[en] Post-exposure annealing of highly sensitive LiF:Mg,Cu,P (MCP-N) detectors, at 100 deg. C over 10 or 20 min prior to readout, is usually recommended for routine dosimetry. The purpose of this anneal is to eliminate low-temperature peaks, especially peak 3, which fades at room temperature in about 3 months. However, as this annealing procedure does not entirely eliminate peak 3, 10% of its thermoluminescent (TL) signal still being readable, a fading correction must be applied. The aim of this work was to optimise the conditions of post-exposure treatment, i.e. its temperature and duration, in order to facilitate the use of MCP-N detectors in routine dosimetry. MCP-N detectors were annealed in standard conditions, i.e. at 240 deg. C over 10 min and exposed to a dose of 5 mGy (¹³⁷Cs). For post-exposure annealing, six different temperatures between 100 deg. C and 150 deg. C and two time periods (10 and 20 min) were tested. TL glow curves were deconvoluted with the GCA code. A post-exposure anneal at 120 deg. C over 10 min was found to be optimal. Heating at this temperature eliminates 100% of the TL signal of peak 3, while maintaining the area and maximum intensity of the main peak 4 unchanged. In this case, no fading correction needs to be applied. Annealing at higher temperatures, up to 150 deg. C, results in a loss of peak 4 signal, and is therefore not recommended. (author)

[en] Radionuclide releases together with escaping fly ashes (from 45x10⁶ kg in previous decades to 8x10⁶ kg annually in 1996) from the main local and several small coal-fired power plants resulted in a relatively small increase in natural radioactivity levels in the Lodz region. The natural gamma terrestrial radiation dose rates (1 m above ground level) were measured at 82 points including in the vicinity of power plants, in the center of the town and on edge of the town. The average dose rate value for the first area was 36±1.2 nGy h^-1, whereas the same dose rate for the edge of town was slightly lower 30±0.9 nGy h^-1, but this difference was statistically significant. Further confirmation of the technologically slightly enhanced exposure of the local population to natural radionuclides was achieved by γ-spectrometry measurement of the uranium and thorium decay series radionuclides in the surface soil profiles (up to 30 cm depth). The average increase of ²²⁶Ra and ²³²Th radionuclides in the top layer of soil (0-10 cm) according to the 20±30 cm depth layer was 21% and 17%, respectively. However, due to the relatively low levels of ²³²Th (14.3 Bq kg^-1) and ²³⁸U (16.8 Bq kg^-1) in this area, the annual average effective dose from the natural terrestrial radiation for the local population is also relatively low, 0.28 mSv only

[en] Short-term measurements of kerma rate from external radiation in the environment have been performed simultaneously at 100 locations over an area of about 15,000 km² using the Rapid Assessment of ACcidental Exposures (RACE) system which is based on LiF:Mg,Cu,P (MCP-N) ultra-sensitive thermoluminescent detectors. The short-term exposure lasted about 5 days, a total of about 128 h between pre-exposure annealing and readout, of which the exposure of the detector at the measurement site lasted about 96 h. To verify the short-term readouts, LiF:Mg,Cu,P (MCP-N) and conventional LiF:Mg,Ti (MTS-N) detectors were exposed at the same locations over a much longer period of 75 d. 100 field sites were selected over a large area in Southern Poland at distances of up to 150 km around Krakow. TL dosemeters, calibrated in terms of air kerma free-in-air using gamma rays from a ¹³⁷Cs source, were field-exposed 1 m above ground. The average kerma rates over 75 d measured using MTS-N (LiF:Mg,Ti) detectors ranged between 47 and 87 nGy.h^-1, using MCP-N between 60 and 107 nGy.h^-1 while those measured over 4 days ranged between 56 and 100 nGy.h^-1. Comparison of ratios of short-term/long-term readouts of MCP-N at rural locations (35 points) gave a mean ratio of 0.99 ± 0.09 (1 SD). Thus, using the RACE system based on MCP-N detectors, one is able simultaneously to monitor environmental radiation kerma rates at a large number of locations over a very large area, over periods of two days, or less. Provided natural background kerma rates at selected monitoring points are available prior to the accident, the RACE system can be applied to assess kerma rates in the environment rapidly, following a nuclear accident. Noting that kerma rates would then be considerably higher, only a few hours of evaluation time would be required. The system could also be useful in reclamation and restoration works in the environment. (author)

[en] Measurements were performed with various LiF-based TLDs on board seven Polish aircraft, flying long-distance or middle-distance routes. All of the 7LiF detectors used (various types of ⁷LiF:Mg,Ti and ⁷LiF:Mg,Cu,P detectors), which measure the non-neutron component of the radiation field, produced consistent results. It was found that the characteristics of the TLD response (ratio of different detector responses, glow curve shapes) after doses of radiation at flying altitudes differ from those obtained after exposure at the CERN facility (CERF), suggesting a lower contribution of densely ionising radiation. The neutron induced TL signal was also more affected by the thickness of the holder, suggesting the presence of a softer neutron energy spectrum at flight altitudes. Further in-flight and CERF exposures of detectors are planned to resolve these issues. (author)

[en] Three different experimental methods of determination of TL light attenuation coefficients were compared using a specially prepared set of LiF detectors with different thickness. The three methods were: (1) a two-detector method in which an irradiated detector is covered during readout by another one; (2) a surface irradiation method in which a detector is twice irradiated with alpha particles and read out first with the irradiated side facing the PM and then upside-down; (3) a whole volume irradiation method in which detectors of different thickness are irradiated homogeneously with gamma rays. The two-detector method and the surface irradiation method produced consistent results, while values obtained with the whole volume irradiation method were quite different. In the surface irradiation method it is necessary to take into account the decrease in the distance between the source of light and the PM tube, when the detector is read out with its irradiated side facing the PM, with respect to the opposite position. Also light reflections from the side walls of the heater were found to play a role. The two-detector method produces the most reliable results and should be considered as the reference method. As established using this method, the attenuation factor for the white, opaque LiF : Mg,Ti detectors applied in all reported measurements was found to be μ=1.69±0.05 mm^-1

[en] One lesson learned from the Chernobyl accident was that the spatial distribution of far-field contamination was strongly non-uniform due to local variation of atmospheric conditions, such as wind direction, rain etc. An environmental monitoring system using highly sensitive thermoluminescent LiF:Mg,Cu,P (MCP-N) detectors has been completed and field-tested. The system consists of 3,000 MCP-N detectors in 1000 TLD cards (three TLDs per card), two Mikrolab automatic TL readers, heating ovens, and specially developed software which includes a database for rapid evaluation of results. The main dosimetric parameters of MCP-N dosemeters, such as thermally-induced fading, light sensitivity, minimum detectable dose, self-dose, zero-dose, energy response up to 6-7 MeV, influence of annealing and readout conditions on detector stability, have been tested. About 100 locations over an area of about 15,000 km² in the south of Poland were selected for measurements lasting from 4 days to 3 months. The kerma rates measured over a 4 day screening period agree well with kerma rates determined over a 75 day monitoring period. Results from short- and long-term exposure periods agree well with those performed using MTS-N (LiF:Mg,Ti) over southern Poland in 1985, before the Chernobyl accident. Thus, using the system based on MCP-N detectors, one is able simultaneously to monitor environmental radiation kerma rates at a large number of locations over periods of four days or less. Provided natural background kerma rates at selected monitoring points are available prior to the accident, the system can be applied to assess kerma rates rapidly in the environment, following a nuclear accident. (author)

[en] A method of measurement of radon concentration in air was developed, based on high-sensitivity LiF:Mg,Cu,P (MCP-N, TLD Poland) thermoluminescent detectors installed in charcoal canisters. The canisters were exposed typically for 72 h in a calibration chamber with a radon concentration ranging from 100 Bq.m-3 to 87 kBq.m^-3. It was found that in these conditions the signal registered by the TL detectors was proportional to the ²²²Rn concentration and the lowest limit of detection (LLD) was at a level of 100 Bq.m^-3. The proposed method can be used in large-scale, multi-site surveys aimed at screening for high levels of indoor radon concentration or for measuring ground radon exhalation rates. (author)

[en] At the Institute of Nuclear Physics in Krakow (INP), in collaboration with the Centre of Oncology in Krakow, several types of miniature thermoluminescent LiF:Mg,Ti and LiF:Mg,Cu,P detectors specially designed for clinical dosimetry in radiotherapy have been developed. The detectors are manufactured in the form of solid pellets of diameter down to 1 mm and typical thickness 0.5 mm, in the form of rods with a diameter of 0.5 mm and a length of a few mm, and as two-layer detectors with a thin (in the range of 0.065 mm) active layer of high-sensitive LiF:Mg,Cu,P. All three types of newly developed detectors have already been applied in proton beam dosimetry, surface dosimetry of eye-plaque brachytherapy applicators, phantom dosimetry for vascular brachytherapy and in vivo dosimetry in interstitial brachytherapy. These detectors were found to be very useful for dose measurements in high dose gradients, where spatial resolution better than 1 mm is required. (author)

[en] In its statement on tissue reactions approved on 21st April 2011, the International Commission on Radiological Protection () reviewed its recommendation concerning the equivalent dose limit for the eye lens and reduced the dose limits for occupationally exposed persons to 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. This limit was approved and written down in the new EURATOM (European Atomic Energy Community) directive 2013/59 and in the IAEA (International Atomic Energy Agency) BSS (Basic Safety Standard) of July 2014. For that reason, the necessity to monitor the eye lens may become more important than it was before. However, specially dedicated dosemeters for the dose quantity Hp(3) are using very rarely. Commonly use are only whole body personal dosemeters for the personal dose equivalent quantities Hp(10) worn on the trunk and ring dosemeters worn on finger to measure the quantity Hp(0.07). Therefore, in this work it was investigated whether dosemeters from routine use calibrated in terms of Hp(10) and Hp(0.07) and worn on thyroid collar and protective apron could deliver similar results like dedicated eye lens dosemeter worn close to the eyes. The results show that the best method if dedicated eye lens dosimeters is not used is to measure doses in terms of Hp(0.07) on the thyroid collar (Pearson product, r=0.85). Obtained results shows also importance of proper localization of eye lens dosimeter (close to the eye, from side of the X-ray source). - Highlights: • The specially dedicated eye-lens dosemeter EYE-D™ has been used in clinical condition in different localization on head. • Data on occupational doses per procedure were collected in different positions. • Correlations between eye lens doses and whole body and skin doses were investigated. • The use of personal and laboratory radiation protection equipment were investigated.

[en] One of the experiences learned from the Chernobyl accident was that the spatial distribution of far-field contamination was strongly non-uniform, due to local variation of atmospheric conditions, wind direction and rain. Active device monitors, which are well suited for early detection of nuclear accident at their location, require expert personnel, power supply and are not readily movable. Monitoring natural background dose rates in the environment with thermoluminescent detectors, TLDs, has been performed for a number of years however, the sensitivity of TL detectors typically used in environmental monitoring, such as LiF:Mg,Ti (TLD-100, MTS-N), CaF₂:Dy or CaSO₄:Dy requires at least 1-3 months exposure time at environmental dose-rate levels, which limits their applicability in case of radiation accidents or screening measurements. The exposure time of TL detectors can be greatly reduced if high-sensitive LiF:Mg, Cu, P TL detectors are applied. MCP-N LiF:Mg, Cu, P (developed at the INP Cracow, Poland in the mid 80's and produced there) detectors show a sensitivity approximately 30 times higher and background 3 times lower than those of conventional TLD-100. In this report dosimetry properties of MCP-N detectors such sensitivity, photon energy dependence of the dose response (-15% - +10% in the photon energy range 20 keV - 7 MeV), fading, the lowest limit of detection, response to cosmic component of radiation have been presented. It was shown that dosimeters based on LiF:Mg,Cu,P detectors allow one to measure the signal from natural radiation background after just a few hours of exposure. Based upon this experience, the system for Rapid Assessment of Accidental Exposures (RACE) was proposed at the Institute of Nuclear Physics (INP) in Cracow, Poland. This system is designed to be able to determine the distribution of dose rates in the environment (e.g. an area of Southern Poland) within periods no longer than a few days. The RACE system was designed for a large number (up to 500) of short-term (1-5 day) exposures or for long-term measurements of dose rate in the environment using dosimeters based on high-sensitive MCP-N detectors. In this work are presented results of first simultaneous measurements at 100 locations in Southern Poland, performed in two measurement periods, of 5 days and 75 days. For verification, conventional MTS-N (LiF:Mg,Ti) TL detectors were also exposed at these locations over a period of 75 days. Finally the applicability of peak area ratios (peak2/peak4 and peak3/peak4) in the glow-curves of LiF:Mg,Cu,P for the estimation of time between exposure and readout (t_ER) was studied. MCP-N detectors were exposed to simulate an ''accidental'' dose at times before readout ranging from 24 hours to three months. The peak 2/peak 4 ratio is well suited for evaluating t_ER below one week, while the peak 3/peak 4 ratio - for t_ER up to three months. The method can be applied in personal and environmental dosimetry to evaluate the date of a high dose-rate, accidental exposure. (author)