Flux detector

A change in interception rate with air flow has been identified as a characteristic of flux detectors such as insect sensory hairs (Kaissling, 1998). However, in some instances (low Pe), an increase in flow will have only a negligible impact on the flux rate, even for a flux detector. This was shown by Berg and Purcell (1977) in the context of cells swimming through a liquid environment. That is, the flow rate doesn t matter if the molecules can walk themselves around just as quickly. For single cylindrical sensors (isolated hairs or filiform antennae), the slower the flow (the lower the Re and Pe), the less the interception rate is expected to increase with an increase in air speed (equations 21.18 and 21.20). 

Kaissling K. E. (1998) Flux detectors versus concentration detectors two types of... 

Kaissling, K.-E. 1998. "Flux Detectors Versus Concentration Detectors Two Types of Chemo-receptors." Chemical Senses, 23 99-111. 

The neutron source referred to above is a normal component of a nuclear reactor core, which produces a stream of neutrons, 5, per second per m of core, independent of the operating power of the reactor. Such a source is included both to initiate the chain reaction at first start-up and to ensure that the neutron flux detectors will always have a recognizably valid signal to detect even when the reactor is shut down. 

In this technique, adsorption is allowed to take place at one temperature and the crystal is then rapidly heated to the desired desorption temperature. This requirement for rapid heating is experimentally very demanding and for this reason, the technique is not often used. The desorption rate can be monitored by measuring the desorption flux as a function of time Kohrt and Gomer [214] used a field emission tip as a flux detector. Alternatively, an adsorbate-sensitive physical property of the surface, such as electron-stimulated desorption [215] or work function [216], can be used. 

Monitoring of core power level during power operation is provided by ex-vessel neutron flux detectors. Flux monitoring at lower powers and at shutdown conditions is provided by source range detectors which are located in the side reflector. The reactor core and reflectors rest vertically on a support structure below the core and are restrained by a core lateral restraint structure located between the outer side reflector and the reactor vessel. 

The Neutron Control Subsystem (NCSS) consists of the drive mechanisms for positioning the control rods, the rod controls, the reserve shutdown control equipment (RSCE) with its controls, and the instruments for measuring neutron flux levels within the reactor vessel (i.e., in-vessel flux mapping units and startup detectors) and around the perimeter of the reactor outside the vessel (i.e., ex-vessel flux detectors). The control rods and the reserve shutdown material are part of the Reactor Core Subsystem (Section 4.2). Most of this equipment is configured into assemblies which are normally installed in penetrations in the top or bottom of the reactor vessel. These assemblies are periodically removed either to provide access to the core for refueling or for maintenance of the equipment. 

Neutron flux detectors positioned by hangers are placed in fuel channels, the reflector and the annular water-filled biological shield tank. They are located as follows ... 

The 90 % NP steady state finally ended with a 13-day irradiation period which permitted irradiating the flux detectors to their saturation point, as well as completing the plant restart programme. On the one hand, the final requalification of the modifications made to the facility to improve protection against sodium fires was performed, with respect to which the good behaviour of that the new, so-called "sandwich", Na leak detection systems should be noted. On the other hand, two specific tests were also successfully performed first of all, with the reactor at power, calibrated... 

The shutdown of the reactor was followed by the very fast recovery of the neutron flux detectors which were sent to the CEA at Cadarache for activity counting, then by the characterization at 180° C of the reactive state of the core before the start of planned maintenance operations and the associated handling campaign. 

An extensive array of in-core flux detectors has always been a feature of CANDU reactors, and this ensures that the flux and power distributions are well known, regardless of the fuel type and fuel-management strategy. 

The most sensitive instruments are SQUID magnetometers (Fig. 1) which in general allow to measure signals down to a range of 10 emu. They are equipped with superconducting pickup coils and a superconducting quantum interference device as flux detector. 

The RPR will be provided with at least 23 miniature In-core, flux detectors, and a traveling wire monitor for calibration purposes. 

The primary function of the in-core instrumentation system is to provide a three-dimensional flux map of the reactor core. This map is used to calibrate neutron detectors used by the protection and safety monitoring system, as well as to optimise core performance. A secondary function of the in-core instrumentation system is to provide the protection and safety monitoring system with the thermocouple signals necessary for the post-accident inadequate core cooling monitor. The in-core instrument assembhes house both fixed in core flux detectors and core exit thermocouples. 

A number of other devices are located in the main vessel the fuel transfer arm, the six control rods, neutron flux detectors, thermocouples, feiled fuel detection and location devices, the core acoustic detection system components, etc. 

The subpopulations of human blood parameters included (HCT) for laser irradiation. A volume of 0.25 ml of blood sample was placed on microscope glass cavity slides 76x26 mm, thickness 1-1.2 mm, cut edges. The sample was irradiated for one second using the 632.8 nm visible beam from a 0.95 mw He-Ne laser. (Encircled Hux Analysis System (EFAS) models 8350, Photon Inc. were employed as a flux detector for the transmitted laser beam). Readings of beam parameter, Elux Peak was recorded after the irradiation. Experiments were repeated for all blood groups under the same experimental conditions laser beam power, beam source-sample distance, sample detector distance, beam exposure time, room temperature and humidity. 

Three low-efficiency (because of the high neutron flux) detectors are placed in the main beam. The first is placed before the background choppers to monitor the incident flux for the purposes of normalization. The second and third are placed just after the Fermi chopper and behind the sample respectively. These are used to accurately determine the incident energy of the neutrons. 

However, a slow increase from a distorted flux shape could permit fuel to be in dryout even if the bulk reactor power is below the average overpower trip set point. Analysis of such events determines the trip set points for the spatially distributed regional overpower (ROP) flux detectors on each shutdown system. 

ROP system. Regional overpower protection system two spatially distributed networks of flux detectors within the core, each connected to one shutdown system, which will trip the reactor if regional or bulk reactor power is excessive. 

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