Approaches to environmental remediation at nuclear sites

Nuclear sites can be quite variable in terms of their history and type of operations. These variances are in turn likely to reflect the type of contamination which may reside in the ground or in groundwater. When a site has been subject to such contamination there will often be a requirement to undertake some level of environmental remediation.

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Aug 02, 2017
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Abstract

Nuclear sites can be quite variable in terms of their history and type of operations. These variances are in turn likely to reflect the type of contamination which may reside in the ground or in groundwater. When a site has been subject to such contamination there will often be a requirement to undertake some level of environmental remediation. This work is aimed at protecting human health and the environment, and the adopted approach will usually focus on meeting a desired end state for the site or to fulfil other more immediate drivers. The International Atomic Energy Agency define remediation as ‘Any measures that maybe carried out to reduce the radiation exposure from existing contamination of land areas through actions applied to the contamination itself (the source) or to exposure pathways to humans’. If we consider a nuclear site through its lifecycle there are many opportunities for activities or incidents to lead to the contamination of ground and groundwater. Common causes of contamination might include:

  • Leaks from buildings and facilities.
  • Leaks from surface storage compounds.
  • Poorly performing waste disposal sites.
  • Spills during the transportation of materials.
  • Leaks from underground pipes.
  • Aerial dispersion from stacks and incinerators.
  • Past practices of allowing liquids to evaporate from hardstands.
  • Cross-contamination of aquifers resulting from poorly designed boreholes.
  • Dispersion of material during the decommissioning of facilities.

The aim of this paper is to highlight the general approaches taken in order to consider and conduct environmental remediation on nuclear sites. The subject is exhaustive, as is the regulatory framework and it is recognised that this article will merely scratch the surface. It is hoped however that personnel not familiar with the subject will gain a better idea of how to approach the question of remediation and where they may find more detailed guidance.

Introduction

When a site has been subject to soil or groundwater contamination, there will often be a requirement to undertake some level of environmental remediation. Such work is aimed at protecting human health and the environment, and the adopted approach will usually focus on meeting a desired end state for the site or to fulfil other more immediate drivers.

This paper will discuss the general approaches to environmental remediation on nuclear sites and will be primarily aimed at practitioners not familiar with the subject but who may believe that some level of remediation might need to be incorporated within their overall site management strategy.

For the purposes of this paper, a ‘nuclear site’ can be defined as a site which in a regulatory and legal sense has a nuclear site licence, thus allowing it to carry out an approved set of activities against which it will be regulated. Though the majority of the discussion will focus on nuclear sites and the UK position, it is important to recognise that other sites and locations exist which maybe radiologically (and non-radiologically) contaminated and not hold a nuclear site licence. Such sites will therefore also be briefly introduced in order to allow an overview and comparison to be provided of the different kinds of challenges.

Owing to the history and operations at nuclear sites, contamination maybe radiological or non-radiological in nature but more often a combination of the two.

The term environmental remediation is often interchanged with similar expressions such as restoration, reclamation or rehabilitation but the definition provided by the International Atomic Energy Agency (IAEA) perhaps puts remediation into a more radiologically focused context. They define remediation as ‘Any measures that maybe carried out to reduce the radiation exposure from existing contamination of land areas through actions applied to the contamination itself (the source) or to exposure pathways to humans’ [1].

Nuclear sites

As highlighted above, for the purposes of this paper a nuclear site is one which holds a nuclear site licence against which it is regulated. Such sites may exhibit variability in terms of their location, their history and original purpose, current operations, legacy challenges and the phase they are at within their overall lifecycle. Many UK sites have a defence or cold war legacy or were utilised for nuclear research activities which in turn reflects their operational history and the types of contaminants which might now reside on or below the surface. Such nuclear sites might include those associated with:

  • Nuclear power plants.
  • Research and test reactors.
  • Fuel production.
  • Fuel fabrication.
  • Waste reprocessing.
  • Health care.
  • Submarines and defence.
  • Radioactive waste disposal.

Many of these types of facility and operations may also be co-located on a particular site rather than purely being located on their own. Sellafield is a good example of a UK site with a complex history and it has former civil reactors, legacy waste disposals and reprocessing facilities [2].

The potential contaminants of concern will in turn vary depending on the type of site and its history of operations. At nuclear power plant sites, for example, it is generally believed that little contamination will have reached the ground but would likely contain fission products [isotopes of caesium (Cs), strontium, iodine (I) etc.] activation products (isotopes of nitrogen, argon, cobalt, carbon etc.) and tritium. At more complex sites such as Sellafield there is the possibility that a range of contaminants will have made their way into the ground/groundwater over time (through legacy disposals, spills, breaches of single skinned silos etc.). Such contaminants might include tritium, technetium, strontium and Cs.

If we consider a nuclear site through its lifecycle there are many opportunities for activities or incidents to lead to the contamination of ground and groundwater. Common causes of contamination might include:

  • Leaks from buildings and facilities.
  • Leaks from surface storage compounds.
  • Poorly performing waste disposal sites.
  • Spills during the transportation of materials.
  • Leaks from underground pipes.
  • Aerial dispersion from stacks and incinerators.
  • Past practices of allowing liquids to evaporate from hardstands.
  • Cross-contamination of aquifers resulting from poorly designed boreholes.
  • Dispersion of material during the decommissioning of facilities.

Drivers for environmental remediation

Prior to undertaking environmental remediation it is worth first considering the three key questions of why, when and how. Some high-level considerations are set out in Table 1 below.

Why?

The first question to ask is why might it be necessary to remediate part or all of a site? Environmental remediation is invariably expensive, will require up-front site characterisation and undoubtedly will produce wastes which themselves need to be disposed of. The costs associated with remediation therefore do not merely relate to the application of a chosen approach or technology. Remediation is all about removing radiation exposure, so it is crucial to understand the drivers behind why remediation might be required, bearing in mind that in many instances the impact from residual contamination maybe extremely low. These drivers are discussed in more detail below.

When?

The when question is equally important and again links into the drivers. A site has a lifecycle, so the timing of any potential remediation needs to take cognizance of other activities and phases of the site's life, i.e. current operations, commissioning of new facilities, decommissioning, setting of interim and final end states. Remediation is often considered at the cessation of site activities as the site moves toward closure and during any institutional control period which maybe required.

How?

How you approach any potential remediation needs to consider the nature of the contaminants, the desired outcome (is the aim to achieve restricted or unrestricted re-use of the land, for example), accessibility challenges and the technologies available. In some instances, an intervention approach might be required, whereas in others monitoring and natural attenuation might be the chosen option.

Table 1: Why, when and how?

Environmental remediation is often a costly exercise, so it is imperative to really understand the drivers for doing it as well as the timing. There are a number of factors that might influence the approach to be taken; for example, is the site still operating, is it being decommissioned, can you access the suspected contamination, how long might institutional control be expected to remain in place on cessation of site activities.

The potential drivers for remediation might include:

  • Achieving an interim or final site end state.
  • De-licencing or partial de-licencing of the site.
  • A known incident.
  • A groundwater plume migrating across the site.
  • Contamination known to be moving outside of the site boundary.
  • Stakeholder concerns.
  • Other regulatory requirements.

In many instances, even when residual contamination is present at a site, the actual impact (now or in the future) maybe extremely low and remediation may therefore not be required. It is important to look for optimised and sustainable approaches where possible.

Fig 1 highlights that a site has a lifecycle, where in simple terms plants and facilities are planned and designed, constructed, operated and finally decommissioned. Remediation activities are often undertaken on cessation of a site's activities (and in many instances will be part of the decommissioning lifecycle) but as the drivers highlighted above show there might be a requirement for remediation at any stage within the lifecycle. So, as Table 1 shows the timing and the drivers for undertaking remediation are clearly interlinked.

Fig 1: Site/facility and remediation lifecycles (sourced from the IAEA)

The Nuclear Decommissioning Authority (NDA) owns 17 of the UK's nuclear sites and within their strategy [3] (Section 3.2 Land quality management) they set out their key expectations and activities for land quality management, namely to:

  • Prevent leaks, spills and the spreading of residual contamination.
  • Develop a land quality management strategy and plan, taking consideration of both radioactive and/or non-radioactive contamination and involving stakeholders.
  • Identify and characterise contamination as soon as practicable.
  • Evaluate management and remedial options and prioritise activities.
  • Keep good records and manage knowledge appropriately.

It can be seen therefore that most if not all of these activities should be performed throughout a site's lifecycle not just on cessation of activities. The NDA expects its licencees to deliver the strategy through plans and procedures that minimise contamination and evaluate existing contamination. Licencees are expected to appraise options for managing contamination on a case-specific basis ensuring action is timely and proportionate to risk. Options should take account of impacts on the site end state [3].

Regulations and guidance 

This paper could not be put into perspective without briefly mentioning the UK's regulatory regime for radiologically contaminated land. The Office for Nuclear Regulation (ONR) regulates nuclear site activities through a series of site licence conditions [4]. Site Licence Condition 34 (Leakage and escape of radioactive material and radioactive waste) relates to waste but also includes contaminated land. Contaminated land is regulated under the Nuclear Installations Act 1965. ONR also has a series of Safety Assessment Principles, with Principles RL.1 through to RL.9 specifically related to Land Quality Management [5]. Land Quality Management is also covered within ONR's Technical Assessment Guide's particularly NS-TAST-GD-083 (Rev 0) [6].

Local authorities (councils) have a duty to inspect land under the Part 2a regime of the Environmental Protection Act 1990 and have the power to determine land as radioactive contaminated land. Once local authorities determine a site as radioactive contaminated land it becomes a special site and the Environment Agency takes over as the regulator [7]. As highlighted above, ONR takes responsibility on nuclear sites so the Environmental Agencies are more interested if contamination has moved across the site boundary. The Environment Agency and the Scottish Environmental Protection Agency can use the Part 2a regime to compel site licencees to assess and remediate radioactively contaminated land outside of their site boundary.

The UK regime is relatively complicated especially as there are nuances between England/Wales and Scotland. For a more detailed summary of the UK regulatory regime pertaining to land quality, it is suggested that the reader refers to Hill [7] which was produced for the SAFEGROUNDS learning network.

Guidance on the assessment of radioactively contaminated land and environmental remediation is extensive but that produced by the Environment Agency [8], Scottish Environmental Protection Agency [9], IAEA [10–12], the Organisation for Economic Co-operation and Development (OECD)/Nuclear Energy Agency (NEA) [13] and the SAFEGROUNDS learning network [14] are particularly useful.

Site assessment and remediation process

An interesting conundrum is perhaps whether the phases undertaken within the remediation lifecycle and the results thereof should dictate the overall strategy and desired end point or if the latter should be set at the outset with the process aimed to demonstrate transparently that the set end point has been achieved. This links back to the ‘why’ question set out in Table 1 above. However, either way once it has been decided that environmental remediation is required it is imperative to undertake the process through a phased approach [15].

For most sites, there will invariably be a range of information readily available pertaining to the site's history, activities undertaken, the subsurface geology and hydrogeology, leaks and spills, areas where wastes may have been stored or disposed of as well as the results of previous site characterisation work or groundwater monitoring. In some instances (legacy sites or sites no longer under institutional control, for example) such data and information maybe sparse. In either case, the available information needs to be reviewed and assigned a quality assurance tag. To supplement the review of records and reports this ‘desk study’ should be complimented through walk over surveys and where possible interviews with former site personnel.

Once the desk study is complete, it is necessary to develop an initial conceptual site model (CSM) of the site from all the existing data. The CSM provides a visual representation of the site and its geological and hydrogeological setting. Importantly, it also captures all known sources, pathways and receptors thus allowing an early appraisal of any pollutant linkages to be made. CSM production is an iterative exercise but this early version allows data gaps to be identified and helps drive any site characterisation required as well as cementing early thoughts on potential remediation requirements.

The CSM is therefore utilised to help design any site characterisation required. As highlighted in section ‘Nuclear sites’, the types of sites and activities are likely to dictate the types of contamination found. Nuclear sites might still have ongoing operations, be undergoing decommissioning or exhibit a mixture of the two. Access might often be a problem, so the site characterisation also has to take this into account in addition to determining the type and number of samples required.

Site characterisation is aimed at providing an understanding of the geology, hydrogeology and any ground/groundwater or surface contamination [16]. Normally a combination of non-intrusive (e.g. geophysics, gross gamma scans, X-ray Fluorescence (XRF), in situ gamma spectroscopy), intrusive (e.g. boreholes, trial trenches) and laboratory analysis methods will be utilised to complement each other. For suspected contaminants such as Am 241, Co 60, Cs 137, K 40, Ra 226, Th 232 and U 238 gross gamma scans or in situ gamma spectroscopy can provide a relatively quick survey approach. For beta emitters such as Sr 90 and Tc 99 laboratory-based beta scintillation would normally be undertaken.

Non-intrusive geophysical techniques allow a better understanding of the subsurface geology to be gained and can also highlight and delineate areas of made ground, buried objects and changes in resistivity. The latter is relevant because through highlighting ‘disturbances’ in the ground it might indicate areas where waste materials might have been previously buried. The techniques commonly used include ground penetrating radar, microgravity, electrokinetics, electromagnetics and different forms of resistivity.

Intrusive techniques such as trial pits/trenches allow the near surface geology (∼4m) to be mapped and any potential localised contamination and water seeps to be observed. Deeper intrusive techniques revolve around the different approaches to drill boreholes, take samples and construct longer-term groundwater monitoring wells. Commonly used techniques for progressing boreholes include augers, window samplers, percussion methods, rotary drilling, cone penetrometer tests and sonic drilling.

Construction of a site CSM is an iterative process and once the site characterisation is complete and the data has been analysed the CSM is revisited and updated.

Potential remediation options are then listed and appraised. Regulators and other stakeholders are undoubtedly going to be interested in this stage of the remediation process, so all work should be undertaken in a transparent manner. A formalised options evaluation process should be undertaken [commonly through a form of multi-attribute decision analysis, best practical environmental option or best available technique (BAT)] [13]. Ideally, all potential options should initially be listed and then evaluated against a set of attributes thus allowing them to be compared against each other. The least likely options can then be eliminated so that those more relevant to the problem in hand can be appraised further, especially in terms of a risk assessment and cost–benefit analysis.

Risk assessments are undertaken in order to quantify first the baseline conditions at the site and then provide a comparison if any of the potential remedial options were to be implemented [15]. These risk assessments evaluate both the current and future risk to human health and the environment and are a crucial part of the overall remediation process. The risk assessment considers regulatory requirements, foreseeable land use scenarios (e.g. recreation, industrial and residential) and the potential contamination of surface and ground water. In many cases release criteria [derived concentration guideline levels (DCGLs)] can be obtained from regulatory agency guidance that is based on default modelling input parameters, while other users may elect to take into account site-specific parameters to determine site-specific DCGLs [13]. Since a heavy emphasis is placed on this component of the remediation process and the fact that risk is a complex subject to communicate it is important to give due consideration to any stakeholder engagement requirements. Assessment tools such as RESRAD [17], RECLAIM [18] and Radioactively Contaminated Land Exposure Assessment (RCLEA) [19] are often utilised to undertake such assessments.

The next stage in the process is the selection and design of the preferred remediation option(s). If working to a specific site end state or if a tranche of land is being released from the site licence, then it will be necessary to confirm the required clean-up criteria with the regulators. Ideally a sustainable and optimised approach can be found which considers the future use of the site/land (restricted or unrestricted use) and provides a balance between dose reduction and cost (especially if any further care and maintenance is required during a post remediation institutional control period). As highlighted previously, in some instances remediation may actually not provide the most sustainable option when potential doses might be extremely low. Importantly, there are other considerations in addition to dose reduction and direct costs. These considerations might include having available waste management solutions, provable technologies, stakeholder aspirations and earmarking a custodian to control records and undertake monitoring and management during any period of institutional (should it be required).

The implementation stage then revolves around the construction and application of the chosen approach. Potential remediation approaches are discussed in section ‘Remediation approaches’ below. A crucial component of carrying out the remediation work is to undertake monitoring in order to verify its success. There should additionally be continual regulatory and stakeholder engagement, disposal of wastes and the maintenance of records.

Once remediation work is complete any remaining plant will be decommissioned and removed from the site and if required a strategy for the institutional control period should be agreed with the regulators.

Remediation approaches

The actual approach chosen to remediate a site has to take cognizance of the extent of the contamination, the site location and the desired end state or clean-up criteria. Removal of all contamination may not necessarily be the most optimum or practical solution. The objective of remediation is to reduce doses to exposed individuals or groups of individuals, to avert doses to such groups or individuals in the future and to reduce or prevent environmental impact on the environment [20]. So, going back to the definition of remediation in the ‘Introduction’ section, the aim is to break the pollutant linkage. Some remediation approaches are passive, others are more active or may involve actual intervention. Remediation can also be carried out in situ or ex situ.

Remedial approaches generally fall into three main categories [15]:

  • Removal of contamination to a more suitable location (a disposal or storage site, for example).
  • Containment of the contamination on site.
  • Dilution of the source of contamination.

Removal of contamination

Contamination can be physically removed from the site through simple approaches such as conventional earth moving, scraping or turf removal and then moved offsite for disposal. This approach was extensively adopted in Fukushima. Fig 2 shows where paddy fields in Fukushima Prefecture have been remediated. At the Harwell site in Oxfordshire (UK), the chemical pits and beryllium pits were successfully remediated through a thorough characterisation and removal of waste materials. Contaminated soils underneath and adjacent to Building 330 which housed the Chicago Pile 5 reactor on the Argonne National Laboratory site near Chicago (US) were excavated and disposed of offsite. Fig 3 shows some of the characterisation and soil removal work taking place around B330.

Fig 2: Remediation of paddy fields in Fukushima Prefecture

Fig 3: Site characterisation and soil removal around B330 at ANL’s Chicago site

Once contamination has been physically removed from a site, it needs to be categorised and treated either as being exempt or as waste (generally very low level waste (VLLW) or low level waste (LLW)). In my opinion, though the removal of large volumes of contaminated soil away from a specific location is in many instances merely transferring the problem from one location to another, and generally at an expense not commensurate with the overall benefit.

Contamination can also either be concentrated, treated and then subsequently removed through a series of remediation techniques such as physical separation, soil washing, pump and treat, electrokinetics, phytoremediation and chemical extraction. A permeable reactive barrier, for example, was installed at the West Valley Reprocessing site in the US in order to remove Sr 90. I believe that such an approach can be very successful for targeting groundwater plumes but the level of success depends heavily on the confidence in the site characterisation data and the choice of barrier design and reactive materials. Fig 4 shows the West Valley Reprocessing site depicting the area of the Sr 90 plume.

Fig 4: West Valley Demonstration Project (photograph courtesy of Erie Research Projects)

The more passive technology of phytoremediation is being utilised in trials to remediate H 3 at the Argonne National Laboratory site. A pump and treat system was successfully installed at Atomic Weapons Establishment, Aldermaston in order to remediate trichloroethylene.

All these approaches rely on the site and its contamination being well characterised.

Contaminant containment

Contamination can be contained in situ through capping, cut-off walls, subsurface barriers, vaults or through a range of immobilisation techniques (vitrification, chemical fixation or solidification with cement). At Fukushima Daiichi nuclear power plant (NPP) cryogenic barriers are being implemented in order to reduce the levels of contaminated groundwater migrating from the NPP site to the ocean.

At the legacy waste trenches at Sellafield they undertook a BAT and the favoured option was to place an improved cap over the trenches thus minimising/preventing meteoric water ingress. In my opinion, this is a sensible approach at this time in the site's lifecycle. It provides an optimised interim position which can be reassessed in the future as the site moves closer to achieving its designated end state and allows the licencee to focus its available funds on the higher priority safety related issues across the site.

Contaminant dilution

Monitored natural attenuation (MNA) is the process whereby an area of contamination is left in situ and monitored over time so that naturally occurring processes might retard and reduce the concentrations of the contaminants [15]. Physical, chemical and biological processes can restrict movement, disperse and degrade contaminants. Some radionuclides have relatively short half-lives and therefore contamination levels are left to decrease over time naturally through radioactive decay. This approach can be useful at sites where the level of contamination is relatively low. MNA is seen by some as the ‘do nothing option’ but it is far from this and should be viewed as potentially providing an optimised and sustainable approach for some specific situations. I strongly believe that this kind of approach should be adopted more readily on nuclear licenced sites.

More detailed information about individual approaches and techniques can be found in the various references listed within this paper, specifically [13–15,20].

Other sites

Apart from nuclear licenced sites there maybe a range of sites which at some time might require environmental remediation. Such sites include:

  • Those with naturally occurring radioactive material (NORM). NORM-related sites might include those where there is mining of rare earth minerals, monazite production, oil and gas industries, desalination plants, phosphate mining.
  • Sites of former nuclear weapons testing (i.e. Maralinga in Australia, Nevada in the US, Semipalatinsk in Kazakhstan).
  • Legacy uranium mining and milling sites (i.e. Wismut in Germany, Mailuu Suu in Kyrgyzstan, Moab in the US and Lisava in Romania).
  • Sites of accidents and emergency situations (i.e. Chernobyl in Ukraine and Fukushima in Japan).

Fig 5 shows the result of remediation and landscaping work of rock piles and tailings at the Lisava mine in Romania, whereas Fig 6 highlights the remediation of uranium mining waste rock piles in Bad Schlema, Germany.

Fig 5: Remediated Lisava mine waste rock piles and tailings in the Banat region of Romania

Fig 6: Remediation of rock piles at the Bad Schlema site

These kinds of sites all bring different kinds of challenges, especially where institutional control is not in place. A brief description of the accident at the Fukushima Daiichi NPP is provided below in order to highlight how the specific drivers for this situation dictated the remediation approaches taken.

Fukushima

In the case of Fukushima Daiichi NPP, as a consequence of the Great East Japan Earthquake and the resulting tsunami, a power loss resulted in the meltdown of three reactor cores. A series of catastrophic events followed and there was a discharge of radioactive material into the atmosphere [primarily Cs (Cs 137) and I (I 131)]. An exclusion zone c20 km from the plant was set up and residents were evacuated as a precaution. The affected areas were then split into two separately designated areas [21]. The Special Decontamination Area consisted of ‘restricted areas’ located within a 20 km radius from the Fukushima Daiichi NPP, as well as ‘deliberate evacuation areas’ where the annual effective dose for individuals was anticipated to exceed 20 mSv. The Special Decontamination Area was further divided into three categories based on estimated annual dose levels:

  • Area 1: Estimated annual dose level is below 20 mSv (and above 1 mSv).
  • Area 2: Estimated annual dose level is between 20 and 50 mSv.
  • Area 3: Estimated annual dose level is over 50 mSv and the annual effective dose is expected to be more than 20 mSv after 5 years.

The Intensive Contamination Survey Area on the other hand included areas called Decontamination Implementation Areas, where an additional annual cumulative dose between 1 and 20 mSv was estimated for individuals.

So, the driver for the chosen remediation activities was clearly to reduce dose rates and facilitate the return of individuals who had been evacuated. The most commonly used methods of decontamination were those that reduced external exposures and could be applied on a large scale. So, remediation effort largely focused on the reduction of external radiation dose through the removal of radioactive contamination from the living environment [21,22]. This was achieved by removing soil and fallen leaves, as well as washing or wiping the contaminated surface of different objects. Additional remediation effort included covering contaminated soil with non-contaminated soil and ploughing gardens and agricultural fields, thus modifying the exposure pathway.

The kind of remediation activities implemented include:

  • Eaves and roof gutters: Wiping and high-pressure washing after removing deposited material.
  • Storm water catch basins: High-pressure washing after removing deposited material.
  • Street gutters: High-pressure washing after removing deposited material.
  • Roofs: Wiping, washing and high-pressure washing.
  • Outer walls: Wiping, washing and high-pressure washing.
  • Gardens and other grounds: Mowing grass, collection of clippings, pruning, surface soil removal, replacing turf and ploughing.
  • Parking lots and other paved surfaces: Washing, high-pressure washing and surface removal (shot blasting, grit blasting etc.).
  • School athletic grounds etc. (dirt): Surface dirt removal.
  • Roads (asphalt paved surfaces): Washing, high-pressure washing and shaving off.
  • Forested areas: Plant material and the upper organic litter layer of forest soil was removed from the first 20 m of forest adjacent to residential areas, farmland and public spaces.

While largely successful, these remediation activities have cost a lot of money and created significant volumes of radioactive waste (mostly in the VLLW category). This has presented a separate challenge as the waste material has been located at hundreds of temporary waste storage sites (which initially only had a projected 3 year lifetime) with very few interim waste storage facilities (projected 30 year lifetime) being successfully located and approved by stakeholders. Fig 7 shows a photograph of a Temporary Waste Storage site within Fukushima Prefecture where the majority of the bags contain contaminated soil and leaf litter. Remediation activities ideally need to provide a balance between dose reduction and the associated costs and potential wastes. The example at Fukushima emphasises the importance of considering lifecycle management principles, as a desire to undertake thorough remediation has resulted in the creation of significant waste volumes which eventually local residents will wish to see removed from the temporary waste storage sites.

Fig 7: Temporary Waste Storage Site within Fukushima Prefecture

Conclusions

Nuclear sites can be quite variable in terms of their history and type of operations. These variances are likely to reflect the type of potential contamination which may reside in the ground or in groundwater. In the UK, such contamination needs to be appropriately managed and in some cases remediated. Any remediation activity needs to take cognizance of the actual drivers, timescales and the desired clean-up objectives. Remediation is an expensive process, so it is important to find sustainable and optimised solutions which are commensurate with the problem in hand. A balance often has to be found between net benefit and the overall through life costs.

Choosing the right remediation option relies heavily on having built up a sound understanding of the site in question through site characterisation and the development of a CSM. Gaining the support and approval of regulators and other key stakeholders is paramount, so the decision-making process should be undertaken in a transparent manner.

In the UK, some nuclear sites are already reducing the licenced site boundary and have set out how they intend to achieve their near to medium term designated site end states. Other sites are looking to achieve their proposed end state in over 100 years from today and institutional control is likely to remain in place for many years after the cessation of operations.

With remediation there is no ‘one size fits all’ and it should be considered on a case-by-case basis.

Acknowledgments

The author would like to thank the following individuals for providing photographs of remediation work carried out by their organisations:

  • Larry Moos from Argonne National Laboratory for providing the photograph of soil remediation work around Building 330 on the Atomic Weapons Establishment site near Chicago, US.
  • Peter Schmidt from Wismut GmbH for providing the photograph of uranium mining waste rock pile remediation near Bad Schlema, Germany.

References

  1. International Atomic Energy Agency: ‘IAEA safety glossary. Terminology used in nuclear safety and radiation protection 2007 edition’ (IAEA, Vienna, 2007).
  2. http://www.sellafieldsites.com/.
  3. Williams L.: Nuclear Decommissioning Authority : ‘Strategy – effective from April 2016’. 2016.
  4. Office for Nuclear Regulation: ‘Licence condition handbook’ (2016).
  5. http://www.onr.org.uk/saps/index.htm.
  6. http://www.onr.org.uk/operational/tech_asst_guides/index.htm.
  7. Hill M.: ‘SAFEGROUNDS – the UK regulatory framework for contaminated land on nuclear licenses sites and defence sites’. CIRIA W36, London, 2010.
  8. Environment Agency: ‘Initial radiological assessment methodology – part 2 methods and input data’. Science Report, SC030162/SR2, 2006.
  9. SEPA: ‘Radiological monitoring technical guidance note 2. Environmental radiological monitoring, version 1.0’ (2010) .
  10. International Atomic Energy Agency: ‘Policies and strategies for environmental remediation’ IAEA Nuclear Energy Series No. NW-G-3.1 (IAEA, Vienna, 2015).
  11. International Atomic Energy Agency: ‘Lessons learned from environmental remediation programmes’ IAEA Nuclear Energy Series No. NW-T-3.6 (IAEA, Vienna, 2014).
  12. International Atomic Energy Agency: ‘Remediation of sites with mixed contamination of radioactive and other hazardous substances’. Technical Report, Series No. 442, IAEA, Vienna, 2006.
  13. Nuclear Energy Agency: ‘Nuclear site remediation and restoration during decommissioning of nuclear installations’. A Report by the NEA Co-operative Programme on Decommissioning, NEA No. 7192, 2014.
  14. Towler P. Rankine A. Kruse P. et al.: SAFEGROUNDS – ‘good practice guidance for the management of contaminated land on nuclear licenced and defence sites’. Version 2. CIRIA, W29, London, 2009.
  15. Laraia M. McIntyre P. La Guardia T. S. et al.: ‘Nuclear decommissioning – planning, execution and international experience’ (Woodhead Publishing, Cambridge, 2012), Chapter 16.
  16. Towler P. Rankine A. Kruse P. et al.: ‘SAFEGROUNDS – good practice guidance for site characterisation’. Version 2. CIRIA. W30, London, 2009.
  17. https://www.web.evs.anl.gov/resrad/.
  18. http://www.nnl.co.uk/commercial-services/environmental-services/reclaim/.
  19. https://www.gov.uk/government/publications/rclea-software-application.
  20. Van Velzen L. et al.: ‘Environmental remediation and restoration of contaminated nuclear and NORM sites’ (Woodhead Publishing, Cambridge, 2015), Chapter 1.
  21. International Atomic Energy Agency: ‘The follow-up IAEA international mission on remediation of large contaminated areas off-site the Fukushima Daiichi nuclear power plant ’ (IAEA, Vienna, 2013).
  22. International Atomic Energy Agency: ‘The Fukushima Daiichi accident. Technical volume 5/5 – post accident recovery’ (IAEA, Vienna, 2015).

 

Go to the profile of Peter Booth

Peter Booth

Nuclear and environmental consultant, Hylton Environmental

I am self employed consultant with 26 years of nuclear related experience acquired both in the UK and internationally. My primary areas of support relate to training, project management, environmental remediation, radioactive waste management, knowledge management and stakeholder engagement. My international work has been achieved in over twenty different countries.

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