Prestressed concrete reactor vessels

VG 400 reactor plant was intended for both electricity production and process heat. The heat is transferred to a methane steam reformer and hydrogen gained is used for ammonia production. The reactor plant parameters are given in Table 3. The key components of the reactor plant are housed in the prestressed concrete reactor vessel (Fig 1). 

Fig. 7. Comparison of several prestressed concrete reactor vessels.

The ideas and features that have emerged during the study as possible aids to decommissioning and dismantling of prestressed concrete reactor vessels fall into four main categories. These are ... 

Density locks (thermal barriers), siphon breakers, and wet thermal insulation Prestressed concrete reactor vessel Long-term passive residual heat removal system Reactivity control without control rods... 

PCRV means prestressed concrete reactor vessel. 

Figure 5.3 is a cut-away view of the FSV reactor core in a prestressed concrete reactor vessel (PCRV), with control rods inserted into the top of the core. The PCRV acted as a pressure vessel, containment, and biological shield. The bottom head had 12 penetrations for the steam generator modules, four penetrations for the helium circulators, and a large central opening for access. A 3/4 in.-thick carbon steel liner anchored to the concrete provided a helium-tight membrane. Two independent systems of water-cooled tubes welded to the concrete side of the liner and kaowool fibrous insulation of the reactor side of the liner limited the temperatures in both the liner and the PCRV. 

The bumup measuring reactor was a graphite moderated thermal reactor with a rated output of 500 W, arranged in the reactor hall below the prestressed concrete reactor vessel. The reactor core (1.0 m 1.2 m 1.1 m) consisted of various graphite plates provided with grooves for accommodation of the 767 strip-shaped fuel elements. The fuel elements have a rectangular cross-section (15 mm 1.1 mm) and a length of between 89 and 711 nun. They contain 93% enriched uranium in a U-Al alloy (20% uranium, 80% aluminum). Total uranium content of the core was 3.9 kg. 

The THTR nuclear power plant was equipped with a partly shielded dismounting and inspection equipment. This equipment was used for work on the fuel circulating system, the helium purification system, the absorber rods and for the inner inspection of the prestressed concrete reactor vessel. In parts, this equipment had already been in use and was therefore contaminated. 

Margen, P. H. and Menon, S. Preparation for exploitation of prestressed concrete reactor vessels for light water reactors. NUCLEX 72, Basef 1972. 

FIP Federation Internationale de la Precontrainte, state-of-art report Design and construction of prestressed concrete reactor vessels, June 1978. 

The state-of-the-art review of the prestressed concrete reactor vessels covers, in this chapter, historical development, the available methods of analysis and design procedures of vessels and their elements such as concrete, prestressing systems, conventional steel, vessel steel liner and anchorages including penetration liners. Each section is presented with a clear-cut discussion on its contents. 

Fig. 5.16 Fort St. Vrain prestressed concrete reactor vessel (Pa = 18 HN/m )...

The concept of shear failure in thick sections of brittle material such as concrete is obscure and in many instances it could be misleading. One clear concept is that concrete failure can easily be put to the test if it is assumed that it is governed by the principal tensile and compressive stress caused by the so-called shear . The problem with this simple concept is the limitation on these stresses. In the prestressed concrete reactor vessels due to variations in loading conditions these principal stresses at any time at any point may vary from biaxial and triaxial compression to compression—tension—tension in any combination. These instant changes can bring about any kind of failure. For example, it may be pure flexural-cumnominal shear failure or principal tensile or compressive failure or by the so-called shear compression failure or in any combination of these. It must be borne in mind that the type of failure is directly related to the vessel overall layout. Before discussing the individual sample examples, it is necessary to know what the above-mentioned terms are and what effect they have on the prestressed concrete vessels. 

Good Paster D. W. et al. Design and analysis of multi-cavity prestressed concrete reactor vessels. Nuclear Enq. Des. Vol. 46, 1978, pp. 101-107. 

Bender M. A status report on prestressed concrete reactor vessels, pressure vessel technology. Nuclear structural engineering. Vols. 1, 2, 1965, pp. 83-90, pp. 206-223. 

Jaeger T. A. Note on stress analysis of prestressed concrete reactor vessels. Nuclear structural engineering I, 1965 pp. 133-136. 

Gomez A. E. et al. Lumped parameter analysis of cyhndrical prestressed concrete reactor vessels. University of Illinois, Chicago Vols 1,2, USA, 1968. 

Bangash Y. Prestressed concrete reactor vessel Timesaving ultimate load analysis. J. Inst Nucl. Engg Vol. 13, No. 4, 1972. 

Bangash Y. A basis for the design of bonded reinforcement in the prestressed concrete reactor vessels Paper 7478S. Supplement (viii). Inst, of Cu. Enqrs 1972. 

Comm J. M. and Smith J. E. Use of small models in design and analysis of prestressed concrete reactor vessels ORNL-4346, IJ.S.A, 197... 

Paul et al. Mortar models of prestressed concrete reactor vessels, J. St. Dir. ASC E, February 1969. 

Prestressed concrete reactor vessels (PCRVs) have been recently adopted as primary containments for both the advanced and high temperature gas-cooled reactors. Among all the problems associated with this structure, the knowledge of predicted movements in certain parts of the vessel is still ambiguous. This chapter attempts to create a basis for the design of many plant components in relation to their built-in tolerances. Although symmetric and absolute relative movements... 

A simplified approach for computing temperature distribution in the steel liner and concrete of prestressed concrete reactor vessels has been presented. A provision is made in this analysis for estimating the cooling pipe pitches, insulation thicknesses and conductances. A 3D finite-element analysis has been carried out for comparison and validation of the above analysis. Notation... 

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