No abstract available

[en] The paper (1) ''Experience of In-Service Surveillance and Monitoring of Prestressed Concrete Pressure Vessels for Nuclear Reactors'', which was presented by Irving at the York Conference in September 1975, gave details of the statutory requirements for the inspection of prestressed concrete pressure vessels in the United Kingdom, with particular emphasis on the prestressing system. Results were presented of periodic examinations under the Licensing Conditions for the vessels at the gas cooled Magnox reactors at Oldbury and Wylfa, which had been operating since 1967 and 1971 respectively, and these were discussed in relation to design expectations and future requirements. The paper also gave strain, moisture and temperature readings obtained from Oldbury PCPVs over a ten year period and compared these with predictions. The purpose of this paper is to update the information presented in the 1975 York paper by summarizing the results which have been obtained since then up to the present time (1978). The results are summarized below under six headings

[en] The invention is to simplify the fabrication of presssure vessels made of prestressed concrete so that no more special presses are needed and that there will be no eccentricities. For this purpose it is proposed to arrange the circumferential tensioning devices along the inside of an external pressure component of the vessel wall and to install radial tensioning members at various points in the pressure section of the vessel wall. The latter are needed to stress the circumferential tensioning devices. Further design details are described. (UWI)

[en] A prestressed concrete pressure vessel is described which is to be used for a nuclear reactor. It is of integrated construction, has a fixed amount of prestressing and can be used at very high internal pressures. The re-inforcement is arranged in U shapes in the concrete and the space of the reactor core and equipment is situated between the two uprights (of the U). Their ends are anchored to the outer walls of the concrete. All ends of the cross braced re-inforcement are equally distributed over the circumference of the common concrete structure along its height. (UWI)

[en] Prestressed concrete reactor pressure vessels consist of prestressed concrete bodies as structural elements, and components such as liner, liner cooling system, and thermal shield. Only a composite action of these different elements makes the use of prestressed concrete for PCRV's possible. The individual elements are subjected to extreme loads and special conditions, and have to satisfy stringent reliability requirements. This is connected with problems of new kind. (orig.)

No abstract available

[en] A simplified method for prediction of creep in concrete is presented. Predicted values are compared with actual test results and with values computed using the ACI recommended method. In addition, a study of the effect of load history on the volume change characteristics of structural concrete is presented and qualitatively compared to actual structural behavior. (orig./HP)

[en] In producing arched surfaces of diaphragm rings for large containers, especially for prestressed-concrete pressure vessels for nuclear power plants, it is of advantage to manufacture these directly on the construction site. According to the invention the, at first level, diaphragm ring is put on the predetermined place, sectionally pressed against and shaped by a shaping tool - with a profiled supporting ring as a counter-acting tool - and afterwards welded together with the annular wall sections of the large container along the shaped parts. The manufacture of single and double configurations of diaphragm rings is described. It is of advantage if shaping and mounting position coincide. (UWI)

[en] The article reviews efficient methods of accomplishing stronger bonds between concrete and outer steel shell through transverse prestressing of the concrete core. Load-strain diagrams are provided for concrete subject to uniaxial and triaxial compression. The authors describe formulas of the basic parametric point, a vertex, of a deformation curve of triaxially compressed concrete. When making estimations using these formulas, the following is considered: long-term stressing of concrete, specifics of its behavior under triaxial compression, and whether it was prestressed. (paper)

[en] The invention applies to a pressure vessel for nuclear reactors whose shell, made of cast metal segments, has a steel liner. This liner must be constructed to withstand all operational stresses and to be easily repairable. The invention solves this problem by installing the liner at a certain distance from the inner wall of the pressure vessel shell and by filling this clearance with supporting concrete. Both the concrete and the steel liner must have a lower prestress than the pressure vessel shell. In order to avoid damage to the liner when prestressing the pressure vessel shell, special connecting elements are provided which consist of welded-on fastening elements projecting into recesses in the cast metal segments of the pressure vessel. Their design is described in detail. (TK)