Radioactive Deposits Research Articles

Effects of Hydrogen Peroxide on Cobalt Deposition Rate on Primary Cooling System ofBoiling Water Reactors

Experimental data of radioactivity deposition rates on stainless steel specimensexposed to high-temperature water including hydrogen peroxide (H2O2) and oxygen (O2) were applied to the evaluation of Co-60 accumulation rates in oxide films on the stainless steel piping of a boiling water reactor (BWR) primary cooling system and then an empirical formula of Co-60 deposition rate coefficient was proposed as a function of exposure time. The empirical formula was applied to the evaluationof the amount of Co-60 deposition on the stainless steel piping of BWR primary cooling systems under normal water chemistry (NWC) and hydrogen water chemistry (HWC) conditions. The results are summarized as follows. 1) The Co-60 deposition rate coefficient was almost independent of O2 concentration ([O2]), while it decreased as H2O2 concentration ([H2O2]) decreased. 2) The proposed empirical formula determined on the basis of experiments under H2O2 conditions could give a much better estimation of the Co-60 deposition rate coefficient on stainless steel under NWC conditions of BWR than the previous formula based on the data under simple O2 conditions. 3) The deposition amounts of Co-60 on stainless steel piping under HWC conditions were evaluated using the formula, which suggested that those without any prefilming treatment were several times as high as those under NWC conditions. 4) The increase in Co-60 deposition under HWC conditions was caused by the less protective film in mitigating Co-60 deposition and it could be avoided by several hundred hours of operation under NWC conditions prior to HWC operation. The effect on material integrity is evaluated to be negligible.

Atmospheric volcanic loading derived from bipolar ice cores: Accounting for the spatial distribution of volcanic deposition

Previous studies have used small numbers of ice core records of past volcanism to represent hemispheric or global radiative forcing from volcanic stratospheric aerosols. With the largest‐ever assembly of volcanic ice core records and state‐of‐the‐art climate model simulations of volcanic deposition, we now have a unique opportunity to investigate the effects of spatial variations on sulfate deposition and on estimates of atmospheric loading. We have combined 44 ice core records, 25 from the Arctic and 19 from Antarctica, and Goddard Institute for Space Studies ModelE simulations to study the spatial distribution of volcanic sulfate aerosols in the polar ice sheets. We extracted volcanic deposition signals by applying a high‐pass loess filter to the time series and examining peaks that exceed twice the 31‐year running median absolute deviation. Our results suggest that the distribution of volcanic sulfate aerosol follows the general precipitation pattern in both regions, indicating the important role precipitation has played in affecting the deposition pattern of volcanic aerosols. We found a similar distribution pattern for sulfate aerosols from the 1783–1784 Laki and 1815 Tambora eruptions, as well as for the total β activity after the 1952–1954 low‐latitude Northern Hemisphere and 1961–1962 high‐latitude Northern Hemisphere atmospheric nuclear weapon tests. This confirms the previous assumption that the transport and deposition of nuclear bomb test debris resemble those of volcanic aerosols. We compare three techniques for estimating stratospheric aerosol loading from ice core data: radioactive deposition from nuclear bomb tests, Pinatubo sulfate deposition in eight Antarctic ice cores, and climate model simulations of volcanic sulfate transport and deposition following the 1783 Laki, 1815 Tambora, 1912 Katmai, and 1991 Pinatubo eruptions. By applying the above calibration factors to the 44 ice core records, we have estimated the stratospheric sulfate aerosol loadings for the largest volcanic eruptions during the last millennium. These loadings agree fairly well with estimates based on radiation, petrology, and model simulations. We also estimate the relative magnitude of sulfate deposition compared with the mean for Greenland and Antarctica for each ice core record, which provides a guideline to evaluate the stratospheric volcanic sulfate aerosol loading calculated from a single or a few ice core records.

Deposition of Aerosolized Particles in the Maxillary Sinuses before and after Endoscopic Sinus Surgery

Recent studies suggest that topical therapy is beneficial in many conditions underlying chronic sinusitis. Current literature has documented low aerosolized particle deposition efficiency into the paranasal sinuses. Mathematical modeling suggests that three factors influence the deposition efficiency: particle size, pressure gradient, and size of the sinus ostium. Ostium size is the most dominant factor. Therefore, we sought to determine if maxillary antrostomy and ethmoidectomy would increase the deposition efficiency. Five cadavers underwent pre- and postoperative scintigraphy after administration of aerosolized Tc-99M. Images were obtained with a gamma-camera and regions of interest (ROIs) were drawn around the maxillary sinuses. Counts per minute in the pre- and postoperative ROIs were then compared using the paired t-test. Results indicated a significant increase in deposition of radioactivity in the maxillary sinuses in the postoperative state (p < 0.01). Topical therapy for chronic sinusitis may be more feasible in the postoperative population.

Comparison of normal tissue pharmacokinetics with 111In/90Y monoclonal antibody m170 for breast and prostate cancer

Radioactivity deposition in normal tissues limits the dose deliverable by radiopharmaceuticals (RP) in radioimmunotherapy (RIT). This study investigated the absorbed radiation dose in normal tissues for prostate cancer patients in comparison to breast cancer patients for 2 RPs using the monoclonal antibody (MAb) m170. 111In-DOTA-glycylglycylglycyl-l-p-isothiocyanatophenylalanine amide (GGGF)-m170 and 111In-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) 2-iminothiolane (2IT)-m170, representing the same MAb and chelate with and without a cleavable linkage, were studied in 13 breast cancer and 26 prostate cancer patients. Dosimetry for 90Y was calculated using 111In MAb pharmacokinetics from the initial imaging study for each patient, using reference man- and patient-specific masses. The reference man-specific radiation doses (cGy/MBq) were not significantly different for the breast and the prostate cancer patients for both RPs in all but one tissue-RP combination (liver, DOTA-2IT). The patient-specific doses had differences between the groups most of which can be related to weight differences. Similar normal tissue doses were calculated for two groups of patients having different cancers and genders. This similarity combined with continued careful analysis of the imaging data might allow the use of higher starting doses in early phase RIT studies.

Quantification of extrapulmonary translocation of intratracheal-instilled particles in vivo in rats: Effect of lipopolysaccharide

Particulate air pollution is associated with respiratory and cardiovascular morbidity and mortality. However, important uncertainties remain in the quantification of extrapulmonary translocation of ultrafine particles into blood circulation. Therefore, the widely used radioiodinated technique was applied to radiolabel polystyrene particles with an average diameter of 56.4 and 202 nm, respectively. The extrapulmonary distribution of these particles (3.7 × 10 5 Bq/rat) was quantified at 0.5, 2, 24 and 120 h after intratracheal instillation in rats. Moreover, we have taken into account the possible involvement of pulmonary inflammation in this process. Rats which received a single intratracheal instillation of free 125I or a single intravenous injection of labeled ultrafine particles served as control. The results indicated that the pulmonary deposition of radioactivity was almost unchanged for both sizes. Only small amounts of radioactivity (1.64–2.49%) were recovered in blood shortly after administration of both types of particle, in healthy rats. However, the extent of particle translocation into the blood of the ultrafine size following the pretreatment with lipopolysaccharides was significantly higher (from 1.96 ± 0.67 to 4.73 ± 0.31%) compared to larger particles (from 2.19 ± 0.77 to 2.21 ± 0.64%). In conclusion, our findings suggest that only a small fraction of intratracheal-instilled ultrafine particles can pass rapidly into systemic circulation, but this translocation is markedly increased following LPS pretreatment. Thus, pulmonary inflammation seems to play a major role in enhancing the extrapulmonary translocation of particles.

Combined administration of barbourin–albumin and hirudin–albumin fusion proteins limits fibrin(ogen) deposition on the rabbit balloon-injured aorta

Introduction There are continuing needs for new antithrombotic agents and procedures. We hypothesized that the slowly cleared recombinant fusion proteins barbourin–albumin (BLAH 6) and hirudin–albumin (HLAH 6) would be effective in limiting fibrin(ogen) and/or platelet deposition in a rabbit model of arterial injury. Materials and methods Recombinant fusion proteins were expressed in Pichia pastoris fermenter cultures and purified by nickel-chelate affinity chromatography. They were injected intravenously into rabbits prior to blood sampling and platelet aggregometry, assessment of deposition of 125I-fibrin(ogen) and 51Cr-platelet onto the balloon-injured thoracic aorta, electron microscopy (EM) and immunohistochemistry of aortic sections, and determination of bleeding time following a standardized ear incision. Results and conclusions BLAH 6 administration elicited a dose- and time-dependent inhibition of platelet aggregation in post-injection whole blood samples, and reduced both fibrin(ogen) and platelet deposition on the injured aorta, although the former effect was both more durable and more significant than the latter. In contrast, HLAH 6 injection reduced fibrin(ogen) but not platelet deposition. Doses of the two proteins ineffective in preventing fibrin(ogen) deposition when given alone were effective when combined, suggesting at least additive effects. Immunohistochemistry and EM supported the radioactive deposition studies, while bleeding times were decreased with combined BLAH 6 and HLAH 6 administration compared to HLAH 6 alone in a rabbit ear bleeding model. The data show that these fusion proteins exert an antithrombotic effect in vivo and may indicate that combined low-dose administration of antiplatelet and antithrombin agents could offer safety advantages in the treatment of thrombosis.

Contamination caused by radium discharged with mine effluents into inland waters

One of the most serious problems occurring during coal extraction in Upper Silesia in Poland is caused by waters with very high salinity. These waters often contain also high concentrations of natural radionuclides, mainly 226 Ra from uranium series and 228 Ra from thorium series. At least 70% of the total amount of radium carried by this waters remains nowadays in underground galleries as radioactive deposits. But, during the period of the most extensive coal extraction up to 225 MBq of 226 Ra and 400 MBq of 228 Ra were released daily into surface along with the other mine effluents. As a result of discharge of radium-bearing waters into settling ponds and later into rivers a significant increase of radium concentration in bottom sediments has been observed. Sometimes there is also a contamination of river beds, soils and biota. The paper describes results of investigation of waters and sediments with enhanced natural radioactivity, that occur in settling ponds, where mine waters have been dumped. Measurements of different factors of radiological hazard were made, such as radium content in the soil from ponds' banks, variations of gamma radiation background and radon exhalation. Additionally radium transfer to vegetation that had transgressed into the ponds has been calculated.

Effects of Hydrogen Peroxide on Radioactive Cobalt Deposition on Stainless Steel Surface in High Temperature Water

In order to understand the effects of hydrogen peroxide on 60Co deposition under water chemistry conditions of boiling water reactors, deposition amounts of 60Co on the stainless steel specimens were measured by changing hydrogen peroxide (H2O2) and oxygen (O2) concentrations in a high temperature water loop, and correlations between the nature of oxide film on the specimen surface and its deposition were examined by separating the contributions of inner and outer oxide layers to the deposition. The results are summarized as follows. 1. The weight change of the specimens and the amount of 60Co deposition were strongly affected by the presence of H2O2. Weight gain of the specimens exposed to various H2O2 concentrations after a 200-h pre-exposure to 200 ppb H2O2 was less than 2μg/cm2 for 1,000 h; this was caused by protection effects of thin and dense oxide film. 2. The amount of 60Co deposition on the specimen exposed to 200 ppb H2O2 was much less than the amounts of those exposed to 10, 5 and 0 ppb H2O2 in the water with 50 ppb H2, but in the case of 200 h-pre-exposure to 200 ppb H2O2, the latter specimens had deposition amounts as low as that of the specimen exposed to 200 ppb H2O2. 3. The amount of 60Co deposition had a fairly linear correlation with the amount of outer oxide layer, except in the case of specimens exposed to the condition without H2O2 from the first. In the latter case, 60Co was expected to be included in a Cr-rich inner oxide layer.

Radial P32 ion implantation using a coaxial plasma reactor: Activity imaging and numerical integration

Beta-emitting biomedical implants are currently employed in angioplasty, in the treatment of certain types of cancers, and in the embolization of aneurysms with platinum coils. Radioisotopes such as P32 can be implanted using plasma-based ion implantation (PBII). In this article, we describe a reactor that was developed to implant radioisotopes into cylindrical metallic objects. The plasma first ionizes radioisotopes sputtered from a target, and then acts as the source of particles to be implanted into the biased biomedical device. The plasma therefore plays a major role in the ionization/implantation process. Following a sequence of implantation tests, the liners protecting the interior walls of the reactor were changed and the radioactivity on them measured. This study demonstrates that the radioactive deposits on these protective liners, adequately imaged by radiography, can indicate the distribution of the radioisotopes that are not implanted. The resulting maps give unique information about the activity distribution, which is influenced by the sputtering of the P32-containing fragments, their ionization in the plasma, and also by the subsequent ion transport mechanisms. Such information can be interpreted and used to significantly improve the efficiency of the implantation procedure. Using a surface barrier detector, a comparative study established a relationship between the gray scale of radiographs of the liners, and activity measurements. An integration process allows the quantification of the activities on the walls and components of the reactor. Finally, the resulting integral of the P32 activity is correlated to the sum of the radioactivity amounts that were sputtered from radioactive targets inside the implanter before the dismantling procedure. This balance addresses the issue of security regarding PBII technology and confirms the confinement of the radioactivity inside the chamber.

Long-term measurements of the global atmospheric electric circuit at Eskdalemuir, Scotland, 1911–1981

A long series of surface potential gradient (PG) measurements made at a remote site at Eskdalemuir, Scotland (55°19′N, 3°12′W) has been recovered from archives. The data span 1911–1981, but measurements between 1950 and 1970 were affected by surface radioactive deposition from nuclear weapons tests. A long-term decline in the monthly mean values is apparent in all months. Close agreement is demonstrated between hourly PG changes observed on the research ship Carnegie and those at Eskdalemuir during selected days in 1928/1929, supporting the global circuit concept. In December, a month in which the correlation between the average hourly PG and the Carnegie curve is high, similar variations are seen between the observations at Eskdalemuir and the annual averages of the ionospheric potential 1970–1976, a global circuit parameter. Changes in the shape of the Carnegie curve are apparent between spring and autumn, using data averaged between 1970 and 1981. The Eskdalemuir data offers long-baseline measurements from which, with careful analysis, changes in the global atmospheric electric circuit may be inferred.

Behavior of 137Cs concentrations in the North Pacific in an ocean general circulation model

We have carried out a first simulation of the spatial distributions and the temporal variations of 137Cs concentrations in the North Pacific in off line calculations by using archived output of an ocean general circulation model (OGCM) developed by the National Center of Atmospheric Research (NCAR). Artificial radionuclides including 137Cs are introduced into ocean surface due to global fallout originating from the large‐scale atmospheric nuclear weapons tests in 1961–1962. The distribution of radioactive deposition used as forcing for this simulation is estimated from global precipitation data and observed values of annual deposition of radionuclides at the Meteorological Research Institute (MRI) in Japan. 137Cs originating from global fallout have been transported into the ocean interior by advection and diffusion, and the 137Cs concentrations reduced by radioactive decay. We assess the skill of the model calculations by comparing simulated values of 137Cs in seawater with the observed values included in the database compiled by MRI because 137Cs is one of the most useful tracers regarding water motion in the ocean. The vertical and horizontal distributions of the calculated 137Cs concentrations were in good agreement with those of the observed 137Cs concentrations, except in the deep layer.

Resuspension: decadal monitoring time series of the anthropogenic radioactivity deposition in Japan.

Monthly atmospheric depositions of (90)Sr and (137)Cs have been observed at the Meteorological Research Institute (MRI), Tsukuba, Japan. This study reports temporal trends and levels of (90)Sr and (137)Cs depositions in the 1990s. Although the current (90)Sr and (137)Cs concentrations declined dramatically, they have been found continuously in the deposition samples throughout the 1990s. During this period, the annual (90)Sr ((137)Cs) deposits at MRI ranged from 70-180 (140-350) mBq/m(2)/year. With a sufficiently long time series, the decreasing trend of the deposition evidently differs from the past stratospheric fallout; it is far slower. Thus, reservoirs other than the stratosphere provide small amounts of (90)Sr and (137)Cs to the atmosphere. A simple calculation clearly refutes the significance of the ocean as a potential source of airborne anthropogenic radioactivity. We will demonstrate that these radionuclides in the deposited materials originate from resuspension processes (soil dust suspension processes). The temporal trends of the time series monitoring reveal differences from those in the UNSCEAR Report 2000, which were predicted by a model that disregarded resuspension. The specific activity of (90)Sr ((137)Cs) in the annual depositions exhibited a 10-year (20-year) half-life. Those data were comparable with values reported in the literature for the half-residence time (HRT) of (90)Sr and (137)Cs in Japanese surface soils. They were also comparable to those calculated from nationwide data of (90)Sr and (137)Cs concentrations in the surface soil (0-10 cm) obtained from the Ministry of Education, Culture, Sports, Science and Technology Environmental Radiation Database (the MEXT Database). Regarding the activity ratio of (137)Cs/(90)Sr, the Japanese nationwide surface soil data collected during the 1990s in the MEXT Database (median: 5.3, n = 584) did not accord with that in the deposition samples (average: 2.1, n = 82) at MRI. This supports our previous hypothesis that Asian dust may transport a large fraction of anthropogenic radioactivity into the Japanese atmosphere. We need to study the fate of long-lived anthropogenic radioactivity dispersed in the environment over greater spatial and temporal scales.

Numerical simulation of 137Cs and 239,240Pu concentrations by an ocean general circulation model

We simulated the spatial distributions and the temporal variations of 137Cs and 239,240Pu concentrations in the ocean by using the ocean general circulation model which was developed by National Center of Atmospheric Research. These nuclides are introduced into seawaters from global fallout due to atmospheric nuclear weapons tests. The distribution of radioactive deposition on the world ocean is estimated from global precipitation data and observed values of annual deposition of radionuclides at the Meteorological Research Institute in Japan and several observed points in New Zealand. Radionuclides from global fallout have been transported by advection, diffusion and scavenging, and this concentration reduces by radioactive decay in the ocean. We verified the results of the model calculations by comparing simulated values of 137Cs and 239,240Pu in seawater with the observed values included in the Historical Artificial Radionuclides in the HAM database, which has been constructed by the Meteorological Research Institute. The vertical distributions of the calculated 137Cs concentrations were in good agreement and are in good agreement with the observed profiles in the 1960s up to 250 m, in the 1970s up to 500 m, in the 1980s up to 750 m and in the 1990s up to 750 m. However, the calculated 137Cs concentrations were underestimated compared with the observed 137Cs at the deeper layer. This may suggest other transport processes of 137Cs to deep waters. The horizontal distributions of 137Cs concentrations in surface water could be simulated. A numerical tracer release experiment was performed to explain the horizontal distribution pattern. A maximum 239,240Pu concentration layer occurs at an intermediate depth for both observed and calculated values, which is formed by particle scavenging. The horizontal distributions of the calculated 239,240Pu concentrations in surface water could be simulated by considering the scavenging effect.

Depth profiles of long lived radionuclides in Chernobyl soils sampled around 10 years after the accident

Depth profiles of the long-lived radionuclides, 137Cs, 90Sr, Pu isotopes and 241Am were examined in undisturbed sandy, peaty and Podsol soils in the Chernobyl 30 km exclusion zone sampled around 10 years after the accident. Two Podsol soils, which have different radioactive deposition characteristics, have also been examined. Activity ratios of 239,240Pu/137Cs, 90Sr/137Cs, and 241Am/137Cs in the 0-1 cm layer of the two Podsol soils differed very much. Speciation of the radionuclides by sequential selective extraction was examined in the soils. Depth profiles of the soils have been analyzed according to the speciation results and soil characteristics.

Chernobyl 137Cs deposition in Austria: analysis of the spatial correlation of the deposition levels

The semivariogram can provide a description of the spatial correlation of a variable that represents a continuous function of space co-ordinates. Therefore, it is not only useful to improve sampling strategies and validate the collected data, but it can also define the main parameters that are involved in most mapping algorithms. The spatial correlation may, however, change depending on the values of the variable, which is not without consequences on the quality of the maps of radioactive deposition. This work investigates the spatial correlation for different levels of 137Cs deposited in Austria. It is shown that low levels (<5 kBq/m 2 ) and high levels (>40 kBq/m 2 ) of radioactivity present less correlation in space than the mid-levels (5– 40 kBq/m 2 ). As a result, maps establishing the probabilities to be under or above a specific deposition threshold will have an uncertainty associated to the estimated values that is directly correlated to the different levels of radioactivity.

Application of In-Service Temperature Lowering to Reduce Radioactivity Corrosion Product Deposition on Carbon Steel Piping of BWR Residual Heat Removal System

Assessment of plant data and experiments on deposition of ion species on carbon steel were carried out in order to develop suitable countermeasures to reduce RHR (residual heat removal) piping dose rate. It was thought that radioactivity deposits on the RHR piping were mainly from radioactive ion species in the coolant and they were enhanced by the dehydration reaction of corrosion products on the piping. From an evaluation for temperature dependence of the dehydration reaction, it was proposed to lower the start-up temperature of RHR operation as a way to reduce radioactivity deposition. Feasibility studies of improved RHR operation were conducted and test operations were carried out in the Shika Nuclear Power Station Unit 1. Application of the improved RHR operation resulted in a temperature reduction from 150°C to 110°C, and a radioactivity deposition reduction on the RHR piping to one-fifth ofthat in conventional RHR operation. The improved RHR operation has now been applied to more than fifteen Japanese BWRs and significant suppression effects of radioactivity deposition have been observed.

Global radioactive deposition on the Yenisey-river catchment and its contribution to the summary contamination of the valley

The results of the retrospective global radioactive contamination mapping of the Enisey-river catchment are presented. The maps of spatial ,J7 Cs distributions of 1964, 1974, 1986, 2000 are compiled using the geo- information technologies in the Institute of Global Climate and Ecology. The territory of mapping is 2600000 km2. The mapping is done from the airbome-gamma-spectrum data obtained at the beginning of 1960, of 1970 and 1990. In 2000 the global levels of IJ7 Cs are 0.4-3 kBq/mJ. A small contribution of Chernobyl deposition can be registered on the maps built later 1986 (0.02-0.15 kBq/m:). The levels of 2.5-3 kBq/m1 in the region of Severo-Eniseyski and Teya localities can be estimated as the tail part of the eastern Chernobyl partem. The present levels of 2.59-122 kBqVm2 are observed on the Enissey valley at distances of 0-1700 km from Krasnoyarsk-26. The parameters of runoff and soil erosion are estimated using the cartographic information, provided by the Laboratory of River Processes and Soil Erosion of the Moscow State University. A part of 137 Cs, accumulated in the Enisey-valley from early 1960 to 2000 with the transport of soil material from interfluve of all Enisey tributaries, will be estimated using a balance model of soil erosion. The contribution of IJT Cs from the catchment to the valley is estimated with respect to total l37 Cs deposited in the valley.

Impacts of the Management of Radioactively Contaminated Land on Soil and Phosphorus Losses in Finland and Scotland

Although radioactive contamination of agricultural land mayrequire food production to cease, in many situations food contamination can be kept below the intervention limits throughapplication of countermeasures. However, the radiological benefits of these measures may be accompanied by negative impacts on the environment. The aim of this work was to assessthe impacts of selected countermeasures on water quality via losses of soil and phosphorus in river catchments in Scotland and Finland. Four countermeasures, suitable for different levelsof radioactive deposition, were studied: deep ploughing, skim and burial ploughing, changes in the feeding of livestock andcessation of production. The assessments were performed using adeterministic mathematical simulation model capable of estimatingthe impact of changes in management practices and land use on thehydrology and on soil and phosphorus losses from land to water.Skim and burial ploughing had the least impacts. Deep ploughinggenerally reduced phosphorus losses but had variable effects on soil loss, which depended on the erodibility of the subsoil. Changes in the dairy feeding regime from roughage-dominated (local grass production) to more concentrates (local cereal production or imported) had variable impacts, depending on the local agricultural systems and management practices. The worstimpacts on erosion and phosphorus losses may occur where large areas of grassland are converted to cereal production. Cessationof agricultural production resulted in large (50–90%) reductions in soil and phosphorus losses. The most recommended ofthe assessed countermeasures is skim and burial ploughing, but its wider use depends on the availability of specialized technical equipment.

Nuclide-dependent local and collector surface effects in sampling of radioactive deposition to ground

After the end of atmospheric nuclear weapons tests and after the Chernobyl accident, the deposition characteristics of 137Cs changed from a predominant wet deposition to the present resuspension mechanism characterised by predominant dry deposition. To study the consequences of this change for deposition sampling, monthly deposition data from two collectors located at a distance of 600 m were compared from 1991 to 2000. On the average, the deposition rates differed by roughly a factor of two for 137Cs, whereas for the cosmogenic 7Be a difference was not detectable with statistical significance. Further, a “funnel” collector with a mostly dry surface collected on the long-term average 36% less of 137Cs, but 8% less of 7Be, than a “pot” collector with a continuously water-covered surface. Since for 137Cs deposition and the bulk deposition a similar behaviour was found, a stronger sensitivity of other resuspension-derived radionuclides against local and collector surface variations can generally be expected.

Assessment of radiation exposures from naturally occurring radioactive materials in the oil and gas industry

Radioactive deposits, often referred to as naturally occurring radioactive material scale, can, because of incompatibility of formation and injection waters, be formed inside production equipment of the oil and gas industry. These scales contain mainly 226Ra and its daughter products, which can cause an exposure risk. The gamma ray dose rates, with the associated occupational doses in the oil and gas industry, and 226Ra concentration in production water, crude oil and hard/soft scale samples were determined. Results obtained are discussed and compared to those from other studies.