| 1. |
- Journeau, C., et al.
(författare)
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Safest roadmap for corium experimental research in Europe
- 2018
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Ingår i: ASCE-ASME J of Risk & Uncertainty in Engineering Systems Part B. - : ASME Press. - 2332-9017 .- 2332-9025. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- Severe accident facilities for European safety targets (SAFEST) is a European project networking the European experimental laboratories focused on the investigation of a nuclear power plant (NPP) severe accident (SA) with reactor core melting and formation of hazardous material system known as corium. The main objective of the project is to establish coordinated activities, enabling the development of a common vision and severe accident research roadmaps for the next years, and of the management structure to achieve these goals. In this frame, a European roadmap on severe accident experimental research has been developed to define research challenges to contribute to further reinforcement of Gen II and III NPP safety. The roadmap takes into account different SA phenomena and issues identified and prioritized in the analyses of severe accidents at commercial NPPs and in the results of the recent European stress tests carried out after the Fukushima accident. Nineteen relevant issues related to reactor core meltdown accidents have been selected during these efforts. These issues have been compared to a survey of the European SA research experimental facilities and corium analysis laboratories. Finally, the coherence between European infrastructures and R&D needs has been assessed and a table linking issues and infrastructures has been derived. The comparison shows certain important lacks in SA research infrastructures in Europe, especially in the domains of core late reflooding impact on source term, reactor pressure vessel failure and molten core release modes, spent fuel pool (SFP) accidents, as well as the need for a large-scale experimental facility operating with up to 500 kg of chemically prototypic corium melt.
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| 2. |
- Langrock, G., et al.
(författare)
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Digital liquid-scintillation counting and effective pulse-shape discrimination with artificial neural networks
- 2015
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Ingår i: Radiochimica Acta. - : Walter de Gruyter GmbH. - 0033-8230 .- 2193-3405. ; 103:1, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- A typical problem in low-level liquid scintillation (LS) counting is the identification of alpha particles in the presence of a high background of beta and gamma particles. Especially the occurrence of beta-beta and beta-gamma pile-ups may prevent the unambiguous identification of an alpha signal by commonly used analog electronics. In this case, pulse-shape discrimination (PSD) and pile-up rejection (PUR) units show an insufficient performance. This problem was also observed in own earlier experiments on the chemical behaviour of transactinide elements using the liquid-liquid extraction system SISAK in combination with LS counting alpha-particle signals from the decay of the transactinides could not be unambiguously assigned. However, the availability of instruments for the digital recording of LS pulses changes the situation and provides possibilities for new approaches in the treatment of LS pulse shapes. In a SISAK experiment performed at PSI, Villigen, a fast transient recorder, a PC card with oscilloscope characteristics and a sampling rate of 1 giga samples s(-1) (1 ns per point), was used for the first time to record LS signals. It turned out, that the recorded signals were predominantly alpha, beta-beta and beta-gamma pile up, and fission events. This paper describes the subsequent development and use of artificial neural networks (ANN) based on the method of "back-propagation of errors" to automatically distinguish between different pulse shapes. Such networks can "learn" pulse shapes and classify hitherto unknown pulses correctly after a learning period. The results show that ANN in combination with fast digital recording of pulse shapes can be a powerful tool in LS spectrometry even at high background count rates.
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| 3. |
- Mlassoedov, A., et al.
(författare)
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Severe accident facilities for European safety targets : The safest project
- 2015
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Ingår i: International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015. - : American Nuclear Society. - 9781510811843 ; , s. 4604-4616
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Konferensbidrag (refereegranskat)abstract
- Severe accident with core meltdown is a threat to the containment integrity. As Chernobyl and Fukushima accidents demonstrate, significant release of radioactive products into the environment can have severe consequences both for people's health and the country's economy. Severe accidents arc the focus of considerable research involving substantial human and financial resources worldwide. The research field encompasses many challenging phenomena, complicated by high temperatures and presence of radioactive materials. No individual country has sufficient resources to address all important phenomena within the framework of a national research programme, therefore optimised use of resources and the collaboration at European and international level is very important. One of the mam objectives of the SAFEST project of the 7th EU framework programme is integrating European severe accident research facilities into a pan-European laboratory for study of corium behaviour in severe accidents The resources of this laboratory will be provided to other interested European partners for better understanding of possible accident scenarios and phenomena in order to improve safety of existing and. in the long-term, of future reactors. The SAFEST consortium will be able to address several severe accident issues related to accident analysis and corium behaviour. It will be a valuable asset for the fulfilment of the severe accident R&D programmes that arc being set up after Fukushima and the subsequent European stress tests, addressing both national and European objectives.
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