G. Miccichè

The accomplishment of the Engineering Design Activities of IFMIF/EVEDA: The European-Japanese project towards a Li(d,xn) fusion relevant neutron source

The International Fusion Materials Irradiation Facility (IFMIF), presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the frame of the Broader Approach Agreement between Europe and Japan, accomplished in summer 2013, on schedule, its EDA phase with the release of the engineering design report of the IFMIF plant, which is here described. Many improvements of the design from former phases are implemented, particularly a reduction of beam losses and operational costs thanks to the superconducting accelerator concept, the re-location of the quench tank outside the test cell (TC) with a reduction of tritium inventory and a simplification on its replacement in case of failure, the separation of the irradiation modules from the shielding block gaining irradiation flexibility and enhancement of the remote handling equipment reliability and cost reduction, and the water cooling of the liner and biological shielding of the TC, enhancing the efficiency and economy of the related sub-systems. In addition, the maintenance strategy has been modified to allow a shorter yearly stop of the irradiation operations and a more careful management of the irradiated samples. The design of the IFMIF plant is intimately linked with the EVA phase carried out since the entry into force of IFMIF/EVEDA in June 2007. These last activities and their on-going accomplishment have been thoroughly described elsewhere (Knaster J et al [19]), which, combined with the present paper, allows a clear understanding of the maturity of the European–Japanese international efforts. This released IFMIF Intermediate Engineering Design Report (IIEDR), which could be complemented if required concurrently with the outcome of the on-going EVA, will allow decision making on its construction and/or serve as the basis for the definition of the next step, aligned with the evolving needs of our fusion community.

Activities on IFMIF lithium target at ENEA

Abstract The status of R&D activity ongoing at ENEA on the lithium target system of the international fusion materials irradiation facility (IFMIF) is reported. The activity has been launched in year 2000 in the frame of IFMIF key element technology phase in order to reduce the key technology risk factors and to guarantee the required availability and reliability of the IFMIF liquid Li target system. The items discussed in the paper are related to the Li jet flow stability numerical analysis, water flow simulation experiment, backplate remote handling simulation and Li target safety analysis.

New Achievements of the Divertor Test Platform Programme for the ITER Divertor Remote Maintenance R & D

The divertor assembly for the ITER fusion reactor consists of a number of rail mounted cassettes (54 now in ITER FEAT) located in the bottom region of the vacuum vessel. These cassettes shall be removed/installed remotely during the life of the reactor by means of specific devices. To demonstrate and optimise the feasibility of the in-vessel maintenance process the Divertor Test Platform (DTP) has been established at the ENEA Research Centre in Brasimone, Italy, as a major part of the large ITER RD the procurement and testing of new sub-systems (e.g. a force reflection manipulator arm), and the development of remote handling techniques including a virtual reality system. Following a short description of the DTP, this paper reports on the new results and achievements, draws the relevant conclusions, and finally discusses future activities.

Engineering design and steady state thermomechanical analysis of the IFMIF European lithium target system

In the framework of the current IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the backplate) while continuing to operate the rest of the target for a longer period (bayonet backplate concept). In this work, the results of the steady state thermomechanical analysis of the IFMIF EU target assembly are briefly reported highlighting the relevant indications obtained with respect to the fulfillment of the design requirements.

Remote operational trials with the ITER FDR divertor handling equipment

Abstract The ITER divertor test platform (DTP) located at ENEAs Research Centre in Brasimone, Italy is a full-scale mock-up of a 72° arc of the ITER 1998 vessel divertor region—the result of a major initiative over the period 1996–2000. Since the implementation of this facility, the design of the ITER vessel—and therefore much of the remote maintenance equipment—has changed substantially. However, the nature and principles of the remote handling equipment are still very similar, and hence many valuable lessons can yet be learned from the existing equipment for the future. In particular, true remote handling tests of the major maintenance subsystems were seen as an important step in determining their suitability for ITER. This paper describes and documents a series of three, discrete, remote-handling trials carried out using most of the major DTP subsystems, and presents an overview of the conclusions and suggestions for future development of ITER cassette remote handling equipment.

R.H. divertor maintenance — the divertor test platform

The ITER divertor assembly consists in 60 cassettes located in the bottom region of the vacuum vessel. Because of erosion and damage, their replacement is expected to be required eight times during the machine lifetime. The cassettes will be remotely withdrawn from the vessel through dedicated ducts and they will be transported to a hot cell for refurbishment. To demonstrate the feasibility of the withdrawal operations, and to optimise the maintenance scenario and the handling equipment design, a test facility has been set-up at the ENEA Research Centre of Brasimone (Italy), i.e. the divertor test platform (DTP) that allows to simulate, in full scale, all handling operations inside the vacuum vessel. This paper describes the objectives, test programme, layout, test results and future activities of the DTP.

Design, manufacturing and testing of a fast disconnecting system for the European target assembly concept of IFMIF

The International Fusion Materials Irradiation Facility (IFMIF) will be equipped with a lithium target assembly to produce the required neutron flux for the irradiation of candidate fusion materials up to a damage rate of 100 dpa (cumulated damage in five years). The present European target assembly design is based on the so called replaceable backplate bayonet concept that was developed with the objective to simplify the maintenance operations for its refurbishment/replacement and to reduce the material for disposal as well. To this purpose it was also conceived to be attached to the lithium pipes and to the beam line by means of remotely operated connections based on clamped flanges with sealing metal gaskets. Accordingly, a custom design of this remotely operated connection, named Fast Disconnecting System (FDS), has been developed for the inlet flanged connections of the European IFMIF target assembly system. So far similar systems, already commercially available, have been used for several types of applications including nuclear ones, although never used neither under the IFMIF-like operating conditions nor fully remotely. The FDS is based on a commercial chain, which provides the required tightening force for the sealing of the edge of the flanges, that can be locked/unlocked by means of a reduced number of screws. The designed FDS prototype is provided with several additional features, to satisfy the operational working condition foreseen for IFMIF in terms of functionalities, safety and maintainability, like: the lithium leakage system; the flanges detachment mechanism; the insulation system and the systems to open the chain or to release the FDS in case of failure. A prototype of the FDS has been manufactured and based on the preliminary tests carried out the suitability to remote handling of the system has been proved. In this paper a description of the design of the FDS together with the outcomes of the remote handling validation tests are given.

Remote Handling Refurbishment Process for the European IFMIF Target Assembly: Concept Design, Simulation and Validation in Virtual Environment

The remote handling (RH) maintenance of components of International Fusion Materials Irradiation Facility (IFMIF) is one of the most challenging activities to be performed to guarantee the required high level of IFMIF plant availability. Among these components, the maintenance of the target assembly (TA) system appears to be critical, because it is located in the most severe region of neutron irradiation. The present European TA design is based on the so-called replaceable backplate (BP) bayonet concept. It was developed with the objective to reduce the waste material and to simplify the procedures for the target and BP replacement, thus reducing the intervention time for their substitution. The RH maintenance activity for the TA comprises a number of in situ refurbishment tasks, such as the removal of the BP, cleaning of surfaces from lithium solid deposition, inspection of the target body, installation of a new BP, and testing of the assembled system. However, there is also the possibility to replace the entire TA and to perform these refurbishment tasks offline in a dedicated hot cell. To accomplish all the refurbishment operations for the TA within the expected time for maintenance, the annual preventive maintenance period for IFMIF has been fixed in 20 days; several 3-D kinematic simulations in virtual reality environment and experimental activities aimed at developing and validating the implemented maintenance procedures for this component were carried out, in collaboration with the IDEAinVR Laboratory of CREATE/University of Naples Federico II, at the research center at ENEA Brasimone, Italy. The in situ refurbishment processes and the target replacement were simulated and tested and the feasibility of each maintenance operation was proved. In this paper, a description of the simulations and the validation activities carried out together with the main outcomes obtained are given.

Electrical aging tests on enameled wire exposed to gamma irradiation

Stator windings of low voltage electrical motors are usually insulated by means of organic enamels. If motors are used in particular industrial plants or in nuclear applications, the enamel adopted to insulate the motor stator windings may be exposed to very intense gamma photonic irradiation fields. In this research activity, attention has been focused on the potential influence of gamma irradiation dose on the performances of an electrical insulation system based on enameled wires having a thermosetting matrix. The aim of this research activity is to assess the prospects of exploitation of such insulating materials inside electromechanical devices intended to operate in presence of gamma photonic fields as in the frame of nuclear plant dismantling or, in general, of the manipulation of radioactive products. Suitable specimens, insulated by the considered enamel, have been set-up using enameled wire exposed to gamma photonic irradiation within a panoramic irradiator endowed with Co60 gamma sources. These pre-aged specimens have been subjected to electrical aging tests up to the enamel breakdown condition, chosen as end-point criterion, in order to study the electrical performances of the considered wires. The peak to peak voltage amplitude of the considered waveform has been set higher than the partial discharges inception voltage level in order to work in presence of surface partial discharges activity. Enamel life curve has been plotted in order to point out gamma irradiation dose influence on the performances of the considered insulating material. The obtained results show the significant effects of the exposure to a gamma irradiation field on the performances of the considered insulating enameled wire.