Nuclear Fuel Cycle

Excerpt from the IAEA Annual Report for 1994

Programme overview

In the nuclear fuel cycle area, the Agency continued to: assist in the decision making process in Member States by furnishing relevant information; provide help in ensuring the safety, reliability and economic viability, and in minimizing the environmental and health impacts, of nuclear fuel cycle facilities; help meet the needs of Member States for the safe management of spent fuel and plutonium; and assist the development in Member States of fuel with improved performance.

Work continued on the compilation of information on uranium resources and production in eastern European countries and countries of the former USSR. Newly acquired information has been incorporated into Uranium 1993 Resources, Production and Demand (Red Book'), a joint publication with the OECD/NEA.

Planning started on organizing an advisory service to be known as Uranium Production Safety Assessment Team. This is intended to help in the safe operation of uranium mining and ore processing through the technical exchange of experience and practice.

In the area of reactor fuel technology and performance, the main effort was aimed at providing a forum for information exchange under the umbrella of the International Working Group on Fuel Performance and Technology.

Problems associated with the increasing amounts of separated plutonium became of special international concern. The Agency continued to collect and develop a worldwide database on separated plutonium in civilian nuclear programmes to determine the present world stockpile of civilian plutonium and forecast its future evolution. Work was started on a safety document for the handling and storage of plutonium.

In the area of spent fuel management, developments in technology and safety are of high priority and reflect urgent needs in Member States. Three safety documents on the safe storage of spent fuel from power reactors were published in 1994. The preparation of a safety document on the safe handling of spent fuel from research reactors was initiated. Implementation began of the Irradiated Fuel Management Advisory Programme to assist and advise Member States on spent fuel management from both power and research reactors.

With regard to the handling and storage of spent fuel from research and test reactors, the responses received to questionnaires sent to research reactor operators were compiled into a spreadsheet. Of great concern is the issue of materials ageing in fuel storage facilities. This is being addressed under several activities, the most important of which is a CRP on the corrosion of aluminium clad research reactor fuels.

Under the subprogramme Information on the Nuclear Fuel Cycle, efforts continued on updating and formulating databases on the Nuclear Fuel Cycle Information System (NFCIS) and the Actinides Database and Fuel Cycle Balance. The NFCIS database will be published in 1995.


RAW MATERIALS FOR REACTOR FUELS

Assessment of uranium resources and projection of supply and demand

World uranium production continued to decline, following a trend that started in 1988. Uranium production in 1994 is estimated to have been below 32 000 t, down slightly from the previous year's production, which was 2000 t less than that estimated in The Annual Report for 1993. The year 1988 also marked the beginning of growing uranium imports from the former USSR. Six countries, namely Australia, Canada, Kazakhstan, Niger, the Russian Federation and Uzbekistan, produced over 66% of the world total. The 1994 worldwide reactor related requirements are estimated to be about 58 500 t U, which is about 26 500 t greater than world production. In other words, only about 55% of the requirements is met by current production.

While it is forecast that demilitarized HEU (high enriched uranium) warheads, blended to LEU (low enriched uranium), will meet some portion of reactor requirements, it is expected that 80% or more of the worldwide reactor requirements of 1 070 000 t U over the period 1995-2010 will be met by uranium production.

Projected uranium demand worldwide for the period 1993-2010 is derived from the expected development of nuclear electricity generating capacity. It is estimated that the world capacity will grow from 337.8 GW(e) in 1993 to about 446 GW(e) in 2010. This results in the projected annual uranium requirements for the same period increasing from 58 500 to 75 000 t. The corresponding projection for the world uranium supply, however, is not available, as the necessary information regarding the production capabilities of important producers in Kazakhstan, the Russian Federation and Uzbekistan has not yet been made known. Considering only the former WOCA (World Outside Centrally Planned Economies Areas), where such information exists, uranium production capability by the year 2010 is estimated to be around 32 000 t. Part of the balance may be met through production from the newly independent States of the former USSR, from eastern Europe and China, where the total 1994 production was estimated at about 10 000 t U. Assuming a stable production level in the latter group of countries, there will be unfilled requirements of about 33 000 t that will have to be met through the expansion of existing facilities and the development of new production centres, as well as from LEU produced from HEU. The contribution to supply from reprocessed uranium and mixed oxide (MOX) fuel is expected to remain modest up to the year 2010. The planned facilities for the use of reprocessed uranium and for fabricating MOX fuel have an annual capacity that could provide a maximum equivalent contribution of less than 5% (about 3 000 t U equivalent) of the projected requirements of 75 000 t U.

The new edition of the joint Agency and OECD/NEA report Uranium 1993 Resources, Production and Demand (Red Book) was published early in 1994, representing a shortening of the preparation time by nearly one year over the previous edition. The Red Book was also issued in a computer accessible electronic version. The 1993 edition had the broadest coverage ever, including reports from 50 countries, 7 of which submitted reports for the first time.

Management of uranium exploiration, deposit development, production and closure

An Advisory Group meeting established the terms of reference for peer review by teams of international experts of the operational safety of uranium mining and milling facilities. The programme advisory service known as the Uranium Production Safety Assessment Team (UPSAT) will provide a technical exchange of experience and practice at the working level and is aimed at strengthening the safety and environmental programmes, procedures and practices of the facilities visited.

Preservation of uranium geology and exploitation data and maintenance of databases

The preparation of a world atlas of uranium deposits is now complete with the integration of data from the former USSR, eastern Europe and China. This atlas makes a contribution to the analysis and understanding of the past and present world uranium supply. It also provides data for deposits that may be of economic interest in the future.

The Agency co-operated in the preparation of the final report of the International Geological Correlation Programme (IGCP) Project 259, a Global Geochemical Database for Environmental and Resource Management, which was sponsored by the International Union of Geological Sciences (IUGS) and UNESCO. This project was established to consider the methodology for quantitative assessment of the geochemical diversity of the Earth's land surface. The Agency contributed its expertise and data on the distribution of natural radioelements obtained through uranium exploration.


REACTOR FUEL TECHNOLOGY AND PERFORMANCE

Reactor fuel materials

At the suggestion of the International Working Group on Fuel Performance and Technology (IWGFPT), work started on an update of the review on the corrosion of zirconium alloys in nuclear power plants. This will be published as an IAEA-TECDOC.

The final report on burnable absorbers for LWR fuels was prepared and will be published in 1995. This report is the result of a CRP held from 1990 to 1994 and illustrates the fuel properties, manufacturing techniques, design approaches, utilization performance and potential impacts on the back end of the fuel cycle of burnable absorber fuel.

Water reactor fuel performance and technology

A Technical Committee meeting on the development of post-irradiation examination (PIE) techniques for water reactor fuel, held in Cadarache, France, reviewed the state-of-the-art in the area of PIE, with special emphasis on recently developed techniques for poolside and hot cell application. The presentations and discussions focused on: non-destructive testing; the development of analytical destructive methods for characterization of fuel and cladding; mechanical testing; and refabrication techniques for re-irradiation of fuel rods in reactors. Papers presented at this meeting demonstrated the significant progress that has been made in PIE and the continuing importance of co-operative approaches in this field.

The 12th plenary meeting of the International Working Group on Water Reactor Fuel Performance and Technology (IWGFPT) was held in May. The Working Group reviewed the programmes of the Agency in that area and made recommendations for future work. Special attention was given to the programmes on fuel safety, the Agencys work in eastern European countries and collaboration with other international organizations.

The second Research Co-ordination meeting of a CRP on fuel modelling at extended burnup (FUMEX) was held after a blind exercise was completed by the participants. The exercise was carried out on six irradiated fuel rods in the OECD/NEA Halden reactor. Nineteen computer codes were involved. Since the previous CRP, carried out in 1984, much progress has been made in hardware and software and in the evaluation of the main fuel parameters. This CRP has shown that modern codes can be run on state-of-the-art PCs. Despite the complexity of the experimental cases chosen for this exercise, the codes could handle the volume of data and required mathematical convergence without difficulties. Most of the codes give a reasonable estimate of fuel temperature in steady state conditions. Some problems still remain with modelling of fission gas release, particularly in the region of 1% release. For several codes there is also a need for improvement in the modelling of transient conditions, especially at high burnup.

A Technical Committee meeting on water reactor fuel element modelling at high burnup and experimental support was held in Windermere, the United Kingdom. Significant advances in the subject have taken place in recent years owing to progress in computer technology, computational methods and the ability to measure fuel centreline temperatures at the start of life and throughout irradiation to high burnup. Fuel thermal conductivity degradation, fission gas release and modelling improvement were discussed.

Plutonium accumulation and emerging problems

Data were collected to update and validate the Agency's inventory estimates and provide a foundation for projecting quantities of separated plutonium in civilian nuclear power programmes. It is estimated that the world inventory of separated civilian plutonium crossed the 100 t level during the early part of 1994. The data collected on projected separation and rates of use for plutonium are being checked and refined.

The services of consultants were used to start the development of a safety practices document for the handling and storage of separated plutonium in civilian nuclear power programmes. Although the level of safety in these programmes is high, the Agency is seeking to improve worldwide information exchange and documentation.

A Technical Committee meeting on unconventional options for plutonium disposition was held at the Institute of Physics and Power Engineering (IPPE) in Obninsk, the Russian Federation, in November. The meeting considered unconventional approaches for plutonium disposition, from the points of view of the fuel cycle and the fuel type. A number of options were discussed, such as Th-Pu, U-Th and Pu in non-fuel matrices to be used in high temperature gas cooled, molten salt and other reactors. Evaluations were made of the technical feasibility, licensing and timeliness aspects. It was concluded that these options require considerable time and resources for their development, demonstration and industrial implementation.


SPENT FUEL MANAGEMENT, TECHNOLOGY AND SAFETY

Spent nuclear fuel arisings, storage options and practices

A symposium entitled Safety and Engineering Aspects of Spent Fuel Storage was organized jointly with the OECD/NEA. The meeting provided an opportunity for an exchange of information on the state-of-the-art and prospects for spent fuel storage, the worldwide situation and the major factors influencing national policies in this field and the directions that national efforts and international co-operation in this area should take. The changes in nuclear policy across the world, together with practical considerations, have made interim storage a necessity in the nuclear power industry. This question is being addressed by utilities, vendors and regulators.

At an Advisory Group meeting on the development of transport and storage casks for spent fuel, national programmes were reviewed and issues concerning multipurpose casks were identified. It was reported that some countries have chosen to develop storage casks with a requirement for transportation. This approach reduces the amount of handling, thus enhancing the safety of the system by reducing the occupational radiation exposure and the potential for radioactive contamination.

A final draft was prepared of a Technical Reports Series document on experience in the selection, design and operation of away-from-reactor (AFR) storage facilities. The document will provide information on examples of good practices and general guidance on the type of criteria to be considered and the processes to be undertaken during evaluation and selection of AFR storage system designs.

A Technical Committee meeting on remote technology related to the handling, storage and/or disposal of spent fuel, was organized in co-operation with Sandia National Laboratories in Albuquerque, USA. It was noted that many operators are becoming aware that remote technology is a cost effective option for a wide range of operations. The previous hands-on option is seen as more problematic; considerations such as regulatory requirements and the cost and availability of radiation workers are making this option less attractive. One of the reasons for the major change has been the development of a new generation of remote handling products, i.e. robots, manipulators, tools, sensors and the associated software and hardware. These products are now easily available and are inexpensive. Adaptation of proven industrial robots to meet nuclear application requirements offers a significant cost advantage over special new designs.

At the request of the Ukrainian State Committee on Nuclear and Radiation Safety, a team of experts visited the Ukraine to advise the regulatory body on existing Agency and international requirements for the interim storage of spent fuel. The experts provided up to date information on detailed technical questions and also discussed the draft spent fuel storage licensing documents.

Handling and storage of spent fuel from research and test reactors

An Advisory Group meeting was held in connection with mounting concern about the integrity of ageing irradiated research reactor fuels in ageing storage facilities. The meeting reviewed the preliminary spreadsheets prepared for a database on the current worldwide situation and gave advice on statistical analyses of the data in the spreadsheets that would yield graphs and tables useful to decision makers and would be suitable for publication.

A regional workshop (for eastern Europe and the Middle East) to discuss the storage and management of spent fuel from research reactors was held in Budapest, Hungary, within the framework of a technical co-operation project. Its purpose was to present an opportunity for the participants to discuss their special problems and concerns about spent fuel storage with experts from Member States who have experience in the design, construction, licensing and day-to-day operation of existing safe, reliable and interim storage facilities, both wet and dry, for various types of research reactor spent fuels. The results of the workshop consisted of the identification of key areas of spent fuel storage technology in which the Agency should collect and disseminate information and a set of recommendations.


INFORMATION ON THE NUCLEAR FUEL CYCLE

Nuclear fuel cycle database

A publication on civilian industrial nuclear fuel cycle facilities was compiled from the updated Nuclear Fuel Cycle Information System database (NFCIS). The publication, which will be issued in 1995, contains information on 433 nuclear fuel cycle facilities in 46 countries. It is planned to continue with the updating of the NFCIS database and to issue it in electronic form.

Benchmarking of the nuclear fuel cycle actinide database continued. The worldwide estimates of nuclear spent fuels arisings, the quantities of actinides generated, fuel fabrication and natural uranium requirements were compared with the available data on actual inventories and requirements of the nuclear fuel cycle. A delay in verification of the model occurred because of poor availability of the actual data. The benchmarking has shown that the error of estimate of nuclear materials is within about 5%. The results of this work are being used for the preparation of various Agency documents.