A repository for the waste that is radioactive in nature is essentially a arrangement of well-though out and naturally existing barriers that help in the isolation of waste emanating from the environment and the activities of human beings. The most profound natural barriers include the surrounding geological formations as well as the host rock, with each possessing the geochemical, hydrogeological as well as geological properties.
The barriers avail the probable conditions, in which the radioactive wastes are centrally emplaced such that retardation of the transportation process of the radionuclides may be released from the most profound, and reliable engineering systems that were to be accessible to the environment.
The ultimate process of selecting the site should carry the geochemical, hydrogeological and geological properties that are quite favorable for waste isolation as this becomes of prime importance (Mongillo and Zierdt-Warshaw 45).
There is however other additional factors that are expected to be set in place and this include the economic, societal as well as technical matters that should be placed into consideration in the site selection.
Apparently, site selection, as well as site characterization to various establishments of the repository sites, has previously been performed in several cases and this case favors the United Kingdom with absolute loyalty to outstanding bodies and organizations involved (United States Congress 57). In most cases, the underground research laboratories are quite significant as they are located near such sites.
The repository sites may further be built near nuclear plants hence facilitating the most immediate dumping site without making unnecessary movements that may further cause more problems.
The primary purpose of the underground research facilities revolves around the detailed investigation of the entire repository site, in this context; the central objective is to explore the general processes that are placed into consideration in the selection of the geological repository sites as well as deducing the characterization of the deep geological disposal of the radioactive waste (United States Congress 61).
The site selection, in this case, favors the deep disposal of the higher activity wastes in bedrock between 500 to 1000 meters below the ground level.
For the purpose of site selection, the paper favors the Sellafield as one of the best location where the facility can be staged. This went alongside the site assessment process that was quite stepwise and at the same time, evaluative in terms of the land use, topography, hydrology and the history of the location of choice.
A recap of the site location process gives a preview of two significant stages, which include the site characterization stage and the site confirmation stage. Brief details on the site characterization stage state that there must be need to sufficiently investigate the site before developing the preliminary site designs as well as conducting the safety assessments.
In this stage, the process demands precedence of suggested multiple sites with variance based on the country’s requirements and policies set in place to control the functionality of the sensitive plants. However, the site confirmation stage suggests on the verification of the site conditions with anticipation of the near future anticipated site conditions.
This is significantly required to prepare and at the same time, submit the application license for the repository construction.
Apart from the brief details of site location process, the paper concentrates on the location, the topography, hydrology and the recent land use at Sellafield. Preliminarily, Sellafield is one of the nuclear reprocessing sites that are close to the Seascale village at the coast of Cumbria, England.
Sellafield is further known to have incorporated the nuclear reactor at Windscale, which implies that there are possible radiations that are released and may be harmful to the public. A short background of the whole area reveals that it was initially a primitive society based in Cumbria which is one of the counties in the Northern side of Britain.
The ROF Sellafield underwent construction in the year 1942 in the Sellafield industrial site with the nearby factory, which had reached the completion stage in 1940.
Sellafield is said to have been owned as well as operated by the UK Atomic Energy Authority. In the year 2008, NDA is said to have contracted the entire management of Sellafield Limited to the Nuclear Management Partners. THORP and Magnox are some of the plants found at the site.
The topography of this part of the world takes the geographic description of Cumbria being northwesterly of the county of England. At an altitude of about nine hundred and seventy eight meters, Scafell Pike makes up the tallest point in the Cumbria.
The land is bordered by a number of English counties such as the County Durham, Lancashire, and Northumberland. The Cumbrian northern boundary is said to stretch from Solway Firth to Northumberland. The place is said to be having many large companies with Sellafield Nuclear Reprocessing plant being the most outstanding with a work force of 10000.
The land use at Sellafield is predominantly meant for in-site disposal of waste with plant operations set in place. Some of the land depressions dividing different areas were vital in building the wall in the area that was north of the Coastline. Reports from research on lands in this area indicate that there has been some seeping of liquids believed to be radioactive into the soil.
Special components of fuel processing are further said to have leaked into the ground leaving the land under many issues that are quite problematic. This is very dangerous as it contributes immensely to the deterioration of the top soil in such area.
Given the current rate at which the soil in the area is being destroyed, it is possible that soon the soil in the area will be of no importance. The soil will not be able to support other activities such as farming and livestock keeping.
Concerning the hydrology of Sellafield, Cumbria is said to the victim of climate change with a historic downpour witnessed in 1955. Based on the statistics taken by the Lake District National Park, Seathwaite is considerably the wettest inhabited place in England. The place, in Cumbria, is said to be experiencing 3500mm of the precipitation in each year.
Flooding in autumn-winter season is a common phenomenon in the whole of United Kingdom statistics reveal that the area has been witnessing increases in river flows that absolutely lead to climate change.
However, the recent cases have been quite irregular thereby distorting the entire climate pattern. This implies that there is a big impact brought by climatic change on the hydrological nature of the place, which used to be wet all the times.
It is an important feature in staging a repository facility that has to ensure full facilitation of safety to both human and the immediate environment. Geology can be defined as the study of discourse or the significant study of solid earth as well as rocks and the involved process that brings about the change of structure (Michie 54). The general case refers to this aspect as the study of solid features.
Geological materials under study include the rocks and the unconsolidated material. Putting Sellafield in mind, the section focuses on addressing tow important considerable aspects, which include the superficial geology and the solid geology of the entire area.
Superficial geology indicates geological deposits that are less than two point six million years old. They are residues that are not attached to each other but make up many of the land features that people see most of the time. This feature is seen in most parts of the West Cumbria.
The deposits are said to be closely associated with glacial re-advances in the latter stages of the renowned Dimlington Stadial that exhibits the glacio-tectonic deformation structures. Studies indicate that the deposits are present in the Sellafield drift domains whereby they can easily recognized as clay dominated lithology in the upper drift sequences.
Natural exposures, excavation together with the geophysical surveys taken at the Drigg as well as Sellafield provide an outstanding exhibit of the deformational structures. The folding and tilting of the entire strata, at the Drigg beach and Sea Scale, indicate the accompaniment of the deformation. The Drigg case gives the impact of the extensional fault thereby bringing about the post-depositional deformation.
Further details on the superficial geology lead to the preliminary deduction of distribution of the bulk lithology types. The geological conceptualization gives the feasibility of the glacial drift by the characterization of the bulk domain. The experimental bulk leads to lithology zonation that involves the lithology description that extracts the knowledge from the borehole details based on drilling records.
From the findngs, it was evident that the clay dominant lithologies were absent in the Sellafield South east section situated in the hydraulic gradient from the significant Separation Area. The drift lithology is significantly located at the western end of the entire Sellafield Buried Channel, the point where it meets with the Ehen Buried Channel.
Solid Geology of the Site
Solid geology is also referred to as bedrock geology, which has its concepts lying behind rock formation among other processes. This is different from the superficial deposits that form the ground layer through agents of erosion that drives materials from one position to another.
Solid geology at Sellafield takes the beneath characteristics with the depth description of the adjacent area that is majorly comprised of the sedimentary formations as a result of the outstanding process acting on the Triassic Sherwood sandstone.
The significant upper layer of the units of Calder sandstone formation underlies both the northern two-thirds and the adjacent offsite sections on both sides. A portion of the young Ormskirk formation that is significantly preserved in a graben structure essentially underlies a third of the southern site (Merritt and Phillips 14).
Calder sandstone formation takes the description outlined in the NIREX Sellafield 10B borehole. The exposure of the discontinuous outcrops on the bed and river banks of Calder indicates the rock bank that exists behind the Waste Encapsulation plants. The significant outcrops of Calder sandstone formation can clearly be seen on the adjacent sides of river Calder as it makes its entrance to the northern perimeter.
The conspicuous NIREX borehole BH3 that finds its location near the Calder landfill forms a 50m intersection with the lower boundary defined by the geophysical data thereby generating a correlation with the offshore boreholes. The Calder is naturally of fine texture in comparison to its counterpart sandstone Ormskirk. The latter is significantly rough in terms its texture.
For this reason, it is quite easy for one to differentiate the two sandstones and avoid unnecessary confusion. Finally, the sandstone weathered zone is considerably described as a prominent feature for both the Ormskirk sandstone formation and the Calder sandstone formation with the western section of Cumbria describing the depth of in-situ weathering region in the entire bedrock.
This layer majorly consists of the litho-fragments as well as, sand that directly overlie the competent sandstone thereby closing the remnants.
Details on hydrogeology may not make sense without borrowing the introductory details from geology. From the geological description, it is evident that Sellafield largely sits on sediments that are commonly referred to as the drift or the superficial deposits that are significantly deposited by a variety of glacial, lake, river as well as the marine processes.
It can further be pointed out that the Triassic sandstone forms the large section of the bedrock in this region. The significant depth of the grained rock is accompanied with the bedding planes that deepen towards the coast from South West (Chaplow 9). The major buried channel lies in the northwest direction of the entire site that is significantly associated with the River Ethen route.
The superficial deposits mainly entail the coarse grained sand having some patchy clay layers. The layer of clay is not consistent. Clay soil is scattered in some sections of the area in small portions that are almost unnoticeable if one does not investigate the site keenly.
The boreholes drilled into sediments essentially interact with the groundwater at a depth approximated to be 5 to 15 meters below accompanied with clay layers that makes the groundwater to appear at a higher level than it would have preferably been expected. The Groundwater found below is normally located on a lower section of the essentially defined superficial deposits that look closely joined to the groundwater.
The deposits are commonly classified as aquifer. However, it is anonymous when it comes to the use made of the water resources in the vicinity of the site but the springs found along the beach are essentially fed by the ground water.
However, it is worth noting that NIREX has been playing an outstanding role in both managing and providing the national facility for the solid low level as well as the intermediate radioactive waste. There is a lot of research carried out continuously in the Sellafield area to find out its suitability when it comes to creation of repositories that are deep enough to handle the disposal of materials that are radioactive in nature.
Subsequently, a good number of boreholes that are deep enough were drilled. A survey of the seismic waves was also initiated to ensure the safety drilling boreholes in the relevant areas. The aftermath of the investigation indicated the borrowable volcanic group of rocks with the top surface beneath the Sellafield site showing a promising location that could provide the center repository.
However, much has to be done on the hydrogeology study before reaching the ultimate conclusion on the suitability of the investigated site. The procedure adopted in determining safety has to adhere to strictly. There is no entity that can be allowed to proceed with activities in any given area without satisfying all the necessary requirements under the law.
A geohazard is considerably a geological state that may significantly lead to a detrimental widespread of risk or damage. Environmental as well as geological conditions may involve both the long term and short term processes. This may, however, be small features that may carry big dimensions thereby affecting the regional socio-economy to a relatively significant extent. Apparently, human activities like drilling in over-pressured zones could lead to risks where mitigation and preclusion measures are seen to be paramount.
Based on the GZA analysis, possible hazards that may result from siting a repository plant at Sellafield revolve around the seismic aspects.
This includes the liquefaction potential, seismically induced settlement and lateral spreading analysis that reflect on the end results that settle on the possible movement of the earth or collapse of the land during the construction process, an undertaking that may consume a significant number of lives of people.
Generally, geohazard resulting from the nuclear facilities are majorly brought by human activities that may eventually cause accidents. In most cases, preparations are always set in place to handle the emergency services that may be needed as a result of the operations carried out (Michie 25).
The most significant aspect revolves around the idea of landfilling processes that stimulate other geological processes. A nuclear repository is significantly accompanied with the land filling process that promotes outstanding activities like mass flow. Heaps as a result of the land filling process may lead to an imbalance of materials on the earth’s surface.
This may prompt mass flows that may further consume the lives of people in the nearby location. Mass flow, though unrelated to the nuclear plant repository, is said to have consumed a significant number of lives in Japan among other areas across the whole world. Large trucks that are used in the construction of the repository site are heavy enough to loosen the compatibility of the soil structure on the earth’s surface.
This means that further the ground is weakened to an extent of reaching the failing point in terms of holding earthly natural geological processes. Preliminarily, loosened ground may be subjective to the most conspicuous agents of soil erosion. This means that the movement of the earth is made possible thereby leaving the site with remnants of the original structure (Nuclear Decommissioning Authority 45).
This is too risky as it might lead to free falling of earthly materials. Secondly, loosened ground is in itself risky in that the earth can no longer handle extra processes after the construction process. Continuation of other processes that interfere with the loosened earth structure may further lead to extended risky processes that may not be easily be mitigated or handled with the available resources.
Loosened structure of the earth makes the ground be prone to such natural processes like faulting, which may have both the positive and negative impacts. The nuclear repository should, therefore, check on the possible Geohazards that may result from the pre-undertaken actions. This may provide room for evaluation of the most appropriate tools and techniques that may handle the process in a safer way.
Looking at the option made in the earlier case, it is evident that the paper addresses the major concern of staging deep disposal of higher activity wastes in bedrock between 500 to 1000 meters below ground level. The significant sight selection lands on Sellafield, a site in Cumbria with multiple large companies especially the nuclear plants.
On assessment basis, the region needs a repository site to safely damp the radioactive waste that results from the outstanding processes carried out in magnificent nuclear plants in Cumbria. Without such a repository site, such plants, among other firms may go ahead in carelessly damping the radioactive waste (Entwisle 795). This may generate a detrimental impact on both the environment and the human health.
The geological study takes into consideration two significant aspects that evaluate the stability of the ground in the surrounding area. The superficial deposits provide the basic information on the materials lying on the surface of the earth such as alluvium and the glacial materials. The solid geology analysis gives a clear impression of the stable ground that can strongly accommodate the site in the underground section.
Significant study of the Calder sandstone formation and the Ormskirk sandstone formation gives a clear picture of the bedrock underneath, which is strong enough to hold the drilling processes thereby enabling the simple and easy way of creating the site.
In this case, one should note that the presence of the bedrock is the core factor in determining the long service of the repository site that has to be located at Sellafield (British Nuclear Energy Society 10).
The deep location of the site goes alongside the sense of avoiding possible avenues on which the agricultural soil layers may be polluted. Considering the assessment of the hydrogeology, it is evident that the ground water is available just 5 to 15 meters below the ground. The site has to be located 500 meters, on the minimum side, below the ground level.
This means that the site will interfere less with the hydrological cycle of the geological structure. Lack of interference to the hydrological system is an acceptable action aimed at conserving the environment for future use. The decision made in locating the site deep enough is, therefore, valid and acceptable.
Conclusion and Recommendations
The paper addresses much on the preliminary assessment for the proposed geological disposal facility. It has given the breakdown of the analytical situations stating the geological characteristics of the stated Sellafield repository site.
The primary details on the location and soil structure of the proposed site played a significant role in pre-weighing the capability of the location in accommodating the constriction of the site, which involves drilling among many other processes.
The geology details give information on both the superficial and solid geology. The assessment section provides the analyzed sections and further proves the strength of the location in supporting the repository site. The choice made in constructing a deep repository site is, therefore, valid and achievable.
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