[en] Quality assurance for ensuring the requisite quality of primary system components includes object-related and system-related measures. The object-related measures include assessment of the fabrication engineering preconditions, checking the documentation relating to design, ordering and fabrication, and supervision of the important fabrication steps and of testing. This work is carried out by independent experts and inspectors and by the KWU. The system-related quality assurance is aimed at creating the organisational preconditions for faultless fabrication, taking also into account the time schedules and costs. This work is carried out by the KWU. (orig.)

[en] The main activities developed during the year of 1988 are described. (E.G.)

[en] A centrifugal pump for moving a fluid such as the coolant fluid of a nuclear reactor is described. It comprises a volute made up of an enclosure with openings for the inlet and outlet of the fluid, a removable suction pipe fixed on the volute on a level with the fluid inlet opening and directed towards its interior, a rotor located inside the volute fixed on a shaft passing through an opening provided in the volute wall as well as an annular diffuser having as circular symmetry axis the rotation axis of the rotor, arranged around the rotor inside the volute and fixed on the suction pipe at one of its ends. The examination and maintenance operations of the internal components of the pump can be carried out with suitable testing appliances introduced through the opening through which the rotor passes

[en] In the design of nuclear power stations all stresses on the pressure-bearing enclosure in respect of their effect on component strength and integrity are investigated. In addition, local and global monitoring during operation is carried out, in order to detect also those stresses which have been hitherto unknown or are caused by malfunctions of components. In this way a realistic assessment of the condition of the pressure-bearing enclosure is possible and any irregularities which can imply malfunctions of components or physical effects not hitherto known can be detected early. (orig.)

[en] A gland is proposed of the valve spindle designed for radioactive or otherwise harmful media, such as in nuclear power plant primary circuits. The gland is installed in the valve cover and consists of a primary and a secondary part and of a gland case partitioning the gland space into two chambers. The bottom face of the gland case is provided with a double-sided collar for controlling the elements of the bottom primary gland while the top face is provided with a removable flange. (M.S.)

[en] Whenever the stress analysis for some secondary pipes is not necessary, it is desirable to uncouple the main system from these secondary pipes. The uncoupling, however, is only allowable on the basis of some acceptability criteria defined in terms of mass and frequency ratios of the main system to the secondary system. At the request of the authorities, it often becomes necessary, at a later date, to also investigate the secondary pipes. The important reduction of costs, the elimination of the effect of ill-conditioning that are more serious in large systems with large differences in the stiffnesses of the elements, the exceeding of the program or computer capacity can be arguments for a separate stress analysis of the secondary uncoupled system. For the stress analysis of the secondary uncoupled system, it is generally not possible to neglect the influence of the main system. This paper presents a method to separately perform the stress analysis of the secondary uncoupled piping systems from the main system already calculated. (orig.)

[en] A hydrostatic radial pump is described characterized by the fact that part of the medium off-taken from delivery is used as a lubricating medium. Two additional bodies are placed alongside a hydrostatic bearing with coils in between them and the pump shaft; the coils have an opposite pitch. The feed channel for the hydrostatic bearing pocket is linked to delivery. The coil outlets are connected to the pump suction unit. Two rotating coils placed alongside the hydrostatic bearing will considerably simplify the communication channel design and reduce the dependence on the pump shaft deflections. The addition of another rotating coil in the close vicinity of the pump shaft or directly on the shaft further increases the efficiency. The bearing can be used in designing vertical circulating pumps for the cooling circuits of nuclear reactors. (J.B.)

[en] The demands are presented on the material properties of tubes used for building reactors and manufacturing equipment of nuclear power plants. These materials are subjected to long-term straining, to neutron flux which affects their physical, chemical and mechanical properties. The composition of the coolant and minute admixtures in it affect the corrosion of the tubes and released hydrogen causes embrittlement. Sodium reacts with certain alloying components. Certain types of austenitic steels, alloys and cladding materials for thermal reactors are given. The most frequently used are Zircalloy 2 and 4. The regulations are given issued by builder of reactors for manufacturers of tubes, for testing, cleaning, packing, etc. A brief description is also given of the manufacture of tubes by extrusion by Schoeller and Bleckmann. (Oy)

[en] The Bureau of nuclear construction control, by reason of its mission, is called upon to verify that the companies involved in the realization of power plants have a satisfactory organization of quality. The very perceptible evolution observed over the past few years bears on a better definition of the needs in this field and on a greater strictness in the elaboration of documents. The objective for the years to come shall be to maintain the present situation, which on the whole is satisfactory, and at the same time simplifying the present systems often burdensome. Independently of this search for simplification, it will be necessary to remain vigilant regarding certain possible deviations. In particular, it is important to avoid the risk that documents, whose initial aim is to prove that the product taken into consideration is suitable, conceal what is really being done

[en] In the course of a fatigue analysis of components of nuclear power plants under plastic stress, extension enhancement factors Ke are employed for establishing the plastic extension oscillation width from elastically calculated stresses. Starting from a criticism of the currently practised method according to the ASME Code, a modification is proposed. (orig.)