Raw materials for reactor fuels
Comprehensive studies were carried out during the year on: uranium supply and demand; the modelling of fuel under extended burnup; a quality assurance system for dry storage technologies; preparation of spent research reactor fuel for shipment back to its country of origin; the safe handling and storage of plutonium; and the corrosion of zirconium based alloys in nuclear power plants.
A guidebook to accompany the Agency map World Distribution of Uranium Deposits was published. Preparation of the map and the guidebook included development of a database containing detailed information on the location, reserves, grade of ore, geology and status of each deposit.
The IAEA-OECD/NEA report Uranium 95 - Resources, Production and Demand (the 'Red Book') was published in 1996. It is the first truly global edition of the Red Book, with information on 54 countries.
After falling nearly 50% from 1988 to 1994, world uranium production in 1995 was around 34 000 t U, representing an increase of 8% over 1994 production - the first increase in production since 1988. Australia, Canada, France, Kazakstan, Namibia, Niger, the Russian Federation, South Africa, the USA and Uzbekistan each produced over 1000 t U and together accounted for 90% of world uranium production. Worldwide power reactor requirements are estimated to be about 62 000 t U per year, which is about 28 000 t U greater than world uranium production. While 55% of the demand is being met by current production, the balance is being filled by inventory drawdown. In the near future, as stockpiles become depleted, demand will be met by increased uranium production and blended down high enriched uranium from dismantled warheads.
At a Technical Committee meeting held in Vienna, experts from 30 countries discussed the application of geoscientific research to such problems as the high concentration of radioelements in some buildings and the rapid detection of isotopes resulting from nuclear power plant failures. They also underlined the importance of updated airborne and ground gamma spectrometry data in the early detection of environmental problems and recommended that a set of standardized units be adopted for expressing levels of radioactivity from various surveys.
The validity and predictive capabilities of fuel performance codes were compared and assessed in a CRP on Fuel Modelling under Extended Burnup (FUMEX), which involved a blind exercise with experimental data provided by the OECD Halden Reactor Project. Nineteen different codes were studied. As a consequence of FUMEX, elementary models and codes have been improved and validated. In addition to FUMEX, a 'mature' fuel modelling code (TRANSURANUS) has been transferred to developing Member States, together with guidance on application of the code to reactor operation and safety assessments. Compilation of a database of well defined experiments suitable for code validation was started in association with the OECD/NEA.
A CRP on the modelling of transport of radioactive substances in the primary circuit of water cooled reactors was initiated in 1996. The aim of the study is to improve computer codes designed for the modelling of radiation field growth, to understand the mechanisms involved and to determine appropriate countermeasures.
Design, materials performance and safety margins of fuel and pressure/coolant tubes were the topics discussed at a Technical Committee meeting held in Vienna on channel reactor fuel. Even though the design and characteristics of various channel type reactors differ considerably, specific common features, such as coolant boiling and on-power loading, were analysed. It was concluded that current operating conditions for both the fuel and fuel channels satisfy requirements. An analysis of data presented internationally for the first time on RBMK fuel and fuel channels led to recommendations for further R&D to improve fuel utilization and operational flexibility.
Under the terms of the 'Record of Decision on a Nuclear Weapons Non-Proliferation Policy Concerning Foreign Research Reactor Spent Nuclear Fuel', published on 13 May 1996 by the US Department of Energy, the first shipments to the Savannah River of US origin foreign research reactor spent nuclear fuel have already begun. Since many of the Member States involved in the programme will be shipping back spent fuel for the first time, a guidelines document on the technical and administrative preparations required for the shipment of research reactor spent fuel was prepared. It will be used in a training course on the same topic to be held at the Argonne National Laboratory in early 1997 and will be updated as experience with the shipments is accumulated.
As part of a CRP on irradiation enhanced degradation of materials in spent fuel storage facilities, a review of the durability of fuel cladding materials in wet storage was prepared. It concludes that zirconium based cladding materials perform very well in wet storage, while aluminium alloys only perform well in water of optimum quality. Stainless steel cladding can degrade as a result of intergranular stress corrosion cracking if it was previously sensitized in the reactor.
Worldwide interest in separated civil plutonium continues to grow as global inventories increase. Refined estimates of present and future separated plutonium inventories were published in the IAEA Yearbook 1996.
Important preparatory work was carried out for an international symposium entitled 'Nuclear Fuel Cycle and Reactor Strategy: Adjusting to New Realities', to be held in co-operation with the European Commission, the OECD/NEA and the Uranium Institute in June 1997. Six working groups were formed to cover all aspects of plutonium management and related fuel cycle and reactor strategies. As part of preparations for the symposium, a new generic model, which takes into account the recycling of uranium and plutonium from spent fuel in power reactors, was developed to calculate global fuel cycle requirements, spent fuel arisings and the production of plutonium in reactors up to the year 2050.
An updated guide on the Nuclear Fuel Cycle Information System (NFCIS) was published eight years after an earlier version. It is an international directory of civilian nuclear fuel cycle facilities that provides information on existing and planned facilities throughout the world. NFCIS is an important reference work for the nuclear industry and currently contains information on 422 civilian nuclear fuel cycle facilities in 46 countries.