[en] The described method can be used for pre-localization of nuclear fuel assemblies containing defective fuel elements, so that the number of assemblies to be examined during reactor shutdown and thus the shutdown period can be reduced. It is based on the determination of the ¹³⁴Cs/¹³⁶Cs ratio in the primary coolant

[en] The invention has been aimed at a procedure for the localization of fuel assemblies with failed elements during reactor operation. The procedure is based on the application of radiometric gauges. The number of the fuel assemblies to be checked in an open reactor can be minimized so that the reactor unavailability time can be shortened. The mean ratio of the ⁸⁵Kr/¹³³Xe concentration has been derived from the ⁸⁵Kr and ¹³³Xe concentration measurements in the primary coolant and the pertinent uncertainty interval has been determined. The fuel assemblies having a ⁸⁵Kr/¹³³Xe concentration ratio within the uncertainty interval are expected to be faulty

[en] Isotopic correlations between the fission product density ratio ¹⁵⁴Eu/¹³⁷Cs in spent nuclear fuel of PWRs and the burnup or the Pu/U ratio have been calculated. A method based on the gamma-spectrometrically measured ratios ¹⁵⁴Eu/¹³⁷Cs and ¹³⁴Cs/¹³⁷Cs and these isotopic correlations is presented which allows determination of burnup, cooling time and Pu/U ratio of spent nuclear fuel without additional information on the fuel irradiation. The method may be applied up to cooling times of more than twenty years. Thus, it is suited as an independent tool for safeguards purposes or technical control at older spent fuel. (author)

[en] The participation of JCR Ispra in this Coordinated Research Project (CRP) involves the measurement, compilation and report of the gamma spectra emitted by various radioactive sources, using standard detectors under reference conditions. Measurements have been performed in the Perla laboratory for a series of radiation sources, including plutonium and uranium samples, using a (dia.1x1) in. NaI detector. In the present work a LaBr₃ scintillator detector with trade name BrillanCe-380 has been used to perform a similar set of measurements. Besides becoming an extension of the previous work and an additional contribution to a spectra database, this work may provide some support for the assessment of potential benefits or disadvantages of scintillators with a better energy resolution for illicit trafficking applications. (author)

[en] Published in summary form only

[en] The search for fuel assemblies with defective fuel rods by sipping tests involves expensive prolongations of the refuelling periods in nuclear power plants. It is attempted to reduce the number of fuel assemblies to be checked by sipping during the refuelling periods by means of rough localization of the defects on the basis of the fission product concentration ratio ¹³⁴Cs/¹³⁷Cs in the primary coolant during reactor operation. First results obtained in two examples of application at WWER type reactors are encouraging. The burnup of the defective assemblies could be correctly predicted from the cesium ratio in these two cases, which was confirmed by sipping tests after reactor shutdown. (author) 6 refs

[en] About 500 nuclear safeguards inspectors are working at the IAEA, EURATOM and as national inspectors in Europe. Up to 50 of them are recruited every year and need training for their new work, comprising all its aspects. More than 1050 trainees have attended nuclear inspector training courses at the Ispra site of the Joint Research Centre of the EU within more than 20 years. A higher number of inspectors need refreshment courses or introductions into new working fields. Moreover, new instruments or techniques require special training, in class, laboratory or in field. The Preparatory course, 'NDA (Non-Destructive Assay of nuclear material) basic physics', is held at the EURATOM headquarters at Luxembourg. It is foreseen mainly for new inspectors. The four NDA laboratory courses in PERLA are of special importance for the inspectors. They demonstrate clearly the possibility for an inspector to verify with non-destructive methods the presence of nuclear material, its quality and its quantity. Most of the EURATOM inspectors have followed them at the beginning of their inspector service. The advanced/special laboratory courses in PERLA combine different elements: the 'Pu physical inventory verification course' comprises inspection planning, qualitative and quantitative measurements and statistical data evaluation. The 'Advanced hands-on RADAR/CRISP/XSEAT course' combines automatic measurement stations, installation of informatics tools, unattended data collection, data evaluation and inspection report. The reaction of course participants proofed that these demanding courses are good for the motivation of experienced inspectors. Special instrument courses are always changing and often held only one or two times. The paper is followed by the slides of the presentation

[en] Isotopic correlation analysis is believed to make quick and accurate determination of nuclear fuel parameters for reactor operation, reprocessing, fuel management and nuclear safeguard. Correlation dependencies have been found between ratios of fission products on one hand, and isotope ratios of the heavy elements on the other. The use of the ¹⁵⁴Eu/¹⁵⁵Eu ratio in correlation analysis was proposed by V. Smulek. The scope of useful applications of this isotopic ratio has been further investigated. A quick and time-saving method to measure the above ratio has been elaborated. The atomic ratios have been found by internal calibration using the computer porgram ABSINT. Besides the atomic ratios of ¹⁵⁴Eu/¹⁵⁵Eu as a function of nuclear fuel burnup have been calculated using the computer program ISOTOP. The correlation between the above ratio and nuclear fuel burnup is best approximated by a quadratic function. (author)

[en] The search for fuel assemblies with defective fuel rods by sipping tests leads to costly prolongations of the refuelling outages of PWRs. The number of fuel assemblies to be checked by sipping during the outages is tried to be reduced by means of rough localization of the defects already during reactor operation. It is shown that in spite of the experimental errors and the nonuniformities of fuel burnup the measurement of the ¹³⁴Cs/¹³⁷Cs concentration ratio in the coolant is suited to meet this aim in some important cases, such as 'early-life' defects in fuel assemblies freshly inserted. It is also useful in fuel rod integrity surveillance if fuel burnup extension by assembly dwell time prolongation is realized by a reactor operator. (author)

[en] Use of self-fluorescent X ray emission of uranium and plutonium materials to evaluate nuclear material spectra is discussed. An analytical description of the X ray excitation is given. Results of measurements and calculations are presented. 10 refs, 1 fig