Other

British Nuclear Fuels Plc

Vt Nuclear Services Limited

Bil Solutions Limited

Christopher Henry Orr

Thomas Dockray

Craig Janson Luff

Duncan Whittemore Macarthur

John A Bounds

James E Koster

Krag Allander

David J Thornley

Christine A Burnett

The method includes providing the volume of waste in a monitoring space; providing a support, the support being provided with a plurality of detectors for radioactive material; monitoring the volume of waste for radioactive material, in one or more parts, to give a monitoring results; and correcting the monitoring result for geometry and/or attenuation to give a corrected result using a correction factor. The correction factor is obtained by a method that includes providing a simulation of an equivalent volume of waste free of radioactive material in an equivalent monitoring space, with equivalent detectors; providing a known activity radioactive source at one or more positions in the volume of waste; determining the detector response to the source in a position, a comparison of the response and known activity contributing to a correction function for that equal volume, one or more such correction functions providing the correction factor.

Monitoring

Method and apparatus is provided for monitoring an item for radioactive material on or associated with the item, the apparatus including an enclosed volume, an item monitoring location, a detection location, ion detectors provided within the detection location, a mover of gas for providing a flow of gas past the item monitoring location to a detection location, so as to revel the level and/or presence of radioactive material on the item. The item may be supported within the monitoring location by one or more rollers to ease its insertion and/or removal. The item monitoring location may be extremely elongate so as to measure pipes and the like. Various designs of roller and gas flow controllers are provided to optimize monitoring.

Apparatus for monitoring an item for radioactive material on or associated with the item

Apparatus and methods are provided for establishing the nature and level of radioactive sources within waste, particularly of a compactable nature. Detectors sensitive to low energy level radiation are provided with protection against dust contamination. Further detector configurations are provided to establish the presence of metallic material and/or higher energy level gamma emissions and/or detectors with a lower sensitivity to the emissions and/or detector configurations sensitive to neutrons are further provided.

Investigations

The invention provides apparatus and methods which facilitate movement of an instrument relative to an item or location being monitored and/or the item or location relative to the instrument, whilst successfully excluding extraneous ions from the detection location. Thus, ions generated by emissions from the item or location can successfully be monitored during movement. The technique employs sealing to exclude such ions, for instance, through an electro-field which attracts and discharges the ions prior to their entering the detecting location and/or using a magnetic field configured to repel the ions away from the detecting location.

The apparatus and method provide a technique for significantly reducing capacitance effects in detector electrodes arising due to movement of the instrument relative to the item/location being monitored in ion detection based techniques. The capacitance variations are rendered less significant by placing an electrically conducting element between the detector electrodes and the monitored location/item. Improved sensitivity and reduced noise signals arise as a result. The technique also provides apparatus and method suitable for monitoring elongate items which are unsuited to complete enclosure in one go within a chamber. The items are monitored part by part as the pass through the instrument, so increasing the range of items or locations which can be successfully monitored.

Ion monitoring

A method and apparatus for monitoring alpha contamination are provided in which ions generated in the air surrounding the item, by the passage of alpha particles, are moved to a distant detector location. The parts of the item from which ions are withdrawn can be controlled by restricting the air flow over different portions of the apparatus. In this way, detection of internal and external surfaces separately, for instance, can be provided. The apparatus and method are particularly suited for use in undertaking alpha contamination measurements during the commissioning operations.

Selective flow path alpha particle detector and method of use

The apparatus and method provide techniques for monitoring the position on alpha contamination in or on items or locations. The technique is particularly applicable to pipes, conduits and other locations to which access is difficult. The technique uses indirect monitoring of alpha emissions by detecting ions generated by the alpha emissions. The medium containing the ions is moved in a controlled manner frog in proximity with the item or location to the detecting unit and the signals achieved over time are used to generate alpha source position information.

Relating to monitoring ion sources

The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

Detectors

Monitoring materials

Collection of ions

The apparatus and method provide a technique for more simply measuring alpha and/or beta emissions arising from items or locations. The technique uses indirect monitoring of the emissions by detecting ions generated by the emissions, the ions being attracted electrostatically to electrodes for discharge of collection. The apparatus and method employ a chamber which is sealed around the item or location during monitoring with no air being drawn into or expelled from the chamber during the monitoring process. A simplified structure and operations arises as a result, but without impairing the efficiency and accuracy of the detection technique.

Electrostatic monitoring

The apparatus and method provide a technique for improving detection of alpha and/or beta emitting sources on items or in locations using indirect means. The emission forms generate ions in a medium surrounding the item or location and the medium is then moved to a detecting location where the ions are discharged to give a measure of the emission levels. To increase the level of ions generated and render the system particularly applicable for narrow pipes and other forms of conduits, the medium pressure is increased above atmospheric pressure.

Relating to ion detection

A method determining the plutonium content of a material containing fluorine involves obtaining the mass ratio of plutonium in a compound comprising plutonium and fluorine, particularly plutonium tetrafluoride, to the total plutonium content. The method utilises a high resolution gamma ray spectrometry technique to obtain a count rate in a pair of gamma ray photopeaks. One of the photopeaks has an energy level of 414 keV, resulting from the decay of plutonium-239, and the other photopeak has an energy level of 583 keV, resulting from the decay of an excited sodium-22 nucleus following an (alpha,n) interaction with fluorine.

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Calderbridge, United Kingdom

Christopher Henry Orr