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Abstract  

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.

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Abstract  

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.

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Abstract  

The PGAA facility at the Budapest Research Reactor has been continually upgraded and developed since its start-up in 1996, as a result of which its performance has improved considerably. The installation of the cold neutron source, the partial change to supermirror neutron guides and their realignment increased the flux by almost two orders of magnitude. The data acquisition has been modernized as well; digital spectrometers were tested and implemented in novel forms of gamma-ray spectrum collection. This year a higher-efficiency HPGe detector and a new data acquisition module were put into operation. Most recently all the neutron guides were changed to supermirror-coated ones to further increase the neutron flux. The improved evaluation software makes possible a more reliable elemental analysis of the samples. In this progress report these developments are critically reviewed. The characteristics of the latest system are also described. It is the first time that a set of new partial gamma-ray production cross sections are presented, which are based on the new intensity values of 14N(n,γ)15N calibration standard.

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Abstract  

At the end of the 1991 Gulf War the U.N. Security Council Resolution called upon IAEA, assisted by the U.N. Special Commission, to carry out inspections of all Iraqi nuclear installations. The IAEA Action Team succeeded in implementing, on very short notice, a comprehensive system of inspection activities, including sampling and analysis at the Agency's Laboratories and other laboratories in Member States. The Agency's Laboratories developed and implemented an analytical strategy with the aim to rapidly and accurately obtain the information necessary for verifying the Iraqi declarations. The analyses ranged from screening for - and /-emitters to accurate determinations of the amounts and isotopic composition of the radionuclides and associated trace elements and compounds. The arsenal of methods included ultra-sensitive radiometric methods, mass spectrometry, neutron activation, X-ray fluorescence and inductively coupled plasma emission spectrometry. Selected results include the detection of uranium chloride compounds, special composition steels, and quantitative accounting of uranium and plutonium production. The selectivity, sensitivity and reliability of the applied analytical techniques in conjunction with validated sampling procedures are essential components of an analytical measurements system that can provide credible results.

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Abstract  

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.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: H. Biggin, N. Chen, K. Ettinger, J. Fremlin, W. Morgan, R. Nowotny, M. Chamberlain and T. Harvey

Résumé  

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 cette étude.

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Abstract  

South Africa signed and ratified the Comprehensive Nuclear Test-Ban-Treaty (CTBT) and accordingly made commitments to the Organization (CTBTO). Of the obligations are the establishment of a Radionuclide Laboratory, the design, installation and operation and maintenance of a radionuclide particulate and noble-gas monitoring station and the nomination of one radionuclide specialist South African to serve on an international team for On-Site Inspection (OSI). The last to provide expertise when the worldwide monitoring network provides strong indications that an illegal nuclear test has been performed at the territory of a State Party. The inspection team will be equipped with amongst others radiation monitors and nuclide specific measuring equipment limited to report on specific radionuclides agreed upon by all State Parties. In real-time operational circumstances one may assume that all members of the team will not be registered radiation workers and accordingly be regarded as members of the public when radiation hazard is to be evaluated. In this paper we try to categorize the radionuclides of interest and evaluate the radiological risk to the OSI-team due to inhalation of airborne radioactive particulate matter during the survey at the site of an anticipated nuclear test. From this study recommendations will be made to the CTBTO for possible implementation of portable sampling and analysis equipment to allow on-site evaluation of the potential internal exposure of OSI-team members.

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Performance validation of step-isothermal calorimeters

Application of a test and reference reaction

Journal of Thermal Analysis and Calorimetry
Authors: B Finnin, M O'Neill, S Gaisford, A Beezer, J Hadgraft and P Sears

Abstract  

Isothermal 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 routines.

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Abstract  

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.

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Abstract  

The necessity to monitor international commercial transportation for illicit nuclear materials resulted in the installation of many nuclear radiation detection systems in Portal Monitors. To overcome the difficulty of innocent alarms due to a large content of natural radioactivity or medical nuclides, Department of Homeland Security (DHS) supported the writing of the ANSI N42.38 standard (Performance Criteria for Spectroscopy-Based Portal Monitors used for Homeland Security) to define the performance of a portal monitor with nuclide identification capabilities, called a Spectroscopy Portal Monitor. To accomplish the necessary performance, several different HPGe detector configurations were modeled using MCNP for the horizontal field of view (FOV) and vertical linearity of response over the detection zone of 5 meters by 4.5 meters for 661 keV as representative of the expected nuclides of interest. The configuration with the best result was built and tested. The results for the FOV as a function of energy and the linearity show good agreement with the model and performance exceeding the requirements of N42.38.

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