[en] To satisfy requirements of industries such as conventional and nuclear power, for heavy gauge plate in large plate weights and to exceptionally high standards of quality and reliability, British Steel Corporation have commissioned a three phase Electroslag Refining (ESR) plant. This unit has a designed production capability of 8,000 tonnes per annum in finished plate weights up to 42 tonnes. An extensive property evaluation programme is being carried out on plates in the thickness range 50 to 150 mm produced from ESR slabs in the range 10 to 34 tonnes. Results obtained to date confirm the exceptionally high levels of cleanliness and isotropy associated with this process coupled with very high levels of through thickness ductility. These properties clearly have important implications for fabricators of heavy steel plate and it is intended that through joint evaluations of ESR material their full technical and commercial advantages will be realised. (author)

[en] This presentation describes procedures that Combustion Engineering has developed to fabricate the steam generators for the System 80sup(TM) Nuclear Steam Supply System, C-E's standard 3800-MWt NSSS. The System 80 steam generators are vertical U-tube steam generators, the type most commonly used in nuclear steam supply systems with pressurized water reactors. While many of the procedures are common to the fabrication of all U-tube steam generators, some are unique procedures of Combustion Engineering's, developed by C-E in advancing the art of fabrication and in determining the best ways to fabricate steam generators of the System 80sup(TM) NSSS design. (author)

[en] The way in which site construction activities on earlier A.G.R.'s were minimised by the shop prefabrication of the liners as panels is described. It is intended to use the same form of construction for the liners for Heysham II and Torness. (author)

[en] It is difficult to observe molten weld pools in arc welding processes whilst welding especially for mechanised systems and remote applications, as may be required for new construction and repair of existing components on nuclear reactors. The paper will describe two techniques of measuring weld pool surface size during welding. One is based on a self scanned photodiode array with an arc interruption system. The output from this system is ideal for control systems, particularly where feedback is required to minimise weld disturbances. The second is based on an optical filtering technique and is more suitable where a visual display is required for monitoring purposes. The techniques have enabled a significant improvement in the study and observation of weld pool behaviour and measurement. (author)

[en] The paper is concerned with the explosive plugging of the boiler and reheater circuits of the AGR pod boilers for the Hartlepool and Heysham power stations. A point charge system for the boiler circuit plugging and a rim charge system for the larger plugs in the reheater circuit are described. The ligament distortion due to plugging has been overcome by a simple support bung. The paper also describes the design and development of a remote controlled manipulator and the various tool heads, which are required to perform all the various operations in reheater tube plugging. (author)

[en] Most proposed fast reactor designs utilise heavy section large diameter austenitic/ferritic joints in the secondary circuits. The design life of such joints is open to doubt and service experience in existing reactor systems is not sufficient to support the case for one specific design. Transition joints of many different designs have been used in conventional fossil fired plant for many years and this paper reports the current operating experience in the CEGB Midlands Region. In all, 10 different designs have been used. These are described and the service experience for each type summarised. External cracking on the ferritic side of the interface was found in the Kellogg (I and II) and the English Elactric (I and II) type joints, both fabricated with austenitic weld metal. Cracks have not yet been observed in the Jessop-Saville graded or the nickel based weld metal designs although the service times are short, > 20,000 h. At present, service experience on conventional plant indicates that no design of joint can be guaranteed to be crack free after 100,000 h at 565⁰C and these welds between 2 1/4 Cr1Mo and austenitic steels, should be sited where there is access for inspection and possible repair. (author)

[en] In the manufacture of heavy nuclear components, the efficiency and quality of the overlay welding are of great importance. In a BWR reactor for example about 60% of the total weld metal weight is overlay welding. To enable an accurate inservice inspection of the components a smooth weld surface and regular fusion line are also essential. As a further development and complement to already existing methods for overlay welding two procedures utilizing a plasma torch and filler wire (phi 1.6 mm) are described. The welding procedures are developed to fulfil the requirements for welding on the quenched and tempered low alloyed steels used for nuclear components. Production welding under normal workshop conditions has been performed with the procedures and the experience gained is related. (author)

[en] Heavy section austenitic steel castings are used for the primary system in the Westinghouse PWR NSSS. Material, non-destructive examination, and fabrication requirements for these castings, which meet section III of the ASME Code, together with other special requirements will be reviewed. These components include primary system piping, valve bodies, and pump casings. The aspects covered will include the factors which influenced the choice of castings, description of the different casting techniques, shop experiences during manufacturing, and service performance. (author)

[en] The Superphenix steam generator is made of Alloy 800 tubing. The chemical composition of material is kept within narrow limits in order to obtain adequate corrosion behaviour, good mechanical properties and also good weldability. An automatic TIG orbital process has been adopted for the butt welds of the steam generator tubes using Inconel 82 filler metal and fabrication of butt welds is now in progress with the commercial process for Superphenix. (author)

[en] This paper describes the application of novel feedback control techniques to the welding of the thermal sleeve joint for fast reactor heat exchangers. It is required to produce a full penetration Tee-butt weld between a tube and flange, without fusion into the tube bore. Two complementary feedback control systems are therefore employed: (a) the penetration of the Tee-butt weld is ensured by viewing the back of the weld with photodiodes, the signals from which control the current and travel speed; and (b) protrusion into the bore is prevented by measuring the radiation from the bore surface by means of photodiodes: the signal from these is applied to a magnetic arc deflector, which controls the position of the arc with respect to the tube to maintain the required bore temperature. The system has been demonstrated experimentally, and it is shown that the feedback control system enables consistently good quality welds to be made in a situation where quality control is notoriously difficult. (author)