Colloids play a major role in the transport of trace metals as well as radionuclides in natural waters. These species are of importance for passive take in biota.Radionuclides may form colloids and pseudocolloids during hydrolysis or through interaction with other components present in the water phase, such as clay minerals or humic substances. Furthermore, aggregation and dispersion and other transformation processes, will influence the colloidal fraction, for instance during storage of samples. Fractionation of radionuclides associated with colloids in natural waters should, therefore, take place in situ or shortly after sampling.Different analytical techniques are useful for the fractionation of colloids, pseudocolloids, and particles. In the present paper, the application of hollow fiber ultrafiltration and dialysis is demonstrated for radionuclides in waste waters from the Oscarshamn nuclear installation in Sweden.The results illustrate that hollow fiber ultrafiltration is a more powerful technique than dialysis. The fractionation is rapid, sorption is of minor significance, the pore size distribution is rather narrow, and the filtering capacity is high.
Authors:H. Biggin, N. Chen, K. Ettinger, J. Fremlin, W. Morgan, R. Nowotny, M. Chamberlain, and T. Harvey
On peut déterminer la présence de cadmium chez l'homme à l'aide de technique de l'analyse par activation neutronique in vivo.
La capture des neutrons thermiques par113Cd conduit à une émission γ prompt qui peut être détectée au moyen d'un semi-conducteur convenable. On a réalisé une installation
à l'Université de Birmingham pour produire au moyen d'un cyclotron un faisceau de neutrons pulsés. Une série d'expérience
a été faites sur des cadavres; ces expériences ont prouvé qu'il est possible de détecter le cadmium à une concentration de
2,0 ppm dans le volume d'un foie humain pour une dose de 1 rem. On discute des résultats et des applications possibles de
Authors:Christopher Ryan, Craig Marianno, William Charlton, and William James
The dissolution of the Soviet Union coupled with the growing sophistication of international terror organizations has brought
about a desire to ensure that a sound infrastructure exists to interdict smuggled nuclear material prior to leaving its country
of origin. To combat the threat of nuclear trafficking, radiation portal monitors (RPMs) are deployed around the world to
intercept illicit material while in transit by passively detecting gamma and neutron radiation. Portal monitors in some locations
have reported abnormally high background counts. The higher background data has been attributed, in part, to the naturally
occurring radioactive materials (NORM) in the concrete surrounding the portal monitors. Higher background increases the minimum
detectable activity (MDA) and can ultimately lead to more material passing through the RPMs undetected. This work employed
two different neutron activation analysis (NAA) methods for the purpose of developing a process to characterize the concrete
surrounding the RPMs. Thermal neutron instrumental NAA (INAA) and fast NAA (FNAA) were conducted on six samples from three
different composition concrete slabs. Comparator standards and quality control materials were used to help ensure that the
methods were both precise and accurate. The combination of INAA and FNAA accounted for 84–100% of the total elemental composition
of the samples. Knowing the composition of the concrete will allow RPM customers to choose suitable materials prior to installation,
thereby increasing the ability of the monitors to detect radiological and nuclear materials.
Authors:B Finnin, M O'Neill, S Gaisford, A Beezer, J Hadgraft, and P Sears
calorimetry is becoming indispensable as a tool for the study of a wide variety
of systems. As with all scientific instruments it is essential that robust
calibration routines be developed in order to validate the data obtained.
Chemical test reactions offer many advantages over (the traditionally used)
joule effect heating methods, not least because they have the potential to
validate instrument performance (i.e. they can be used to assess all aspects
of calorimeter operation). In this work the results of a validation exercise,
conducted by Thermal Hazard Technology as part of an installation routine,
using the base catalysed hydrolysis of methyl paraben are discussed. In the
case described, a systematic misreporting of the reported temperature of a
calorimeter was identified, caused by an upgrade to the calorimeter's
firmware, a discrepancy which may not have been noted using traditional electrical
calibration methods and one which highlights the importance of both manufacturers
and end-users adopting chemical test reactions into their test and validation
Materials of significant inhomogeneity require big samples to be analyzed. With the exception of very few installations worldwide
the near-core neutron irradiation positions are not spacious enough to fulfil this condition. The use of beam geometry activation
analysis (BEAMGAA) has actually turned out to be an alternative as the activities obtained are proportional to the product
of flux and sample mass. In the case of hard photon radiation delivered by the 30 MeV-Linac of BAM, equipped with a programmable
scanner of the electron beam for dose equalization, a nearly uniform distribution could be obtained in a volume of 7 cm×7
cm×2 cm. It is shown that big sample volumes up to 7 cm×7 cm×10 cm can be treated and non-linearities of irradiation can be
perfectly taken into account by the self-adjusting method of consecutive correction factors (COCOFA). Nevertheless, the concept
of “sliced samples” has to be considered when maximum correctness of the analytical results has to be guaranteed. With the
measures described in photon activation analysis a quality level was realized which was not reached hitherto.
Authors:A. Sanchez, D. Singleton, B. Walters, and J. Cobb
The British Nuclear Fuels Limited (BNFL) complex (Sellafield) in Cumbria discharges into the atmosphere, under authorization by the Environment Agency (and previously, the Ministry of Agriculture, Fisheries and Food (MAFF), radioactive waste consisting of gases, mists and dusts. As part of MAFF's radiological surveillance programme, the intake of radionuclides via food ingestion by members of the public living near this nuclear installation is routinely assessed from measurements made on local food and environmental samples and by using computer models simulating the dispersion and incorporation of radioactivity into foodstuffs. In this study, the individual diets of adults and children living near the Sellafield complex and those from a control group were assessed for their radionuclide content. The participants were selected via a food survey questionnaire which was aimed at identifying those who consume home grown fruits and vegetables or derive these from local sources. The diets were collected over a one-week period in August 1995 and following radiochemical analyses of the diets for239+240Pu,137Cs,90Sr,14C, and129I, the doses received by the participants from these nuclides were extrapolated over a one-year period and compared to doses calculated from food surveillance data and to doses predicted using the MAFF food-chain computer model.
Authors:W. Knaepen, W. Bergwerf, P. Lancée, W. Van Dijk, J. Jansen, R. Janssen, W. Kiezenberg, R. Van Sluijs, M. Tijsmans, K. Volkers, and P. Voors
Gas and oil companies frequently encounter build up of Naturally Occurring Radioactive Material (NORM) in their production and processing facilities. In the Netherlands NORM is subject to strict national regulations and, consequently, installations have to be screened on a regular basis. The availability of accurate and reliable NORM sampling and analysis techniques is therefore essential. A number of years ago, the Nederlandse Aardolie Maatschappij B.V. (NAM) actively initiated an investigation on analysis techniques for NORM samples from gas and oil companies. Within this framework, Shell Research Amsterdam organized a four-stage interlaboratory test programme in which representative samples of increasing complexity were analyzed by a number of Dutch institutes. Whereas a large spread in results was observed in the first stage, results in the last stage deviated less than ±10% from the values certified by an independent referee institute, even for comple, sludge samples. It was found that in particular the use of different values for the -yields and branching ratios amongst the institutes was responsible for the initial spread.
( 2001 ), Dry installation of a radiant floor or wall hydronic heating system, metal radiating plates that attach to the edges of side-by-side boards and provide metal slots for holding hot water
Bastianini, F. – Rizzo, A. – Galati, N. – Deza, U. – Nanni, A.: Discontinuous Brillouin strain monitoring of small concrete bridges: Comparison between near-to-surface and „smart” FRP fiber installation techniques. Proceedings of SPIE – The International