Radioactive Waste Management

Excerpt from the IAEA Annual Report for 1994

(Editor's note: The format of scientific notations in this electronic presentation is being standardized.)


Programme overview

In response to a request by Member States for more international guidance and co-ordination in the field of radioactive waste management and in recognition of the need to assist some Member States in improving their waste management programme infrastructures, the Agency in 1994 focused on: the continued implementation of the Radioactive Waste Safety Standards (RADWASS) programme; the development of radiological and safety criteria for waste disposal and the co-ordination of international radiological and environmental assessment projects; and the implementation of programmes for improving national infrastructures and the development of mechanisms for better and more effective technology transfer. Other areas receiving emphasis included direct advisory and review services, guidance on the safety, technical and planning aspects of decommissioning, quality assurance management for waste packaging and disposal systems, safety assessment of near surface disposal facilities and the environmental restoration of contaminated land masses.

The RADWASS programme continued to be one of the core efforts of the Agency's waste management programme. In addition, RADWASS became a basic foundation for many of the tasks and projects within other subprogrammes. The importance of RADWASS to Member States was again reaffirmed during the 1994 regular session of the General Conference by a resolution which requested the Agency to maintain emphasis in the field of radioactive waste management. In addition, to better co-ordinate, harmonize and facilitate consensus for key RADWASS documents, a subgroup of the International Radioactive Waste Management Advisory Committee (INWAC) was created to review all documents requiring approval of the Board of Governors.

In a resolution adopted at the regular session of the General Conference in September 1994, Member States invited the Board of Governors and the Director General to commence preparation for a convention on the safety of waste management and begin the process of collecting relevant background information (including appropriate RADWASS documents) that would be useful in drafting the convention.

With the changes in eastern Europe and the countries of the former USSR, information has become available revealing the existence of environmental problems. Workshops were organized in 1994 to focus on detailed planning methods and technologies available for the restoration of contaminated sites.

The Agency is the competent international body on matters related to radioactivity to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (London Convention 1972). In 1994, the Agency was requested to develop guidance on exemption in the context of disposal of materials at sea. The disposal of radioactive wastes by dumping at sea was banned by international agreement in February 1994. The purpose of the Agency's work is to provide guidance on how to define radioactive in the context of the London Convention.

A CRP on the validation of environmental model predictions (VAMP) was completed. The objective of the VAMP studies, started in 1988, was to provide a mechanism for the validation of assessment models by using the environmental data on radionuclide transfer which have resulted from the Chernobyl release. The project has resulted in both technical and administrative achievements in the field of model validation.

Efforts are under way to upgrade waste management programme infrastructures in Member States which generate wastes primarily from nuclear applications. In addition, development began of Minimum Acceptable Waste Infrastructure criteria to be used for evaluating waste management programmes and needs in developing Member States. Activities are co-ordinated under an Agency model project on waste management and through advisory missions.

The development of a report on in situ solidification processes aimed at converting contaminated soil and sludges, currently stored in underground tanks, into a durable leach resistant product which will meet current requirements for near surface waste disposal, was restarted in 1994 after temporary deferment in 1993 due to budgetary constraints.

The first draft of a technical manual on the application of the Sealed Radiation Sources (SRS) Registry as a tool for record keeping and information management was prepared in late 1994, after deferred funds from 1992 were released.

IAEA-MEL contributed to the International Arctic Seas Assessment Project (IASAP) by offering assistance in analytical quality assurance, radioactivity monitoring, computer based dispersion modelling, radiological assessment and database provision. It participated in the 1994 Russian-Norwegian expedition to the Arctic dump sites to sample and subsequently analyse water, sediment and biota in the region. The first set of analyses of sea water and sediment samples from a joint expedition to the Sea of Japan was completed. The IAEA-MEL also continued its involvement in the Agency's Emergency Response System and in an expanded environmental monitoring programme in which waste effluents provide useful isotopic signals in the marine and aquatic environment.

IAEA-MELs contribution to marine carbon flux studies was acknowledged by its winning, along with collaborators in France, of the 1994 Philip Morris Scientific Prize for Biogeochemistry.


HANDLING, TREATMENT, CONDITIONING AND STORAGE OF RADIOACTIVE WASTES

Quality assurance and quality control requirements for radioactive waste packages

Work continued on providing technical guidance on quality assurance (QA) requirements for all types of waste packages. A report specifying QA requirements to be met during container fabrication, waste immobilization and packaging, interim storage and waste emplacement operations was completed and approved for publication. A second report, being developed in parallel, will provide guidance on the QA arrangements and process controls for low and intermediate level wastes which need to be established to ensure that the waste packages produced will meet waste acceptance criteria for disposal.

Support for the safe management of spent radiation sources in developing countries

A report on the methods to identify and locate spent radiation sources was completed and approved for publication. A report was prepared providing practical guidance on conditioning and interim storage methods for spent radium sources. Two expert missions, in which actual conditioning of spent radium and other spent sealed sources was carried out, were completed in 1994.

Technical manuals for the handling and processing of radioactive wastes generated from nuclear applications

A series of technical manuals was completed with the publication of the last two documents. This series was undertaken to meet the needs of Member States that generate small volumes of radioactive wastes, providing straightforward and low cost solutions to waste handling and processing problems. A second phase of the programme was initiated during the year to determine areas of applications not covered in the initial programme development. A supplementary document on the handling and disposal of radioisotopes used for agricultural studies is in preparation.


RADIOACTIVE WASTE DISPOSAL

Technologies for near surface disposal systems for low and intermediate level radioactive wastes

A report on the design of near surface disposal facilities was completed. The document identifies technical principles and requirements, phases of implementation and design considerations. The requirements cover detailed items to be considered with respect to waste and site characteristics, engineered barriers, operational considerations and post-closure performance assessment. Conceptual, basic and detailed design phases are defined, as well as specific technical objectives and the scope of design activities for each phase. The document also includes a summary of Member State experience and a checklist of design requirements.

Technologies for deep geological disposal systems for high level radioactive wastes

A document on the methodology for selecting, siting and characterizing a geological repository for high level wastes was completed. This report presents the general processes and factors to be considered in selecting geological repository sites. The report also reviews Member State experience in selecting and characterizing sites for geological repositories, including the knowledge and data gained in siting underground research laboratories.


DECONTAMINATION AND DECOMMISSIONING OF NUCLEAR INSTALLATIONS

Project planning and management for decommissioning operations

A report describing and assessing safe enclosure as a precursor to dismantling a nuclear installation was finalized and approved for publication. The report reviews the relevant safety, technical and economic factors for this possible decommissioning strategy.

During 1994, the focus of a project on environmental restoration in the countries of eastern Europe and the former USSR was the identification and characterization of radioactively contaminated sites. Before any action in regard to environmental restoration could be taken, it was necessary to obtain an overview of the environmental state in each of the countries. The Agency therefore requested selected Member State experts to survey and categorize the sites according to location, volume, radioactive concentration, proximity to populous areas and potential spreading of contamination. An IAEA-TECDOC collecting the results of the project will be published in 1995.


RADIOLOGICAL AND ENVIRONMENTAL ASPECTS OF WASTE MANAGEMENT

Application of exemption principles to radioactive waste management

Since the international consensus was reached on principles for the exemption of radiation sources and practices from regulatory control in 1988, published as Safety Series No. 89, the principles have been used as a basis for developing practical guidance for use in relation to radioactive waste management. Various national and international studies concerned with deriving clearance levels for very low level wastes and for the recycle and reuse of materials from the nuclear fuel cycle have been published since 1988. On the basis of all of these studies, international guidance has been developed on clearance levels for radionuclides in solid materials. These levels, termed 'unconditional clearance levels', can be used as a basis for decision making when it is desired to release materials containing very small amounts of radionuclides from regulatory control. It is expected that the levels will find use in relation to transboundary movements of materials. For use in this application, there should be no further need for concern after release no matter what the use or destination of the materials might be and, therefore, the values have been derived taking into account amounts of exposure in a wide range of possible circumstances. After extensive review by expert groups, a document on this subject, containing values derived taking into account exposures in a wide range of possible circumstances, has been approved for publication as RADWASS Safety Guide No. 111-G-1.5.

Development of safety criteria for radioactive waste repositories

The discussions of the INWAC Subgroup on Principles and Criteria for Radioactive Waste Disposal on the subject of appropriate indicators of safety for waste repositories and of the nature of safety assessments at long time-scales, which have taken place over the last three years, culminated in the publication of a report (IAEA-TECDOC-767). It is expected that the concepts and ideas contained in the report will be used in the future development of RADWASS documents on the subject of geological disposal. The Subgroup is continuing to discuss other issues related to the safety of waste repositories, notably the problem of complying with regulatory criteria at long times in the future when predictive uncertainties become large.

Safety assessment in radioactive waste management and disposal facilities

The first test case of a CRP on the safety assessment of near surface disposal facilities was completed and evaluated. A report on the test case, in which the results of participants are presented, analysed and discussed, has been prepared and approved for publication as an IAEA-TECDOC.

Validation and assessment of radionuclide transfer models

In 1988, the Agency started a CRP on the validation of environmental model predictions (VAMP) with the following objectives: to provide a mechanism for the validation of assessment models by using the environmental data on radionuclide transfer which resulted from the Chernobyl release; to acquire data from affected countries for that purpose; and to produce reports on the current status of environmental modelling and the improvements achieved as a result of post-Chernobyl validation efforts. In October 1994, the last meeting of the VAMP programme was held in Vienna. At this meeting, the progress made and the achievements of the programme were reviewed. The results of the VAMP study are in the process of being documented in the IAEA-TECDOC series.

Environmental studies in relation to marine disposal

The Agency is committed to presenting a report in 1996 on the potential impact of the high level radioactive wastes dumped in the shallow waters of the Kara Sea, and on the feasibility of possible remedial measures, to the London Convention 1972. Progress was made on this project in 1994, especially in obtaining a more detailed understanding of the nature of the wastes and of the form of their containment. It has been possible to postulate release rates of radionuclides from the wastes into the surrounding water as a function of time. The national modelling groups taking part in the project are improving their ability to represent radionuclide movement in the Kara and surrounding seas. The third joint Norwegian-Russian cruise to the area in 1994 obtained useful data on the wastes dumped in two of the bays. The measurements made during the cruise confirmed that very little radioactivity has been released to date from the dumped wastes. IAEA-MEL participated in the third joint Russian-Norwegian exploratory cruise to the Kara Sea to sample and subsequently analyse seawater and sediment samples. It also organized analytical laboratory control exercises for the participating Norwegian and Russian laboratories. Analyses of samples from the 1993 cruise have shown that leakage from dumped objects in the Stepovovo and Tsivolky Bays of Novaya Zemlya has occurred, leading to contamination with 137Cs and 60Co of locally restricted areas, but at radiologically insignificant levels.

A set of analyses was completed of seawater and sediment samples from the first joint expedition (Japan, Republic of Korea and the Russian Federation) to the Sea of Japan. The measured levels of typical anthropogenic radionuclides in the marine environment (239+240Pu for alpha emitters, 90Sr for beta emitters and 137Cs for gamma emitters) represent the expected global fallout concentrations.

IAEA-MEL also participated in the cruise to sample sea water and sediment around the sunken nuclear submarine Komsomolets in the Norwegian Sea. The samples are presently under investigation.

Support for marine radioactivity monitoring

During 1994, two reports on intercomparison exercises were completed. Sea water and fish were collected in the Irish Sea for large scale intercomparison exercises. A specific exercise was organized at the request of the French Commissariat l'energie atomique to analyse biological samples collected around the Mururoa atoll. The Laboratory also continued its association with the Helsinki Commissions Group of Experts on Monitoring of Radioactive Substances in the Baltic Sea and three specific intercomparison exercises on sediment samples were completed.

A new technique based on liquid scintillation counting was established for the analysis of soft beta emitters of 3H, 129I and 241Pu in the marine environment, while collaboration with the Japan Atomic Energy Research Institute has allowed renovation and upgrading of the inductively coupled plasma mass spectrometer used for multi-element and radionuclide assays.

IAEA-MEL analysed several samples in the framework of the programme on environmental monitoring for safeguards purposes and participated in the intercomparison exercise for the analysis of safeguards samples.

A final report of a CRP on sources of radioactivity in the marine environment and their relative contributions to overall dose assessment from marine radioactivity was completed and for the first time dose rates based on 137Cs and 210Po in sea water and fish have been estimated for the world population. It has been shown that the doses to humans from anthropogenic radionuclides (137Cs) in the marine environment are generally two to three orders of magnitude less than the doses from natural radionuclides (210Po).

In-service training in radionuclide measurements and radiotracer applications in environmental studies continued to be a major focus in IAEA-MELs activities. As a means of hands-on training, IAEA Fellows from Colombia and Turkey directly participated in laboratory experiments aimed at assessing the behaviour of natural and artificial radionuclides in corals and other benthic organisms. In addition, Fellows from Mexico, France and Belgium, funded by external sources, participated in similar research projects dealing with laboratory radiotracer applications.

Research radionuclides in the marine environment

As part of the International Joint Global Ocean Flux Studies (JGOFS), particle flux samples from 200 and 1000 m depths covering a period of 323 days were obtained in the northwestern Mediterranean using sediment traps moored in the deep sea. These long term, time-series samples were essential for quantifying variations in carbon removal to the deep sea.

In the Adriatic, four cruises were undertaken to examine the flux of carbon and radionuclides in contrasting areas of high and low sedimentation rates. Emphasis was placed on the use of radioactive disequilibrium between particle reactive 234Th and its soluble parent 238U to evaluate the downward flux of particulate organic carbon produced in the surface layers. Through the EC sponsored ELNA programme, three stations in the northern Adriatic were profiled for these natural radionuclides. Additional sampling to test the 234Th scavenging model for carbon export and the seasonal scavenging behaviour of 210Po and 210Pb by particles was carried out in the northwestern Mediterranean under the French JGOFS programme DYFAMED.

Techniques were developed in the application of multitracer gamma spectrometry for simultaneously measuring the transfer of radionuclides and heavy metals through key marine food chains. Laboratory experiments utilizing these techniques have demonstrated that certain bottom dwellers such as starfish and sea urchins accumulate and strongly retain the key radionuclides 137Cs, 241Am and 60Co as well as several heavy metals. These results are essential for developing radionuclide food chain transfer models in the Arctic and other seas.

In collaboration with the European Oceanological Observatory in Monaco, methodologies were developed to culture coral in small microcosms in which multitracer techniques were used to quantify the uptake and release rates of radionuclides and trace elements in different tropical coral colonies. Results showed a marked preferential uptake and strong binding of certain artificial radionuclides (such as 241Am) into coral skeleton rather than in the living tissues, an observation which suggests that dead corals may serve as a sink for certain long lived radionuclides.

To better evaluate the intake of the key natural radionuclide 210Po by humans living in the Mediterranean basin, fresh seafood samples of fish, shrimp, oysters, clams, mussels and squid were collected and analysed for 210Po and its parent 210Pb. The effect of cooking procedures on 210Po and 210Pb concentrations in seafood was also examined, as well as the natural radioactivity ingested with complete meals of similar seafoods which were obtained commercially.

Laboratory research continued on the interaction and behaviour of 210Po and 210Pb in marine biota and particulates. Work focused on measuring rates of 210Po and 210Pb sorption by sedimenting particles and on the influence of organic matter on the sorption processes. In addition to various classes of non-living detrital particles, the role of marine bacteria in 210Po and 210Pb cycling was investigated.


WASTE MANAGEMENT PLANNING AND INFRASTRUCTURE

Assessment of waste management status and trends

The second edition of the Radioactive Waste Management Profiles, which contains data provided by Member States during the 1991-1992 biennial update, was published. The Profiles contain data about national programme plans and activities, including data on waste management authorities and organizations, waste type and volume, treatment and conditioning methods, storage and disposal plans, and site information.

Radioactive Waste Safety Standards (RADWASS)

The RADWASS programme, which seeks to provide a series of documents in the fields of radioactive waste management, decontamination and decommissioning, and environmental restoration, is periodically reviewed by INWAC. In 1994, an Extended INWAC was formed to review all RADWASS documents prior to approval by the Board of Governors. This Committee reviewed two high category documents, the Safety Fundamentals and a Safety Standard on establishing a national system for radioactive waste management. Although broad consensus on these documents was reached, some Member States requested further harmonization with other Agency Safety Series publications before submission to the Board of Governors.

In a resolution adopted at the regular session of the General Conference in September, Member States invited the Board of Governors and the Director General to commence preparation for a convention on the safety of waste management and continue the process of collecting relevant background information (including appropriate RADWASS documents) that would be useful in drafting the convention. Preparations for such a convention have been initiated.

Direct assistance and support for national waste management programmes

In December 1993, the Nuclear Regulatory Authority of Slovakia requested the Agency to review the pre-operational safety report for the Mochovce waste disposal facility. This facility is a near surface repository for the disposal of low and intermediate level short lived radioactive wastes generated by the Bohunice and the proposed Mochovce nuclear power plants. The Agency convened a team of experts from Canada, Finland, France, Germany and Spain under the Waste Management Assessment and Technical Review Programme (WATRP). The expert team reviewed the source material provided by the Nuclear Regulatory Authority and met with Slovak experts during a meeting held in May.

Four Waste Management Advisory Programme (WAMAP) missions were conducted to: Lebanon, Saudi Arabia, the United Arab Emirates and Uruguay. The mission to Saudi Arabia was a joint RAPAT-WAMAP mission.