Table of contents

This review deals with the instrumentation for the measurement of physical and chemical characteristics of liquid sodium in reactor coolant and related applications. It covers flow, temperature, acceleration and pressure, displacement, void fraction and level. Also included are the descriptions of instruments for monitoring the general purity and the specific impurities of oxygen, hydrogen and carbon. Greater attention is given to the more unusual instruments. The introduction leads to a brief description of the sodium circuits of a typical fast reactor and the properties of sodium which are relevant to successful instrumentation are outlined.

A survey on the available Guinier cameras. This is essentially an X-ray diffraction camera using monochromatic X-radiation and powder samples.

Experimental determinations are made of spectrum line peak intensity and half-width as the entrance slit width is varied. The experimental results agree qualitatively with theoretical calculations and give the same value for the optimum slit width.

A monochromatic pulse from a tunable dye laser is amplified by a flashlamp-pumped dye amplifier to produce an energy of 1.2 J at lambda =5890 AA, with a bandwidth of Delta lambda <or=0.1 AA and a repetition rate of one pulse per second. The technical properties and emission characteristics of the oscillator amplifier system are described.

An instrument has been developed for the direct measurement of the local shear stress on the surface of circular cylinders. An element of the cylinder surface 50.8 mm long and 3.18 mm wide is suspended in such a way that under the effect of a shear force it is free to move a small amount in the direction of flow. This movement is calibrated in such a way to indicate the magnitude of the frictional force. The instrument was tested on a cylinder 89 mm in diameter; the results proved that the device is accurate, efficient and reliable.

The equivalent circuit for a cylinder of low conductivity material placed in a solenoid field is considered using a novel approach. Expressions are derived for the equivalent current sheet (azimuthal) conductance and the equivalent filament conductance of such a cylinder. In particular, a closed form expression for a special solenoid-cylinder geometry is presented. The discussion shows how these results may be used in the design of electrodeless conductivity measuring systems operating below 1 MHz.

An apparatus is described which is simply constructed and will measure anisotropy fields in small (mm) spheres or discs of single crystal material, at frequencies in the range 2 Hz to 50 kHz. At these frequencies and at readily accessible temperatures the anisotropy is often found to relax. Both the cubic anisotropy and any relaxing uniaxial components may be determined, several examples being given in the text.

The making of carbon films, mainly for use in electron microscopy, by evaporation on to a supercooled organic glass is described. The substrate is dibenzylamine tartrate, with an additive. When molten, standard support grids can be floated on it, so that the substrate is automatically flush with the upper surface of the grids. Large batches of grids can be made in this way without individual handling. Some of the physical properties of evaporated carbon films are discussed.

This apparatus is designed to collect as much as possible of the light emitted from the surface of a solid specimen, while giving a minimum unwanted signal due to backscattered electrons. The light collector is a mirror in the shape of an ellipsoid of revolution, with the specimen at one focus and an optical microscope objective lens below the other focus. From the lens the light is led out of the vacuum by fibre optic light guides. For studies at room temperature, a wide-band spectrometer has been used in the range 400-700 nm. This spectrometer, which is based on a continuous interference filter, gives a minimum loss of light intensity.

Although hexamine exhibits a low electro-optic coefficient, large strain-free crystals offer practical devices for both DC and high frequency modulation at reduced operating voltages. A modulator with a light aperture of f/10 has a half-wave voltage of 4.5 kV and shows an extinction ratio of 2000:1. In a multipass mode the voltage can be reduced to less than 100 V but with a consequent loss of angular aperture and light transmission. Precautions taken during modulator construction in order to preserve crystal isotropy included the selection of gold leaf as electrode material and flexible mounts to support the section.

A modular pulse programmer suitable for diverse nuclear resonance experiments is described which provides analogue control of pulse width and digital control of pulse spacing. Because of its flexible nature the programmer can generate all commonly used pulse sequences from a simple two-pulse sequence to complex multiple pulse sequences. It outmodes hard wired programmers and in addition is designed so that a common pulse programmer fault, that errors in pulse spacing depend on the preceding delay, is removed.

Details are given of measurements made on open spherical X-band resonators suitable for use as the sampling cavity in a microwave radio refractometer. The resonators, with dimensions comparable to a wavelength, have loaded Q's in the region of 10⁴. A resonator, constructed of brass spherical reflectors and silica spacing rods resonating at 10.5 GHz, has a temperature coefficient of 0.5 N units/ degrees C and an open area to volume ratio of 1 cm^-1. Results indicate that this resonator, because of its relatively large open area, allows a much faster change of atmospheric content than the conventional TE₀₁₁ resonator with open end plates.

The influence of different ion source parameters on the extraction of ions in a magnetic-sector mass spectrometer has been studied by means of computer-calculated ion trajectories. Ion trajectories have also been calculated for different masses when voltage scanning is applied. The decrease in sensitivity for high mass numbers (mass discrimination) is explained by the decrease in the number of ions extracted from the source and by the decrease in the transmission of the spectrometer tube.

Given a model which represents a certain specimen, a method is described for computing the expected Mossbauer spectrum for transmission or reflection geometries which includes the effects of thickness, imperfect geometry, nonlinearity of the spectrometer scale and arbitrary source line shape.

Gaseous air pollutants can be detected by means of lasers in combination with an opto-acoustic detector. Different characteristics of such a laser-acoustic air pollution monitor, called here a spectrophone, are described. A test system is described by which polluted air can be produced synthetically, and with this system it is possible to characterize, calibrate and compare different opto-acoustic detectors. Experimentally obtained detector parameter values are reported and interpreted. In addition, experimental spectrophone characteristics are presented.

A new Teflon cell technique is described for measuring the thermoelectric power of solids and liquids up to 40 kbar pressure and in the temperature range 0-250 degrees C. The same cell could also be utilized for resistivity and DTA work. Some new representative data on the thermopower variation of mercury both in the liquid and solid phases are reported.

A grating monochromator particularly designed for use with a distant synchrotron radiation source is described. It has two reflections and a constant deviation and is intended to suppress higher spectral orders in its output. Measurements are presented which determine its resolution, efficiency and order sorting capability, and a comparison is also made with other instruments currently being designed for or in use with synchrotron radiation sources.

Geometrical correction factors for a closed-end Ge(Li) detector have been computed for application to gamma-gamma angular correlation studies. The FORTRAN IV program is included in the appendix.