Power Range Channel

The output of each power range channel is directly proportional to reactor power and typically covers a range from 0% to 125% of full power, but varies with each reactor. The output of each channel is displayed on a meter in terms of power level in percent of full rated power. The gain of each instrument is adjustable which provides a means for calibrating the output. This adjustment is normally determined by using a plant heat balance. Protective actions may be initiated by high power level on any two channels this is termed coincidence operation. 

Figure 37 shows a typical power range channel. 

Method III Note Use both power range channels. 

The BF3 proportional counter is used to monitor low power levels in a nuclear reactor. It is used in the "startup" or "source range" channels. Proportional counters cannot be used at high power levels because they are pulse-type detectors. Typically, it takes 10 to 20 microseconds for each pulse to go from 10% of its peak, to its peak, and back to 10%. If another neutron interacts in the chamber during this time, the two pulses are superimposed. The voltage output would never drop to zero between the two pulses, and the chamber would draw a steady current as electrons are being produced. 

Sensor measurements are recorded in situ by a battery-powered, eight-channel, miniature digital tape recorder (MDTR) (Oxford Medical Systems Ltd.) with range, 0-1.023 V resolution, 0.1% scan period, 15 s (alternatively 5 s) duration (C120 cassette), 25 h (alternatively 8 h) and data capacity, 6000 scans. Direct (bandwidth 100 Hz) or pulse-width modulated analog signals (range, 120 mV bandwidth, 0-8 Hz and resolution, 1-2 %) can be recorded on the additional three tracks of the same cassette. 

This is confirmed to a large extent by the representation of the mean power losses in the various collision processes, also given in Fig. 3 (right). It can be easily observed from the course of the loss in elastic collisions jn and of the total loss in collisions / / that in the steady-state neon plasma, the dominant contributor to the power loss changes around the field strength E = 0.5 V/cm from elastic to inelastic collisions. With respect to the latter. Fig. 3 additionally shows that the excitation of the s levels represents the dominant power-loss channel among the three inelastic power losses P" jn, jn, and P jn in the range... 

The nuclear instrumentation must be operable prior to reactor startup. The automatic rod control during startup will not operate if more than one of the three ex-vessel wide-range channels is out of service. The Safety Protection Subsystem requires at least three of its four nuclear input channels operating. The power range neutron flux control will not operate automatically with more than two of the six input channels out of service. 

Failures in the ex-vessel neutron detectors can result in erroneous signals. However, sufficient redundancy in neutron detectors exists so that loss of a detector does not result in unsafe operation or necessitate immediate plant shutdown. The startup control and power range fltix control both utilize several signals based on the input from several neutron detectors. Comparators between redundant channels automatically disconnect suspect inputs from the average signal and alert the operator. 

Kundu et al. at Samsung [54] developed a microreactor for methanol steam reforming in the power range 5-10 W. The microreformer was 30 mm wide and long and comprised evaporation and steam reforming zones. Parallel and serpentine channels for steam reforming were tested alternatively the serpentine arrangement... 

The reactivity computer measures real time variation of reactivity. It can be used virtually with all neutron detectors for the reactor power monitoring simulataneously. In order to cover the startup channels, numerical methods for inverse point kinetics are accutely reviewed and tested in detail to verify error trend and to search the best algorithm. The program made for the test itself can be utilized for the simulation of other reactivity measurements to verify source of error and its trend - such as the gamna background effect when an uncompensated ionization chamber is used, the source effect, conventional rod drop method, etc. The reactivity computer can be used at any reactor power level from startup to power range. So far, it has been utilized for the control rod calibration, reactivity coefficient measurement, etc. 

Fig. 2 presents a typical block diagram of a measuring channel in the source and intermediate ranges. Fig. 3 is for a channel in the power range. 

Fig. 3. Block diagram of the measuring channel in the power range...

Inductor. The channel inductor assembly consists of a steel box or case that contains the inductor refractory and the inductor core and coil assembly. The channel is formed within the refractory. Inductor power ratings range from 25 kilowatts for low temperature metals to 5000 kilowatts for molten iron. Forced air is used to cool the lower power inductors, and water is generally used to cool inductors rated 500 kilowatts or more. 

Hearth. The hearth of a channel induction furnace must be designed to satisfy restraints that are imposed by the operating inductor, ie, the inductor channels must be full of metal when power is required, and it is also necessary to provide a sufficient level of metal above the channels to overcome the inward electromagnetic pressure on the metal in the channel when power is appHed. Once these requirements are satisfied, the hearth can then be tailored to the specific appHcation (13). Sizes range from stationary furnaces hoi ding a few hundred kilograms of aluminum to rotating dmm furnaces with a useful capacity of 1500 t of Hquid iron. 

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