Monitor tubes

In order to obtain as much information as possible c.oncerning the reactor and to isupply some of the data required by the control system, monitor tubes snd thermocouples will be built into the reactor structure. Their functions in the control system are discussed in Chap. 5 (Section 5.2.1) their physical structures and locations are described briefly below. 

The structure of a monitor tube is shown in Fig. 2.8.A. It consists of a. housing which acts as a support arid enclosure for four small tubes. Three of these tubes are open at the end, two being used as pitot, total and static 

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Tubing, catheters, cannulas, endotracheal tubing, feeding and pressure monitoring tubing... 

Because of the high resolution required for monitor tubes, phosphors with smaller particle sizes (4-6 pm) than for entertainment tubes are often needed. For monitor tubes which reproduce slow movement only, phosphor mixtures with longer decay times are used to diminish image flickering. For the reproduction of faster movement, phosphors with shorter decay times are used. For monochrome monitors with amber as the image color Cd5(P04)3Cl Mn2 + or a blend of Y202S Eu3+ and (Zn, Cd)S Cu+ is used. 

Alternatively, one can convert the adsorption system into a partition system by adding a displacer to the sample in the vial headspace. One typical example is the determination of residual halocarbon solvent in decaffeinated instant coffee using an excess of water as displacer [45]. For analytes adsorbed on activated charcoal — which is used in personal monitoring tubes — benzyl alcohol is an effective choice for desorbing the volatile analyte [49,64]. 

In color television, where the image is reproduced by selective cathode excitation of three phosphors (blue, green and red) deposited on the internal face of the screen, yttrium oxysulfides activated with trivalent europium (Y202S Eu ) facilitate such a gain in the brilliance of red over ZnS Ag (more than double it) that they have totally replaced it at a cost about five times less. The exceptional performance of the rare-earth phosphors has also been used gainfully in a vast number of cathode tubes for professional applications color computer monitors, tubes for aviation use, projection television, etc. 

It will be noted in the drawing that the four tubes are spiraled down through 20 in. of lead to provide adequate shielding. The whole monitor tube is held in the bottom plug by the threaded section of the distributor body so that if necessary any or all of the monitor tubes can be removed or replaced. 

Thickness of Door Under Bottom Plug. In. addition to shielding the water monitor tubes, the door under the bottom plug must protect personnel from neutrons escaping the steel thermal shield..- Calculations verifying the adequacy of the door for neutron protection are reviewed as follows . 

Monitor tube water flow < 80% of normal differential X ... 

The core plate consists of a circular plate with round openings. The core plate provides horizontal support and guidance for the control rod guide tubes, incore flux monitor tubes, peripheral fuel supports, and startup neutron source holders. The last two items are also supported vertically by the core plate. The entire assembly is bolted to a support ledge in the core shroud. The core plate also forms a portion within the core shroud, which causes the recirculation flow to pass into the orificed fuel support and through the fuel assemblies. 

The JPDR is a BWR-type (45 MWt) demonstration reactor. It started to generate electricity for the first time in Japan in October 1963. In 1972 the power was increased to 90 MWt for enhancement of neutron irradiation capability. The JPDR was shut down in March, 1976 due to several problems such as cracking on the nozzle of in-core monitor tubes, the failure of control rod drive mechanism and other complications. Table I shows the major specifications, operation history and radioactive inventory of the JPDR. 

Operating conditions all gas lift valves apart from the bottom orifice valve are closed. The energy to the system is delivered by a compressor. The performance of the system is monitored by observing flowrates and the casing and tubing pressures. 

Sensors on the tree allow the control module to transmit data such as tubing head pressure, tubing head temperature, annulus pressure and production choke setting. Data from the downhole gauge is also received by the control module. With current subsea systems more and more data is being recorded and transmitted to the host facility. This allows operations staff to continuously monitor the performance of the subsea system. 

Monitoring and control of the production process will be performed by a combination of instrumentation and control equipment plus manual involvement. The level of sophistication of the systems can vary considerably. For example, monitoring well performance can be done in a simple fashion by sending a man to write down and report the tubing head pressures of producing wells on a daily basis, or at the other extreme by using computer assisted operations (CAO) which uses a remote computer-based system to control production on a well by well basis with no physical presence at the wellhead. 

Tubing corrosion due to FIgS (sour corrosion) or COg (sweet corrosion) may become so severe that the tubing leaks. This would certainly require a workover. Monitoring of the... 

Sand production from loosely consolidated formations may lead to erosion of tubulars and valves and sand-fill in of both the sump of the A/ell and surface separators. In addition, sand may bridge off in the tubing, severely restricting flow. The presence of sand production may be monitored by in-line detectors. If the quantities of sand produced become unacceptable then downhole sand exclusion should be considered (Section 9.7). 

ELECTROMAGNETIC MONITORING OF MICROSTRUCTURE AND MECHANICAL PROPERTIES FOR COLD-ROLLED 12Kh2MFSR STEEL TUBE by V.A.Burganova, L.V. Kochman, V.A. Kuz mina and L.P. Chukanova, Vol.10, No. 4, 1974, pp. 432 -437... 

The techmque was first employed, in real-world conditions, for monitoring external corrosion in the large diameter steel tubing used for oil well casings. In the late fifties, T.R. Schmidt at Shell Developments, pioneered the technique in those demanding applications, although the technique itself was invented, by W.R. MacLean, (Ref. 1) somewhat earlier. T.R Schmidt has written a history (Ref. 2) of much of the early work in the technology, which contains many references, others which may be of interest are held on the NTIAC database (Ref 3). 

Fig. 1 The view of the polar display with monitors arcs and control panel for SFT6000N board parameters. Recorded signal is from the eddy current probe moved along in a brass tube of inner diameter 20 mm with 2 mm holes as artificial flaws. SFT6000N card operates with 40 kHz injection voltage firequency.

The encircling probe was characterised with its mirror in water. As we did not own very tiny hydrophone, we used a reflector with hemispherical tip with a radius of curvature of 2 mm (see figure 3c). As a result, it was possible to monitor the beam at the tube entrance and to measure the position of the beam at the desired angle relatively to the angular 0° position. A few acoustic apertures were verified. They were selected on an homogeneous criteria a good one with less than 2 dB of relative sensitivity variations, medium one would be 4 dB and a bad one with more than 6 dB. 

The pyrolysis of CR NH (<1 mbar) was perfomied at 1.3 atm in Ar, spectroscopically monitoring the concentration of NH2 radicals behind the reflected shock wave as a fiinction of time. The interesting aspect of this experiment was the combination of a shock-tube experiment with the particularly sensitive detection of the NH2 radicals by frequency-modulated, laser-absorption spectroscopy [ ]. Compared with conventional narrow-bandwidth laser-absorption detection the signal-to-noise ratio could be increased by a factor of 20, with correspondingly more accurate values for the rate constant k T). 

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