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Improving the Regulation and Management of Low-Activity Radioactive Wastes Appendix B International Approaches for Management of Low-Activity Radioactive Waste This appendix overviews international practices for regulating and managing low-activity radioactive wastes (LAW) as well as ongoing efforts in individual countries or internationally toward harmonizing these practices. This overview is not intended as a definitive survey of international practices, but rather to provide international perspectives for improving U.S. practices, as described in Chapter 2 and Appendix A of this report. The multiplicity of international approaches makes it difficult to develop a systematic picture—but provides fertile ground for greater exchange of ideas and information that can lead to mutual strengthening of LAW management in all countries. The following examples have been chosen mostly from among countries that have a well-developed nuclear industry and therefore have experience with a variety of practices for managing waste. From these examples, an attempt is made to identify issues and trends relevant to strategies for LAW management and opportunities for further improvement and harmonization. This synthesis provided insights that helped the committee develop its findings and recommendations. WASTE CLASSIFICATION There is no internationally endorsed classification of waste at present; each country identifies its own categories of waste. This results in a diverse nomenclature (at least 20 different denominations for various waste categories exist throughout the world) that does not facilitate direct com-
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Improving the Regulation and Management of Low-Activity Radioactive Wastes parison. However, common features can be identified, especially for nuclear waste that falls under one of three main classification systems. Under the first, waste is classified by its mode of disposition (“management” routes). Adopted by France, Spain, and, more recently, Japan, this classification defines four categories of waste: slightly radioactive waste (or very low level waste, VLLW), low and intermediate short-lived waste (LILW—SL), low and intermediate long-lived waste (LILW—LL), and high-level waste (HLW). These categories generally differ from one another by orders of magnitude of activity content. The distinction between short- and long-lived waste is based on the half-life (30 years) of cesium-137. However, these categories, though clearly different, are not defined a priori by generic cutoff values. These values are determined on the basis of waste acceptance criteria for a given management option when sufficient assessment results are available to allow deriving limits that are considered safe. An example of this waste classification mode is given in Table B.1. A second classification system defines categories of waste on the basis of their main characteristics. Adopted by the United Kingdom and formerly by Germany, it more or less identifies the same broad categories of waste mentioned under the first classification, but with possible differences in the cutoff values that separate the categories. These values are defined a priori, in a generic manner; for example, the United Kingdom defines LLW as waste containing no more than 4 GBq/t in alpha emitters and 12 GBq/t in beta and gamma emitters, intermediate-level waste (ILW) as waste of low thermal output and activity of the order of 1,000 TBq/m3, TABLE B.1 Waste Classification in France Activity Slightly radioactive Dedicated surface disposal (Centre de stockage TFA de Morvilliers) Low and Intermediate level Surface disposal (Centre de Stockage de l’Aube) for wastes with half-life less than 30 years Low and Intermediate level Specific disposal options for wastes with half-life greater than 30 years, e.g., TENORM, graphite waste, are under study High level Management options under study (Law of December 30, 1991)
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Improving the Regulation and Management of Low-Activity Radioactive Wastes and HLW as waste of high thermal output (20 kW/m3) and activity concentrations ranging from 5,000 to 50,000 TBq/m3. The third system, which considers the origin of the waste, has been adopted in some countries, among them the United States and Finland. The situation in United States is described in Appendix A. As a complementary example, the Finnish situation is interesting because, as in United States, the classification of waste according to origin leads to separate management options for waste having the same characteristics, but broad categories similar to those for the other classification approaches also are identified. In Finland, a distinction is made first between wastes from the nuclear industry, which are controlled by nuclear energy legislation, and wastes of other origins, which are controlled by radiation protection laws. These categories are both subdivided into low- and intermediate-level (LILW) waste and HLW. Disposal of LILW is at different sites according to which power supplier, Teollisuuden Voima Oy (TVO) or Imatran Voima Oy (IVO), has produced the waste. Disposal of HLW is to be in a single site in a deep geological formation. From this short overview, one may sense the apparent complexity of worldwide classification systems for radioactive waste, but in most cases four main categories (VLLW, LILW—SL, LILW—LL, and HLW) can be identified. These approaches formed the basis for a waste classification system proposed by the International Atomic Energy Agency (IAEA, 1994), which is shown in Chapter 2 Table 2.1. The system was endorsed for publication by IAEA member states as a means to facilitate communication and exchange among countries, but it has not been incorporated directly into any country’s national regulations. The system does not explicitly address naturally occurring radioactive materials (NORM) wastes (see the later section on Management of Nonnuclear Waste) and some revisions are being considered. MANAGEMENT OF SLIGHTLY RADIOACTIVE WASTE (VLLW) Management of VLLW generally is split into two types of practices: clearance and disposal. Clearance of waste consists of allowing waste to be freed from control, meaning that its level of activity is not of concern for radiation protection and any use can be made of the cleared waste. This practice has been adopted in many countries, for example, the United Kingdom, Sweden for metallic waste, Japan, and Spain. Germany uses two types of clearance mechanisms: free release of waste but also specific clearance, allowing higher levels of activity to be released, but restricting further disposition options to recycling or storage. Some countries do not currently allow clearance of waste, but manage
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Improving the Regulation and Management of Low-Activity Radioactive Wastes VLLW solely by disposal in facilities approved for radioactive waste. This is the case in the United States, where surface disposal of VLLW in USNRC licensed facilities is required (although case-by-case exemptions are possible, see Chapter 2). France does not oppose the clearance of waste for the purpose of recycling valuable material. However, this option is generally not used because of high public concern and comparatively poor economic benefit. The approach that is actually used in France begins with identifying zones in nuclear installations where products are suspected to be radioactive. All products inside these zones are thus considered radioactive; all products outside these zones are considered conventional waste and need not be subjected to further regulatory control for reasons of radiological protection. The radioactive waste content and level of activity are reconstructed through process analysis and history of operations. The validity of the estimated radionuclide content is verified by measurement. The slightly radioactive waste is then sent to a dedicated facility (the VLLW disposal facility at Morvilliers) for disposal if it meets the facility’s acceptance criteria. The level of activity accepted at this site is on the order of 10 Bq/g. The European Commission allows member states to choose whether to clear or to dispose of VLLW, but, in the case of clearance, it provides guidance on activity levels (EC, 2000a). IAEA (2004b) also has recently proposed guidelines on clearance levels, which apply to any material that contains radioactive elements. When levels are below those recommended in the guide, control of the material would not be justified for reason of radiation protection and thus can be used without restriction. These approaches for VLLW management have been implemented and are fairly consistent among countries but essentially are used only for waste from the nuclear industry. Waste from NORM can still give rise to special considerations for its management, even at very low levels of activity, as described in the section on “Management of Nonnuclear Waste.” LILW MANAGEMENT Disposal of LILW is widely considered to be the preferred management route and is practiced in most countries. However, the design of LILW disposal facilities may be significantly different. Further, for essentially the same types of waste, countries have chosen to implement different disposal options: surface or shallow land disposal or geological disposal (see Table B.2). European Nordic countries and Germany have adopted deep geological disposal of LILW. There are, of course, differences in depth, design, and type of host rock among options implemented or envisaged, but all
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Improving the Regulation and Management of Low-Activity Radioactive Wastes TABLE B.2 Examples of Disposal Options for LILW Country Short-lived LLW and LILW Long-lived LLW and LILW Option Characteristics Option Characteristics France Surface disposal: Centre de Stockage de l’Aube Multibarrier concepts: (i) waste package; (ii) disposal vaults, impervious cover; (iii) site features (dry disposal above water table) Under study Subsurface disposal of TENORM and graphite waste Spain Surface disposal: El Cabrila Under study Japan Surface disposal: Rossasho-Mura Multibarrier concepts: (i) waste package, (ii) disposal vaults, (iii) low-permeability media, (iv) multilayer cover Under study Germany Geologic disposal: Morsleben (salt), Konrad (not licensed yet) Accepting all waste except thermogenic ones. Disposal in cavities of large volume (salt site) Finland Geological disposal: Loviisa and Olkiluoto (granite) Multibarrier concepts: (i) Olkiluoto, two silos at 70- and 100-m depths, for LLW and ILW respectively; (ii) Loviisa, two tunnels at 110-m depth for LLW and ILW, and one cavity for decommissioning waste Sweden Subsurface disposal: SFR (granite) Multibarrier subsurface system: (i) Waste package, steel or concrete containers; (ii) disposal cavities or silo; (iii) host rock at 50-m depth below sea level aThe El Cabril facility has recently begun operating specially designed cells for very low-level waste. Cell designs are based on hazardous waste regulations. Total radioactivity in the VLLW cells is restricted to be below 1 percent of the total site inventory (Zuloaga, 2003).
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Improving the Regulation and Management of Low-Activity Radioactive Wastes provide a high level of protection with regard to intrusion risks. Thus, these countries do not subdivide their LILW according to half-life. Their geological facilities generally accept all except heat-producing nuclear waste. This is not the case for countries that have implemented surface disposal of LILW, such as the United Kingdom, Spain, France, or Japan. Sweden also uses near-surface burial at reactor sites for low-level nuclear reactor waste. The relative lack of robustness of near-surface facilities with regard to intrusion or natural events requires limiting the amount of activity that may be accepted for disposal, especially of the long-lived radionuclides. Therefore, surface disposal of LILW is mainly dedicated to short-lived waste (<30 years) to allow for substantial reduction of the risk potential of the waste within the period of time during which institutional control of the facility is maintained (some 100 years). The amount of activity accepted for surface disposal may vary from one country to another. For example, U.S. Nuclear Regulatory Commission (USNRC) Class C waste is about 10 times higher in cesium-137 and strontium-90 content than waste accepted in Centre de l’Aube (France). Such a difference does not necessarily reflect inconsistencies in disposal practices. Acceptance criteria are mostly site and design dependent and a wide variety of conditions are encountered (e.g., sites may be located in wet or desert areas, waste may or may not be located at higher levels above the water table, disposal may be in trenches or engineered vaults). Another source of difference is in the approach used to assess disposal safety and to appraise impact acceptability (the “integrated” risk approach as opposed to the separate appraisal of elements supporting acceptability). This is further addressed the sections on “Management of Nonnuclear Waste” and “Global Approaches at the International Level.” Whatever the approach, surface disposal requires that the threshold values above which waste will not be accepted in such a facility be clearly defined and that waste be managed within disposal options that are robust against events that may jeopardize waste confinement. There is quite good consistency among European countries in limiting maximum actinide concentrations to levels of a fraction of 1 Ci/t of waste. This is also consistent with the definition of U.S. transuranic waste (with actinide content above 0.1 Ci/t). Because surface disposal of LILW is an option that has the benefits of a rather large knowledge base and wide industrial experience, reasonable agreement on the safety issues to be addressed has been obtained (EC, 1996b; IAEA, 1999).
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Improving the Regulation and Management of Low-Activity Radioactive Wastes MANAGEMENT OF NONNUCLEAR INDUSTRY WASTE: NORM, URANIUM MINE AND MILL TAILINGS, AND DISUSED SEALED SOURCES Internationally, wastes produced by the nuclear power and defense industries generally have received careful attention in regard to keeping their risks under control in the short and long term, which has led to fairly consistent management practices among countries, but the picture is much more difficult to draw for nonnuclear radioactive wastes. The need to control NORM waste for purposes of radiological protection is a new concern. This type of waste is not associated with the nuclear industry, and, there has been little public awareness of its radiation risks. More attention, of course, has been paid to mine and mill tailings with regard to radiological protection, but historically, they generally have been regulated and controlled by different bodies than for the nuclear industry. This has led to separate considerations on how to manage risk arising from tailings versus nuclear waste. As for spent sealed sources, their widespread distribution for various uses involves a multiplicity of stakeholders (producer, owner, user, regulator, and so on) for their management, and there is a strong dependence on the specific practices in each country. Also, the focus has been more on keeping track of the sources than on their disposal, which generally have not been considered together with management practices for nuclear waste. However, there is definitely a growing international concern to include management of nonnuclear waste in a more consistent framework (see “Global Approaches at the International Level”). The following examples illustrate some of the current practices and areas of improvements in this field. NORM Waste There is obviously a distinction to be made regarding the volumes of waste to be managed: quantities that can be shipped to dedicated centers (100 to 10,000 tons) and quantities that require on-site management (extraction residues and tailings amounting to millions of tons). In France, disposal of waste in the first category is, in most cases, in centers for industrial wastes (surface disposal in vaults). These centers are designed to accept only nonradioactive waste (i.e., waste that is of no concern for radiological protection purposes). The operator must demonstrate that NORM waste can be handled and stored safely, without requiring any specific provisions regarding radiological protection. This is accomplished by assessment of the potential occupational exposure to workers
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Improving the Regulation and Management of Low-Activity Radioactive Wastes at the disposal centers. Acceptability of waste is appraised with reference to an effective dose limit of 1 mSv. There are presently no generic criteria for the amount or concentrations of radioactive isotopes that would guarantee acceptability for disposal as industrial waste. In practice, waste is controlled at the center’s entrance by external measurement of the truckload. If the alarm threshold is reached in the portal monitors, the waste must undergo detailed verifications to locate potential orphan radioactive sources. If the verifications are negative and the alarm is due to uniform distribution of radioactivity attributable to NORM, then the operator must demonstrate that the waste will not give rise to unacceptable exposures. In most cases, waste disposed in this way is of very low natural activity and in moderate quantity, so that it is unlikely to generate impacts of concern to workers or the public. Nevertheless, ways to improve NORM waste management in France are being developed. It is planned to better identify waste producers who are likely to generate waste of concern for radiological protection and to provide guidance for the assessment of waste impact. In parallel, this may lead to defining activity levels and volumes of waste above which facilities receiving the waste should be licensed to dispose of radioactive substances. This should help to better screen waste that may require additional safety measures for its disposal. Categories of waste have already been identified (mostly coming from the rare-earth extraction industry) that are much too active to be accepted in centers for industrial waste disposal. A specific disposal option together with some nuclear waste (graphite) is being studied. Germany’s approach to NORM waste management has evolved considerably. Formerly based only on consideration of an exemption level of 500 Bq/g for the total content of naturally occurring radionuclides in material outside the nuclear industry, radiation protection issues have been more thoroughly addressed through the elaboration of a list of residues for which radiological protection may be relevant and through assessment of public exposures in the short and long term for residues of concern. From studies carried out on the subject, criteria have been derived for different options of NORM waste management. These are presented in Table B.3. In Germany, deposits of NORM waste in very large volumes are frequently encountered for which realistic impact assessments have been performed (Goldammer, 2004). The assessments consider the long-term evolution of impacts and the possibility of intrusion onsite with the use of waste in building material. The author points out that in some cases, exposures significantly above 1 mSv cannot be ruled out for large-volume deposits, even at a concentration as low as 1 Bq/g (for each radionuclide
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Improving the Regulation and Management of Low-Activity Radioactive Wastes TABLE B.3 Criteria for TENORM Disposal in Germany Use or Disposal Option for TENORM Criterion in Bq/g Use or disposal of waste rock covering an area over 1 ha in the catchment area of a usable aquifer U-238 ≤ 0.2 and Th-232 ≤ 0.2 Disposal of more than 5.000 tons annually in the catchment area of a usable aquifer U-238+Th-232 ≤ 0.5 Residues added to building materials with ratio above 20% (house construction) or above 50% (other construction types) U-238+Th-232 ≤ 0.5 Other use or disposal not covered by the above cases U-238+Th-232 ≤ 1 Underground disposal U-238+Th-232 ≤ 5 of uranium and thorium decay chains), and questions such concentration being recommended internationally as a general exclusion level. Indeed, Germany recommends threshold values of 0.2 Bq/g for large deposits of waste rock. That value is also consistent with the general exemption levels adopted by South Africa, which faces problems of management of huge quantities of residues from mineral extraction, and has set a limit of 0.2 Bq/g for radium-bearing deposits, below which regulation for radiological protection purposes can be disregarded. Uranium Mine and Mill Tailings Throughout the world, millions of tons of tailings from uranium ore extraction are piled in surface areas close to where the ore was mined and processed. Most tailings show natural activity levels high enough to require that some measures be taken to ensure radiological protection of the public and the environment. Mainly, two types of disposal options are encountered: Residues and waste rock are spread in layers in thalwegs or in open pits and often are contained by dams so as to protect nearby rivers from dispersion of the residues into surface waters. These may be covered by layers of comparatively low-activity material (usually waste rock of low grade) for protection against radiation, radon emissions, or airborne dust. The other broad type of disposal option is to cover the waste with a layer of water (a few meters deep), generally by flooding areas where tailings have been piled. Each country has its own regulations with regard to radiological protection of the public from hazards arising from such disposal sites. In many cases, requirements are made for controlling exposures from the
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Improving the Regulation and Management of Low-Activity Radioactive Wastes sites and monitoring them to make sure that added exposure and activity discharge into water remains acceptable. In Europe, EC Directive 96/29 sets a limit of 1 mSv (above natural background) for public exposure, which applies to uranium tailings disposal (EC, 1996a). Demonstrating compliance with this requirement may be difficult because the discrimination between exposures from natural background radiation and those occasioned by uranium tailings disposal is not easy. However, in most cases, the disposition method (cover by rock or water) together with water control and restriction of access to the site are efficient in keeping site-related exposures comparable to background. The main issue raised today concerns the long-term evolution of these exposures from possible on-site intrusion and loss of performance of protective covers. The issue has not yet been resolved, but there is clearly growing international concern about addressing it. IAEA (2002) has published a safety guide acknowledging these problems and clearly recommending that separate considerations be made between “historical” deposits, which may be need intervention so as to keep exposures within acceptable limits, and ongoing practices involving mining and associated waste management, which must balance occupational and public protection goals in the short and long term. The IAEA recommends, where possible, better isolation of the waste from the accessible environment, in particular in mine pits. Whatever the case considered, the waste volume, as for some NORM waste, limits the disposition options that can be envisaged. Further, these large-volume disposition options cannot easily be compared with the options currently used for nuclear industry wastes. Nevertheless, uranium mine tailings should be part of the overall plan for achieving consistent levels of risk in managing all LAW. IAEA has recently launched work to include uranium tailings as well as nonnuclear waste disposal in a common framework, as discussed in the section on “Global Approaches at the International Level.” Disused Sealed Sources As mentioned before, approaches to managing disused sealed sources depend on the regulatory structure in each country and a multiplicity of interests. The European Commission (2000b) report lists at least six key organizations involved in the life cycle of a source: regulator, manufacturer, original equipment manufacturer, distributor, user, and waste management organization(s). The report offers an overview of the systems of management of sealed sources in member states of the European Union (EU). Although the systems are different, there is always control by one or
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Improving the Regulation and Management of Low-Activity Radioactive Wastes more of the parties involved, usually the manufacturer or the user. In most cases, the user needs to be licensed to posess sealed sources, but the level of control from regulators, once a license has been approved, is disparate from one member state to another. The number of sources lost does not seem to reflect the regulatory structure in EU member states, but the authors of the report point out areas of improvement and good practices in management systems. One of the main problems raised for the management of disused sealed sources is the risk of bankruptcy of the user (licensee), thus breaking the management chain. Preventive measures can include a fund for managing orphan sources, as implemented in France, or an annual license fee discouraging users from holding sources for a long period without considering their disposition route, as applied in Finland. The report also points out that the risk of loss of disused sources left for storage at users’ premises is increasing and that there is a need to focus on the management of sources of higher hazard potential. Areas identified for improvement include harmonizing practices among countries and avoiding dilution of responsibilities, hence, more centralized practices and control are needed. In particular, the report outlines the benefits of creating national databases that allow separate recording of sources in- and out-of-service; implementing centralized interim storage facilities; and issuing a common code of practices among countries since transboundary movement of sources is frequent. It is also believed that system efficiency would be enhanced when under the control of one organization or a lead regulator. Very few countries have developed definitive disposal options for sealed sources. Further, there are many instances in which lost sources have caused serious injuries, or where safety conditions for storage or disposal of sources are poor. To help remedy this, international practices encourage the return of sources to their manufacturers from users in countries where elimination routes are not likely to become available, e.g., developing countries. IAEA advises countries in the safe management of sources and has implemented case-by-case storage solutions where sources cannot be removed. There is need to establish guidance and common practices for the international shipment of these sources as well as their storage and disposal. GLOBAL APPROACHES AT THE INTERNATIONAL LEVEL Important efforts have been made by the international community to achieve a unified system for protecting workers and the public from the hazards of ionizing radiation. The Basic Safety Standards (BSS) (IAEA, 1996) is a worldwide reference. The BSS sets out the concepts of exclusion
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Improving the Regulation and Management of Low-Activity Radioactive Wastes of exposures that are not amenable to control, exemption of practices that are not relevant to radiation protection dispositions, and clearance of radioactive material for which regulatory control can be relaxed. These concepts are fundamental for regulating and managing LAW. The BSS makes a clear distinction between requirements relevant to normal practices and those relevant to intervention situations (where actions must be taken to reduce exposures resulting from accidents or from some past practices). For this latter case, levels are proposed in the BSS for which the implementation of intervention actions is recommended. As for practices, the BSS recommends that they be justified and that effective doses incurred from normal activities involving radioactive substances do not exceed 20 mSv/year (averaged over five years and not exceeding 50 mSv in a single year) for the worker, and 1 mSv for the relevant critical groups of the public. BSS also requires optimization of practices with regard to radiation protection, in the sense that individual doses must be kept as low as reasonably achievable (ALARA), economic and social factors being taken into account. European Commission Directive 96/29, which supersedes national regulation in EU member states (25 countries concerned today), enforces application of the same requirements for justification of practices, optimization, and dose limitations and defines a set of exemption levels. It also requires member states to define appropriate dispositions and levels in intervention situations. The directive covers all activities involving radioactive material. It also addresses the possibility of enhanced exposure to natural radiation resulting from nonnuclear activities and requests member states to take the appropriate disposal actions to comply with the requirements set for normal practices or intervention situations. There is thus a unified system for radiation protection that covers waste-management-related activities including the disposal of waste originating from nuclear as well as nonnuclear industries. However, there are areas that require further guidance, in particular for achieving practical criteria for the management of slightly radioactive waste, for appraising long-term radiation protection issues, and for assessing safety and bringing consistency in management of waste from all origins. Concerning clearance levels or activity concentrations in material that may be disregarded for purposes of radiation protection, additional guidance is given by the European Commission (2000a) Report 122 and IAEA Safety Guide RS-G-1.7 (IAEA, 2004b), as explained in the section on “Management of Slightly Radioactive Waste (VLLW).” Concerning the application of radiation protection requirements to potential long-term exposures that are specific to radioactive waste disposal, the most definitive guidance in this field is given by the International Commission on Radiological Protection (ICRP, 1998) in its Publication 81
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Improving the Regulation and Management of Low-Activity Radioactive Wastes (ICRP-81). As a broad summary, ICRP recommends applying “constrained optimization,” rather than dose limitation, for achieving protection of the public from the long-term hazards occasioned by waste disposal. These recommendations clearly acknowledge the difficulty that is specific to long-term evolution of waste disposal. Shifting from a dose limitation system to a constrained optimization system is relevant to the fact that, for disposal, only projections of future doses to the public can be made. Dose limitation implies control of real exposures from a particular practice and possible action to reduce them, in particular for optimization purposes. However, one cannot rely on this control for long-term disposal. Thus, optimization must be made a priori so that doses will be ALARA. ICRP-81 sets two conditions for optimization: The first is that disposal should be implemented through application of sound technical and managerial principles; the second is that the projected dose should be kept under, or close to, given values. For a normal situation (all barriers performing as expected, no accidental events, no intrusion, and so on), ICRP recommends applying a constraint of 0.3 mSv (consistent with the protection goal of 1 mSv, but accounting for the fact that total exposures to the public may come from disposal as well as other sources). ICRP also gives guidance for appraising the “acceptability” of exposures potentially incurred in case of intrusion into the disposal area and recommends consideration of two values of effective dose: 10 mSv and 100 mSv. ICRP considers these values to be indicators for appraising the level of safety achieved by disposal in case of future intrusion, since intruders are considered to have no knowledge of the site and thus do not deliberately intrude. In this sense, future intrusion may be considered similar to a situation occurring today, where people may be subjected to exposures from unknown disposal sites on which they have accidently intruded, and possibly calling for intervention. According to ICRP, intervention is rarely needed when exposures are below 10 mSv, whereas it is almost always required when they exceed 100 mSv. Finally, although guidance can be found in many fields of interest for the management of radioactive waste, there are still discrepancies in the application of safety measures and assessments, depending on the category of waste considered, which cause difficulties in appraising whether the disposal routes implemented or envisaged for each category are appropriate. Important guidance can be found concerning methods and requirements for safety assessments in IAEA safety standards. A joint convention on the safety of spent fuel management and the safety of radioactive waste management was adopted in 1997, obliging each contracting party to apply common safety standards and to report on the consistent implementation of waste management (IAEA, 1997). However, these are not sufficient to establish a strategy for radioactive waste management
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Improving the Regulation and Management of Low-Activity Radioactive Wastes that would clearly define all elements necessary to achieve consistency in this field. That is why IAEA has recently launched the development of a common framework for the disposal of radioactive waste, aimed at providing a basis on which radioactive waste can be classified, identifying appropriate generic waste disposal options for each category, and defining the means for achieving safety of disposal options. Similar strategies for waste management can be found at the national level. For example, France’s national plan for radioactive waste management encompasses all types of waste (except HLW, which is addressed within the framework of specific legislation), regardless of origin, and aims at achieving consistency in its approaches. The mandate for the French Safety Authority for Nuclear Facilities is to involve political representatives, associations, institutional stakeholders (other regulators, expert organization, national agencies), and waste generators in the planning process. SUMMARY There is rather good consistency in the management options adopted internationally for LLW coming from the nuclear industry. Operational solutions for VLLW are now available (disposal or clearance) and surface disposal options are generally consistent in the sense that the categories of waste liable to be accepted at surface centers are fairly comparable among countries that implement this management route. There might be substantial differences in the preferred design options, but in all cases, LLW management includes thorough safety assessments to account for long-term risks. There remain inconsistencies in the activity levels of long-lived waste that can be accepted for surface disposal. Since surface disposal is not robust in the long term against intrusion and natural risks, these levels should be rather homogeneous, which is not necessarily the case today. Differences of several orders of magnitude may exist in long-lived radionuclide concentrations in VLLW, LLW, and nonnuclear waste allowed for surface disposal in various countries. There is therefore a need for greater harmonization. If discrepancies exist, they should be justified by demonstrating that the options chosen are optimal. For instance, limits could be justified so as to accommodate waste with long-lived content that cannot be easily separated from short-lived waste, disposal of some waste in available facilities may be preferred so as to avoid safety problems of interim storage, and so on. NORM waste and uranium mill tailings management are of concern from the viewpoint of radiological protection. Even if solutions for the near-term protection of the public and the environment are adequate,
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Improving the Regulation and Management of Low-Activity Radioactive Wastes there is a need to better consider long-term risks associated with disposal—consistent with the requirements for nuclear waste. However, the very large volumes involved may require specific considerations so as to define optimal solutions for their safe management. Among other issues, this should lead to defining levels for NORM waste that may be disregarded within respect to radiological protection needs. On the other hand, higher levels that would require additional protection, so that such waste is unlikely to be affected by external events, also need to be identified. Internationally, there is convergence toward considering that a value of 1 mSv of added dose to the public is an appropriate limit for normal exposures arising from waste management activities. However, it is a requirement to demonstrate that exposures are ALARA. There are significant differences in applying this principle among countries, ranging from the technological approach (designing a confinement system to be as robust as possible) to a fully integrated risk-based probabilistic approach. The technological approach involves demonstrating the ALARA standard by designing the facility against plausible risks and showing that better technical solutions are not available without incurring undue costs. This approach is quite convincing with regard to uncertainties in meeting a risk objective, but it is based on a somewhat arbitrary expert appraisal of the design. The integrated approach has the merit of unifying a criterion of acceptability, which is helpful for discussions among stakeholders. However, it can be fragile because it is based on calculations that can be revised over time (probabilities of long-term evolution are very difficult to assess and the dose limits or parameters to calculate it may vary). Whatever approach is preferred, demonstrating ALARA always involves nontechnical arguments. Hence, a key step is to involve the public and stakeholders in ALARA decisions. In arriving as such decisions, it seems important to distinguish ongoing practices from remedial actions (intervention) considering that actions to avoid hypothetical doses in the future may result in unnecessary exposures to workers and other societal impacts. A good example would be applying ALARA to NORM waste and uranium mill tailings, where interventions involving of millions of tons of waste obviously would be difficult. There is clearly growing interest in harmonizing management of waste from all sources and achieving a consistent framework in which generic waste management solutions can be identified to establish a consistent policy for disposing of all types of waste and providing adequate answers for industrial needs. All stakeholders’ involvement will be required to achieve such a framework.
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