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[Radiotoxicological surveillance of personnel occupationally exposed to the hazards of internal radiocontamination in a nuclear center].

At the Casaccia Nuclear Centre the personnel occupationally exposed to a risk of internal contamination from radioactive substances is controlled by means of periodic radiotoxicological analyses. About 30,000 analyses of natural uranium, enriched uranium, thorium, gamma emetters, plutonium, americium, etc. in urine have been carried out since 1962. In the case of accidental acute radiocontamination by inhalation, wound and ingestion, special control on urine, blood, feces, nasal swabs, etc. must be schedules. The results can be very useful to the medical staff in order to take the most suitable therapeutical measures or to calculate the body burden.

Air Pollutants, Radioactive↗

[Iridodiagnosis in the system of the follow-up of the health status of the population living in an area contaminated by radioactive substances].

The authors substantiate the practical employment of the iridodiagnosis screening-test using a system of archiving and visualization of the iris at the first stage of prophylactic medical examination and management. The economical and medical efficacy of the method has been established. Use of iridodiagnosis improved the detectability of pathologic conditions as compared with complex medical examination. Many specialists were freed from mass medical screening. The expenses for prophylactic medical examination became ten times less.

Adult↗

The radioactivity of coloured rain in Thessaloniki, Greece.

The radioactivity of coloured rain precipitated over Thessaloniki, Greece, on 4-5 April 1988 was determined. The long-lived fission product radionuclides such as 137Cs, 134Cs, 144Ce, 106Ru and 125Sb were identified in dust originating from the Sahara desert which was precipitated with the rain to produce coloured rain. Caesium-137 concentrations reached 1000 Bq kg-1, resulting in a deposition of 3.03 Bq m-2, which is four orders of magnitude lower than measured on 5-6 May 1986 after the Chernobyl reactor accident.

Air Pollution, Radioactive↗

EC intercomparisons for laboratories monitoring environmental radioactivity.

International measurement comparisons are organised regularly for EU laboratories involved in monitoring radioactivity, with emphasis on meeting routine measurement conditions. Using the recent comparison of 137Cs in air filters as an example, the whole cycle is described: establishment of traceable reference values, spiking of individual filters for the comparison and their quality assurance, treatment and measurement of filters in the participating laboratories and evaluation of comparison results. The treatment of an individual result, deviating widely from the reference value, is discussed. Monte-Carlo simulations allow to estimate the maximum errors possibly made due to a non-suitable measurement geometry.

Air Pollutants, Radioactive↗

Description of the properties of unattached 218Po and 212Pb particles by means of the classical theory of cluster formation.

A review is given of the classical theory of cluster formation to see whether it is a useful description of the behaviour of unattached radioactive particles. Special attention is given to the predictions concerning the size of the clusters, their growth, and their dependency on humidity and other trace gases. The theory is compared with the experimental observations of the last two decades. It is found that the theory predicts most of the properties of 218Po and 212Pb particles. It cannot explain the conflicting results regarding the humidity dependency of the unattached particle size. An important prediction of the theory is the failure of the unattached particle concept in some environmental conditions.

Air Pollutants, Radioactive↗

Discrimination of airborne radioactivity from radon progeny.

Naturally occurring radon and thoron progeny are the most interfering nuclides in the aerosol monitoring system. The high background and fluctuation of natural radioactivity on the filter can cause an error message to the aerosol monitor. A theoretical model was applied in the simulation of radon and thoron progeny behavior in the environment and on the filter. Results show that even a small amount of airborne nuclides on the filter could be discriminated by using the beta:alpha activity ratio instead of gross beta or alpha counting. This method can increase the sensitivity and reliability of real-time aerosol monitoring.

Air Pollutants, Radioactive↗

Environmental dose assessment for low-level radioactive effluents discharged from Tokai reprocessing plant.

In the normal operation of the Tokai reprocessing plant, low-level radioactive effluents are discharged to the atmosphere and the ocean under rigid control. Radiation exposures to the population around the plant have been estimated for potential pathways with site-specific parameters such as food consumption, concentration factors of marine organisms, and meteorological conditions. External exposures to a radioactive cloud and internal exposures from inhalation and oral intake of radionuclides are evaluated for airborne effluents. External exposures to a contaminated fishing net and fishing boat are considered pathways for fishermen. External exposure to a contaminated beach and internal exposure via oral intake of marine products are evaluated for liquid effluents. Since the plant began operation in 1977, estimated effective dose equivalents for the public have been less than the annual effective dose equivalent limit of 0.1% recommended by the International Commission on Radiological Protection (1977).

Air Pollution, Radioactive↗

[Genetic disorders in the pollen cells of waxy barley in radioactive contamination after the Chernobyl accident].

Genotoxic effects during microsporogenesis and gametogenesis were studied in barley of the waxy strain grown on 3 experimental plots situated in the region of the Chernobyl disaster (plot 1 in the town of Chernobyl, plots 2 and 3 in the town of Yanov, 3 km away from the damaged power plant). It was determined that an increased level of radionuclide pollution and chronic irradiation during ontogenesis results in higher incidence of meiotic disturbances and abnormalities during formation of the male gametophyte. Incidence of waxy reversions in pollen grains depends on the activity of radionuclide pollutants as well. We suggest that selection affecting both diplont and haplont forms will provide for the absence of significant aberrations in subsequent plant generations.

Accidents↗

Atmospheric deposition of cosmogenic 7Be and 137Cs from fallout of the Chernobyl accident.

Atmospheric (tropospheric) depositional fluxes of the naturally occurring 7Be of cosmogenic origin and 137Cs from fallout of the Chernobyl accident were measured over a 7-year period (January 1987-December 1993) at Thessaloniki, Greece (40 degrees 38' N, 22 degrees 58' E). The annual total deposition fluxes of 7Be varied between 854 Bq/m2 (1987) and 1242 Bq/m2 (1992), showing a minimum in the years 1988-89. The annual total deposition fluxes of 137Cs varied between 183 Bq/m2 (1987) and 16.4 Bq/m2 (1992), showing a significant decrease as expected for natural removal and radioactive decay and no new releases from nuclear facilities or weapons testing. The annual average total deposition velocity for 7Be was from 0.3 cm/s (1988) up to 0.8 cm/s (1991), while for 137Cs the corresponding values were much higher, hence 137Cs was associated with larger atmospheric particles. High 7Be concentrations in air were related to the very little solar activity (1987-88 and 1993-94), while low 7Be concentrations in air related to the high solar activity (1989-91). Maximum 137Cs concentrations in air were registered during the spring 1991 and 1992, reflecting some stratospheric inputs. An unusual highly elevated value of 137Cs concentration in air, reaching 0.25 mBq/m3, was observed during the summer 1990.

Air Pollutants, Radioactive↗

Atmospheric xenon radioactive isotope monitoring.

The Comprehensive Nuclear Test Ban Treaty (CTBT) organisation is implementing a world-wide monitoring network in order to check that the State Signatories comply with the treaty. One of the monitoring facilities consists of an atmospheric noble gas monitoring equipment. According to the requirements annexed in the treaty, the French Atomic Energy Commission (CEA) developed a device, called SPALAX, which automatically extracts xenon from ambient air and makes in situ measurements of the activities of four xenon radioisotopes (131mXe, 133mXe, 133Xe, 135Xe). The originality of this device is noticeable essentially in the gas sample processing method: thanks to the coupling of a gas permeator and of a noble gas specific adsorbent, it can selectively extract and concentrate xenon to more than 3 x 10 E6. This process is carried out continuously without cryogenic cooling, without any regeneration time. The detection of the xenon radioactive isotopes is done automatically by high spectral resolution gamma spectrometry, a robust technology well-suited for on-field instrumentation. In the year 2000, a prototype was involved in an international evaluation exercise directed by the CTBT organisation (CTBTO). This exercise demonstrated that the SPALAX equipment perfectly met the requirements of the CTBTO for such systems. On the basis of the continuous 24-h resolution record of the atmospheric xenon radioactive isotopes concentrations, the SPALAX system also demonstrated that ambient levels of 133Xe can fluctuate quickly from less than the detection limit to over 40 x 10(-3) Bq m(-3). In order to build an industrial version of this equipment, the CEA entered into a partnership with a French engineering company (S.F.I., Marseille, France), which is now able to produce an industrial version of SPALAX, i.e. more compact and more efficient than the prototypes. The 133Xe minimum detectable concentration is 0.15 x 10(-3) Bq m(-3) air per 24 h sampling cycle.

Air Pollutants, Radioactive↗

Measurements of radioactive gaseous releases to air from target halls at a high-energy proton accelerator.

Measurements of induced radioactivity concentration in air were made at five target halls associated with the Fermilab high-energy proton synchrotron. A gas flow-through ionization chamber was used to continuously sample air released from an exhaust stack at each location. The radioactive decay of a grab sample of air from each target hall was recorded, and a best-fit of each decay curve was made via iterative steps to determine the mixture of radionuclides present. The radionuclides 11C, 13N, 15O, 38Cl, 39Cl, and 41Ar were identified. Two distinct radionuclide mixtures or "signatures" were found and were correlated to the geometry of the proton loss point. The normalized activity release rates for the five target areas agree within a factor of two of the average value of 2.7 muBq per proton for 800 GeV protons.

Air Pollutants, Radioactive↗

Overview of radiation safety in the tin by-product (amang) industry of South East Asia.

Processing of by-product heavy minerals (amang) from tin mining involves potential exposure to external and internal sources of radioactivity. The radioactivity arises through the presence of thorium and uranium series radionuclides in the various minerals. Monazite is the most radioactive mineral, containing 3% to 7% thorium by weight, while ilmenite is generally the least radioactive mineral containing typically less than 0.05% thorium. External exposure occurs when workers are in close proximity to accumulations or stockpiles of the radioactive minerals, whereas internal exposure occurs when workers are involved in dusty processes. This paper summarizes the nature of the amang industry in South East Asia and presents the results of preliminary measurements of external radiation and airborne radioactivity in twelve Malaysian and Thai plants. Although constrained by a paucity of exposure data, it is concluded that radiation doses to some amang plant workers may approach or exceed international standards and that appropriate control measures are required as a matter of priority, Radiation doses may approach or exceed 100 mSv in situations where workers are exposed to excessive levels of ambient dust and no protective measures are used. Observations and recommendations are made relating to monitoring and surveillance, instruction and training, and engineering and administrative protection measures.

Air Pollutants, Radioactive↗

Transport of the radioisotopes iodine-131, cesium-134, and cesium-137 from the fallout following the accident at the Chernobyl nuclear reactor into cheesemaking products.

The transport of radiation contamination from milk to products of the cheese making process has been studied. The concentration of radioactive iodine and cesium in samples of sheep milk and cheese (Gruyère) products was measured for 10 consecutive production d. Milk with concentration 100 Bq/L in each of the radionuclides 131I, 134Cs, and 137Cs cheese with concentration 82.2 +/- 3.9 Bq/kg in iodine and an average of 42.3 +/- 2.3 Bq/kg in the cesium isotopes is produced. The corresponding concentrations in cream extracted from the same milk are 26.7 +/- 2.8 Bq/kg (131I) and 18.6 +/- 1.9 Bq/kg (134Cs, 137Cs).

Accidents↗

[Influence of nuclear reactor accident at Chernobyl' on the environmental radioactivity in Toyama].

The environmental radioactivity caused by the reactor accident at Chernobyl' was investigated from May 7 to May 31 of 1986 in Toyama. Measurement of radioactivities in airborne particles, rain water, drinking water, milk, and mugwort are carried out by gamma-ray spectrometry (pure Ge detector; ORTEC GMX-23195). Ten different nuclides (103Ru, 106Ru, 131I, 132Te-I, 134Cs, 136Cs, 137Cs, 140Ba-La) are identified from samples of airborne particles. In the air samples, a maximum radioactivity concentration of each nuclide is observed on 13th May 1986. The time of the reactor shut-down and the flux of thermal neutron at the reactor were calculated from 131I/132I and 137Cs/134Cs ratio. The exposure dose in Toyama by this accident is given as follows: internal exposure; [thyroid] adult-59 microSv, child-140 microSv, baby-130 microSv, [total body] adult-0.2 microSv, child, baby-0.4 microSv, external exposure; 7 microSv, effective dose equivalent; adult-9 microSv, child-12 Sv, baby-11 microSv.

Accidents↗

Radionuclide transport processes in terrestrial ecosystems.

Some major principles and the status of knowledge concerning the transport of radionuclides through terrestrial ecosystems are reviewed. Fundamental processes which control the flow of radionuclides between ecosystem components such as air, soil, plants, and animals are described, with emphasis on deposition, resuspension, plant uptake, ingestion, and assimilation. Properties of radionuclides, organisms, and ecosystems are examined in relation to their influence on the accumulation of radioactive materials by plants and animals. The effects of the physicochemical nature of the radionuclide; morphology, physiology, and behavior of the organism; and soil, nutrient, and trophic characteristics of the ecosystem are highlighted. Observations in natural ecosystems on radionuclides such as 137Cs, 90Sr, 131I, 3H, and 239Pu are used to illustrate current concepts. An assessment of the degree to which the processes controlling radionuclide behavior are understood and of our ability to simulate and predict such behavior with computerized models is offered. Finally, brief comments are made on research needs.

Air Pollutants↗

Determination of MDA for a two count method for stripping short-lived activity out of an air sample.

When measuring airborne activity of isotopes with very low annual limit of intakes, interference from natural radioactivity presents an obstacle to obtaining timely results. One method for solving this problem is to perform two separate counts of the sample and mathematically strip-out the contribution from the short-lived component. While this method can process a large volume of samples with little or no preparation time, the sensitivity of the analysis is hard to determine. In an attempt to determine the sensitivity of the analysis and to quantify the parameters that affect it, an equation for the minimum detectable activity was derived. Actual air sample data were then evaluated against this equation to determine its usefulness.

Air Pollutants, Radioactive↗

Survey of 99mTc contamination of laboratory personnel: its degree and routes.

Internal contamination of personnel preparing 99mTc labeled radiopharmaceuticals was confirmed by detection of radioactivity in urine. Observation of work habits, whole-body scanner studies, nose swabs, and wipe tests in the hot laboratory demonstrated that: (a) contamination of the laboratory coat occurred during radiopharmaceutical preparation; (b) the degree of personnel contamination appeared to be higher among the short in stature; and (c) no gross evidence was found to indicate that internal contamination took place through an air-borne route. While the calculated internal radiation dose is minimal, even this could be avoided if particular precautionary practices are observed.

Absorption↗

The measurement of radon working levels at a mineral separation pilot plant in Cox's Bazar, Bangladesh.

Beach Sand Exploitation Centre at Cox's Bazar, Bangladesh, produces commercial grade concentrations of magnetite, ilmenite, zircon, etc., from the high-grade accumulations available along the beach and foredune of Cox's Bazar. Solid state nuclear track detectors (CR-39 foils) were used to determine indoor radon concentration of radioactive mineral sands and the technologically enhanced radiation level inside the pilot plant of the Centre. It is found that the concentrations at processed mineral stock areas are high, and the maximum concentration was found to be 2,103 +/- 331 Bq m(-3) (0.23 +/- 0.03 WL). The indoor concentration of radon and its decay products in the raw sand stock area and at other locations was in the range of 116 +/- 27 Bq m(-3) (0.03 +/- 0.003 WL) to 2,042 +/- 233 Bq m(-3) (0.22 +/- 0.03 WL).

Air Pollutants, Radioactive↗