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Abstract: Common density/moisture gauges used in highway and construction industries are normally equipped with gamma and neutron sources, usually a 137Cs source of hundreds of MBq and an 241Am-Be source of the order of 1GBq, respectively. Operators of such devices are workers professionally exposed to ionizing radiation, subject to personal dosimetry. Gamma radiation personal doses received during operation, maintenance and transport are controlled by the officially authorised dosimetry centres using the appropriate dosemeters (typically TLD based dosemeters). Nevertheless, neutron personal dosimetry is generally not performed, as it is estimated that the neutron dose is small compared to the gamma dose. Ten units of the UAB PADC based neutron dosemeter have been distributed among workers involved in the transport and usage of the gauges of the Payma Cotas, S.A.U Company and have been collected after being exposed for two months. The neutron field outside a particular gauge has been characterised using the UAB active neutron spectrometer, based on Bonner spheres, and measurements with neutron and gamma monitors have been performed around the device itself and around its transport case. Results of this neutron field characterisation together with those of the neutron personal dosimetry, of the operators involved in the gauge transport and usage, are presented. [Copyright &y& Elsevier]

Abstract: The UAB PADC based neutron dosimeter was designed to have similar dose responses for thermal and for fast neutrons. A set of calibrations with ISO neutron sources and the realistic SIGMA neutron field at IRSN Cadarache showed this behaviour. Nevertheless, a noticeable decrease of the response to epithermal neutrons is expected because of the small values of cross sections for neutrons at this energy range. The EC NUDAME program gave the opportunity to expose several units of our dosimeter to quasi-monoenergetic beams at the IRMM Van der Graaf accelerator for calibration purposes. The revision of the IRSN Cadarache values with an improved uncertainty treatment and the results of the calibration at IRMM Van der Graaf, in relation to the reference values of the neutron source term obtained using our Bonner sphere spectrometer, are presented in this work. [Copyright &y& Elsevier]

Abstract: The Spanish Nuclear Safety Council (Consejo de Seguridad Nuclear, CSN) recommends performing neutron individual dose assignments at workplaces based on ambient dose equivalent measurements using area monitors and by estimating the amount of time that workers spend in the different monitored environments. In addition, some Spanish nuclear power plants estimate the neutron dose equivalent using albedo thermoluminescence dosemeters (TLD). In the period 2004–2006, our group, together with other research centers, participated in a project, funded by the CSN, with the support of the Spanish Nuclear Power Plants Association (UNESA), to investigate in situ which could be the best practical procedure for individual neutron dose monitoring in nuclear power plants. As part of this survey, several units of the UAB PADC based neutron dosemeter were exposed, on a methacrylate phantom simulating a human body, at four different places inside the containment building of the Ascó I nuclear power plant. The influence of different types of calibration neutron fields is analysed and the dose equivalent for each point is estimated. [Copyright &y& Elsevier]

Abstract: A project has been set up to study the effect on a radiotherapy patient of the neutrons produced around the LINAC accelerator head by photonuclear reactions induced by photons above ∼8 MeV. These neutrons may reach directly the patient, or they may interact with the surrounding materials until they become thermalised, scattering all over the treatment room and affecting the patient as well, contributing to peripheral dose. Spectrometry was performed with a calibrated and validated set of Bonner spheres at a point located at 50 cm from the isocenter, as well as at the place where a digital device for measuring neutrons, based on the upset of SRAM memories induced by thermal neutrons, is located inside the treatment room. Exposures have taken place in six LINAC accelerators with different energies (from 15 to 23 MV) with the aim of relating the spectrometer measurements with the readings of the digital device under various exposure and room geometry conditions. The final purpose of the project is to be able to relate, under any given treatment condition and room geometry, the readings of this digital device to patient neutron effective dose and peripheral dose in organs of interest. This would allow inferring the probability of developing second malignancies as a consequence of the treatment. Results indicate that unit neutron fluence spectra at 50 cm from the isocenter do not depend on accelerator characteristics, while spectra at the place of the digital device are strongly influenced by the treatment room geometry. [ABSTRACT FROM AUTHOR]

Abstract: The NEUTOR project was set up to study radiotherapy patient exposures to the neutrons produced around the LINAC accelerator head by photon radiation above ∼8MeV. These neutrons may reach the patient directly, or they may interact with the surrounding materials until they become thermalised, scattering all over the treatment room and affecting the patient as well. A miniaturised version of the UAB PADC based neutron dosemeter is used, together with thermoluminescence Li-6/Li-7 pairs, in several positions inside an anthropomorphic female phantom to determine doses received by the patient at several organs or tissues. Irradiations were made at a 15MV LINAC (Hospital Universitario Virgen de la Macarena, Sevilla, Spain), an 18MV LINAC (Hospital General Universitario de Valencia, Spain) and a 23MV LINAC (Universitätsklinikum Heidelberg, Germany). Preliminary patient dose maps obtained from the UAB PADC dosemeter measurements (considering an average calibration factor for all neutron energies) are reported in this work. [Copyright &y& Elsevier]