Primary System Design

The circumscribed diameter of the core is 2.4 m. The core and primary system design data is summarized in Table XVni-6. 

Serpante, J.P. et.al., The EFR Primary System Design Advances and Improvements. Proc. Int. Conference on Fast Reactor and Related Fuel Cycles, Kyoto, Japan, 28 October - 1 November 1991. 

An integrated primary system design. The reactor vessel contains the whole primary circuit including steam generators (SGs) and control rod drive mechanisms (CRDMs). The design achieves a compact primary system and containment. It also eliminates initiating events for loss of coolant (LOCA) and control rod ejection accidents, which makes it possible to realize a simple safety design without safety injection and containment spray systems, Fig. VI-1. 

The hybrid heat transport system (HHTS). The MR employs natural circulation and a self-pressurized primary coolant system, altogether resulting in a simple primary system design without reactor coolant pumps and pressurizer it also reduces maintenance requirements. In addition, the use of HHTS concept makes it possible to reduce the size of the reactor vessel. The HHTS is a kind of two-phase natural circulation system. The coolant starts boiling in the upper part of the core two-phase coolant flows up in the riser and is condensed and cooled by SGs. Such design approach increases coolant flow rate and thus, reduces the required height of the reactor vessel (RV) to transport the heat from the core, Fig. VI-2. 

The small containment vessel and reactor building achieved by the integrated primary system design and simplified systems. 

By adopting the integrated primary system design and the HHTS without reactor coolant pumps and main coolant pipelines, the possibility of accidents that may cause fuel failure, such as a large-break loss of coolant accident (LOCA), rod ejection (R/E), loss-of-flow (LOF) and locked rotor (L/R), is essentially eliminated. During the normal operation, the water level in the reactor vessel is controlled by injection from the charging pumps. However, since the diameter of the pipes connected to the primary system (reactor vessel) is less than 10 mm, water level can be maintained to submerge the top of the core without any injection. 

Owing to the low chemical reactivity of lead with water, in contrast with sodium in the SFR, current LFR projects generally dispense with the intermediate loop between the primary system and the steam—water loop or other power conversion equipment. In fact, LFR primary system designs, especially in the past, have been very similar to those normally adopted for the SFR, but with the replacement of the intermediate heat exchanger with the SG or, in the case of SSTAR, with the lead—CO2 heat exchanger. 

While the European design efforts leading to the ELSY/ELFR/ALFRED series of LFR concepts were being conducted, parallel efforts were being pursued to develop an array of innovative designs. Projects in Russia, Japan, Korea, the USA, and China concurrently pursued a variety of different concepts with considerable innovation and creativity with respect to primary system design as well as the entire reactor systems. 

In summary, the primary system designs of the GIF reference reactors (as well as a multitude of other design concepts in various stages of development) provide a range of different approaches to primary system design appropriate for LFR reactor systems. 

The high melting temperature of lead (327°C) requires that the primary coolant system be maintained at temperatures to prevent the soUdihcation of the lead coolant or at least to maintain a recirculation at the core level to allow its cooling. The use of a pool-type configuration and appropriate primary system design can provide a safe and effective resolution to this issue. 

Chemical Regeneration. In most MHD system designs the gas exiting the toppiag cycle exhausts either iato a radiant boiler and is used to raise steam, or it exhausts iato a direct-fired air heater and is used to preheat the primary combustion air. An alternative use of the exhaust gas is for chemical regeneration, ia which the exhaust gases are used to process the fuel from its as-received form iato a more beaeftcial oae. Chemical regeaeratioa has beea proposed for use with aatural gas and oil as well as with coal (14) (see Gas, natural Petroleum). 

A current vehicle fuel system designed for evaporative emission control should address enhanced SHED, running loss, and ORVR emission level requirements (see Table 1). A typical vehicle fuel system is shown in Fig. 4. The primary functions of the system are to store the liquid and vapor phases of the fuel with acceptable loss levels, and to pump liquid fuel to the engine for vehicle operation. The operation of the various components in the fuel system, and how they work to minimize evaporative losses during both driving and refueling events, is described below. 

The electrical distribution system design and equipment selection must consider requirements of the utility company for protection and metering. Available short circuit currents from the utility distribution network to the primary of the facility s main transfoiTner must be considered in selecting circuit protection devices for the facility distribution system. 

Oil-field chemistry has undergone major changes since the publication of earlier books on this subject Enhanced oil recovery research has shifted from processes in which surfactants and polymers are the primary promoters of increased oil production to processes in which surfactants are additives to improve the incremental oil recovery provided by steam and miscible gas injection fluids. Improved and more cost-effective cross-linked polymer systems have resulted from a better understanding of chemical cross-links in polysaccharides and of the rheological behavior of cross-linked fluids. The thrust of completion and hydraulic fracturing chemical research has shifted somewhat from systems designed for ever deeper, hotter formations to chemicals, particularly polymers, that exhibit improved cost effectiveness at more moderate reservoir conditions. 

New promising designs have been proposed such as the one under an extensive industrial study on plate IHX to develop fabrication, ISI methods and a design standard for gas reactors [51], and another plate-type design for the indirect cycle reactor plant [52]. These works demonstrate that a plate IHX would simplify integration in the primary system because of its drastically reduced size. 

The primary donor in Photosystem I P700 is thought to be a special pair of chlorophyll a molecules. Katz and Hindman (18) have reviewed a number of systems designed to mimic the properties of P700 ranging from chlorophyll a in certain solvents under special conditions where dimers form spontaneously (19) to covalently linked chlorophylls (20). Using these models it has been possible to mimic many of the optical, EPR and redox properties of the in vivo P700 entity. 

Carbon Monoxide Carbon monoxide is a key intermediate in the oxidation of all hydrocarbons. In a well-adjusted combustion system, essentially all the CO is oxidized to CO2 and final emission of CO is very low indeed (a few parts per million). However, in systems which have low temperature zones (for example, where a flame impinges on a wall or a furnace load) or which are in poor adjustment (for example, an individual burner fuel-air ratio out of balance in a multiburner installation or a misdirected fuel jet which allows fuel to bypass the main flame), CO emissions can be significant. The primary method of CO control is good combustion system design and practice. 

The primary purpose of such systems is the extinguishment of fire in the protected hazard area. For this purpose, suitable foam-solution discharge densities should be provided by system design and by provision for adequate supplies of air/water at suitable pressures. 

The primary purpose for this discussion of EF T of the molecules is to provide the one who employs a trace chemical sensor with means to increase the probability of locating and identifying the source. A thorough understanding of the transport processes presents options to the system designer and the operator to make a system more successful. 

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