摘要:

The control and instrumentation of nuclear reactors is a rapidly developing subject which is becoming of ever-increasing importance to a growing body of instrument engineers. Many of the problems of instrumental design are common with other industrial plants and follow conventional lines. Some, however, are more specialized, and arise principally from the radioactive nature of the reactor and its unusual dynamic behaviour. The paper presents a survey of the overall instrumentation of a typical research reactor. Emphasis is placed on the less-well-known problems of measurement and control, and to assist in their understanding a brief account is given of the mode of operation of a nuclear reactor, and a short Section on reactor kinetics is also included. The types of instruments in present-day use are described, and indications are given of their shortcomings. New developments are briefly reviewed. The paper concludes with a Section on reactor safety. The philosophy of safety-circuit design is outlined, and examples are given of instruments and circuits which conform to this basic code and which have been used on a number of experimental reactors at Harwell.

DOI:10.1049/pi-b-1.1956.0214

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The physical principles of nuclear reactors which affect the design of their control and instrumentation are described. Data are presented for the kinetic behaviour of the neutron flux for reactivity changes in a variety of reactor types. The nuclear reactions inherently produce various nuclides, and the effects of these on reactor control and operation are discussed. These nuclides include the delayed-neutron emitters, which cause a slowing down of the reactor kinetic response; β- and γ-emitters, which continue to produce heat for a long time after the neutron-reactions producing them have been shut down; and the fission-product poisons. Reasons are given for the system of neutron-flux instruments normally used, and details are given of the principles of design of the various types of instrument.

DOI:10.1049/pi-b-1.1956.0215

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The paper describes the design and the electrical characteristics of a neutron-sensitive d.c. ionization chamber suitable for a wide range of applications in nuclear-reactor-control instrumentation systems. Thermal-neutron sensitivities of 10−15–10−14amp/n/cm2/sec can be obtained using boron trifluoride filling or boron-coated electrodes with hydrogen filling. The corresponding γ-radiation sensitivities are of the order of 10−12–10−11amp/r/h. Virtually complete collection of the ionization current is possible, up to neutron flux levels of 1011n/cm2/sec, with a polarizing voltage of a few hundred volts. The residual current due to neutron-induced activities in the chamber falls to less than 10−6times the full-power neutron current some 20 min after shut-down.The siting of ionization chambers has an important bearing on their range of utilization in control-instrumentation systems, and this is discussed briefly in relation to the electrical characteristics of the chambers described.

DOI:10.1049/pi-b-1.1956.0216

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The paper outlines some of the practical design problems associated with the engineering of control mechanisms in nuclear reactors. Safety is emphasized in all the design aims, and examples are given of some of the systems in use at Harwell. The scope of the paper is limited to control mechanisms for low and moderate-power experimental reactors, although some of the problems which will be met in future power-producing reactors are mentioned.

DOI:10.1049/pi-b-1.1956.0217

出版商:IEE    

年代:1956

数据来源: IET

摘要:

Commencing with the first self-balancing bridge or potentiometer devised in 1897, a review is given, in historical form, of the several types of servo-operated recording instruments that have been devised since that date. These recorders are all of the type in which a correcting action takes place in the instrument itself, thus making available considerably more power for the recording stylus or pen than is available in direct-acting instruments. A more detailed discussion is then given of the principal types of modern instruments, classified according to the circuit component which is varied to produce balance, namely resistor or potentiometer, capacitor, electromagnetic device. Most instruments record against time as one of the variables, but function plotters, in which the relation between two variables other than time is plotted, are discussed, as also are scanning recorders devised for recording from a large number of input points. Several other special types are also included.

DOI:10.1049/pi-b-1.1956.0222

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The paper gives an account of the factors underlying the siting, planning and design of the Crystal Palace station. The steps taken to attain a high standard of reliability and the considerations that determined the selection of the Crystal Palace site and the choice of effective radiated power and aerial gain are stated.The requirements with which the installation had to conform are given, and the building, plant and equipment are described.The considerations determining the design of the aerial system are discussed, and its construction is described. The paper also states the performance of the aerial system.

DOI:10.1049/pi-b-1.1956.0224

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The initial requirement for the Broadcasting House-Crystal Palace Television link is for one channel in each direction, but it is likely that a second channel will be needed later. The transmission of two programmes over a single tube would make 0.975 in coaxial cable economic over this distance of 9 miles and would permit transmission between terminals without intermediate equipment. To meet the need of good performance with simple low-cost equipment, a double-sideband system with amplitude modulation has been developed. To allow for later development, e.g. a wider-band channel for colour, the carrier frequency of the monochrome channel has been placed at 15 Mc/s.In the transmitting terminal the video signal is translated into the band for transmission over the cable, and in the receiving terminal the incoming signal is corrected for the loss, attenuation and delay distortions which occur in transmission, and the video signal is recovered. The performance of the link is given in terms of the measured amplitude and differential delay characteristics, transient response, linearity and signal/noise ratio.

DOI:10.1049/pi-b-1.1956.0225

出版商:IEE    

年代:1956

数据来源: IET

摘要:

The paper describes television transmitting equipment designed to operate in two parallel chains to ensure reliability.The vision transmitters are designed to work with considerable distortion and noise in the input signal, and the noise-rejection and clamp circuits developed for this purpose are discussed. The use of tetrodes in the output stage of the vision transmitter enables receiver-type valves to be used throughout the modulator, and permits the advantage of high-level modulation to be exploited.The methods of phasing of both radio and vision frequencies are described.The implications of colour television on design are discussed and the means adopted in these transmitters to assure faithful colour transmission are described.

DOI:10.1049/pi-b-1.1956.0226

出版商:IEE    

年代:1956

数据来源: IET

摘要:

A source of intermittent noise in oxide-cathode receiving valves is identified with the presence of variable leakage paths between certain electrodes. The dependence of this phenomenon on valve parameters is discussed and mention is made of an improvement in valve design which inhibits the growth of inter-electrode leakage.

DOI:10.1049/pi-b-1.1956.0229

出版商:IEE    

年代:1956

数据来源: IET

摘要:

To provide a standard temperature noise source for use with S-band radiometers, the noise power from the argon discharge tube CV1881 has been calibrated at 2860 Mc/s using radiometer techniques. The absolute value of the effective temperature of the tube with a discharge current of 180 mA, when mounted across a waveguide parallel to the E-plane and properly matched, is 11 140° K (15.73 dB) with a maximum error of 260° K (0.10 dB), and represents a considerable improvement in accuracy over previous measurements. Since this tube shows a high degree of stability and consistency, it is suggested that it could be used as an absolute standard noise source for the measurement of the noise factor of receivers.

DOI:10.1049/pi-b-1.1956.0230

出版商:IEE    

年代:1956

数据来源: IET