Handling, treatment, conditioning and storage of radioactive wastes
The Agency's 1996 programme on radioactive waste management focused on: the establishment of international principles and standards for the safe management of wastes; preparations for the convention on the safe management of radioactive waste; development of infrastructures and tools for strengthening and solving waste management problems in developing Member States; and assessing waste management situations and needs as a consequence of past practices. New advisory committees were established to advise the Agency on its activities related to waste technology and safety. The International Radioactive Waste Technology Advisory Committee (WATAC) met for the first time in October to review the 1995-1998 Agency programme in these areas and to facilitate the exchange of information and experience between Member States represented on WATAC. The Waste Safety Standards Advisory Committee (WASSAC) was established to review waste safety documents intended for publication in the Safety Standards series.
Progress was made in the preparation of guidance on waste minimization methods applicable at different nuclear facilities. A report completed in 1996 provides a number of different options and technologies for the treatment of boric acid containing waste. These are aimed at the recovery of boric acid from waste streams and its possible reuse.
In co-operation with national authorities, the Agency implemented a training programme with the aim of providing technical expertise to developing Member States in various aspects of radioactive waste management. Incorporating the results of over 20 regional and interregional training courses held between 1991 and 1995, guidance material was prepared for use by Member States in conducting training courses on the management of low and intermediate level waste (LILW). The report covers the requirements for organizing courses, an annotated outline of such courses and a selection of practical exercises and demonstrations.
Two CRPs on fostering research in developing Member States in the field of waste processing technologies for LILW from nuclear applications were concluded in 1996. One CRP on treatment technologies for LILW was designed to help develop reliable, simple and low cost processes for specific institutional waste to be made compatible with long lived radioactive waste forms. A number of new treatment technologies were developed and tested, and are in use in some of the countries that participated in the project. The other CRP dealt with inorganic sorbents that in many cases have been proved to be advantageous in the treatment and immobilization of liquid radioactive waste. Specific properties of synthetic and composite sorbents can be designed and controlled during their synthesis. This facilitates the preparation of a range of sorbents suitable for the treatment of specific waste streams. However, the variety of inorganic sorbents, both natural and synthetic, that are in use worldwide requires the setting up of standardized procedures for comparative evaluation. Several standard testing procedures and sets of reference waste streams were thus developed in the CRP.
Difficulties encountered in the short term in many Member States in the development of disposal facilities have led to more effort being devoted to the storage of radioactive wastes. A report was prepared to provide guidance on various technological aspects of radioactive waste package storage, and to place storage in the context of the entire waste management process. The report reviews current practices and experience in waste storage, summarizes the various actions required before, during and after interim storage and links various activities involving the storage of radioactive waste.
At a symposium entitled 'Experience in the Planning and Operation of Low Level Waste Disposal Facilities', held in Vienna in July, it was demonstrated that the majority of the Agency's Member States, while not employing nuclear power, were utilizing nuclear technology in such areas as medicine, industry and research. These applications as a rule produce low level waste (LLW) which has to be managed and disposed of. The symposium showed that LLW disposal is based on proven technologies and the safety of disposal can be satisfactorily ensured over the time periods currently envisaged. It was also pointed out that while developing Member States are looking for adequate, affordable and safe solutions, in developed Member States there is a trend towards increasing technical sophistication.
For several years the Agency has organized an annual group forum for the discussion and resolution of outstanding issues related to the disposal of radioactive wastes, mainly the problem of assuring and demonstrating the long term safety of waste repositories. The second report of this group was issued in 1996 and contains discussions on interface issues between nuclear safeguards and radioactive waste management, aspects of the post-closure phase of a repository and the application of the concept of 'radiological optimization' to radioactive waste disposal.
A three year assessment study of the radiological impact of high level radioactive waste dumping in the Arctic seas (the International Arctic Seas Assessment Project (IASAP)) was completed. An executive summary of the study report was presented to the Contracting Parties to the Convention on the Prevention of Marine Pollution by Dumping Of Wastes and Other Matter (the London Convention, 1972). The study examined various aspects of radiological assessment, making use of the results obtained from several exploratory cruises to the affected area. In addition, three-dimensional hydrodynamic and compartmental modelling of dispersal from possible releases of radionuclides from dumped wastes to the open Kara Sea and the Arctic Ocean was carried out by IAEA-MEL. One of the study's conclusions was that the current radiological risks presented by the dumped wastes are negligible and that the future risks to population groups most likely to be exposed are also small. No justification was found on radiological grounds for instituting a programme of remedial action in relation to the wastes. However, a reassessment of the situation was recommended if the current military restrictions over the fjords of Novaya Zemlya, where much of the waste was dumped, are removed.
As a contribution to IASAP, IAEA-MEL verified laboratory experimental approaches to estimating radionuclide coefficients (Kds) for Kara Sea sediments. Comparisons of field derived and radiotracer derived Kds values showed that radiotracer techniques used with natural sediments can, under carefully controlled conditions in the laboratory, accurately predict Kds coefficients that have been measured in far more costly field tests.
Closely related radioecological experiments have determined the potential usefulness of starfish, a common bottom species in the Arctic seas, as bioindicators of americium-241, caesium-137 and cobalt-60 contamination in these waters. Laboratory radiotracer food chain studies demonstrated that starfish can accumulate from 75 to 100% of the radionuclides ingested with their food and can retain them in their tissues for several months.
The analysis of sediment and seawater samples collected during the 1994 and 1995 Japan-Republic of Korea- Russian Federation expeditions to the Far Eastern seas has been completed and a final report issued. The analytical results did not show any effects from the dump sites. Dispersion modelling of possible releases of radionuclides from dumped wastes in the Far Eastern seas was also completed. The results have shown that the turnover time of water in the Far Eastern seas may be about 25 years, which is shorter than expected by a factor of 4. However, the simulated surface water concentrations of caesium-137 released from wastes may reach values an order of magnitude lower than the present environmental levels.
A sampling expedition to the Mururoa and Fangataufa Atolls in French Polynesia was carried out. A new progressive technique based on in situ gamma spectrometry of seabed sediments was used to study the spatial distribution of radionuclides in sediment and to optimize sediment sampling. Hundreds of water, biota and sediment samples were collected in both lagoons and are being analysed in seven Member State laboratories and at IAEA-MEL.
A Global Marine Radioactivity Database (GLOMARD) was established to provide Member States with information on radioactivity baselines and records for radiological assessments and international and national monitoring programmes. All available data on radionuclide concentrations in the Arctic seas have been included in GLOMARD to study the temporal and spatial distributions of radionuclides. The data show that in recent years the concentrations of strontium-90 and caesium-137 in the Kara and Barents Seas have been decreasing, the dominant contribution being from reprocessing plants and global fallout.
A CRP on the applications of tracer techniques in studies of processes and pollution in the Black Sea was completed. The project resulted in: a comprehensive and up to date assessment of radionuclide distributions, trends, inventories and sources in the Black Sea environment; an evaluation of doses delivered through marine exposure pathways to humans and biota; and the development of applications of radioactive and stable isotope tracers to understand the fate of pollutants in this particularly complex and stressed environment.
Bioassay tests have been designed to examine the possible enhancement of natural radioactivity in marine organisms living in the vicinity of non-nuclear industries. Initial experimental results indicate that polonium-210 in gypsum and other phosphatic wastes from the phosphoric acid industry is bioavailable to marine molluscs exposed to sea water containing such wastes.
Progress was made in 1996 to broaden the funding base for Agency projects focused on the application of nuclear techniques to understand oceanic processes. A subcontract was established under the European Union sponsored Aegean Sea Hydrothermal Fluxes project through which the Agency will use nuclear techniques to examine the potential environmental enhancement of natural radionuclides and trace elements emanating from shallow water hydrothermal vents off Milos Island. Such background data on geochemical sources are important in order to gauge the relative importance of industrial inputs of the same elements to enclosed seas such as the Mediterranean.
At the request of the French authorities, the Agency convened an international team of experts to review the short lived waste management programme and activities, both planned and implemented, at the Centre de l'Aube. On the basis of source material and a report provided by Andra (Agence nationale pour la gestion des déchets radioactifs, France), the team evaluated the programme and formulated recommendations in several areas such as verification, control and testing, and safety assessment.
A Contact Expert Group (CEG) was established by a number of countries interested in having an international forum for harmonizing and following up co-operation in the area of radioactive waste management in the Russian Federation. The first CEG meeting was held in March 1996 in Moscow. CEG Secretariat services are being provided by the Agency.
The first demonstration of predisposal waste management methods and procedures was held at the Çekmece Nuclear Research and Training Centre in Turkey. Participants from Albania, Greece, the Syrian Arab Republic and the host country attended this hands-on training session. A regional centre for Latin America has also been established at the Lo Aguierre nuclear research centre in Chile.
A team of specialists from Brazil completed the conditioning of the national inventory of old radium sources in Uruguay. The conditioning, which was carried out with Agency staff in attendance, will ensure that these radium sources can be safely stored until deep geological repositories are available for disposal. This operation was the first in a series that will eventually remove spent radium sources from the list of highly dangerous radiation sources in Member States.
Proper assessment of the waste management situation in Member States is necessary in order to prepare adequate work plans for technical co-operation activities. To support these activities, a waste management part in the Country Profile Database was established. This section will complement the corresponding database on radiation protection. Information on more than 20 countries has so far been included.