Towards a common object model and API for accelerator controls

An Object-Oriented Application Programming Interface (OO API) can provide applications with an abstract model of the components of an accelerator. The main question is how to encapsulate different control systems into one single abstract model. The abstract model of an 00 API can be described in a formal way via object models in order to clarify the semantic issues, to describe the important concepts (device, attributes, ...), and to decompose the objects up to the granularity where the model of some objects can be shared between labs. A C++ API (as well as C API) can be derived from the object-model. This paper presents a common object model which is derived from the object-model. This paper presents a common object model which is derived from both the current CERN-PS model and the current ERSF model. We describe the technical difficulties we encountered in migrating existing control systems into a shared but usable model. We also aim to increase the universality of the model by taking into account the CDEV library, as well as CORBA. A high-level description of the model will be presented with examples of the derived API

Health monitoring of bolted joints using modal-based vibrothermography

This article presents a novel modal-based vibrothermographic approach for health monitoring of loosening bolted joints in coupled structures. In this article, the theoretical background supporting this proposed approach is firstly presented. Through finite element analyses on a simple bolted structure with varying joint conditions achieved by adjustment of bolt loads, the relationship between the bolt load and the temperature increase in the vibrating bolted joint during vibrothermographic tests was revealed. Experimental vibrothermographic tests on a more complex structure were completed to verify the observations from the finite element analyses while demonstrating the viability of the vibrothermographic approach in a laboratory environment. It has been shown that this vibrothermographic approach was able to determine the stage of a bolted joint in its progression of failure by tracing the changes in the temperature increase in relevant regions during vibrothermographic tests. Moreover, additional tests have been performed to illustrate that this approach was effective even by using only the residual responses of the structure’s vibration that were away from the resonances, which indicates it is more applicable to structures with higher damping as such structures have stronger residual responses during vibration that can be utilized. In the concluding observations of the article, the procedure for practical application of this approach is summarized, and its potential for further development is discussed

Low-Frequency Vibrothermography Using Lightweight Piezoelectric Actuators:The Location of Excitation and Application to Composite Materials

This article presents a novel infrared thermographic approach for damage detection by utilizing the heat generated around damage sites during vibrations below 1000 Hz induced by lightweight piezoelectric actuators. In this research, the optimal location of excitation was first investigated through finite element analyses, where two generalized equations were obtained to describe the relationship between the excitation and the resulting displacement response. These observations were then verified experimentally on an aerospace-grade composite plate, followed by vibrothermographic tests conducted on the same structure to demonstrate the effectiveness of the proposed damage detection process employing only a single lightweight piezoelectric disk as the actuator

Some new insights in swelling and swelling pressure of low active clay

This paper presents a multidimensional chemo-mechanical model for saturated clay treated as a two-phase deformable and chemically reactive porous medium. The constitutive relation is an extension of the original chemo-mechanical model proposed by Gajo et al. (2002) and Loret et al. (2002), in which a q-p formulation was proposed with a Cam-Clay-like elastic response. A novel hyper-elastic law is proposed in which shear stiffness and bulk stiffness change with stress state and ion concentration in pore solution. The proposed constitutive model and the associated coupled finite element formulation are implemented in a 2D, commercial, finite element code (ABAQUS) in the form of user-defined external subroutines. The proposed framework is used to simulate the oedometer tests performed on a low activity clay extracted from Costa della Gaveta slope. The computed chemo mechanical behaviour of the material prepared with distilled water is compared with the experimental results obtained from reconstituted specimens. Moreover, swelling and swelling pressure are computed for the overconsolidated material reconstituted with 1 M NaCl solution and then exposed to distilled water. The comparison of simulations and experiments shows a good agreement

Conceptual design of the enhanced coolant purification systems for the European HCLL and HCPB test blanket modules

The Coolant Purification Systems (CPSs) is one of the most relevant ancillary systems of European Helium Cooled Lead Lithium (HCLL) and Helium Cooled Pebble Bed (HCPB) Test Blanket Modules (TBMs) which are currently in the preliminary design phase in view of their installation and operation in ITER. The CPS implements mainly two functions: the extraction and concentration of the tritium permeated from the TBM modules into the primary cooling circuit and the chemistry control of helium primary coolant. During the HCLL and HCPB-TBSs (Test Blanket Systems) Conceptual Design Review (CDR) in 2015 it was recognized the need of reducing the tritium permeation into the Port Cell #16 of ITER. To achieve this and, then, to lower the tritium partial pressure in the Helium Cooling Systems in normal operation, the helium flow-rate treated by each CPS has been increased of almost one order of magnitude. In 2017, to satisfy the CDR outcomes and the new design requirements requested by Fusion for Energy (F4E, the European Domestic Agency for ITER), ENEA performed a preliminary design of the “enhanced” CPSs. This paper presents the current design of the “enhanced” CPSs, focusing on design requirements, assumptions, selection of technologies and preliminary components sizing

Hydraulic characterization of the full scale mock-up of the demo divertor outer vertical target

In the frame of the pre-conceptual design activities of the DEMO work package DIV-1 “Divertor Cassette Design and Integration” of the EUROfusion program, a mock-up of the divertor outer vertical target (OVT) was built, mainly in order to: (i) demonstrate the technical feasibility of manufacturing procedures; (ii) verify the hydraulic design and its capability to ensure a uniform and proper cooling for the plasma facing units (PFUs) with an acceptable pressure drop; and (iii) experimentally validate the computational fluid-dynamic (CFD) model developed by the University of Palermo. In this context, a research campaign was jointly carried out by the University of Palermo and ENEA to experimentally and theoretically assess the hydraulic performances of the OVT mock-up, paying particular attention to the coolant distribution among the PFUs and the total pressure drop across the inlet and outlet sections of the mock-up. The paper presents the results of the steady-state hydraulic experimental test campaign performed at ENEA Brasimone Research Center as well as the relevant numerical analyses performed at the Department of Engineering at the University of Palermo. The test facility, the experimental apparatus, the test matrix and the experimental results, as well as the theoretical model, its assumptions, and the analyses outcomes are herewith reported and critically discussed

Thermofluid-dynamic assessment of the EU-DEMO divertor single-circuit cooling option

Until 2019, the thermo-hydraulic development of the EU-DEMO divertor was based on the “double-circuit” concept, in which two independent cooling circuits served by two different Primary Heat Transfer Systems were used to cool the Plasma-Facing Components (PFC) and the Cassette Body (CB). During the Divertor Final Design Review Meeting, held in May 2020, the possibility to adopt a single cooling circuit to serve both components was suggested. This new cooling circuit was originally conceived with the aim of simplifying remote maintenance, with potential benefits for some aspects of safety and balance of plant design and integration. During the years from 2020 to 2022, in the framework of the Work Package DIV 1 - “Divertor Cassette Design and Integration” of the EUROfusion action, University of Palermo and ENEA carried out a research campaign focussed on the preliminary thermofluid-dynamic assessment of this new concept, highlighting its strengths and weaknesses. The research campaign was carried out following a theoretical–computational approach based on the finite volume method and adopting the commercial computational fluid-dynamic code ANSYS-CFX. The steady-state thermal-hydraulic performances of the single-circuit DEMO divertor concept were assessed in terms of coolant pressure drop and flow velocity distribution, mainly in order to check coolant aptitude to provide a uniform and effective cooling to CB, shielding liner, reflector plates, PFCs and the newly introduced neutron shields to improve the shielding of the vacuum vessel. Moreover, the margin against critical heat flux distributions among the plasma-facing channels were assessed by adopting appropriate correlations, to check the compliance with the applicable constraints. Models, loads and boundary conditions assumed for the analyses are herewith reported and critically discussed, together with the main results obtained