[en] An air filled dry store for long term storage of irradiated Magnox fuel elements has been built at Wylfa Power Station. The basic principles leading to definition of the design criteria and the associated design features adopted are described. The first three years operation of the store have been remarkably uneventful, with contamination within the store air circulation system remaining at background levels. (author)

[en] For the verification of a new concept of a prestressed concrete pressure vessel with elastic hot liner and elevated and adjustable wall temperature, an investigation program was performed, which led to the erection of a large scale prototype vessel. An extensive testing program on properties of concrete at elevated temperatures was performed and measuring techniques in the elevated temperature range were developed. The prototype vessel was subjected to an extensive test program, including a number of temperature and pressure cycles to cover the entire range of the intended operating conditions from 150⁰C to 300⁰C liner temperature and up to 100 bar. During operation the behaviour of the liner, the insulating and structural concrete and prestressing system were recorded. The results of the individual operating cycles are discussed by correlating the measured data of temperature, strain and stresses. Emphasis is given on the influences of the elevated concrete temperature and the elastic liner behaviour. (U.K.)

[en] The optimisation and substantiation of welder spacer platens for Heysham II and Torness AGR boilers are discussed. Aspects described include the analysis of the sustained and cyclic thermal loading using integrated overall structural and subcomponent models, data manipulation and assessment criteria, substantiation against aerodynamically induced vibration. Aspects of the mechanical test programme in support of the work are also described. (author)

[en] The status of ongoing structural materials programs being conducted in the U.S. to support development and deployment of the high-temperature gas-cooled reactor (HTGR) is described. While the total U.S. program includes work in support of all variants of this reactor system, emphasis is placed on work aimed at support of the steam cycle/cogeneration version of the HTGR. Work described includes activities to develop design and performance prediction data on metals, ceramics, and graphite. (author)

[en] Problems with the stability of the centrebody gag in the AGR at Hinkley Point B during commissioning resulted in a reappraisal of the centrebody gag for Hartlepool/Heysham I. The design of the mark 3 gag, development tests and further development of the design are discussed. (U.K.)

[en] a summary of progress in the U.S. HTGR Program from the perspective of utilities and energy users is given. Major points of discussion include the increasingly favorable experience at Fort St. Vrain, progress in the development of the HTGR-Steam Cycle/Cogeneration Lead Plant design, and an overview of the Utility/User proposal for Lead Plant deployment. (author)

[en] The BERSAFE finite element system has been used to examine the structural integrity of graphite core bricks. Internally produced stresses due to irradiation shrinkage and creep have been examined using a special graphite version of the program. The effect of different corrosion profiles on the load bearing capacity of a brick has also been examined. The existing approximate rule for determining brick strength using the concept of an effective weightloss has been evaluated. (author)

[en] As a contribution to improve further the operational safety of prestressed concrete pressure vessels (PCPV) a concept was developed based on a hot liner in direct contact with coolant. Thus the liner is accessible for inspection, leak detection and repair, leading to an increased availability of the plant. As a further safety consequence the concept calls for a liner which is kept in all operational and emergency conditions under elastic compression well below the yield point. This second requirement is satisfied by using specially suited high strength liner materials in combination with a simple temperature control system adjusting the vessel wall temperature in relation to the liner temperature. In this way the vessel can also be adapted readily to varying working conditions. The principles of the concept are discussed in comparison with other existing or future vessels and design details are given. (U.K.)

[en] Significant changes were implemented between 1960 and 1970 in the fuel elements used in French natural uranium-graphite-gas reactors. Safety tests conducted on heavily irradiated fuel rods in the PEGASE facility are described together with the evolution of a number of manufacturing or controlling processes. (U.K.)

[en] The heat transfer and fluid flow aspects of the development of AGR fuel from the original fuel element clusters of smooth pins proposed for but never used in the Windscale Advanced Gas-cooled Reactor to the current designs employing roughened pins is treated in detail. Topics covered include the concurrent acquisition of experimental data and the development of theoretical methods on the effects of roughness, numbers, dimensions and spacing of pins, of various design features such as support grids and braces and anti-stacking grooves, and of departures from ideal dimensions caused by pin bowing, deposits and manufacturing tolerances. Conduction in fuel and can across the intervening gap, radiation between cans and graphite, turbulent diffusion of heat, effects of varying heat flux boundary conditions and coolant physical properties are all taken into account. The philosophy behind the design of laboratory cluster experiments to check and correct the theoretical methods for predicting thermal hydraulic performance from the basic components is discussed and validation of the methods by reactor measurements is considered with due regard to the definition of nominal, peak systematic and peak random temperatures and to the difficulty of measuring temperatures in-pile. (author)