Reactivity devices

The reactivity devices employed for the above functions of RRS are as follows ... 

The liquid reactivity devices consist of the light water zone control units and the liquid poison addition system. 

A battery is a reactive device, meaning that it behaves differently when applying a pure DC (direct current) load as opposed to an AC (alternating current) or pulsed load. A battery consists of resistive (R), capacitive (C), and inductive (L) resistance. The term impedance (Z) includes all three parameters in one, displayed in an ohmic value that varies with frequency. 

For each class of PIE it may be sufficient to analyse only a limited number of bounding initiating events that can then represent a bounding response for a group of events. The basis for these selected bounding events should be described in this section. Those plant parameters important to the outcome of the safety analysis should be identified. These would typically include reactor power and its distribution core temperature cladding oxidation and/or deformation pressures in the primary and secondary system containment parameters temperatures and flows reactivity coefficients reactor kinetics parameters and the worth of reactivity devices. 

Shutdown systems have a separate acceptance criterion. Modem PHWRs have two independent, redundant and diverse shutdown systems with separate logic and reactivity devices from the control system and from each other [5]. Each system, on its own, must be capable of shutting the reactor down after any accident, independently of the mitigation provided by the normal reactivity control devices. In general, two diverse trip parameters are required on each shutdown system for each accident over the range of operating conditions (unless it is impracticable or detrimental to safety to provide dual parameter coverage). As a result, it is not required to perform analysis of either transients or accidents without shutdown [6],... 

RRS. Reactor regulating system. Digital system that controls reactivity devices and the major process systems. 

Another powerftil class of instmnientation used to study ion-molecule reactivity is trapping devices. Traps use electric and magnetic fields to store ions for an appreciable length of time, ranging from milliseconds to thousands of seconds. Generally, these devices mn at low pressure and thus can be used to obtain data at pressures well below the range in which flow tubes operate. 

Clusters are intennediates bridging the properties of the atoms and the bulk. They can be viewed as novel molecules, but different from ordinary molecules, in that they can have various compositions and multiple shapes. Bare clusters are usually quite reactive and unstable against aggregation and have to be studied in vacuum or inert matrices. Interest in clusters comes from a wide range of fields. Clusters are used as models to investigate surface and bulk properties [2]. Since most catalysts are dispersed metal particles [3], isolated clusters provide ideal systems to understand catalytic mechanisms. The versatility of their shapes and compositions make clusters novel molecular systems to extend our concept of chemical bonding, stmcture and dynamics. Stable clusters or passivated clusters can be used as building blocks for new materials or new electronic devices [4] and this aspect has now led to a whole new direction of research into nanoparticles and quantum dots (see chapter C2.17). As the size of electronic devices approaches ever smaller dimensions [5], the new chemical and physical properties of clusters will be relevant to the future of the electronics industry. 

Another troublesome aspect of the reactivity ratios is the fact that they must be determined and reported as a pair. It would clearly simplify things if it were possible to specify one or two general parameters for each monomer which would correctly represent its contribution to all reactivity ratios. Combined with the analogous parameters for its comonomer, the values rj and t2 could then be evaluated. This situation parallels the standard potential of electrochemical cells which we are able to describe as the sum of potential contributions from each of the electrodes that comprise the cell. With x possible electrodes, there are x(x - l)/2 possible electrode combinations. If x = 50, there are 1225 possible cells, but these can be described by only 50 electrode potentials. A dramatic data reduction is accomplished by this device. Precisely the same proliferation of combinations exists for monomer combinations. It would simplify things if a method were available for data reduction such as that used in electrochemistry. 

The requirements of thin-film ferroelectrics are stoichiometry, phase formation, crystallization, and microstmctural development for the various device appHcations. As of this writing multimagnetron sputtering (MMS) (56), multiion beam-reactive sputter (MIBERS) deposition (57), uv-excimer laser ablation (58), and electron cyclotron resonance (ECR) plasma-assisted growth (59) are the latest ferroelectric thin-film growth processes to satisfy the requirements. 

Reactivity is measured by placing a standard quantity, 100 mL, of isopropyl alcohol in a 500- or 1000-mL Dewar flask equipped with a stirrer and a temperature-measuring device. The temperature of the alcohol is adjusted to 30°C. Thirty-six grams of the sample are added and the temperature is observed as a function of time from the addition until a maximum is reached. Reactivity is defined as the temperature rise divided by the time interval to reach this maximum. Other alcohols may also be used for measuring reactivity (30). 

An important use of bromine compounds is in the production of flame retardants (qv). These are of the additive-type, which is physically blended into polymers, and the reactive-type, which chemically reacts during the formation of the polymer. Bromine compounds are also used in fire extinguishers. Brominated polymers are used in flame retardant appHcations and bromine-containing epoxy sealants are used in semiconductor devices (see... 

Dry-Throwaway Processes. Dry-throwaway systems were the precursor of processes that removed SO2 iu the ductwork, eg, the BCZ and IDS processes. Here, however, the device is a spray chamber similar to the wet scmbbers such as the three modules of the Colstrip iastallation (Fig. 12). Into the upper portion of the chamber a slurry or clear solution containing sorbent is sprayed. Water evaporates from the droplets, the sorbent reacts with SO2 both before and after drying, and the dry product is removed ia a downstream baghouse or ESP (72). Unfortunately, dry scmbbiag is much less efficient than wet scmbbiag and lime, iastead of the much less expensive limestone, is required to remove SO2 effectively. Consequentiy, a search has been conducted for more reactive sorbents (72—75). 

Complete siftproofness can be had by the tape-over-sewn procedure, whereby the tape is glued onto the finished sewn closure by a device downstream from the sewing head. For siftproofness at high production rates, the pinch-style glued closure is used. The pinch-bag closure has the adhesive preapphed to the open end by the Bagmaker. After the bag has been filled, the closing machine reactivates the adhesive by heat prior to sealing. 

U.sliifi ihyrisior devices (GTOs) Thyristor (GTO) inverter circuits are used for higher ratings of machines than above and to contiol larger powers such as lor those for reactive power conli ol. 

This device controls the generator and maintains a steady-stale armature voltage automatically within the predefined limits. It also serves to control the reactive kVAr loading during a parallel operation or when the machine is being used as a synchronous condenser for reactive power compensation through a quadrature droop control (QDC) as noted below. 

The series capacitors tire connected in series with the power lines to provide reactive control to an individual load or to a power distribution or transmission system. They are therefore switched with the pow er lines and are thus permanently connected devices. 

In SVCs Ihe number of switchings is of no relevance, as they arc free from inrush currents. Switching is performed at the instant when the cuiTcnt wave is passing through its natural zero. Static devices in various combinations and feedback control systems, which may be computer-aided, can tilmost instantaneously (< I cycle) generate or absorb reactive power, as may be demanded by the system. Correction... 

This part considers reactive power control with the use of shunt and series capacitors. The controls may be manual or automatic through electromagnetic or static devices. Protection of capacitors and capacitor banks as well as design, manufacturing and test requirements, installation and maintenance are also covered, the main thrust being on the application of power capacitors. 

---