Abstract: The apparatus comprises a stack of corrosible members retained in position by a support, and measurement means, for example a dial gauge, arranged to measure any change in the height of the stack when exposed to a corrosive environment. Electrical potentials and/or mechanical stress can be applied to the stack in order to ascertian the influence thereof on corrosion. The use of a plurality of corrodible surfaces enables amplification of dimensional changes and enables measurements to be obtained in a relatively short time.

Abstract: A method of measuring temperature comprises the steps of consecutively launching (1, 2) input pulses of light at two different wavelengths into a temperature sensing element in the form of an elongate optical fibre (3); passing Raman scattered light from said element and deriving from said input pulses to intensity detectors (7, 8); obtaining from the detectors (7, 8) output signals indicative of the intensity of the Raman scattered light; and processing said output signals to provide a temperature measurement. A known position (10) along the optical fibre (3) is maintained at a known temperature to provide a reference for deriving temperature measurements at other positions along the optical fibre.

Abstract: It is known to detect a single breakdown of the electrical insulation separating the rotor winding from the earthed rotor body of a generator: such a failure does not lead to intense arcing, however, as there is no return path for current flowing to earth. Disclosed is a potential divider network which allows continuous monitoring of the voltages between earth and the two ends of the winding: a second breakdown can be rapidly detected since it results in a shift in both the position and magnitude of the effective resistance to earth from that associated with the first breakdown.

Abstract: The permissable level of radioactivity due to airborne actinides is extremely low: the satisfactory discrimination of actinide emissions from other sources is, consequently, a problem. This specification discloses the combination of (a) selecting only the larger airborne particles, (b) measuring the activity of emissions at the energy characteristic of actinide decay of these particles and (c) decay analysis of the measurements to reject emissions which are characteristic of high energy processes but which have lost sufficient energy to fall within the measurement band.

Abstract: A carbon-in-ash monitor uses a fluidized bed furnace to burn any carbon in sampled boiler flue ash and evolve carbon dioxide therefrom. Fluidizing gas (air) is provided to the bed a measured flow rate and a batching arrangement feeds successive batches of ash of measured mass to the furnace at a measured frequency. A CO.sub.2 monitor measures the amount of CO.sub.2 evolved to determine the carbon content of the ash. Batches are provided using a vibratory table to transport ash from a point of supply to the table and a point of delivery of ash in a stream from the table. The vibratory table is horizontal and is driven so that the mode of vibration can be selected to reverse the direction of ash transport.

Abstract: Temperature is measured by launching pulses of light into an elongate optical fibre and determining the temperature at positions along the fibre from the intensity of light scattered at those positions. The input pulses can have either the same or two different wavelengths, and the scattered light can be either Raman or Brillouin scattered and either forward scattered or backscattered. One position along the fibre can be maintained at a known temperature in order to provide a reference for other calculations. In particular embodiments the temperature is derived from the ratio between the intensities at two anti-Stokes wavenumber shifts or between an anti-Stokes scattered and a Rayleigh scattered intensity measurement. Otherwise the intensities of Stokes and anti-Stokes shifted Brillouin back scattered light can be used to derive the temperature.

Abstract: A method of applying a descaling reagent comprising a one-electron reducing agent which is a low oxidation state transition metal ion in combination with a complexing agent to a surface to be treated to descale the surface which method comprises:(i) maintaining a low oxidation state transition metal ion either in solution under an inert atmosphere in a container made of or lined with an inert material or as a solid salt under an inert atmosphere;(ii) preparing a solution of the complexing agent and removing oxygen therefrom; and(iii) mixing the ingredients from steps (i) and (ii) either in situ in contact with the surface to be treated, or mixing the ingredients from steps (i) and (ii) prior to application to the surface to be treated under conditions whereby no substantial decomposition of the so-formed reagent occurs.

Abstract: An optical fiber apparatus measures an external parameter, such as temperature, at any of a number of different locations using time-domain reflectometry techniques. Sensor devices, each comprising a chip or plate of ruby glass, are interconnected by optical fibers. A laser launches along the fiber string short pulses of light at a first wavelength on the absorption edge of the ruby glass and a second wavelength in the transmission region away from the edge. A timer controls sampling circuits to measure backscattered energy at each wavelength at spaced times corresponding to spaced points along the fiber on opposite sides of a selected sensor device. A processor calculates the absorption loss in the sensor device at each wavelength by comparing the backscattered energy from the two points on opposite sides of the device, and calculates the differential absorption loss by comparing the losses at the two wavelengths. Embodiments employing a wedge shaped absorber are used to measure displacement.

Abstract: A metal cable corrosion monitor comprises a sensing head (14) located about a multi strand cable (1). The sensing head includes a field windings (3) for applying a magnetic field coaxially to a portion of the cable to be monitored. A pick-up coil (2) encircles the portion and detects magnetic flux parallel with the cable and linking with the area of the pick-up coil. The signals from the pick-up coil are processed by a high gain amplifier (8) and phase sensitive detectors (7) and (6), the former phase sensitive detector producing an output in phase with the field winding driving frequency and the latter phase sensitive detector producing a quadruture output relative to the field winding driving frequency. By observation of the amplitude and the phase output parameters it is possible to detect corrosion of a single or multi strand cable. A particular format of field winding is disclosed whereby the effects of induced inter strand currents can be reduced.

Abstract: An apparatus for monitoring particulate matter in the fluid comprises a filter means (28) through which fluid is arranged to flow. A pressure sensing means (46) senses the fluid pressure difference across the filter means and produces a pressure signal indicative of the magnitude of the pressure difference. A processing means (49) receives the pressure signal and evaluates therefrom the rate of change of the magnitude of the pressure difference in order to give an indication of particulate matter levels in the fluid. In this way on line monitoring of the debris generation in, for example an oil system, can be effected so that abnormal increases in debris can be detected and long term trends in the build-up of debris can be observed. A particular form of filter medium is also disclosed wherein the filter mean can be transported so that a filter record can be maintained and systematic X-ray analysis of the filter record can be effected.

Abstract: Oxide deposits containing chromium are dissolved by contacting the deposits sequentially with(i) a permanganate salt in acid solution to remove chromium therefrom as hexavalent chromium;(ii) a reducing agent in acid solution to destroy excess permanganate ions and manganese dioxide formed by reduction of the permanganate; and(iii) a mixture of a reducing agent and complexing acid to dissolve the residual chromium depleted oxide.

Abstract: A method of applying a descaling reagent comprising a one-electron reducing agent which is a low oxidation state transition metal ion in combination with a complexing agent to a surface to be treated to descale the surface which method comprises:(i) maintaining a low oxidation state transition metal ion either in solution under an inert atmosphere in a container made of or lined with an inert material or as a solid salt under an inert atmosphere;(ii) preparing a solution of the complexing agent and removing oxygen therefrom; and(iii) mixing the ingredients from steps (i) and (ii) either in situ in contact with the surface to be treated, or mixing the ingredients from steps (i) and (ii) prior to application to the surface to be treated under conditions whereby no substantial decomposition of the so-formed reagent occurs.

Abstract: A method for the quantitative determination of a chemical species capable of promoting the disproportionation of Hg.sub.2.sup.2+ to Hg.sup.2+ and Hg.degree. in solution which method comprises causing the species to react with a solution comprising Hg.sub.2.sup.2+ to thereby produce a measurable concentration of Hg.degree. in a gaseous phase above the solution, and determining the Hg.degree. present in the said gaseous phase.The method is particularly applicable to the determination of low concentrations (e.g. as low as 0.1 p.p.b.) of SO.sub.2 in gas mixtures, such as air.

Abstract: An insulator having a central portion or stem and one or more sheds is provided with a barrier over at least one of the sheds whereby a substantial improvement in withstanding flashover is obtained yet significant damage to the surface of the insulator is avoided. The barrier comprises a sheet of dielectric material positioned over the upper surface of a shed but spaced away therefrom, the sheet extending radially outwardly to overhang the periphery of the shed. The barrier is furthermore spaced radially away from the central portion or stem of the insulator over at least a substantial part of the inner periphery of the barrier. The barrier may be made of rigid material, for example, constructed from a plurality of sectors but is preferably made from a flexible material so that it can be fitted around an existing conventional insulator. The underside of the barrier is preferably provided with a number of projections for spacing it away from the upper surface of the shed.

Abstract: In a gas cooled nuclear reactor, cesium metal release into the coolant gas is dependent on the coolant channel surface temperature in the core. The present invention relates to a filter for removing cesium from the coolant gas before it passes to the heat exchanger. The filter comprises a block or blocks of graphite having holes therein with a hydraulic diameter between 1 mm and 6 mm and a ratio of length to equivalent hydraulic diameter between 170 and 1000. This filter is arranged at one end of the reactor core so that the gases pass straight from the core into the filter block.

Abstract: Particle fuel, such as is used in high temperature nuclear reactors, and having the fuel material coated with a pyrolytic carbon coating impermeable to gaseous fission products and embedded in a matrix of graphite, incorporates radium 226 which may be included in the binder for the grains of the fuel. During the manufacturing process, the integrity of the pyrolytic carbon coating can be checked before irradiation in a reactor by circulating an inert gas such as argon over the particles at a temperature in excess of 800.degree.C. This may be carried out in the final carbonisation step during manufacture or immediately before vacuum degassing. The inert gas after passing over the particles is checked for the presence of radon 222, for example by passing the gas into a decay chamber having a filter in its outlet to collect radio active solid daughters of radon and counting the alpha particles emitted by the material collected by the filter.