Scottish Government

3. STORAGE, DISPOSAL AND TREATMENT

This Chapter provides:

• An overview of the proposed Policy for storage, disposal and treatment of higher activity radioactive waste (the Waste);
• A summary of the relevant aspects of the environmental baseline in relation to storage, disposal and treatment of the Waste;
• The likely environmental effects of the Policy for storage, disposal and treatment of the Waste. This includes the risks of exposure to radioactivity as well as the wider environmental effects;
• The likely environmental effects of the reasonable alternatives to the Policy for storage, disposal and treatment of the Waste.

Proposed Policy

Storage and Disposal

3.01 The Policy allows for both storage and disposal of higher activity radioactive waste. Storage is defined as placing the Waste in a suitable facility with the intent to retrieve it at a later date. Disposal is the emplacement of the Waste in a specialised land-based disposal facility without the intent to retrieve it at a later time. This means that the time of emplacement is the time of disposal, even if the facility is eventually closed many years later. Retrieval may be possible for both storage and disposal. However, if this is intended from the outset, the appropriate term is storage, as opposed to disposal.

3.02 Storage is supported over the long-term but should not be indefinite.

3.03 As noted in the Policy, there are different views on whether radioactive waste can be disposed of, as it can take a very long time for Waste to decay to a state where it is no longer hazardous. However, having reviewed the types of material which require to be managed, the Scottish Government has concluded, in consultation with stakeholders, that there may be opportunities to safely dispose of some types of Waste in near surface facilities. Disposal is not associated with a specific timeframe because, as explained above, it implies that there no intention to retrieve the Waste over an indefinite period. Ongoing control and monitoring in accordance with regulatory requirements may be appropriate for some Wastes.

Treatment

3.04 Consideration of the environmental implications of treatment forms an integral part of the evaluation of the overall effects arising from the storage and disposal of the Waste. The majority of the Waste will require treatment before it can be stored or disposed of. The Policy states that treatment could be used in support of compliance with the Waste Hierarchy (Figure 7). The Policy does not extend to include the reprocessing of spent nuclear fuel as this is not currently classified as radioactive waste.

Figure 7: The Waste Hierarchy

Why treat the Waste?

3.05 The Waste may be treated for several reasons including:

• to stabilise the Waste so that it can be stored or disposed of more safely;
• to separate material that can be reused or recycled from the radioactive component of the Waste; or
• to reduce the volume of Waste for storage or disposal.

Treatment of Waste can result in an increase or decrease to the volume of the original Waste but it can also produce secondary waste as part of the treatment process

What treatment options are currently used in the UK?

3.06 Higher activity radioactive waste has only been produced for a relatively short period of time (tens of years). There are treatment options currently available but these are limited. However, the Nuclear Decommissioning Authority ( NDA) and other waste owners and producers in the UK are carrying out research into options for treating different types of radioactive waste.

The technologies currently used to treat radioactive waste in the UK are:

• Encapsulation

This is the baseline treatment currently used for many higher activity wastes in Scotland. Encapsulation involves the immobilisation of waste by mixing it with a matrix material within a container in order to produce a more solid and stable waste form.

• Surface Contamination

The treatment of contaminated metals is usually a two-step process. The first step is to remove surface contamination. This is typically achieved through an automatic grit-blasting process which removes the surface of the metal and a proportion of the contamination with it. In some cases this treatment is sufficient to clean up the metal enough so that no further treatment is needed.

• Metal Smelting

However, if further treatment is needed to remove more contamination, metallic wastes can be subjected to melting as the next step in the process. During the melting process radioactive contamination is concentrated in slag on the surface of the molten metal. Some contamination may also be released into the off-gas system and captured. The process has an additional advantage of homogenising the melt, which has benefits for characterising the material post-treatment.

• Vitrification

Vitrification is the process of incorporating materials into molten glass and is a technology currently applied to the solidification of liquid high-level radioactive waste (there is no HLW in Scotland) from the reprocessing of spent fuel. It is potentially suitable for desiccant, sludges, hazardous chemical, ion exchange resins, and potentially some other types of waste. This is not however, appropriate for graphite, contaminated and activated metals.

What treatment options are used elsewhere in the world?

3.07 There are other treatment options used, for example:

• Bitumen
• Incineration
• Chemical Treatment
• Thermal Treatment

Thermal treatment technology

3.08 Thermal treatment is a term given to any Waste treatment technology that involves high temperatures in processing the feedstock and is normally deployed to enable the volume of radioactive waste for storage or disposal to be reduced. All thermal treatment technologies require an off-gas system to capture any gaseous radioactive waste produced during treatment and give the ability to manage the concentrated radioactive waste product that is produced as a result of the process.

3.09 The actual methods of treatment will be determined by the particular type of Waste and the Policy objectives. A range of methods can be used to treat Waste, with different processes being suitable for different materials. By way of example, based on current knowledge of the Waste in Scotland and available technology, the following thermal treatment technologies, already used elsewhere in the world, may be suitable:

• Joule heating melter - may be suitable for desiccant and sludges, hazardous chemicals, ion exchange resins, catalysts, and ion exchange resins and potentially feasible for some other wastes.
• Joule heating in container vitrification - may be suitable for most types of waste including graphite, but not for activated metals.
• Calcine hot isostatic pressing - may be suitable for desiccant, sludges, hazardous chemicals, ion exchange resins, catalysts, Pu/U contaminated materials, and potentially feasible for some other wastes.
• Plasma arc - possibly suitable for most types of waste, excluding activated metals.
• Steam reformation - potentially can be used for most types of waste except contaminated and activated metals.

Research and Development

3.10 Any new technology proposed for treating higher activity radioactive waste will have to be evaluated for its suitability for different radioactive waste streams because each Waste stream has different characteristics that the treatment will need to be able to handle.

3.11 Any new treatment will also need to be demonstrated at the appropriate scale to show how the process can be controlled in order to produce radioactive waste products that are acceptable for storage or disposal as required.

Where can Waste be treated?

3.12 Where Waste will be treated will depend on the treatment being applied and the location of available facilities for the treatment. Treatment may be carried out on the site where the Waste is generated or the Waste might need to be sent elsewhere for treatment. The Policy notes that treatment facilities may not be available in Scotland or the UK, and as a result transportation of the Waste to facilitate treatment overseas may be required. Exporting of Waste overseas is covered by international agreements including Transfrontier Shipment Regulations. Appropriate authorisation is required before export for treatment is granted consent. The Policy also states that any exported Waste must be returned to Scotland, and not disposed of in the destination country. Alternatively, in the future treatment facilities could be constructed in a single centralised location or adjacent to Waste storage or disposal facilities in Scotland. Mobile treatment plants could also be deployed to deal with some types of Waste.

Relevant Aspects of the Baseline Environment

3.13 Emissions from man-made sources of radiation are low when compared with exposure from the natural environment, and overall levels have been falling for some time. Natural sources of radiation account for the majority (84%) of exposure to the UK population from ionising radiation with a further 14% of exposure arising from medical uses. The remaining 2% of exposure comes from occupational exposure, products containing radioactive material, fallout from weapons testing and nuclear accidents, and authorised disposals of radioactive material. The exposure from authorised disposals is less than 0.1% of the average total dose of 2.4 mSv.

3.14 Routine discharges from sites which could result in public exposure to radiation require appropriate authorisation and are subject to strict limits. Radioactive discharges to water from nuclear industry sites in Scotland are primarily to sea, but atmospheric emissions can also lead to contamination of the wider environment. As noted in Section 3 of the Supplementary Information a plethora of legislative and regulatory controls are already in place to avoid adverse effects of this type of activity on the population. Data show that actual discharges from Chapelcross, Hunterston, Torness and Dounreay fall far below authorised limits. Radiological dose for workers (including contractors and employees) at NDA sites was low for all of the sites in Scotland, with no instances arising of the legal dose having been exceeded since the NDA was established ( reference 30).

3.15 In the period 1996-2004, relatively high annual dosages were recorded in a group of seafood consumers on the Dumfries and Galloway Coast, largely as a result of liquid discharges from Sellafield. This, however, remained far bellow the regulatory limit. Localised incidents at Dounreay and some other nuclear sites in Scotland are considered to be a result of historic practices on the sites. Changes in the operations of the nuclear installations in Scotland mean that discharges to water fell between 1996 and 2004 ( reference 31).

Likely environmental effects of the proposed approach

Risk of exposure to radioactivity

3.16 The publication Near-surface Disposal Facilities on Land for Solid Radioactive Wastes Guidance on Requirements for Authorisation (the Near Surface GRA) ( reference 32) has been produced by SEPA, the Environment Agency and Northern Ireland Environment Agency (February 2009). This provides a fuller definition of storage and disposal, and explains that the types of facility used for disposal vary according to the type of Waste to be disposed. The Near Surface GRA sets out a framework within which developers and operators of disposal facilities are required to operate. A key aspect of this is the production of an environmental safety case to demonstrate how people and the environment will be protected from any potential adverse effects arising from the disposals.

3.17 With regard to potential exposure to radioactivity, no significant effects are expected from the decision within the Policy to allow disposal as well as storage, as appropriate for the materials concerned. The principles which underpin the Near Surface GRA have formed the basis for the Policy, as described in Chapter 1 (paragraph 1.05 - 1.06). Under both the Policy and the Near Surface GRA, facilities for both storage and disposal are required to comply with these principles. As a result of this, and taking into account the broader international and national framework for protection of the environment and the population from radioactivity, it is expected that key environmental hazards, including radiological exposure, would be avoided or mitigated to acceptable levels as appropriate.

3.18 Any impacts arising from the treatment of the Waste are not considered to be a direct result of the Policy, but would be subjected to site level controls, monitoring and enforcement in any case. The treatment processes could result in the production of secondary wastes, both radioactive and non-radioactive, and are therefore closely regulated. As the Policy does not specifically propose that treatment facilities are developed, these effects should be regarded as secondary effects at this stage in the process. Allowing the Waste to be transported to facilitate treatment, and for materials to be returned following treatment, is also not considered to present a significant risk of radioactive exposure for the population or the environment, given the strict controls which are in place to regulate the transportation of radioactive waste. These controls are considered in more detail in Chapter 5.

Wider potential environmental effects

3.19 The following wider environmental effects could arise as a result of the Policy:

• Biodiversity, soil, water, air, population and human health could be directly or indirectly affected by facilities for both storage and disposal. Beyond controls of radioactive emissions (discussed above), the Near Surface GRA states that some solid radioactive waste can present non-radiological hazards, including chemical toxicity and biological hazards. Prospective operators are therefore required to take this into account when considering where facilities should be located and how they should be designed. Examples of hazardous substances include asbestos, poisonous inorganic chemicals ( e.g. heavy metals) poisonous organic chemicals ( e.g. cyanides) and gases ( e.g. including greenhouse gases such as methane) which are flammable. Pollution and other adverse effects can also arise from the transport movements which would be generated during the construction and operation of this type of facility. However, where treatment reduces the volume of Wastes, benefits for these receptors could be expected and conversely processing that leads to an increase in volume could increase some of these effects as a result of a need for larger facilities with greater storage capacity.
• long-term storage of the Waste in facilities which are potentially vulnerable to unforeseeable events including terrorist attack or accidents. This risk may be greater for storage facilities, compared to disposal, as storage would imply that the Waste is more readily accessible. Any facility which is expected to operate beyond the accepted period of institutional control (300 years) is reliant on the ability of people in the future to maintain their integrity, actively manage and repair facilities and containers, and ultimately replace them as required. CoRWM recommend that new stores are designed to ensure they do not require a major refurbishment or replacement over their lifetime, although this assumes that this would be limited to the time required for storage prior to disposal. The Policy will necessitate replacement of the stores in the future, given the timescales involved. If technology allows disposal in near-surface facilities, the volume required for new stores will reduce over the long-term, limiting the environmental effects that would otherwise arise from long-term storage. Treatment ensures that materials are stabilised, thereby reducing any hazards and responsibilities for current and future populations.
• The transportation requirements arising from the export of materials to specialist overseas facilities for treatment, and from the return of treated materials, raises an increased risk to population and human health, the marine environment, and also wider ecosystems, as a result of higher travel distances overall. However, as demonstrated by the Sustainability Appraisal of the NDA Strategy for LLW facilities and discussed further in Chapter 5 below, actual impacts from transportation of Waste are not expected to be significant and relate more to perceived risk, given the existing regulatory arrangements ( reference 33).
• Dominant perspectives on institutional control accept that the technical timescales for managing this Waste greatly exceed the key social factors such as the lifespan of government institutions ( reference 34). However, defining the actual implications of institutional control has proved difficult given the number of variables which can not be pre-determined. This view is emphasised by CoRWM, who state that it is difficult to predict social developments over periods of more than a few decades as most social systems are considerably more difficult to predict than geological evolution ( reference 35). However, a report to the House of Lords Science and Technology Select Committee acknowledged that surface storage of conditioned, packaged Wastes in modern facilities for several decades is feasible and safe ( reference 36). This view was further emphasised in a report from the IAEA which provided the example of the COVRA facility in the Netherlands. An evaluation was conducted as to the suitability of storage at this facility for up to 300 years. It was generally concluded that although social and political factors cannot be predicted over such a period, the factors were not considered to pose a significant problem ( reference 37). Therefore, as the Scottish Government's Policy focuses on arrangements for storage facilities for at least 100 years, with the capability of extension beyond 100 years if necessary, it can be concluded that the risks associated with loss of institutional control has been accounted for as far as possible at this point in time.
• Visual effects, including on landscape and cultural heritage, as well as general amenity could arisefrom the construction and siting of storage and disposal facilities . These will be largely dependent on the location of the facilities as discussed in Chapter 4. Opportunities for treatment options that reduce the volume of Wastes, as opposed to increasing it, could significantly reduce these effects by minimising the volume of storage or disposal space required.
• In terms of climatic factors, greenhouse gas emissions could be generated from both storage and disposal, through chemical processes that take place as the composition of the Waste changes over time. Construction would generate transport borne emissions but these would be temporary, and over the medium to long-term operational traffic would be very minor. More significantly, however, the long-term nature of this type of operation means that the likely impacts of climate change on the facilities are difficult to predict with any level of accuracy, although it will continue over the lifetime of any such facility ( reference 38). Disposal would imply that retrievability is more challenging as compared to storage, potentially increasing the vulnerability of these facilities to environmental change including climate related impacts over the long-term. Consequently long-term storage and disposal facilities may require adaptation measures to be built in, depending on their location and the eventual impacts of climate change. This can be addressed in broad terms within the assessment but will require fuller attention as the implementation of the Policy progresses at the site selection stage.
• In terms of material assets, no significant effects on transport infrastructure would arise specifically from this part of the Policy, as these would be dictated by locational decisions and the design of facilities and processes (as discussed in Chapters 4 and 5). However, in conceptual terms, storage of Waste over the long-term could be viewed as more supportive of the principles of sustainable Waste management than disposal, when considered in relation to the Waste Hierarchy, as it leaves options open for recovering materials as the technology develops to reuse or recycle them.

3.20 The Near Surface GRA requires full site investigation to be undertaken at the site selection stage, including full characterisation of soils, water, biodiversity and human settlement, in addition to the more technical analysis of factors such as hydrogeology. Many of the potential effects of these types of facility would be mitigated through appropriate site selection, operational requirements, monitoring and design measures. More detailed requirements for mitigating more specific effects arising from the sub-components of storage and disposal are explained in the following Chapters.

Likely environmental effects of reasonable alternatives

3.21 The key reasonable alternative to allowing both storage and disposal of the Waste that was considered during the development of the Policy was only allowing storage and indicating a presumption against disposal generally. Research has suggested that storage infers a greater and unacceptable burden on future generations (as compared to disposal), and that it carries additional security and health risks ( reference 39). These risks primarily take the form of loss of institutional control (discussed above) lack of available funding and loss of knowledge about how the stores should be managed, as the stores continue to exist into the medium and long-term. However, measures can be taken to avoid these situations arising to an extent, such as multiple protective barriers being built into storage options ( reference 40) and as noted above, whether it covers storage or disposal, the Policy has been designed with the timescales associated with institutional control in mind.

3.22 Focusing only on disposal was not considered to be a reasonable alternative by the Scottish Government during the course of the Policy development process, not least because any opportunities for disposal need to be preceded by a storage programme. In addition, some of the types of Waste in Scotland cannot be disposed of in near surface facilities and therefore need to be stored until further technological developments emerge. This amounts to around a quarter of the total Waste in Scotland.

3.23 However, to provide perspective on the implications of the Policy, it is worth noting the key aspects of the debate on storage versus disposal. These relate more to ethical considerations, given the very long-term and emergent nature of radioactive waste management options. Although it has been suggested that conceptually a stronger commitment to disposal could result in a lighter burden for future generations and provide long-term benefits as compared to storage, views on this remain divided amongst stakeholders ( reference 41) and are fundamentally influenced by widely varying ethical standpoints. Whilst the arguments against long-term storage relate to the long-term management burden this imposes, there equally remain unresolved concerns about environmental risks arising from the disposal process.

3.24 As a result, there is no definitive environmental case which indicates that either storage or disposal should be prioritised, even if they could be viewed as mutually exclusive options. Both storage and disposal raise issues which necessitate a prudent and flexible approach to the Policy, to allow for solutions to emerge over the long-term as the technology and society evolve.