International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source Research Articles

Global Flux Calculation for IFMIF-DONES Test Cell Using Advanced Variance Reduction Technique

Global neutron flux and dose maps for the test cell (TC) of the IFMIF-DONES (International Fusion Materials Irradiation Facility–DEMO Oriented NEutron Source) have been calculated applying the advanced variance reduction tool ADVANTG. The neutronics model of the TC has been updated to the current IFMIF-DONES design of the target assembly, the high flux test module, and the lithium quench tank as well as the TC surrounding rooms. A weight-window (WW) mesh has been produced using ADVANTG with the well-configured setups for IFMIF-DONES conditions. This WW mesh has been adjusted to achieve reasonably good statistics for the global flux mesh tally. It is concluded that the thickness of the beam upstream and lateral wall can be reduced by 0.5 m without strongly affecting the shielding performance. The neutron streaming through the gaps of the shielding plugs to the access cell above the TC requires local shielding to allow frequent access during operation.

The IFMIF-DONES project: preliminary engineering design

The need of a neutron source for the qualification of materials to be used in future fusion power reactors has been recognized in the European Union (EU) fusion programme for many years. The construction and exploitation of this facility is presently considered to be critical to the construction of the DEMOnstration Power Plant (DEMO). This issue has prompted the EU to launch activities for the design and engineering of the International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source (IFMIF-DONES) facility based on and taking profit of the results obtained in the Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) project, presently conducted in the framework of the EU–Japan Bilateral Agreement on the Broader Approach to Fusion.These activities and research and development work for the IFMIF-DONES plant are presently taking place in the framework of a work package of the EUROfusion Consortium, in direct collaboration with the Fusion for Energy organization. The main objective of these activities is to consolidate the design and underlying technology basis in order to be ready for the start of the IFMIF-DONES construction as early as possible.In this paper, an overview and the present status of the IFMIF-DONES engineering design is presented for a generic site, making emphasis on the recent design evolution from previous phases.

Planned material irradiation capabilities of IFMIF-DONES

IFMIF-DONES (International Fusion Materials Irradiation Facility - DEMO-oriented Neutron Source) is currently being developed in the frame of the EUROfusion Early Neutron Source work package (WPENS), based on the results achieved in the ongoing IFMIF/EVEDA (Engineering Validation and Engineering Design Activities) project by Japan and Europe in the frame of the Braoder Approach (BA) agreement. The neutron source's limited product of “irradiation volume × neutron fluence” on one hand and the large potential test matrix (defined by number of material grades, test types, irradiation- and test temperature levels and damage dose levels) on the other hand, require a careful selection of test conditions by collaborative effort of the communities of DEMO designers, fusion materials science and the irradiation facility designers. This paper describes achievable irradiation conditions in the High Flux Test Module (HFTM) of IFMIF-DONES, characterized by levels and gradients of irradiation temperatures and nuclear responses (dpa, H and He production). The HFTM development focuses on 9%-Cr Reduced Activation Ferritic Martensitic steel irradiations, but also the possibilities of tungsten and copper alloy irradiations are explored. Possible specimen arrangements and issues of the Small Specimens Test Technique are also discussed.

IFMIF-DONES HFTM neutronics modeling and nuclear response analyses

IFMIF-DONES (International Fusion Materials Irradiation Facility- DEMO Oriented NEutron Source) is a neutron irradiation facility aiming at providing material irradiation data for the construction of DEMOnstration fusion power plants. This work presents nuclear analyses and associated neutronics modeling conducted on an updated design of the High Flux Test Module (HFTM) of IFMIF-DONES. Neutron fluxes, damage dose rates and gradients, gas production and nuclear heating have been calculated for the standard profile in 20 × 5 cm2 and a reduced size in 10 × 5 cm2 of the deuteron beam with 40 MeV energy and 125 mA current. The results indicate that the reduced beam can provide higher damage dose rates fulfilling the DONES requirement. On the other hand, the reduced beam size results in less irradiation uniformity, higher gas production to damage dose ratios, as well as stronger peak nuclear heating.

Neutronics assessment of different quench tank location options in IFMIF-DONES

The quench tank (QT) location in the test cell is an open issue for IFMIF-DONES (International Fusion Material Irradiation Facility- DEMO Oriented NEutron Source) design. Neutronics assessments have been carried out on two QT location options. A parametric study of the neutron streaming in the lithium chute shows a quasi-linear dependence of the neutron flux on the void thickness. For both options, activation calculations at key locations of the QT system indicate that the contact dose rate is higher than the hands-on dose limit over the whole maintenance period. In addition, the shutdown dose rates in the lithium facility room after 1-day shutdown exceed the hands-on dose limit in different levels. Therefore, remote handling is required for the maintenances of the QT in both considered locations.

The test cell configuration under IFMIF-DONES condition

The test cell (TC) in IFMIF-DONES (International Fusion Material Irradiation Facility – Demo Oriented NEutron Source) is the meeting area of the three major systems (test systems, lithium systems, and accelerator systems) to host the irradiation test module, lithium target assembly and the end section of the accelerator line. Although the design of the TC, to a large extent, inherits that of the reference IFMIF-EVEDA (Engineering Validation and Engineering Design Activities) TC, design justifications are required to solve the existing major open issues such as cavitation of the lithium flow, activation and maintainability of key components, and etc. In this paper, these major open issues of the reference TC layout are addressed and a TC reconfiguration proposal, featuring arranging the lithium quench tank inside the TC, is introduced. The two concepts are investigated, analyzed, and compared on the aspects of lithium flow stability, tritium generation rate, key component maintenance scenarios, irradiation shielding, and in-TC components arrangement.