drums). The Center has been receiving more than 260,000 drums (about 52,000 m3) of waste at the end of December, 2013.

Application of risk-based approach to post-closure safety assessment in radioactive waste disposal: An integration of complex radiation exposure situations

Based on the concept of risk, the post-closure safety criteria for High Level Radioactive Waste (HLW) disposal are under development in Korea. For compliance with the safety criteria of disposal, the risk-based safety assessment methodology should be implemented. In this paper, the authors suggest a risk-based approach to safety assessment for Korea radioactive waste disposal to evaluate an aggregative radiological risk for scenarios of complex radiation exposure situations; accordingly, the most plausible three cases are carefully selected. This risk-based approach deals with the scenarios from the viewpoint of the receptor to estimate the total risk. For respective exposure situations, it considers the occurrence probabilities of the relevant exposure scenarios as the probability of giving rise to doses to estimate the total risk to a representative person by aggregating the respective risks. In addition, the probability of an exposure scenario is estimated on the assumption that the initiating events influence release mechanisms and transport pathways. This integrated approach enables a systematic risk assessment and is informative when judging the probable overall risk for complex exposure situations of radioactive waste disposal. In this paper, the risk-based approach is applied for the case of the Low and Intermediate Level Radioactive Waste (LILW) Disposal, and also the results should be applicable to the HLW disposal facilities.

Use of an Accelerated Migration Test to Study Alteration of Backfill in Contact with Concrete

Zhishin clay and Black Hill bentonite are used as raw clay materials in this study. These clays are mixed with Taitung area hard shale to produce the backfill material for potential application as barrier for the disposal of low-level radioactive waste. The interaction between concrete barrier and the backfill materials is simulated by an accelerated migration test to investigate the effect of concrete on the expected functions of backfill material. The results show some decrease in swelling potential in the backfill material near the interface. Also, backfill material close to the contact with concrete exhibits greater change in the ratio of calcium/sodium concentration, due to the release of calcium ions from the concrete material.

低レベル放射性廃棄物処分におけるセメント系材料の設計と施工に関する基礎的研究

低レベル放射性廃棄物処分におけるセメント系材料の設計と施工に関する基礎的研究

Background and anthropogenic radionuclide derived dose rates to freshwater ecosystem – Nuclear power plant cooling pond – Reference organisms

The radiological assessment of non-human biota to demonstrate protection is now accepted by a number of international and national bodies. Therefore, it is necessary to develop a scientific basis to assess and evaluate exposure of biota to ionizing radiation. Radionuclides from the Ignalina Nuclear Power Plant (Lithuania) were discharged into Lake Druksiai cooling pond. Additional radionuclide migration and recharge to this lake from a hypothetical near-surface, low-level radioactive waste disposal, to be situated 1.5 km from the lake, had been simulated using RESRAD-OFFSITE code. This paper uses ERICA Integrated Approach with associated tools and databases to compare the radiological dose to freshwater reference organisms. Based on these data, it can be concluded that background dose rates to non-human biota in Lake Druksiai far exceed those attributable to anthropogenic radionuclides. With respect the fishery and corresponding annual committed effective human dose as a result of this fish consumption Lake Druksiai continues to be a high-productivity water body with intensive angling and possible commercial fishing.

Physical modelling of in-ground waste repository capping systems

This paper describes a series of geotechnical centrifuge tests carried out to investigate aspects of landfill capping system performance, in the context of a low-level radioactive waste disposal site. The effects of the basic cap geometry (sloping or flat) and the subsidence pattern imposed as the underlying waste degrades (ramp or step, i.e. slope or displacement discontinuity) are shown to influence cap performance. The effect of moving the toe of a sloping cap outside the landfill subsidence zone, thereby increasing the depth of inert fill below the cap, is also shown to be effective in limiting the displacements transmitted to the resistive layer. Analysis of the runoff from sloping capping systems shows that if the resistive layer fails, there is the potential for the infiltration rate through the cap to increase from near zero to almost 100% of the incident rainfall.

Movement of a tritium plume in shallow groundwater at a legacy low-level radioactive waste disposal site in eastern Australia

Between 1960 and 1968 low-level radioactive waste was buried in a series of shallow trenches near the Lucas Heights facility, south of Sydney, Australia. Groundwater monitoring carried out since the mid 1970s indicates that with the exception of tritium, no radioactivity above typical background levels has been detected outside the immediate vicinity of the trenches. The maximum tritium level detected in groundwater was 390 kBq/L and the median value was 5400 Bq/L, decay corrected to the time of disposal. Since 1968, a plume of tritiated water has migrated from the disposal trenches and extends at least 100 m from the source area. Tritium in rainfall is negligible, however leachate from an adjacent landfill represents a significant additional tritium source. Study data indicate variation in concentration levels and plume distribution in response to wet and dry climatic periods and have been used to determine pathways for tritium migration through the subsurface.

Determination of the leaching rate of radionuclide 134Cs from the solidified radioactive wastes in Syrian Portland cement and cement–microsilica matrixes

The suitability of Syrian Portland cement for disposal of solidified low-level radioactive waste was assessed by measuring the leaching rate of 134Cs. In ordinary cement concrete, a leaching rate of 1.309 × 10−3 g/cm2 per day was measured. Mixing this concrete with microsilica reduced significantly the leaching rate to 3.106 × 10−4 g/cm2 per day for 1% mixing, and to 9.645 × 10−5 g/cm2 per day for 3% mixing. It was also found that the application of a latex paint reduced these leaching rates by about 10%. These results, along with mechanical strength tests (under radiation exposure, high temperature, long water immersion and freeze–thaw cycling) indicate that Syrian Portland cement is suited for the disposal of low-level radioactive waste.

Mineralogy of selected geological deposits from the United Kingdom and the Republic of Ireland as possible capping material for low-level radioactive waste disposal facilities

Solid low-level radioactive waste (LLW) is currently being disposed at a number of facilities in the United Kingdom (UK). The safety of these facilities relies to some extent on the use of engineered barriers, such as a cap and a liner, to isolate the waste and protect the environment. Generally, the material used as the barrier layer within such a cap should be of low permeability and it should retain this property over long timescales (beyond a few decades normally required for facilities containing non-radioactive wastes). The objective of this research is to determine the mineralogy of selected geological deposits from the UK and Republic of Ireland as part of a larger project to examine their suitability as a capping material, particularly on LLW sites. Mineral transformations, from weathering, may impact on the long-term performance of the cap and even the disposal facility. These transformations could be brought on or enhanced by climate change. X-ray diffraction (XRD) was carried-out on the sand, silt and clay fractions of the London Clay, Belfast Upper Boulder Clay, Irish Glacial Till, Belfast Sleech, and Ampthill Clay geological deposits. Minerals were present that could pose both positive and negative effects on the long-term performance of the cap. Smectite, which has a high shrink swell potential, may produce cracks in London Clay, Belfast Upper Boulder Clay and Ampthill Clay capping material during dry, hotter periods as a possible consequence of future climate change; thus, resulting in higher permeability. Ampthill Clay and Belfast Sleech had elevated amounts of organic matter (OM) at 5.93% and 5.88%, respectively, which may also contribute to cracking. Over time, this OM may decompose and result in increased permeability. Gypsum [CaSO 4] in the silt and sand fractions of Ampthill Clay may reduce the impact of erosion during wetter periods if it is incorporated into the upper portion of the cap. There are potential negative effects from the acidity created by the weathering of pyrite [FeS 2] present in the silt and sand fractions of Belfast Sleech and Ampthill Clay that could impede the growth of grasses used to stabilize the surface of the capping material if this material is used as part of the vegetative soil layer. Additionally, acidic waters generated from pyrite weathering could negatively impact the lower lying capping material and the disposal facility in general, because they could react with contaminants and weaken vessels storing contaminants. However, calcium carbonate [CaCO 3] present in the silt and sand fractions of these deposits, and dolomite [CaMg(CO 3) 2] in Belfast Sleech, may counter act the acidity.

Fe(III) Reduction in the Subsurface at a Low-level Radioactive Waste Disposal Site

The low-level radioactive waste (LLW) repository located near to the village of Drigg, Cumbria is the principal site for disposal of LLW in the United Kingdom. To gain a better understanding of the potential microbial processes that could control radionuclide mobility in the LLW repository, we studied of a range of anaerobic processes in microcosms constructed from sediments at the site. Sediment samples taken from both former disposal trenches and the far-field region of the site were analyzed for the presence of Fe(II) and bioavailable Fe(III) using chemical extractions and assays. Near-field (trench) sediments were found to have undergone some microbial reduction of iron, with acid-extractable Fe(II) present and 16S rRNA genes affiliated to known Fe(III)-reducing microorganisms detected in clone libraries constructed by PCR using broad-specificity primers. In far-field material, no Fe(II) was detectable although poorly crystalline Fe(III) was present. No 16S rRNA genes affiliated with known Fe(III)-reducing microorganisms were observed in clone libraries prepared with broad-specificity primers, suggesting that they were not numerically dominant in the far-field sediments. Time-course microcosm experiments were set up by amending the near- and far-field material with 10 mM acetate. The utilization of nitrate, poorly crystalline Fe(III) and sulfate was monitored to identify the sequence of terminal electron accepting processes in the sediments. Analysis of the microbial community after Fe(III) reduction had terminated revealed a large increase in 16S rRNA gene sequences affiliated to known Fe(III)-reducing bacteria, with a close relative to Ferribacterium limneticum accounting for 55% of the community. 16S rRNA analysis of the sediments post-Fe(III) reduction revealed the presence of some Fe(III)-reducing microorganisms such as a close relative of Rhodoferax ferrireducens. Nitrate, iron and sulfate data were then modeled with a biogeochemical reactive transport computer model that includes representation of microbial growth kinetics, and which is used to simulate the evolution of the subsurface geochemistry at the repository site. The potential impact of these processes on radionuclide mobility at LLW sites is discussed.

What Comes to Mind When You Hear the Words ‘Nuclear Waste Repository’? A Study of 10,000 Images

Attempts by the federal government and the nuclear industry to develop sites for disposal of high-level and low-level radioactive wastes have been stymied by public and political opposition. The record of strenuous protest against nuclear waste repositories, as well as the findings of numerous public opinion surveys, make it clear that public opposition is widespread and deeply felt. It is also clear that there is an immense gap between the perceptions of the pubic and the views of technical experts and nuclear-industry officials. Given the seriousness of nuclear waste as a public issue, it is surprising that there have been only a few attempts to understand the deeper meaning of nuclear fears and opposition to nuclear waste disposal sites, and to provide some insight into the nature and pervasiveness of people's concerns. One step toward a deeper understanding would be to define the origins of these concerns, the emotions and images that underlie them, and their tractability or stability over time. In the present study, the authors recorded 10,000 word-association images from more than 3,300 respondents to four surveys during the period between April, 1988 and January 1, 1990. Each of the 10,000 images was assigned to one of thirteenmore » general or superordinate categories, which expressed the dominant theme of the response. All but one superordinate categories contained subordinate categories. All in all there were 92 distinct categories. The two dominant superordinate categories, (1) negative consequences and (2) negative concepts accounted for more than 56% of the total number of images. Many of the smaller categories and subcategories were also quite negative in tone. The five leading subordinate categories, dangerous toxic, death sickness, environmental damage, bad, and scary, accounted for more than 42% of the total number of images. 27 refs., 6 tabs.« less

Case Law

Canada – R. v Bruce Power Inc. (2009) European Union – Judgement of the European Court of Justice in the Case Land Oberosterreich v CEZ (2009) United States – Judgement of a U.S. Court of Appeals on the design basis threat security rule (2009) Judgement of a U.S. Court of Appeals on consideration of the environmental impacts of terrorist attacks on nuclear facilities (2009) Judgement of a U.S. District Court on interstate compacts�f authority to restrict private disposal of foreign low-level radioactive waste (2009)

Evaluation of geogrid as a reinforcement layer in clay based engineered barriers

Imperviousness of clay based barrier, which is provided in cover system of low-level radioactive waste disposal sites, is essential to mitigate the environmental hazard. The objective of this paper is to examine the influence of geogrid reinforcement on the deformation behaviour of clay based cover systems subjected to differential settlements. A series of centrifuge tests were performed on model clay barriers with and without the inclusion of geogrid reinforcement at 40 gravities. Motor-based differential settlement simulator was custom designed and developed for inducing continuous differential settlement in high gravity environment. By maintaining type and location of the geogrid within the clay barrier as constant, the thickness of clay barrier is varied. The performance of the clay barrier with and without geogrid layer having an overburden pressure equivalent to that of cover system was monitored by measuring water breakthrough at the onset of differential settlements. It was observed that both 0.6 m and 1.2 m thick clay barriers with and without overburden experienced cracks extending up to full depth. In comparison, geogrid reinforced clay barrier was found to sustain large distortions with an enhanced imperviousness. With the provision of an overburden equivalent to that of cover system, integrity of geogrid reinforced clay barrier was found to be retained even after inducing a distortion level of 0.125. This implies that provision of thickness of clay barrier equal to 0.6 m reinforced with a suitable geogrid may be adequate in sustaining higher distortion levels.

Modeling migration of strontium in sand and gravel aquifer in the candidate VLLW disposal site

For the very low level radioactive waste (VLLW) disposal site, it is essential to study the regional hydrogeological condition and the transportation process of nuclide in the disposal site with the engineering barrier. The candidate VLLW repository located at the confluence of two rivers in the southwest of China, which included the characters of enrichment of the rainfall, closing to the river and inhomogeneous media. Several key aspects were focused on: (1) identified the geological and hydrogeological condition and characteristic of the VLLW disposal site, and found the recharge, runoff and drainage route and the head of the groundwater, the boundary and the spatial change of the unconfined aquifer; (2) got the parameters of simulating model by the in situ pumping experiments and correlation coefficients from the soil column experiments and batch tests; (3) calibrated the model with the data of the observed observation wells; simulated the steady state flow and migration of Sr from the repository with fine-particle barrier in 300 years by application the MODFLOW and MT3D module in the Groundwater Modeling System (GMS). The result showed that the barrier was an effective measure for the management of the disposal VLLW.

Effects of meteorological models on the solution of the surface energy balance and soil temperature variations in bare soils

summary A complete evaluation of the soil thermal regime can be obtained by evaluating the movement of liquid water, water vapor, and thermal energy in the subsurface. Such an evaluation requires the simultaneous solution of the system of equations for the surface water and energy balance, and subsurface heat transport and water flow. When only daily climatic data is available, one needs not only to estimate diurnal cycles of climatic data, but to calculate the continuous values of various components in the energy balance equation, using different parameterization methods. The objective of this study is to quantify the impact of the choice of different estimation and parameterization methods, referred together to as meteorological models in this paper, on soil temperature predictions in bare soils. A variety of widely accepted meteorological models were tested on the dataset collected at a proposed low-level radioactive-waste disposal site in the Chihuahua Desert in West Texas. As the soil surface was kept bare during the study, no vegetation effects were evaluated. A coupled liquid water, water vapor, and heat transport model, implemented in the HYDRUS-1D program, was used to simulate diurnal and seasonal soil temperature changes in the engineered cover installed at the site. The modified version of HYDRUS provides a flexible means for using various types of information and different models to evaluate surface mass and energy balance. Different meteorological models were compared in terms of their prediction errors for soil temperatures at seven observation depths. The results obtained indicate that although many available meteorological models can be used to solve the energy balance equation at the soil–atmosphere interface in coupled water, vapor, and heat transport models, their impact on overall simulation results varies. For example, using daily average climatic data led to greater prediction errors, while relatively simple meteorological models may significantly improve soil temperature predictions. On the other hand, while models for the albedo and soil emissivity had little impact on soil temperature predictions, the choice of the atmospheric emissivity models had a greater impact. A comparison of all the different models indicates that the error introduced at the soil atmosphere interface propagates to deeper layers. Therefore, attention needs to be paid not only to the precise determination of the soil hydraulic and thermal properties, but also to the selection of proper meteorological models for the components involved in the surface energy balance calculations.

Disruption or Convention? A Process-based Explanation of Divergent Repertoires of Contention Among Opponents to Low-level Radioactive Waste Disposal Sites

Violence, disruption and convention constitute three well established categories of collective action repertoires available to contemporary social movements. What factors shape differences in repertoire selection across social movement groups? I take a process-based approach to answer this question, examining two grassroots opposition movements to the disposal of low-level radioactive waste in the United States. The two rural New York State counties I consider each faced a state-imposed low-level radioactive waste site proposal in 1988. Activists in each county mounted vigorous collective opposition to the proposed facility, while exhibiting distinct repertoires of collective action. Activists in Allegany County pursued disruptive civil disobedience, while activists in Cortland County pursued a conventional repertoire of citizen lobbying and litigation efforts. Similarities across a variety of demographic, political, and social characteristics in these two counties leave the standard explanations for repertoire selection put forth in the social movement literature wanting. I argue that the relationship developed between the respective county governments and citizen activists during the waste-site proposal dispute had a dramatic effect on the dominant repertoire of collective action adopted by each community. More specifically, identifying the presence or absence of the social mechanism of brokerage between local government and activists is crucial to understanding the different trajectories of these movement groups. This article highlights the utility of fine-grained process-based analysis as a complement to variable-based approaches for explaining social movement activity, and the importance of the mechanism of brokerage among local government and activists for understanding bottom-up movements responding to proximate grievances, such as the environmental justice movement.