Publications by authors named "D Ridikas"

6 Publications

Improved performance of neutron activation analysis laboratories by feedback workshops following interlaboratory comparison rounds.

Accredit Qual Assur 2021 14;26(3):157-164. Epub 2021 Jun 14.

NUQAM Consultancy, Zuid-Beijerland, The Netherlands.

The International Atomic Energy Agency (IAEA) implemented an innovative project for assisting neutron activation analysis laboratories in improving the validity of their results by feedback workshops for discussion of results from participation in interlaboratory comparisons rounds in 2010. The participants learned during these meetings to identify the most probable sources of errors in their analytical procedures and how to implement corrective actions to prevent reoccurrence. The outcome of successive rounds between 2010 and 2018 is discussed and experiences during the feedback workshops are given. The quantitative evaluation of the results shows an overall improvement in satisfactory performance. Moreover, there is a clear indication that improvements are consolidated in most laboratories but also stimulate laboratories to develop to a higher level of excellence. Regional differences in performance are also analysed.
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http://dx.doi.org/10.1007/s00769-021-01473-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8200377PMC
June 2021

The Neutrons for Science Facility at SPIRAL-2.

Radiat Prot Dosimetry 2018 Aug;180(1-4):115-119

LPC, 6 Bd du Maréchal Juin, Caen Cedex, France.

The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV-40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the 7Li(p,n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors.
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http://dx.doi.org/10.1093/rpd/ncx257DOI Listing
August 2018

Estimation of Mo production rates from natural molybdenum in research reactors.

J Radioanal Nucl Chem 2017 24;311(1):409-418. Epub 2016 Sep 24.

Vietnam Atomic Energy Institute, 01 Nguyen Tu Luc, Dalat, Vietnam.

Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, the International Atomic Energy Agency organized a round-robin exercise where the participants measured and calculated specific saturation activities achievable for the Mo(n,γ)Mo reaction. This reaction is of interest as a means to locally, and on a small scale, produce Mo from natural molybdenum. The current paper summarises a set of experimental results and reviews the methodology for calculating the corresponding saturation activities. Activation by epithermal neutrons and also epithermal neutron self-shielding are found to be of high importance in this case.
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http://dx.doi.org/10.1007/s10967-016-5036-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5219034PMC
September 2016

Non-destructive method of characterisation of radioactive waste containers using gamma spectroscopy and Monte Carlo techniques.

Radiat Prot Dosimetry 2005 ;115(1-4):113-6

CEA Saclay, DSM/DAPNIA F-91191 Gif-sur-Yvette, France.

During the decommissioning of the SATURNE accelerator at CEA Saclay (France), a number of concrete containers with radioactive materials of low or very low activity had to be characterised before their final storage. In this paper, a non-destructive approach combining gamma ray spectroscopy and Monte Carlo simulations is used in order to characterise massive concrete blocks containing some radioactive waste. The limits and uncertainties of the proposed method are quantified for the source term activity estimates using 137Cs as a tracer element. A series of activity measurements with a few representative waste containers were performed before and after destruction. It has been found that neither was the distribution of radioactive materials homogeneous nor was its density unique, and this became the major source of systematic errors in this study. Nevertheless, we conclude that by combining gamma ray spectroscopy and full scale Monte Carlo simulations one can estimate the source term activity for some tracer elements such as 134Cs, 137Cs, 60Co, etc. The uncertainty of this estimation should not be bigger than a factor of 2-3.
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http://dx.doi.org/10.1093/rpd/nci253DOI Listing
March 2006

Activation analysis of concrete and graphite in the experimental reactor RUS.

Radiat Prot Dosimetry 2005 ;115(1-4):104-9

CEA Saclay, DSM/DAPNIA, F-91191 Gif-sur-Yvette, France.

The decommissioning and dismantling of nuclear installations after their service life involves the necessary disassembling, handling and disposing of a large amount of radioactive equipment and structures. In particular, the concrete that has been used as a biological reactor shield and graphite that has been used as a moderator-reflector represent the majority of waste, requiring geological disposal. To reduce this undesirable volume to the minimum and to successfully plan the dismantling and disposal of radioactive materials to storage facilities, the activations of the structures should be accurately evaluated. In the framework of the decommissioning and the dismantling of the experimental reactor of the University of Strasbourg, detailed activation estimates have been conducted to characterise the graphite and the structural materials present in the reactor environment. For this purpose, the chemical compositions of fresh graphite samples and different types of concrete have been determined by activation analysis in the research reactors OSIRIS and ORPHEE of CEA Saclay (France). Then, the activations of graphite, concrete and other materials have been calculated in the whole reactor, as a function of the three main nuclear data libraries, i.e. ENDF, JEF and JENDL. In parallel, the activations of representative graphite and concrete samples have been measured experimentally. The comparison of theoretical predictions with experimental values validates the approach and the methodology used in the present study and tests the consistency and the reliability of the nuclear data used for activation analysis. We believe that a similar approach could also be used for the decommissioning of industrial nuclear reactors.
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http://dx.doi.org/10.1093/rpd/nci049DOI Listing
March 2006
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