Proposal of an improved design of IFMIF Test Cell components for enhanced handling and reliability
Introduction
IFMIF, International Fusion Materials Irradiation Facility, is a facility aimed to test and qualify materials for the future fusion reactors [1], [2]. IFMIF consists in two linear accelerators producing energetic deuterons which impact on a liquid lithium target. It produces an intense neutron source focussed on the test samples. The samples and the liquid lithium target are installed in a pit named Test Cell [1], [3], Fig. 1.
Due to neutron radiation the components in the Test Cell are highly activated, reaching a contact dose of 105 Sv/h [1] for the most activated component. The radiation doses in the Test Cell and in the area around the Test Cell opening, the Access Cell, are high enough to require remote handling (RH).
A design adequate for remote maintenance is critical for the success of the activated facility since availability, reliability, safety and occupational exposures depend decisively on it. The essential guidelines for the design of remotely maintained facilities are simplicity, accessibility, modularity, standardization, the use of positioning aids, lifting and griping fixtures for RH and favour vertical access on the components [4], [5]. Simplicity intends the use of few, simple and rad-reliable elements. Accessibility comprises geometrical and visual access on the components in a degree according to the frequency of maintenance. Modularity in essence intends the separation in independent sound modules having localised interfaces. Positioning aids intend an accurate, fast and simple assembling and positioning of the components by using staggered alignment guides and reference points and surfaces. The main benefits are an increase in the availability of the facility because of the reduction of the planned and unplanned maintenance periods, and the reduction of construction and operative costs due to standardization and simplicity in components and RH equipment.
This paper is a conceptual design aimed to solve some drawbacks of the present reference design of the Test Cell, being particularly focussed in modifications of the components in the Test Cell in order to improve the remote handling operations, trying to keep most of the other positive features of the present reference design.
Section snippets
Present reference design of the Test Cell
The reference design of the Test Cell is based on large stepped shielding plugs supporting the Test Modules at the lower end [1], [3], Fig. 2. These plugs are named VTA1, VTA2 (Vertical Test Assemblies 1 and 2) and VIT (Vertical Irradiation Tubes). They close the top of the Test Cell during irradiation as shown in Fig. 1, and contain the pipes and cables (Fig. 2) that feed the Test Modules. The weights of the VTAs and VIT range from 9 to 13 tons. As illustrated in Fig. 2, the Test Modules are
Brief outline
Modularity could be applied to the VTAs as illustrated in Fig. 3, conceiving three separate components: the Test Module, a simplified shielding plug without conduits and a conduit plug. A conduit plug is a shielded plug containing pipes, cables and connectors.
The separation of the weighty VTA Plugs and the light Test Modules allows conceiving simple positioning alignment guides for the Test Modules.
Enhanced accessibility is achieved if the conduit plugs are located at the sides of the Test
Advantages
Access to the components is faster, safer and more reliable because only one simple shielding plug needs to be removed.
The cost of the exceptional high precision RH crane and shielding plugs is highly reduced by using location guides for the light Test Modules and wedged shaped shielding plugs for easier installation/removal.
Collision risk of the Test Modules is avoided because the large inertial forces of the VTA Plugs are independent from the Test Modules.
Flexibility for future experiments
Conclusions
The present reference design of the components in the Test Cell of IFMIF has been enhanced. The guidelines for the design of remotely maintained facilities have been further fulfilled. The proposal establishes a separation among the shielding plugs, Test Modules and conduits, and it defines positioning alignment guides for the Test Modules. As a consequence, modularity, accessibility and positioning have been improved while simplicity is kept. Further studies are necessary to detect and solve
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New progresses in the IFMIF target and test cell design and a proposal for the specimen flow
2011, Nuclear Engineering and DesignCitation Excerpt :At the beginning of the current engineering validation and engineering design activities (EVEDA) phase of IFMIF project, the TTC design concept that is described in the CDR report (IFMIF International Team, 2003b) was considered as a reference, as shown in Fig. 1. Considering the critical issues, e.g. considerable difficulties in the tightness of the sealing and accurate/flexible positioning of the TMs, observed for this reference design, an improved conceptual design, named as the modular test cell (MTC) concept (named as merged test cell concept for a time), has been introduced and developed (Tian et al., 2010) based on this reference design and other revised design options (Queral et al., 2009; Tian et al., 2010). As shown in Fig. 2, the MTC concept features separated TTC shielding, independent TM positioning system and independent TTC vessel.
Preliminary definition of the remote handling system for the current IFMIF Test Facilities
2011, Fusion Engineering and DesignCitation Excerpt :The TM, the previously mentioned Cells and some other technical rooms constitute the Test Facilities of IFMIF. An appropriate design of both the RH system and the components to be manipulated is essential for the success and availability of IFMIF [4]. A new conceptual design of the TC was developed during 2009 [5], Fig. 1, where the functions of shielding, conduits and TM were separated.
IFMIF target and test cell - Conceptual designs, boundary condition definitions and current status of preliminary engineering design
2010, Fusion Engineering and DesignCitation Excerpt :One of the other designs, as shown in Fig. 3(b), intended to use an in-cell brace system to hold TMs and the positioning system which is driven by spindles. Another design concept proposed by Queral et al. [5] applies a separated single shielding plug and independent cylindrical conduit plugs for passing pipes and cables from the access cell into the TTC, as shown in Fig. 3(c). All of these designs made efforts on simplifying shielding blocks, separating functions, and implementing precise and flexible positioning of TMs.
Initial Exploration of High-Field Pulsed Stellarator Approach to Ignition Experiments
2018, Journal of Fusion EnergyRadioprotection analysis for the high energy beam transport line of the accelerator facility of IFMIF
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2010, International Conference on Nuclear Engineering, Proceedings, ICONE