Component design, PWRs

VI.6] ASSOCIATION FRANgAISE POUR LES REGLES DE CONCEPTION ET DE CONSTRUCTION DES MATERIELS DES CHAUDIERES ELECTRO-NUCLEAIRES (AFCEN), French Nuclear Construction Code RCCM Design and Construction Rules For Mechanical Components of PWR Nuclear Facilities, Subsection Z, Appendix ZG, Fast Fracture Resistance, Framatome, Paris (1985). 

RCCM (2002), Design and construction rules for mechanical components of PWR nuclear islands, RCC-M, AFCEN, Paris. 

A variety of nuclear reactor designs is possible using different combinations of components and process features for different purposes (see Nuclear REACTORS, reactor types). Two versions of the lightwater reactors were favored the pressurized water reactor (PWR) and the boiling water reactor (BWR). Each requites enrichment of uranium in U. To assure safety, careful control of coolant conditions is requited (see Nuclearreactors, water CHEMISTRY OF LIGHTWATER REACTORS NuCLEAR REACTORS, SAFETY IN NUCLEAR FACILITIES). 

SMART (System-integrated Modular Advanced ReacTor) is an advanced integral PWR(Pressurized Water Reactor) tihat produces 330MWt at fiill power. Major primary components are housed within a single pressure vessel. New, advanced and innovative features are incorporated in the design to provide the reactor with significant enhancements in safety, reliability, performance, and operability. Major design and safety characteristics of SMART can be summarized as follows ... 

This section provides a description of Western PWR RPVs which includes design features, applicable material specifications and differences among the various RPV components, and describes the characteristics of PWR RPV embrittlement. 

In the development of the MARS design, well-proven technological features of most experienced PWR s were extensively maintained for all components of the primary circuit (geometry of fuel rods lay-out of the primary cooling system type of control rods and of control rod drive mechanisms most core internals etc.). 

The Rolls-Royce prefabricated nuclear plant is a 300 MW power station mounted on two barges. The nuclear Island is contained on one barge and the conventional plant on the other. Essentially the nuclear Island consists of a compact 4-loop PWR using standard components and designed to meet UK safety criteria with appropriate equipment redundancy and diversity (Fig. 1). The reactor has been designed to take full advantage of PWR safety Improvements since the Three Mile Island incident in 1979. Basic data are given in Table 1. 

The MASLWR design implements proven fuel technology and many standard components. Fuel and replacement components could be obtained from several different vendors. Additional advancements in PWR fuel design and materials would be readily applicable to MASLWR. Furthermore, the MASLWR is designed to operate at lower temperatures and pressures than a typical PWR, reducing the stress placed on these advanced materials. 

These characteristics relate to the RCS component of a PWR that is designed to maintain the RCS operating pressure and to compensate for any changes in reactor coolant volume and pressure with temperature. The pressurizer is the only component of the RCS of a PWR which contains steam. For all reactors that do not use a pressurizer, data providers should enter... 

Several PWR plants have been provided with specific lines and an associated automatic logic to prevent the occurrence of water hammer in the Steam Generators feed-water lines. In other PWR plants, the operating procedures have been modified for the same purpose. New steam generators, used as replacement components in some plants, have a specific design against water hammer failures. 

The plant is designed with significantly fewer components and significantly fewer safety significant components than a current PWR of a comparable size. 

The core and major components of the APIOOO are to designs proven by their use in currently operating Westinghouse PWRs ... 

The Westinghouse APIOOO design employs construction methods and a plant layout that are conducive to safe operations during construction. Much ofthe design is modular which allows the build and test of sub assemblies to be undertaken in a factory environment. The size of the plant and the number of components is also significantly less than previous generations of PWRs. These approaches reduce site construction work and the risks from those activities. Modular constmction in a factory environment also has a positive effect on product quality, which improves safety and facilitates reduced maintenance requirements during the operation of the plant. 

One reason this design was adopted was due to reasons of transport. The Soviet Union was a vast country, and their preference was for a design where the components could be readily transported by rail. The RBMK did not have a massive reactor pressure vessel like the BWR or PWR designs. Hence, the RBMK could be built... 

The RA-8 critical facility has been designed and constmcted to measure neutronic parameters typical of the CAREM core. It provides a reactor shielding block and a reactor tank that can be adapted to contain custom designed reactor cores. Experiments were performed using fuel rods of the same radial geometry and pitch as in the CAREM-25 fuel element. Components of the neutronic calculation lines were validated with the use of data for VVER type reactors obtained in the experiments at ZR-6 Research Reactor (Central Research Institute for Physics, Academy of Sciences, Hungary) and data for PWR critical experiments. 

The general design of both types of light water reactor has already been illustrated diagrammatically in Fig. 7.1. The layout of the main components of the primary circuit of a PWR is shown in Fig. 12.3. The circuit consists of the core vessel itself, together with the four steam generators and main... 

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