Alessandro Alemberti

ELSY—European LFR Activities

The European Lead Fast Reactor has been developed in the frame of the European lead system (ELSY) project funded by the Sixth Framework Programme of EURATOM. The project, coordinated by Ansaldo Nucleare, involved a wide consortium of European organizations. The ELSY reference design is a 600MWe pool-type reactor cooled by pure lead. The project demonstrates the possibility of designing a competitive and safe fast critical reactor using simple engineered technical features, whilst fully complying with the Generation IV goals. The paper focuses on the main aspects of the proposed design for the European lead fast reactor highlighting the innovation of this reactor concept and overall objectives. Special attention has been dedicated to safety starting from the first step of the design development taking into account other important aspects, such as the investment protection, the compactness of the primary system as well as sustainability. The main safety features of the proposed innovative decay heat removal (DHR) systems are presented. From the beginning of 2010, and for a duration of three years, the European Commission (EC) is financing the new project Lead European Advanced Demonstration Reactor (LEADER) as part of the 7th Framework Program. This paper highlights the main objectives of the LEADER project.

The SPES3 Experimental Facility Design for the IRIS Reactor Simulation

IRIS is an advanced integral pressurized water reactor, developed by an international consortium led by Westinghouse. The licensing process requires the execution of integral and separate effect tests on a properly scaled reactor simulator for reactor concept, safety system verification, and code assessment. Within the framework of an Italian R&D program on Nuclear Fission, managed by ENEA and supported by the Ministry of Economic Development, the SPES3 facility is under design and will be built and operated at SIET laboratories. SPES3 simulates the primary, secondary, and containment systems of IRIS with 1 : 100 volume scale, full elevation, and prototypical thermal-hydraulic conditions. The simulation of the facility with the RELAP5 code and the execution of the tests will provide a reliable tool for data extrapolation and safety analyses of the final IRIS design. This paper summarises the main design steps of the SPES3 integral test facility, underlying choices and phases that lead to the final design.

Investigations on the phenomenology of ex-vessel core melt behaviour (COMAS)

Within the COMAS (corium on material surfaces) project, representative experimental and analytical investigations on the ex-vessel spreading behaviour of prototypic corium were performed to provide a realistic technical basis for the development of core catchers for future nuclear reactor generations. In various large-scale experiments, melts in the Mg-range with real corium compositions and temperatures around 2000 °C were tested using different substratum materials (concrete, ceramics, cast iron). These tests were carried out at Siempelkamps CARLA melting facility for radioactively contaminated metal scrap supported by laboratory experiments at Siemens, Erlangen. The COMAS results indicate that for a sufficiently high melt release rate a quick and homogeneous coverage of an ex-vessel spreading compartment as realized in the Franco-German EPR project can be expected. Regarding the analytical assessment, it can be concluded that some spreading codes have reached a sufficient level to provide guidelines for the evaluation of spreading concepts. Open questions are mainly related to segregation and immobilization of the melt.

Design of a Decay Heat Removal System for EFIT Plant

The Integrated Project EUROTRANS, funded by the European Commission as part of the 6th European framework program, provides the advanced design of a multi purpose research oriented Accelerator Driven System (ADS), called XT-ADS (eXperimenTal-ADS), and the preliminary design of an industrial scale ADS, called EFIT (European Facility for Industrial Transmutation) [1]. EFIT [2] [3] is fuelled with Minor Actinides (U-free fuel) and its main design options overcome the limits of previous ADS projects, particularly as concerns the economic aspects, maintaining meanwhile the high safety level, the high reliability and low investment risks. EFIT is endowed with three different systems to remove decay heat, this paper deals with the Decay Heat Removal System 2 (DHR2). DHR2 mainly consists of an isolation condenser (IC) connected to the secondary side of the Steam Generators (SGs). DHR2 is a passive safety system: system operation is based on condensation of the steam coming from the SG unit and gravity head injection of the condensate back to the SG inlet. The system has been designed to satisfy the following two requirements: • to evacuate the decay power maintaining acceptable values of the vessel and fuel temperature; • to avoid lead solidification also in the configuration of maximum efficiency.Copyright

A CFD Analysis of Flow Blockage Phenomena in ALFRED LFR DEMO Fuel Assembly

A CFD study has been carried out on fluid flow and heat transfer in the HLM-cooled Fuel Pin Bundle of the ALFRED LFR DEMO.In the context of GEN-IV Heavy Liquid Metal-cooled reactors safety studies, the flow blockage in a Fuel sub-assembly is considered one of the main issues to be addressed and the most important and realistic accident for LFR Fuel Assembly. The present paper is a first step towards a detailed analysis of such phenomena, and a CFD model and approach is presented to have a detailed thermo-fluid dynamic picture in the case of blockage. The closed hexagonal, grid-spaced fuel assembly of the LFR ALFRED has been modeled and computed. At this stage, the details of the spacer grids have not been included, but a conservative analysis has been carried out based on the current main geometrical and physical features. Reactivity feedback, as well as axial power profile, have not been included in this analysis. Results indicate that critical conditions, with clad temperatures around ∼900°C, are reached with blockage larger than 30% in terms of area fraction.Two main effects can be distinguished: a local effect in the wake/recirculation region downstream the blockage and a global effect due to the lower mass flow rate in the blocked subchannels; the former effect gives rise to a temperature peak behind the blockage and it is dominant for large blockages (>20%), while the latter effect determines a temperature peak at the end of the active region and it is dominant for small blockages ( 15% could be detected by putting some thermocouples in the plenum region of the FA.© 2014 ASME

The ARCADIA Project in Support of the ALFRED Concept

The FP7 Euratom project ARCADIA (Assessment of Regional CApabilities for new reactors Development through an Integrated Approach), launched in November 2013, has the aim to assess the regional capabilities of the EU New Member States (NMS) to effectively contribute in bringing closer the European research to ESNII (European Sustainable Nuclear Industrial Initiative) and NUGENIA (NUclearGEneration II&III Association) objectives. In particular, for the ESNII, the project will work in support to the ALFRED concept towards its realization in Romania, and for NUGENIA it will approach safety aspects of Gen III/III+.The project focuses on the identification of the primary needs for the ALFRED project, mainly to what concerns engineering and technology, supporting infrastructures, competences and regulatory aspects. At the same time, it investigates the existing national and regional supporting structures — with a particular attention to the ones in Romania and in all the participating NMS — for defining a map of competences potentially eligible to satisfy the identified needs. Since the most of the existing competences and experiences rely on present generation systems, the review will also provide a frame for potential support to NUGENIA on Gen III/III+ systems, as well as the starting point for building the Gen IV culture and future capabilities.On the other hand, ARCADIA takes the profit of the large participation to the project itself to carry out an advising activity to the ALFRED Consortium (FALCON), addressing recommendations regarding the national and international best practices and guidelines for the advancement of the ALFRED project.Investigation of the existing Research Reactors, among the Project Partner, for their potential involvement in future (potential) experimental activities in support of both the ALFRED project realization and the Gen III/III+ safety activities will be also considered. Networking, Cooperation and Dissemination activities are also included in the project in order to provide the connection with the international scientific community, with the European institutional organizations and with the general public. This work gives an overview of the project objectives, structure and contents, with focus on the international effort towards the GenIV.Copyright