Reference to Section

THERMOHYDRAULICS OF REACTOR CORE AND SOME ASPECTS OF FAST 

High power rating and temperature impose special requirements to fast reactor thermohydraulics. Analysis of thermohydraulic issues assumes reliable hydraulic and heat transfer relationships to be worked out. As a result, distributions of the coolant flow rate, its velocity, and finally, fuel and core structure temperatures would be obtained. All mentioned parameters are required for evaluation of core integrity and mechanical behaviour. 

Method developed for predicting temperature distributions should be capable of accounting for the effects of geometrical differences and the wide range of operating conditions of the core and blanket subassemblies, as well as control rods of LMFRs. 

For prediction of subassembly coolant flow rate and temperature distributions a wide range of coolant flow and thermal convection regimes must be considered including laminar and turbulent flow natural, forced and mixed (forced + natural) convection and steady state and transient reactor conditions. 

Thermohydraulic performance prediction for the core subassemblies begins with calculation of the subassembly flow rate necessary for determining the limiting design parameter (e.g. lifetime or maximum local cladding midwall temperature) in the limiting subassembly of each flow orificing zone. 

Control and Human-Machine Interface Technologies (Proc. Int. Top. Mtg College Station, PA), Vol. 2, American Nuclear Society, LaGrange Park, IL (1996) 883-891. 

Management of Ageing of Major Nuclear Power Plant Components Important to Safety Steam Generators, IAEA-TECDOC-981, IAEA, Vienna (1997). 

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The amount of processing required in the field depends upon the composition of the gas and the temperature and pressure to which the gas will be exposed during transportation. The process engineer is trying to avoid liquid drop-out during transportation, since this may cause slugging, corrosion and possibly hydrate formation (refer to Section 10.1.3). For dry gases (refer to Section 5.2.2) the produced fluids are... 

In such cases the development scheme for the original reserves may have to be modified to make processing capacity available for the new hydrocarbons. The economics of such a scheme can be affected negatively if substantial engineering modifications have to made to meet new safety legislation. For more background to ERD refer to Section 3. 

Referring to Section XI-6B, the effect of the exclusion of coions (ions of like charge to that of the interface) results in an increase in solution concentration from rq to Rq. Since the solution must remain electrically neutral, this means that the counterions (ions of charge opposite to that of the interface) must also increase in concentration from Ro to Rq. Yet Fig. V-1 shows the counterions to be positively adsorbed. Should not their concentration therefore decrease on adding the adsorbent to the solution Explain. 

Referring to Section V-2, the double-layer system associated with a surface whose potential is some value j/o requires for its formation a free energy per unit area or a t of... 

Because of the relatively strong adsorption bond supposed to be present in chemisorption, the fundamental adsorption model has been that of Langmuir (as opposed to that of a two-dimensional nonideal gas). The Langmuir model is therefore basic to the present discussion, but for economy in presentation, the reader is referred to Section XVII-3 as prerequisite material. However, the Langmuir equation (Eq. XVlI-5) as such,... 

The representation of molecules by molecular surface properties was introduced in Section 2.10. Different properties such as the electrostatic potential, hydrogen bonding potential, or hydrophobicity potential can be mapped to this surface and seiwe for shape analysis [44] or the calculation of surface autocorrelation vectors (refer to Section 8.4.2). 

Scale-Up of Mixers For the details associated with the design and scale-up of agitated vessels, the reader is referred to Section 18 which covers this topic in great detail. The intention here is to provide only some of the generalprinciples involved which have particular apphcation to liquid-hquid extraction. 

This is a vital relationship, which reveals that during start-up and until such speed, the reactance of the motor windings / 2> the rotor current will also remain almost the same as the starting current and will fall only at near the rated speed. (Refer to the current curves in Figures 1.5(a) and (b)). The initial inrush current in a squirrel cage induction motor is very high. In a slip-ring motor, however, it can be controlled to a desired level. (Refer to Section 5.2.1.)... 

The system may be regarded as balanced when the negative sequence component does not exceed 1 % of the positive sequence component over a long period, or 1.5% for short durations of a few minutes and the zero sequence component does not exceed 1 % of the positive sequence component. Refer to Section I2.2(v) for more details on positive, negative and zero sequence com-ponents. 

Resistive losses within the current-carrying conductors, i.e. within the electrical circuit itself, caused by the leakage flux (Figure 2.6), as a result of the deep conductor skin effect. This effect increases conductor resistance and hence the losses. For more details refer to Section 28.7. 

For a higher ambient temperature, the end temperature of the winding will exceed the permissible limit by the amount the ambient temperature is higher. For example, for a class E motor, an ambient temperature of 30°C will cause the end temperature to reach I25°C as against 115°C permissible by the resistance method. For details refer to Sections 9.1 and I 1.3.2. 

A typical relay is shown in Figure 12.29(b). These relays can also be made digital to be connected to a central control system for close monitoring and control of a process. Now they can have much wider application, such as better communication and information feedback facilities, to optimize a process and maximize productivity. For more details refer to Section 13.2.. ) or contact the manufacturers. 

The generation of an asymmetrical current on an a.c. system, leads to the inference that a short-circuit condition will give rise to a d.c. component due to a shift in its zero axis. During the sub-transient state the value of the asymmetrical current will be the phasor sum of the symmetrical /sc and the asymmetrical current components. For details refer to Section 14.3.6. 

When such devices are used at more than one location in a circuit, their ratings must be meticulously coordinated to ensure isolation of the faulty circtiit alone. Refer to Section 12.4.2 and Figure 12.21 for more clarity. 

Petroleum jelly is not recommended due to its low tracking lempeialure. The minimum tracking temperature is recommended to be 200°C, the same as for the busbars during a fault. Also refer to Section 28.4.1. 

If Ihe main incoming male contacts are made ol aluminium alloy, which is normally a eompnsilioii of aluminium-magnesium and silicon, they must be provided wiili a coat of bron/e. copper and tin to give it an adequate mechanical hardness and resistance to corrosion. For more details refer to Section 27.2..5. 

In HT switchgear assemblies provide a surge arrester or a lightning arrester, wherever necessary. Also refer to Section 17.11. 

All control scheirres shown with auxiliary contactors and timers can be easily replaced with PLCs and microprocessor-based controls. Refer to Section 13.2.3 for mote details. 

To damp the transient voltages on the primary side. For markings refer to Section 15.10.1 and Figure 15.35. 15.4.5 Control transformers... 

For all such loads, the machines will require a derating. For appropriate selection it is therefore essential first to determine the eontent and magnitude of harmonies and then to consult the manufacturer for the selection of the machine. To determine the magnitude of harmonic contents, refer to Section 23.7. 

Differential proteetion (Relay Code 87) To detect a stator phase-lo-phase fault by a three-pole differential protection relay, current setting 10 0%. For scheme diagrams, refer to Section 15.6.6(1). 

To determine the fault level of the system when two or more machines are operating in parallel refer to Section 13.4.1(5). 

Protection for the machine should be such that the voltage surges and their rise limes, whenever they occur in the system, shall fall within this envelope of the machine. (Refer to Section 17.10 for a total surge protection.)... 

Equipment may be designed for more than one BIL values as noted in the various tables referred to above for motors, switchgears and other equipment. The choice of BIL for equipment for a paniciilai application will depend upon the extent of exposure the equipment may be subject to in normal service and the security level required by the system and the surge protection. For more details refer to Section 13.4.1(3). 

To assess the loss parameter of the lu tester, under normal operating eonditions (posver frequeney), the following data, typieal (for the above arresters) may also be obtained from the manufacturer. Also refer to. Section 18,2. 

The residual voltage may also be measured by a residual voltage transformer (RVT) (Figure 20.10). Refer to Section 15.4.1 for more details. 

This is not a method of providing an artificial neutral, as in the previous case, but to detect an unbalance or residual voltage (zero sequence voltage) in a three-phase three-wire or a three-phase four-wire ungrounded system. The residual or zero sequence voltage that may appear across the open delta will be the reflection of an unbalance or a ground fault in the system (Figure 20.10). Also refer to. Section 15.4.1 for more details. 

A directional G/F relay basically is a power-measuring device, and is operated by the residual voltage of the system in conjunction with the residual current detected by the three CTs used for non-directional protection, as shown in Figure 21.19. To provide directional protection, therefore, a residual VT is also essential, in addition to the three residual CTs. The voltage phasor is used as a reference to establish the relative displacement of the fault current. In healthy conditions, i.e. when the current flows in the right direction. = 0. (refer to. Section 15.4.3 for details), and the relay remains inoperative. The relay operates only when the current flows in the reverse direction. 

Where necessary, surge arresters may be used to dampen the high transient switching voltages. Refer to Section 17.11. 

Coupling capacitor or CVT is used when it is required lor measurement and protection. For details on CVT refer to Section 15.4.1.3,... 

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