ABSTRACT
The response of albedo dosemeters depends on the energy and angle of the incident neutron radiation. For their use as personal dosemeters, a field-calibration factor has to be applied. The presently used single sphere method for field calibration can be extended and optimised by putting five albedo dosemeters on the surface of a polyethylene sphere and two TL cards in the centre. To investigate the potential of this extension, reference measurements and Monte Carlo calculations were performed and the fluence response of the detectors at different positions on and within the sphere was determined. Calculated response functions demonstrate that information on the energy and directional distribution of neutron fluence can be extracted with this simple set-up for unknown neutron fields.
Subject(s)
Neutrons , Occupational Exposure/analysis , Radiation Monitoring/methods , Radiation Protection/methods , Thermoluminescent Dosimetry/instrumentation , Thermoluminescent Dosimetry/methods , Workplace , Computer Simulation , Equipment Design , Humans , Monte Carlo Method , Radiation Dosage , Radiation Monitoring/instrumentationABSTRACT
The new albedo dosemeter-type AWST-TL-GD 04 has been calibrated in the CERF neutron field (Cern-EU high-energy Reference Field). This type of albedo dosemeter is based on thermoluminescent detectors (TLDs) and used by the individual monitoring service of the Helmholtz Zentrum München (AWST) since 2015 for monitoring persons, who are exposed occupationally against photon and neutron radiation. The motivation for this experiment was to gain a field specific neutron correction factor Nn for workplaces at high-energy particle accelerators. Nn is a dimensionless factor relative to a basic detector calibration with 137Cs and is used to calculate the personal neutron dose in terms of Hp(10) from the neutron albedo signal. The results show that the sensitivity of the albedo dosemeter for this specific neutron field is not significantly lower as for fast neutrons of a radionuclide source like 252Cf. The neutron correction factor varies between 0.73 and 1.16 with a midrange value of 0.94. The albedo dosemeter is therefore appropriate to monitor persons, which are exposed at high-energy particle accelerators.
Subject(s)
Neutrons , Occupational Exposure , Radiation Protection , Thermoluminescent Dosimetry , Calibration , Equipment Design , Humans , Radiation Dosage , Radiation Monitoring , Sensitivity and SpecificityABSTRACT
A new official albedo dosemeter based on thermoluminescent detectors has been introduced in 2015 by the individual monitoring service of the Helmholtz Zentrum München for monitoring persons who are exposed occupationally against photon and neutron radiation. To enhance the sensitivity for fast neutrons, a new badge with an enlarged albedo window has been developed at TU Dresden. The properties of the new albedo dosemeter are discussed, and the results of official intercomparisons and field calibrations are shown.
Subject(s)
Neutrons , Radiation Monitoring/instrumentation , Radiation Protection/instrumentation , Thermoluminescent Dosimetry/instrumentation , Calibration , Equipment Failure Analysis , Germany , Humans , Occupational Exposure/analysis , Occupational Exposure/prevention & control , Photons , Radiation Dosage , Radiation Dosimeters , Radiation Monitoring/methods , Radiation Protection/methods , Radiometry , Reproducibility of Results , Sensitivity and Specificity , Thermoluminescent Dosimetry/methods , UncertaintyABSTRACT
The Individual Monitoring Service of the Helmholtz Zentrum München is currently using the BeOSL dosimetry system for monitoring â¼15 000 persons per month. This dosimetry system has a modular structure and represents a complete new concept on handling dosemeters in a large-scale dosimetry service. It is based on optically stimulated luminescence dosemeters made of beryllium oxide. The dosimetric and operational properties of the system are shown and discussed.
Subject(s)
Aluminum Oxide/chemistry , Occupational Exposure/analysis , Radiation Monitoring/methods , Beryllium/chemistry , Beta Particles , Computer Systems , Electronics , Germany , Humans , Luminescence , Occupational Exposure/prevention & control , Photons , Radiation Monitoring/instrumentation , SoftwareABSTRACT
Personal neutron dosimetry has been performed in Germany using albedo dosemeters for >20 y. This paper describes the main principles, the national standards, regulations and recommendations, the quality management and the overall performance, giving some examples.
Subject(s)
Neutrons/adverse effects , Radiometry/instrumentation , Thermoluminescent Dosimetry/instrumentation , Calibration , Equipment Design , Germany , Humans , Occupational Exposure , Quality Control , Radiation Dosage , Radiation Monitoring , Radiation Protection , Radiometry/standards , Radiometry/statistics & numerical data , Thermoluminescent Dosimetry/standards , Thermoluminescent Dosimetry/statistics & numerical dataABSTRACT
The GSF-Personal Monitoring Service uses the TLD albedo dosemeter as standard neutron personal dosemeter. Due to its low sensitivity for fast neutrons however, it is generally not recommended for workplaces at high-energy accelerators. Test measurements with the albedo dosemeter were performed at the accelerator laboratories of GSI in Darmstadt and DESY in Hamburg to reconsider this hypothesis. It revealed that the albedo dosemeter can also be used as personal dosemeter at these workplaces, because at all measurement locations a significant part of neutrons with lower energies could be found, which were produced by scattering at walls or the ground.
Subject(s)
Environmental Exposure/analysis , Particle Accelerators/instrumentation , Radiation Monitoring/instrumentation , Radiation Protection/instrumentation , Thermoluminescent Dosimetry/instrumentation , Equipment Design , Equipment Failure Analysis , Internationality , Neutrons , Radiation Dosage , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
In a preliminary study, in vivo skull measurements and in vitro urine measurements of 210Pb and nulU have been performed to find out the individual, chronic exposure to waterborne natural radionuclides of a small group of Finnish people. For their domestic water, the studied individuals use water from drilled wells containing elevated concentrations of natural uranium and its daughter nuclides ((234,235,238)U, 222Rn, (226,228)Ra, 210Po, 210Pb). Enhanced 210Pb and 235U activities were observed in several people. A positive correlation is observed between the U concentration in urine (microg d(-1)) and the number of counts (cpm) in the gamma ray energy peaks originating from the decay of 235U and 234Th respectively. Calibration of the detector set-up and the determination of background sources are in progress.
