[en] Reprocessing is responsible for a large fraction of the cost of generating a unit of electricity using nuclear power. In the United Kingdom, spent fuel from Advanced Gas Cooled Reactors (AGRs) will be reprocessed at the Thermal Oxide Reprocessing Plant (THORP) being constructed at Sellafield. Scottish Nuclear, now responsible for spent fuel storage from both the Hunterston and Torness Reactors, will use THORP but is also planning to reduce cost by using a dry fuel store on the power station sites where irradiation occurred, followed, after about fifty years, by direct disposal in deep underground repositories. Dry Store facilities are being constructed on both sites. If it becomes economic to operate fast reactors at some later date, the separation of plutonium for their fuel can be undertaken then as appropriate. (UK)

[en] Reactor output and availability are closely related to fuel design and performance and the SSEB, in collaboration with the Central Electricity Generating Board have followed a policy of continuous analysis and improvement. The position reached is set out and some views on further improvements, are given. The strategy of increasing fuel burn-up on Hunterston A power station has brought significant dividends in the form of major benefits in fuel cycle cost and station availability. Significant improvements in output and availability at Hunterston B have resulted from increasing the fuel cycle burn-up, from 18 GWd/t U to 21 GWd/t U and introducing on-load refuelling. Additional benefits are soon to be obtained by further extending the burn-up to 24 GWd/t U. Further reduction of typically Pound 2-7 million/year in fuel cycle costs over the remaining life of the stations would be made by extending the burn-up to 30 GWd/t U at Hunterston B and Torness. There would be additional savings of about Pound 4 million/year in replacement fuel costs if the reactors continued to be refuelled at 30% power at Hunterston B and 40% power at Torness. (author)

[en] The use of nuclear fuel in CEGB and SSEB Magnox reactors over a period of twenty years is reviewed in relation to the operational requirements of safety, reliability and economy. AGR experience to date, although more limited than Magnox is also considered. The currently perceived scope for introducing further changes to fuel element design whilst retaining overall cost effectiveness is presented. The importance of post-irradiation examination in supporting nuclear power station operation is noted. (author)

[en] An overview of the development of CAGR on-load refuelling is presented from early experiences at Hinkley Point B and Hunterston B through the present phase of batch refuelling at low reactor power to the eventual aim of refuelling individual channels at high reactor power. The operational and economic incentives for the continued development of CAGR on-load refueling are presented. The principle elements of a refuelling safety case are described, together with a discussion of the refuelling power limitations which are imposed by the present design of fuel and plant. The potential for improvements, both in design and in the detail of the safety argument, are described with particular emphasis on the developments which are necessary to the eventual achievement of CAGR refuelling at or close to full power. (author)

[en] The refuelling equipment at Hunterston A is unique in that it removes and replaces fuel from beneath the reactor core. After initial problems the equipment has operated successfully for over 20 years and has recently been re-assessed for a further ten years' operation. Experience with Hunterston A refuelling equipment is summarized briefly in this Paper. In general terms there was comparable early experience with a quite different design of refuelling equipment installed on the B station. After initial testing, followed by a period of off-load batch refuelling, improvements have been made to the B Station refuelling equipment. These have included an additional cooling system, further lines of electrical and mechanical protection and provision of a dropped stringer reactor trip guard line operated from the refuelling machine. Following these changes, on on-load refuelling commenced in August 1982 and this regime has continued successfully since then. The changes made, operational experience gained and contribution of refuelling equipment to station availability is reviewed in this Paper. (author)

[en] This paper summarizes the fuel storage requirements in Scotland and the selection of a Dry Fuel Store of the Modular Vault Dry Store (MVDS) design developed by GEC ALSTHOM Engineering Systems Limited (GECA). A similar design of store has been selected and has been constructed in the USA by Foster Wheeler Energy Corporation in collaboration with GECA

[en] The advanced gas cooled reactor (AGR) was designed for on-load refuelling at close to full reactor power. Constraints identified during the design and safety assessment process have resulted in all operational AGRs being limited to off-load batch refuelling in early operations. The economic penalties of this operating mode have led to a major development programme aimed at better understanding all aspects of the refuelling process to enable on-load refuelling to be re-established while, at the same time, demonstrating improved safety margins in line with recent trends. The design of the AGR fuel assembly and fuel route is briefly described together with the fundamental safety objectives for handling fuel. The principal hazards are identified as fuel sleeve damage during handling, fuel tie bar failure causing a dropped fuel stringer and, ultimately, the possibility of dropping a complete fuel assembly, made worse in each case if either air can be present in the coolant or if the containment boundary is simultaneously breached. The development of safety arguments to allow on-load refuelling is described for each of these hazards with the aim of showing a low risk of occurrence and limited consequences for sleeve damage and dropped fuel stringer events, and such a remote risk of occurrence for more extreme faults that the more significant potential consequences can be tolerated. Particular emphasis is placed on design changes and operating procedures which have been introduced to improve safety margins and the further improvements which are presently under development, including those with potential for limiting the consequences of some very unlikely faults. With the safety improvements achieved and in prospect it is concluded that high load refuelling is still a realisable economic goal for the AGR without compromising modern safety standards. (author). 2 figs

[en] A comprehensive programme of research and development backs the AGR stations being built and operated in the UK today. With the basic technology proven, and the AGR system reaching maturity, the emphasis in the programme has moved to maximising plant performance and lifetime without prejudice to the good safety characteristics of the system. The research and development is shared appropriately by all sectors of the UK nuclear industry; it is co-ordinated at all levels to form a joint national programme. (author)

[en] The performance of CAGR fuel in the Electricity Board's reactors is reviewed in the light of operating experience and the post-irradiation examination assessments which have been carried out. The results show that the extrapolation of the design from the Windscale AGR prototype has been very successful. Future trends in fuel design in order to achieve the higher burn-up targets now being specified are discussed. (author)

[en] The performance of CAGR fuel in the Board's reactors is reviewed in the light of operating experience and the post-irradiation examination assessments which have been carried out. The results show that the extrapolation of the design from the Windscale AGR prototype has been very successful. Future trends in fuel design in order to achieve the higher burn-up targets now being specified are discussed. (author)