The roadmaps towards fusion power developed in different countries commonly foresee the construction of two fusion machines before the industrial prototypes: ITER and DEMO. It has also been recognized that materials development and validation under irradiation are not only of highest importance for the economic success but are on the critical path for early use of fusion power. As a consequence, IFMIF, or an equivalent neutron source, is also considered an indispensable element of international roadmaps to fusion power. A key issue that determines the relative schedule of the neutron source operation and DEMO is the availability of a comprehensive database for irradiated structural materials. The timely availability of validated data is essential for the final design, safety assessment and the basis for reliable operation and lifetime evaluation of DEMO components. Data generated are latest needed and expected within the same time frame as results from ITER operation.

In the last years the Fusion Roadmaps developed in EU is based on the objective of electricity production from fusion reactor around mid of the century, speeding up the design and construction phase of DEMO (foreseen to be started around 2040) and, at the same time, to reduce the neutron dose requirements on the materials. So, an initial DEMO phase is foreseen with a maximum dose around 20 dpa, for components integration testing, and a second DEMO phase with a maximum dose around 50 dpa [5].

In this way, the requirements for the early phase of the neutron source are significantly reduced and opens the possibility of a staged approach to IFMIF in which its construction can be developed in phases being the first one focused on DEMO needs, giving rise to the so-called DONES (DEMO Oriented Neutron Source) project. This staged approach will allow a wider distribution of the required investments along the time as well as some relaxed specifications for the neutron source design.

This approach has become the reference one EU and a specific activity was started in 2015 in order to develop the design of this facility up to a level to be ready for the start of its construction as early as 2020. A first step in this direction was the DONES Conceptual Design Report (ADD REF) issued in 2014. A second relevant step is the DONES Preliminary Engineering Design Report for a generic site.
The DONES PEDR aims to describe the design status of the Plant and all the integration activities required for a complete description of the facility. The degree of detail included in these descriptions is different for each system or study but the full package of documentation is able to provide an integral view of the Plant characteristics.

The DONES PEDR includes the following documents:

· Executive Summary

· DONES Plant Description Document (this report) aimed to describe the main technical characteristics of DONES at the Plant and system level.

· Design Description Documents for the 29 DONES Plant Systems.

· Annexes to the DONES PDD including additional info in the following topics:

Annex I. Design Requirements and Guidelines, including a compilation of the different design guidelines applied in the project.

Annex II. Product Breakdown Structure and Interface Management System.

Annex III. Preliminary Safety Analysis Report (not included in the present edition).  

Annex IV. RAMI

Annex V. Operation and maintenance, including the Plant Operations Handbook, Materials Flow analysis, Maintenance Plan and Remote Handling Handbook.

Annex VI: Integrated Modelling including the Monitoring overview, Beam Dynamics. Analysis and Vacuum Modelling.

Annex VII. 3D CAD Model

Annex VIII. Upgrade to IFMIF