Reliability studies of a high-power proton accelerator for accelerator-driven system applications for nuclear waste transmutation

The main effort of the present study is to analyze the availability and reliability of a high-performance linac (linear accelerator) conceived for Accelerator-Driven Systems (ADS) purpose and to suggest recommendations, in order both to meet the high operability goals and to satisfy the safety requirements dictated by the reactor system. Reliability Block Diagrams (RBD) approach has been considered for system modelling, according to the present level of definition of the design: component failure modes are assessed in terms of Mean Time Between Failure (MTBF) and Mean Time To Repair (MTTR), reliability and availability figures are derived, applying the current reliability algorithms. The lack of a well-established component database has been pointed out as the main issue related to the accelerator reliability assessment. The results, affected by the conservative character of the study, show a high margin for the improvement in terms of accelerator reliability and availability figures prediction. The paper outlines the viable path towards the accelerator reliability and availability enhancement process and delineates the most proper strategies. The improvement in the reliability characteristics along this path is shown as well

Analysis of Common Cause Failures Coupling Factors and Mechanics from Ageing Point of View

The investigation of ageing phenomenon impact on CCF potential was the main goal of Task 5 of the EC JRC Ageing PSA (APSA) Network. This report is devoted to investigation of close links between CCF potential and ageing, and provides expert opinions (based on the questionnaire answers) regarding connection between common cause failure potential and ageing phenomenon, as the influence of the individual prevention factors against CCF. In the questionnaire, two main topics were discussed: -What is the strength of relation between the individual CCF coupling factors (contributing to total CCF potential) and ageing phenomenon? -For those CCF coupling factors, which have been evaluated as coincident with ageing phenomenon (at least medium level of coincidence) - what is the effect of CCF prevention measures on the coupling factor versus ageing relation? A specific color scale was used to specify the strength value of CCF coupling factor and ageing phenomenon relation and to define the strength of potential influence of prevention factor on the strength of link between CCF potential and ageing phenomena. The strength value assigned in the table was commented (reflection in operational experience, assumptions etc.). The strength between CCF coupling factors and ageing and the influence of the individual prevention factors against CCF was evaluated based on available operational experience and expert judgments.JRC.F.5-Nuclear Reactor Safety Assessmen

Reliability Assessment of Passive Safety Systems for Nuclear Energy Applications: State-of-the-Art and Open Issues

International audiencePassive systems are fundamental for the safe development of Nuclear Power Plant (NPP) technology. The accurate assessment of their reliability is crucial for their use in the nuclear industry. In this paper, we present a review of the approaches and procedures for the reliability assessment of passive systems. We complete the work by discussing the pending open issues, in particular with respect to the need of novel sensitivity analysis methods, the role of empirical modelling and the integration of passive safety systems assessment in the (static/dynamic) Probabilistic Safety Assessment (PSA) framework

Del 3.1: Risk integration methods for high risk industries

Nuclear power plants are exposed to a variety of hazards, which may result in risks (the product of the likelihood of the hazard and resulting consequence). One of the key objectives of the NARSIS project is to improve the integration of external hazards and their consequences with existing state-of-the-art risk assessment methodologies in the industry. Accordingly, the main goals of this deliverable are to:- Review the various aspects of risk integration and associated methodologies- Review case histories of accidents in complex industrial set-ups, both nuclear and non-nuclear, and highlight prevalent ‘latent weaknesses’ that eventually led to these accidents- Review deterministic and probabilistic methods to identify latent weaknesses- Review risk integration methods currently used in high-risk industries such asnuclear, chemical and aviation- Review accident investigation procedures and international initiatives associated withmajor nuclear accidents- Discuss specific risk integration method(s) that are relevant to the NARSIS projectGeo-engineeringSafety and Security Scienc

Identification and Categorisation of Safety Issues for ESNII Reactor Concepts. Part I: Common phenomena related to materials

With the aim to develop a joint proposal for a harmonised European methodology for safety assessment of advanced reactors with fast neutron spectrum, SARGEN_IV (Safety Assessment for Reactors of Gen IV) Euratom coordination action project gathered together 22 partners’ safety experts from 12 EU Member States. The group consisted of eight European Technical Safety Organisations involved in the European Technical Safety Organisation Network (ETSON), European Commission’s Joint Research Centre (JRC), system designers, industrial vendors as well as research & development (R&D) organisations. To support the methodology development, key safety features of four fast neutron spectrum reactor concepts considered in Deployment Strategy of the Sustainable Nuclear Energy Technology Platform (SNETP) were reviewed. In particular, outcomes from running European Sustainable Nuclear Industrial Initiative (ESNII) system projects and related Euratom collaborative projects for Sodium-cooled Fast Reactors, Lead-cooled Fact Reactors, Gas-cooled Fast Reactors, and the lead-bismuth eutectic cooled Fast Spectrum Transmutation Experimental Facility were gathered and critically assessed. To allow a consistent build-up of safety architecture for ESNII reactor concepts, the safety issues were further categorised to identify common phenomena related to materials. Outcomes of the present work also provided guidance for identification and prioritisation of further R&D needs respective to the identified safety issues.JRC.F.5-Nuclear Reactor Safety Assessmen