[en] A brief historical review was made of low-level radiation studies for general populations living around nuclear facilities. In addition, technical and methodological problems were identified and discussed which often arise in all epidemiological studies designed to determine the possible health effects of low-level radiation released from nuclear facilities. Need for extremely large populations for prospective cancer studies was discussed, but accompanying ascertainment difficulties were also emphasized. More epidemiological studies are needed to provide adequate assessment of the potential health hazards of nuclear facilities

[en] The present paper describes some of the ways enterocytes adapt their normal patterns of development to cope with modest increases in crypt cell production rate. Preliminary results also show how disease affects some of these adaptive processes and speculation made as to whether the effect could be used as a bio assay for cytotoxic drugs and radiation damage. (author)

[en] Although linear induction accelerators (LIAs) are quite reliable by most standards, they are limited in repeating rate, average power, and reliability because the final stage of energy delivery is based on spark gap performance. In addition, they have a low duty factor of operation. To provide a higher burst rate and greater reliability, the researchers used new technology to develop a magnetic pulse compression scheme that eliminates all spark gaps and exceeds requirements. The paper describes the scheme. The magnetic drive system can be tailored to drive induction cells from a few kA to over 10 kA at 500 kV, with average beam power levels in the megawatts. This new 5-MeV, 2.5-kA LIA under construction at the Lawrence Livermore National Laboratory (LLNL) will be used for the development of high brightness sources and will provide a test bed for the new technology, which should lead to LIAs that surpass the radio frequency linacs for efficiency and reliability, as well as fit other industrial applications, such as sewage sterilization

[en] The method of plutonium (Pu) determination at the Brunswick Laboratory (NBL) consists of a combination of ion-exchange purification followed by controlled-potential coulometric analysis (IE/CPC). The present report's purpose is to quantify any detectable Pu loss occurring in the ion-exchange (IE) purification step which would cause a negative bias in the NBL method for Pu analysis. The magnitude of any such loss would be contained within the reproducibility (0.05%) of the IE/CPC method which utilizes a state-of-the-art autocoulometer developed at NBL. When the NBL IE/CPC method is used for Pu analysis, any loss in ion-exchange purification (<0.05%) is confounded with the repeatability of the ion-exchange and the precision of the CPC analysis technique (<0.05%). Consequently, to detect a bias in the IE/CPC method due to the IE alone using the IE/CPC method itself requires that many randomized analyses on a single material be performed over time and that statistical analysis of the data be performed. The initial approach described in this report to quantify any IE loss was an independent method, Isotope Dilution Mass Spectrometry; however, the number of analyses performed was insufficient to assign a statistically significant value to the IE loss (<0.02% of 10 mg samples of Pu). The second method used for quantifying any IE loss of Pu was multiple ion exchanges of the same Pu aliquant; the small number of analyses possible per individual IE together with the column-to-column variability over multiple ion exchanges prevented statistical detection of any loss of <0.05%. 12 refs

[en] During the past year, several magnetic pulse compression systems have been built and applied to the ETA accelerator. In view of their excellent performance, a non-linear magnetic system has been adopted for the ATA grid drive in place of the spark gap driven Blumlein. The magnetic system will give us a much higher reliability and greater flexibility by being independent of the high pressure gas blown system. A further advantage of this system will be the capability of achieving higher rep-rates in case of a future upgrade. System design and performance under burst mode will be described

[en] The increased interests in upgrading the ATA accelerator has warranted a preliminary look at applying the magnetic drivers to achieve both higher energy and higher average power. The goal of this upgrade is to satisfy the FEL requirements and to keep the capability of producing a higher current beam for CPB experiments at reduced energy. ATA Note 247 showed that a possible solution to obtain higher energy was simply to add additional cells, run them at higher voltage and accept a 30 ns pulse width with about 5% energy variation. Considering the recent history of the cells and the doubling of the voltage stress that would be required at the insulator, it seemed prudent to review the overall system reliability and try a different approach

[en] Full text of publication follows: The dynamic adsorption properties of activated carbons containing a variety of pore size distributions surface polarities have been studied. The aim of the study was to identify the optimum carbon porosity and polarity for adsorption of volatile organic chemicals from humid air streams. Carbons were prepared using a combination of templating [1] and controlled rate activation [2] techniques. Variations in the activating agent and conditions also enabled different levels of surface polarity to be incorporated. In this way, highly meso-porous and highly microporous carbons were prepared, with a range of mixed micro/meso-porous carbons also being studied in order to assess the effects of pore size and pore size distribution on the dynamic adsorption properties. The carbons were characterised using static nitrogen and water adsorption isotherms. Carbons (ca. 100 mg) were packed into 0.45 mm diameter tubes and tested in a flowing air stream against several volatile hydrocarbons. Breakthrough was analysed using gas chromatography or mass spectrometry. Testing was carried out in dry (RH≤10%) or humid (RH80%) air streams in order to assess the impact of pre-adsorbed water vapour on the performance of each of the carbons. Total uptakes from dynamic testing have been shown to correlate with adsorption isotherm data for the hydrocarbons, measured using a Hiden Isochema Intelligent Gravimetric Analyser (IGA). The data have been used to assess the ease with which pre-adsorbed water can be displaced, thereby enabling the effect of carbon porosity on filtration under realistic conditions to be studied. [1] Han, S.J., Kim, M., Hyeon, T.; 'Direct fabrication of meso-porous carbons using in-situ polymerized silica gel networks as a template'; Carbon, 41, 2003, 1525-1532; [2] Dawson, E.A., Parkes, G.M.B., Barnes, P.A., Chinn, M.J.; 'an investigation of the porosity of carbons prepared by constant rate activation in air'; Carbon, 41, 2003, 571-578. (authors)

[en] Magnetic switching offers an alternative to overcoming the rep-rate and life limitations of the spark gaps in the ETA/ATA induction accelerators. The principle has been applied for many years to radar modulators but at much lower power levels and longer pulse lengths. Comparatively recent developments in magnetic materials together with some optimal circuits have made it possible to go well beyond the state of the art. A magnetic modulator has been built which steps up and compresses a 25 kV, 5 μs pulse into a 250 kV, 50 ns pulse. A second magnetic modulator has been built and installed to replace four Blumleins and spark gaps in order to provide triggers for the complete ETA injector and accelerator. The paper outlines some practical and theoretical considerations affecting the design of the magnetic pulse generator

No abstract available

[en] Efforts directed at finding a 10 kHz switch to replace the current 1 kHz gas blown spark gap have culminated in a prototype for an upgrade of ATA. The design and performance of this prototype as well as possible options and recommendations concerning an eventual upgrade are described. 4 references, 9 figures