A new approach to assessment and management of the impact from medical liquid radioactive waste

The Swedish regulations concerning disposal of clinical radioactive waste are currently under revision and a graded approach is proposed for risk limitation purposes. To assist the revision procedures, a screening study was performed to estimate public exposures from liquid releases from hospitals to public sewers. The results showed that doses to sewage workers were above the dose constraint of 100muSva(-1) especially for (131)I and (99m)Tc. Hence, a dynamic model, LUCIA, was developed for realistic assessments in which radionuclide transportation in sewers was modelled. Probabilistic simulations were performed to obtain probability distributions of radionuclide concentrations in sludge. Concurrently, estimates of the effective doses to sewage workers decreased significantly and were below 10muSva(-1) except for (111)In and (131)I. However, the Kd-coefficients representing the partition of radioactivity between water and sludge in sewers are highly uncertain for (111)In. As shown by sensitivity studies, these values are the major determinant of the exposures in sewers.     

Calibration of a portable HPGe detector using MCNP code for the determination of 137Cs in soils

In situ gamma spectrometry provides a fast method to determine (137)Cs inventories in soils. To improve the accuracy of the estimates, one can use not only the information on the photopeak count rates but also on the peak to forward-scatter ratios. Before applying this procedure to field measurements, a calibration including several experimental simulations must be carried out in the laboratory. In this paper it is shown that Monte Carlo methods are a valuable tool to minimize the number of experimental measurements needed for the calibration.     

A detailed evaluation of the individual health benefits arising in a domestic property following radon remediation--a case-study in Northamptonshire, U.K

Radon gas occurs naturally in the environment with variable distribution, concentrating sufficiently in the built environment in some areas to pose a public health risk. Radon levels can be successfully reduced in affected buildings, and large-scale remediation programmes have been justified in terms of accrued costs and benefits. We present results from a house where radon levels in the main living-room and master bedroom were monitored on an hourly basis over extended periods before and after radon remediation by sub-slab depressurisation. These results were combined with results from a recent occupancy survey to estimate the health impact on occupants spending varying times in the home. Prior to remediation, mean hourly radon exposure is moderately linearly correlated (R(2)=0.66-0.78) with time spent in the house. Following remediation, correlation is significantly enhanced (R(2)=0.91-0.95), but the exposure reduction of an occupant following remediation is less than that predicted using the NRPB protocol.     

Assessment of Self-Organizing Map artificial neural networks for the classification of sediment quality

The application of mathematical tools in initial steps of sediment quality assessment frameworks can be useful to provide an integrated interpretation of multiple measured variables. This study reveals that the Self-Organizing Map (SOM) artificial neural network can be an effective tool for the integration of multiple physical, chemical and ecotoxicological variables in order to classify different sites under study according to their similar sediment quality. Sediment samples from 40 sites of 3 estuaries of Cantabria (Spain) were classified with respect to 13 physical, chemical and toxicological variables using the SOM. Results obtained with the SOM, when compared to those of traditional multivariate statistical techniques commonly used in the field of sediment quality (principal component analysis (PCA) and hierarchical cluster analysis (HCA)), provided a more useful classification for further assessment steps. Especially, the powerful visualization tools of the SOM, which offer more information and in an easier way than HCA and PCA, facilitate the task of establishing an order of priority between the distinguished groups of sites depending on their need for further investigations or remediation actions in subsequent management steps.     

A performance estimate for the detection of undeclared nuclear-fuel reprocessing by atmospheric 85Kr

To test the sensitivity of using atmospheric (85)Kr to detect undeclared separation of plutonium from irradiated nuclear-reactor fuel, measurements of atmospheric (85)Kr taken in Tsukuba, Japan are analyzed to determine: (1) a lower limit of detection for discovering anthropogenic (85)Kr emissions, (2) the probability of detecting plutonium separation at the Tokai Reprocessing Plant, and (3) the extent to which these results can be generalized to other sites. A LLD of at least 3.4 sigma=0.14 Bq/m(3) with a theoretical false-positive rate of 0.05% is recommended for safeguards' purposes. At this threshold, the continuous separation of 100, 300, and 900 g equivalent weapon-grade plutonium per day was found to correspond to 10%, 50%, and 80% probability of detection, respectively. The smallest detected concentration was for the continuous separation of 45 g/day, with a probability of detection of about 0.6%. It was found that the detection rate is determined predominantly by the weather.     

Differences in responses of herpetobionts and geobionts to impact from the Kosogorsky Metallurgical Plant (Tula region,Russia)

The influence of the Kosogorsky Metallurgical Plant (KMP; Tula region, Russia) on the abundance and biodiversity of carabid beetles and soil macrofauna and on the trophic activity of soil biota was studied. Metal concentrations in the impact plot were many times higher than those in the control plot located on the same transect. As the transect approached KMP, both the abundance of soil invertebrates (geobionts) and trophic activity of the soil biota remained unchanged, whereas the abundance and diversity of carabids (herpetobionts) decreased drastically. It is suggested that the impact of the KMP on herpetobionts is accounted for by modification of the structure of ecosystems and that herpetobiontic and geobiontic groups of the macrofauna respond differently to this impact because of differences in the ecological mechanisms of population response.     

Sustainable Development and Strategic Thinking

From an economic point of view, the industrial economy is efficient to overcome situations of a scarcity of goods. From a technological point of view, the resource efficiency of the manufacturing processes of the industrial economy has been permanently improved during the last 200 years. In addition, cleaner processes have been developed. However, from an ecologic point of view, an increasing world population with increasing consumption has produced a ＂global footprint＂ which approaches the carrying capacity of the planet. A circular economy and its high-value spin-offs-a lake economy and a performance or functional service economy-can fulfil customers＇ needs with considerably less resource consumption, less environmental impairment in production and considerably less end-of-life product waste, especially in situations of affluence, when a considerable stock of physical goods and infrastructures exists. Also, in situations of a scarcity of natural resources, both energy and materials, often characterised by rapidly rising resource prices, the economic actors of a circular economy have a high competitive advantage over the actors of the industrial economy, due to much lower procurement costs for materials and energy. From a social point of view, a circular economy increases the number of skilled jobs in regional enterprises. However, the shift from a linear manufacturing economy to a circular or service economy means a change in economic thinking from flow （throughput） management to stock （asset） management： in a manufacturing economy with largely unsaturated markets, total wealth increases through accumulation as resource throughput （flow） is transformed into a higher stock of goods of better quality （but in a manufacturing economy with largely saturated markets, wealth represented by the stock of goods will no longer increase）; in a circular or service economy, total wealth increases through a smart management of existing physical assets （stock） that are adapted to changes in both technology and customer demand. This second approach not only applies to physical capital but equally to social capital, such as health and education and green GDP. To measure the social wealth of a population, it is not the amount of money spent on schools and hospitals that matters, butif this expenditure has led to a better education of the students, and a better health of the people.     

Analysis of radiocaesium in the Lebanese soil one decade after the Chernobyl accident

Fallout from the Chernobyl reactor accident due to the transport of a radioactive cloud over Lebanon in the beginning of May 1986 was studied 12 years after the accident for determining the level of (137)Cs concentration in soil. Gamma spectroscopy measurements were performed by using coaxial high sensitivity HPGe detectors. More than 90 soil samples were collected from points uniformly distributed throughout the land of Lebanon in order to evaluate their radioactivity. The data obtained showed a relatively high (137)Cs activity per surface area contamination, up to 6545Bqm(-2) in the top soil layer 0-3cm. The average activity of (137)Cs in the top soil layer 0-3cm in depth was 59.7Bqkg(-1) dry soil ranging from 15 to 119Bqkg(-1) dry soil. The horizontal variability was found to be about 45% between the sampling sites. The depth distribution of total (137)Cs activity in soil showed an exponential decrease. Estimation of the annual effective dose due to external radiation from (137)Cs contaminated soil for selected sites gave values ranging from 19.3 to 91.6 micro Svy(-1).     

Impact of dredging in a shallow coastal lagoon: Microtox Basic Solid-Phase Test, trace metals and Corophium bioassay

The aim of this work was to measure survival of the amphipod Corophium insidiosum and luminescence inhibition in the marine bacterium Vibrio fisheri on surface sediment samples collected from a shallow coastal lagoon (Pialassa Baiona, northern Adriatic Italian coast) before execution of dredging operations to deepen the main inner channel of the lagoon and restore the water circulation. Trace metal (Cd, Cu, Cr, Hg, Ni, Pb) concentrations, grain size and organic carbon matter content as loss of ignition were also measured. Toxicity testing with V. fisheri was carried out according to the Microtox Basic Solid-Phase Test (BSPT) protocol. The preliminary outcomes of this work show that: (a) the investigated area can be categorised as moderately degraded; (b) there is no evident spatial pattern in sediment toxicity and trace metal concentrations; (c) Microtox responses are not biased by sediment characteristics such as silt, clay and organic matter content.