A new compilation of the atmospheric 85krypton inventories from 1945 to 2000 and its evaluation in a global transport model.

This paper gives the yearly (85)Kr emissions of all known reprocessing facilities, which are the main sources of (85)Kr in the atmosphere since 1945, for the years 1945 until 2000. According to this inventory 10,600 PBq (Peta=10(15)) of (85)Kr have been globally emitted from the year 1945 until the end of 2000. The global atmospheric inventory at the end of the year 2000 amounts to 4800 PBq. These emissions have been incorporated into the ECHAM4 atmospheric general circulation model as point sources. Monthly mean model results are compared with measurements made at different locations and times. The influence of each source on the measured concentrations at various locations is studied. The calculated concentrations are found to give reasonably good agreement with the observations, indicating that the emission inventory is realistic. Although, at all northern hemispheric observation sites the model tends to slightly overestimate the concentrations. A possible reason for this overestimation can be found in model features (coarse resolution in time and space). The most prominent discrepancy that is consistently repeated at all northern hemispheric stations occurs in the early 1990s. This could most likely be related to an overestimate of sources. Possibly, the Russian emissions declined earlier than assumed in the current database. Another discrepancy between observations and simulations indicating an incompleteness of the release data is found at some southern hemispheric sites. The variability of their observations could only be explained by regional sources. However, several spikes occur after 1992 when no reprocessing facility is known to be in operation in the southern hemisphere. Production of isotopes for radiopharmaceuticals like technetium-99m from highly enriched uranium is the most likely explanation.

Intercomparison experiments of systems for the measurement of xenon radionuclides in the atmosphere.

Radioactive xenon monitoring is one of the main technologies used for the detection of underground nuclear explosions. Precise and reliable measurements of (131m)Xe, (133g)Xe, (133m)Xe, and (135g)Xe are required as part of the International Monitoring System for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). For the first time, simultaneous testing of four highly sensitive and automated fieldable radioxenon measurement systems has been performed and compared to established laboratory techniques. In addition to an intercomparison of radioxenon monitoring equipment of different design, this paper also presents a set of more than 2000 measurements of activity concentrations of radioactive xenon made in the city of Freiburg, Germany in 2000. The intercomparison experiment showed, that the results from the newly developed systems agree with each other and the equipment fulfills the fundamental requirements for their use in the verification regime of the CTBT. For 24-h measurements, concentrations as low as 0.1 mBqm(-3) were measured for atmospheric samples ranging in size from 10 to 80 m(3). The (133)Xe activity concentrations detected in the ambient air ranged from below 1 mBqm(-3) to above 100 mBqm(-3).

Variability of atmospheric krypton-85 activity concentrations observed close to the ITCZ in the southern hemisphere.

Krypton-85 activity concentrations in surface air have been measured at Darwin, which is located in northern Australia and is influenced by seasonal monsoonal activity. Measurements between August 2007 and May 2010 covered three wet seasons. The mean activity concentration of krypton-85 measured during this period was 1.31±0.02Bqm(-3). A linear model fitted to the average monthly data, using month and monsoon as predictors, shows that krypton-85 activity concentration measured during the sampling period has declined by 0.01Bqm(-3) per year. Although there is no statistically significant difference in mean activity concentration of krypton-85 between wet and dry season, the model implies that activity concentration is higher by about 0.015Bqm(-3) during months influenced by the monsoon when a north westerly flow prevails. Backward dispersion runs using the Lagrangian particle dispersion model Hysplit4 highlight possible source regions during an active monsoon located deep in the northern hemisphere, and include reprocessing facilities in Japan and India. However, the contribution of these facilities to krypton-85 activity concentrations in Darwin would be less than 0.003Bqm(-3).

Trace analysis of aerosol bound particulates and noble gases at the BfS in Germany.

The Federal Office for Radiation Protection (BfS) performs trace analysis measurements in both the frameworks of the German Integrated Measuring and Information system as well as of the International Monitoring System for verification of the Comprehensive Nuclear-Test-Ban Treaty. Therefore, different kinds of measurements of aerosol bound radionuclides as well as of radioactive noble gases in the atmosphere are performed. BfS as coordinating laboratory for trace analysis is responsible for the quality control. A quality assurance programme was set up with German institutions and expanded to European laboratories. The existing quality assurance programme of the Comprehensive Nuclear-Test-Ban Treaty Organisation for measurements of aerosol bound radionuclides will be extended for noble gas measurements. Applied methods, achieved measurement results and the different kinds of quality assurance are presented and discussed.

EEG and haemodialysis. A structural survey of EEG spectral analysis, Hjorth's EEG descriptors, blood variables and psychological data.

Computerized EEG was performed in 20 patients with renal failure before and after haemodialysis (HD), applying spectral analysis and Hjorth's EEG descriptors in EEG quantification, correlation and factor analysis as statistical procedures to analyse the connections of EEG, blood variables and psychological performance. The main results were: (1) Moderate uraemic encephalopathy -- according to Kiley's (1971) standards -- was present in most of our patients, before and after HD. (2) Before HD, EEG slowing was most strongly connected with the creatinine level and EEG acceleration with hyperkalaemia, which in most cases accompanied a high urea level. (3) Significant EEG changes after HD were: decrease of percentage delta activity, increase of Hjorth's 'mobility', decrease of Hjorth's 'complexity'. (4) The theta/alpha ratio (Matousek 1968) was significantly correlated with the patient's general clinical state after HD. (5) Visual discrimination, memory and maximal tapping speed improved significantly after HD. Only Hjorth's EEG parameters were correlated with test performance in that patients with low voltage and fast EEGs did worse in visual discrimination.

85Kr measurement system for continuous monitoring at the Meteorological Research Institute, Japan.

A 85Kr measurement system for continuous monitoring based principally on the BfS-IAR method (activity measurement of 85Kr by gas counting coupled with gas chromatographic separation, using pure CH4 as carrier and Counting gas) was implemented for the first time in Japan. In this paper, a detailed description of the system and procedures is given and the inter-comparison results of our system with the BfS-IAR system are presented. A consistent temporal concentration change with high accuracy and consistency of the respective data with the BfS-IAR data (maximum difference of 5%) were achieved with the Meteorological Research Institute (MRI) system, which shows that the system is valid and reliable for the purpose of background monitoring for 85Kr in air. Also, the 85Kr monitoring record at the MRI during 1995-2001 is described. The record distinctively shows the Northern Hemispheric background 85Kr concentrations at the mid-latitude and the elevated concentrations affected by the operation of a nuclear fuel reprocessing plant in Tokai-mura, Ibaraki. Japan.