[en] MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Application) is a multipurpose research facility currently being developed at SCK CEN. MYRRHA is based on the ADS (Accelerator Driven System) concept where a proton accelerator, a spallation target and a subcritical reactor are coupled. MYRRHA will demonstrate the ADS full concept by coupling these three components at a reasonable power level to allow operation feedback. As a flexible irradiation facility, the MYRRHA research facility will be able to work in both critical as subcritical modes. In this way, MYRRHA will allow fuel developments for innovative reactor systems, material developments for GEN IV and fusion reactors, and radioisotope production for medical and industrial applications. MYRRHA will be cooled by lead-bismuth eutectic and will play an important role in the development of the Pb-alloys technology needed for the LFR (Lead Fast Reactor) GEN IV concept. MYRRHA will also contribute to the study of partitioning and transmutation of high-level waste. Transmutation of minor actinides (MA) can be completed in an efficient way in fast neutron spectrum facilities, so both critical reactors and subcritical ADS are potential candidates as dedicated transmutation systems. However critical reactors heavily loaded with fuel containing large amounts of MA pose reactivity control problems, and thus safety problems. A subcritical ADS operates in a flexible and safe manner, even with a core loading containing a high amount of MA leading to a high transmutation rate. The MYRRHA design has progressed through various framework programmes (FP) of the European Commission in the context of Partitioning and Transmutation. The XT-ADS version was a short-term, small-scale (57 MW_th) experimental facility, and has been developed within the EUROTRANS project in the FP6 (2005-2010). The most recent version FASTEF is a further upgrade of XT-ADS, still conceived as a flexible irradiation facility, now able to work in both sub-critical and critical modes. FASTEF has been developed within the CDT project in FP7 (2009-2012). The MYRRHA design has now entered into the Front End Engineering Design (FEED) Phase. A tendering process has been launched to select a consortium of engineering companies to support the FEED. In this paper, the most recent developments in the design of the MYRRHA facility are presented. (author)

[en] The deployment of innovative nuclear systems including MYRRHA ADS system relies primarily upon the availability of structural materials able to withstand their harsh operation conditions, in particular with respect to the material compatibility with the coolant under intense irradiation. The materials selection and qualification are critical issues for successful development of such nuclear systems. The selection of structural materials should rely on a number of their intrinsic properties with respect, among others, to thermo-mechanical loading conditions, coolant-material interaction effects, irradiation and their synergetic effects of all previously mentioned. Therefore, it is important to be able to appropriately characterize these materials. However, the behaviour of materials under operation conditions of innovative nuclear systems is not appropriately covered by the available testing and evaluation standards requiring updates of existing standard procedures and sometimes development of new ones. Today, individual laboratories rely on their own experience and on experimental and irradiation facilities available to them. Although it is possible to extract helpful qualitative information, it is difficult to interpret the various data quantitatively. The main goal of materials R and D and qualification programme for MYRRHA candidate materials is to provide reliable material property data for design and licensing of MYRRHA. It also aims to assist with the following activities: a) design of various components; b) fuel development; c) safety analysis; d) coolant technology development; e) elaboration of the surveillance program. At the moment the efforts are distributed over the following four overlapping activities: a) Identification of key material issues for design and licensing of MYRRHA; b) Development of test and evaluation guidelines for structural materials characterisation; c) Assessment of material properties; d) Development of testing infrastructure. The three major material degradation effects that have been identified so far for nuclear systems with lead-bismuth coolant and for MYRRHA in particular are liquid metal corrosion, environmentally assisted cracking and irradiation effects. In this paper we will report on the material R and D approach for MYRRHA and the progress accomplished so far. (author)

[en] Optimizing the life cycle of nuclear systems under safety constraints requires high-performance experimental programs to reduce uncertainties on margins and limits. In addition to improvement in modeling and simulation, innovation in instrumentation is crucial for analytical and integral experiments conducted in research reactors. Significant efforts have been made recently to improve in-pile instrumentation for the benefit of material testing reactors. The quality of nuclear research programs obviously relies on an excellent knowledge of their experimental environment, which constantly calls for better online determination of neutron and gamma flux. But the combination of continuously increasing scientific requirements and new experimental domains-brought, for example, by Generation-IV programs-also necessitates major innovations for in-pile measurements of temperature, dimensions, pressure, or chemical analysis in innovative mediums. To face these challenges, the CEA (French Nuclear Energy Commission) and the SCK.CEN (Belgian Nuclear Research Centre) have combined their efforts and now share common developments through a Joint Instrumentation Laboratory. Significant advances have thus been obtained in the field of in-pile measurements, on one hand by the improvement of existing measurement methods (for example, a unique fast neutron flux measurement system using fission chambers with ²⁴²Pu deposit and a specific online data processing has been developed), and on the other hand by the introduction in research reactors of original techniques such as optical dimensional measurements or acoustical fission gas release measurements. (authors)

[en] To be able to answer the world's increasing demand for energy, nuclear energy must be part of the energy mix. As a consequence of the nuclear electricity generation, high-level nuclear waste (HLW) is produced. The HLW is presently considered to be managed through its burying in geological storage. Partitioning and transmutation (P and T) has been pointed out as the strategy to reduce the radiological impact of HLW. Transmutation can be achieved in an efficient way in fast neutron spectrum facilities, both in critical fast reactors as well as in accelerator driven systems (ADSs). For more than two decades, the European Commission has been co-funding various research and development projects conducted in many European research organisations and industries related to P and T as a complementary strategy for high-level waste management to the geological disposal. In 2005, a European strategy for the implementation of P and T for a large part of the HLW in Europe indicated the need for the demonstration of its feasibility at an 'engineering' level. The R and D activities of this strategy were arranged in four 'building blocks': 1. Demonstration of the capability to process a sizable amount of spent fuel from commercial light water reactors (LWRs) in order to separate plutonium, uranium and minor actinides. 2. Demonstration of the capability to fabricate at a semi-industrial level the dedicated fuel needed as load in a dedicated transmuter. 3. Design and construction of one or more dedicated transmuters. 4. Provision of a specific installation for processing of the dedicated fuel unloaded from the transmuter, which can be of a different type than the one used to process the original spent fuel unloaded from the commercial power plants, together with the fabrication of new dedicated fuel. MYRRHA contributes to the third building block. MYRRHA is an ADS under development at SCK.CEN in collaboration with a large number of European partners. One of the objectives of the new MYRRHA facility is to address the technical feasibility of transmutation of HLW. Within this paper the development of the MYRRHA project and its role as transmutation facility are described briefly. (authors)

[en] CEA (French Nuclear Energy Commission) and SCK-CEN (Belgian Nuclear Research Centre) have combined their efforts and now share common developments in the domain of in-pile measurements through the setting of a Joint Instrumentation Laboratory. Significant progresses have thus been obtained recently in the field of in-pile measurements, on one hand by improvement of existing measurement methods, and on the other hand by introduction in research reactors of original measurement techniques. This paper highlights the state-of-the-art and the main requirements regarding in-pile measurements, particularly for the needs of current and future irradiation programs performed in material testing reactors. Some of the main on-going developments performed in the framework of the Joint Instrumentation Laboratory are also described, such as: -) a unique fast neutron flux measurement system using fission chambers with ²⁴²Pu deposit and a specific online data processing, -) an optical system designed to perform in-pile dimensional measurements of material samples under irradiation, -) an acoustical instrumentation allowing the online characterization of fission gas release in Pressurized Water Reactor fuel rods. For each example, the obtained results, expected impacts and development status are detailed

[en] MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) is a multipurpose research facility currently being developed at SCK·CEN. MYRRHA is based on the ADS (Accelerator Driven System) concept where a proton accelerator, a spallation target and a subcritical reactor are coupled. MYRRHA will demonstrate the ADS full concept by coupling these three components at a reasonable power level. As a flexible irradiation facility, the MYRRHA research facility will be able to work in both critical as subcritical modes. In this way, MYRRHA will allow fuel developments for innovative reactor systems, material developments for GEN IV and fusion reactors, and radioisotope production for medical and industrial applications. MYRRHA will be cooled by lead-bismuth eutectic and will play an important role in the development of the Pb-alloys technology needed for the LFR (Lead Fast Reactor) GEN IV concept. MYRRHA will also contribute to the study of partitioning and transmutation of high-level waste. Transmutation of minor actinides (MA) can be completed in an efficient way in fast neutron spectrum facilities (critical reactors and sub-critical ADS). A sub-critical ADS operates in a flexible and safe manner even with a core loading containing a high amount of MA leading to a high transmutation rate. The sub-criticality is therefore rather a necessity for an efficient and economical burning of the MA. The MYRRHA design has progressed through various framework programs of the European Commission in the context of Partitioning and Transmutation. The MYRRHA design has now entered into the Front End Engineering Phase covering the period 2012-2015. The engineering company which will handle this phase has been selected and the works have begun in 2013. As stated above, MYRRHA will demonstrate the ADS full concept by coupling the three components (accelerator, spallation target and subcritical reactor) at reasonable power level to allow operation feedback, scalable to an industrial demonstrator and allow the study of efficient transmutation of high-level nuclear waste. Since MYRRHA is based on heavy liquid metal technology (lead-bismuth eutectic), it significantly contributes to the development of Lead Fast Reactor Technology. In critical mode, MYRRHA will play the role of European Technology Pilot Plant in the roadmap for LFR. During the presentation we will focus on the ADS program in the EU through the MYRRHA project. We will present the most recent developments of the MYRRHA design in terms of primary system, reactor building and plant layout as existing mid-2014. (author)

[en] The MYRRHA reactor (Multi-purpose hYbrid Research Reactor for High-tech Applications), currently developed at SCK•CEN, will allow the demonstration of transmutation of high-level nuclear waste, fuel developments for innovative reactor systems, material developments for GEN IV and fusion reactors, and radioisotope production for medical and industrial applications. Since MYRRHA is based on heavy liquid metal technology with Lead Bismuth Eutectic (LBE) coolant, it can significantly contribute, during its development and in its operational phase, to the development of Lead Fast Reactor (LFR) technology for both large and SMR systems cooled with Lead Bismuth Eutectic or with Lead. To support the MYRRHA development, SCK•CEN has launched a strong R&D programme to address the main design and licensing challenges, in particular those related to the use of liquid Lead-Bismuth Eutectic as reactor coolant. In this frame SCK•CEN has constructed and commissioned various LBE test facilities for heavy liquid metal chemistry and conditioning research, the heavy liquid metal corrosion research for materials for advanced fast reactors, the testing of mechanical rotating components in heavy liquid metals, reactor component testing in a heavy liquid metal loop and a facility for the validation of complex flows in liquid metal pool systems. These facilities are used for the qualification of the key materials and components of MYRRHA and can also be used for the development of materials and components for fast reactors of all power ranges, including SMR type, working with LBE or Lead as coolant. The paper describes the SCK•CEN concept roadmap for lead SMR type power reactors based on MYRRHA technology developed from the ongoing R&D programme. The existing research facilities and their applicability for the development of lead SMR type systems are presented. (author)

[en] Optimizing the life cycle of nuclear systems under safety constraints requires high-performance experimental programs to reduce uncertainties on margins and limits. In addition to improvement in modeling and simulation, innovation in instrumentation is crucial for analytical and integral experiments conducted in research reactors. The quality of nuclear research programs relies obviously on an excellent knowledge of their experimental environment which constantly calls for better online determination of neutron and gamma flux. But the combination of continuously increasing scientific requirements and new experimental domains -brought for example by Generation IV programs-necessitates also major innovations for in-pile measurements of temperature, dimensions, pressure or chemical analysis in innovative mediums. At the same time, the recent arising of a European platform around the building of the Jules Horowitz Reactor offers new opportunities for research institutes and organizations to pool their resources in order to face these technical challenges. In this situation, CEA (French Nuclear Energy Commission) and SCK. CEN (Belgian Nuclear Research Centre) have combined their efforts and now share common developments through a Joint Instrumentation Laboratory. Significant progresses have thus been obtained recently in the field of in-pile measurements, on one hand by improvement of existing measurement methods, and on the other hand by introduction in research reactors of original measurement techniques. This paper highlights the state-of-the-art and the main requirements regarding in-pile measurements, particularly for the needs of current and future irradiation programs performed in material testing reactors. Some of the main on-going developments performed in the framework of the Joint Instrumentation Laboratory are also described, such as: a unique fast neutron flux measurement system using fission chambers with Pu-242 deposit and a specific online data processing, an optical system designed to perform in-pile dimensional measurements of material samples under irradiation, an acoustical instrumentation allowing the online characterization of fission gas release in Pressurized Water Reactor fuel rods. For each example, the obtained results, expected impacts and development status are detailed. (authors)

[en] Partitioning and transmutation (PT) has been pointed out in numerous studies as the strategy that can relax constraints on geological disposal, e.g. by reducing the waste radiotoxicity and the footprint of the underground facility. Therefore, a special effort has been made to investigate the potential role of PT and the related options for waste management all along the fuel cycle. The research infrastructure dedicated to PT studies is MYRRHA, the phase one of MYRRHA consists in a linear accelerator up to 100 MeV coupled to a proton target facility (called MINERVA) and it will be operational around 2026. This paper presents the main achievements in various projects in support to MYRRHA: MYRTE, MARISA, MAXSIMA, SEARCH, FREYA and ARCAS. The goal of MYRTE is to perform the necessary research in order to demonstrate the feasibility of transmutation of high-level waste at industrial scale through the development of the MYRRHA research facility. The project MARISA reviewed advanced fuel cycles and approaches for the long-term management of radioactive waste. MAXSIMA project will provide support to MYRRHA for neutron transport and shielding analysis. SEARCH project is in charge of safety related aspects of the chemical behaviour of the liquid metal coolant and of the fuel in the reactor. The FREYA project will validate the methodology of sub-criticality monitoring that is envisaged for the online sub-criticality monitoring in MYRRHA. The ARCAS projects intends to look at the economical aspects of the most realistic scenario for PT. (A.C.)

[en] The ESNII Plus project: 'Preparing ESNII for Horizon 2020' (2013-2017), is a combination of Collaborative Project and a Coordination and Support Action performed in the 7. European Framework Program. This project merges the contribution of 35 European partners. This crosscutting project is devoted to develop a broad strategic approach for advanced fission systems in Europe in support of the European Sustainable Industrial Initiative (ESNII) as well as perform Research/Development activities on technical issues in support to the development of ESNII fast reactors ASTRID, ALLEGRO, ALFRED and MYRRHA. This paper summarizes the work done in the different areas of the project: -) structuring ESNII for HORIZON 2020, -) strategic road-mapping, -) support to facilities development, -) industrial perspectives, -) training and dissemination, -) core safety, -) fuel safety, -) seismic studies, and -) instrumentation for safety