Design, mechanical analysis and manufacturing of the IFMIF LIPAc beam dump shielding

Abstract

The International Fusion Materials Irradiation Facility (IFMIF) aims to provide an accelerator-based, D-Li neutron source to produce high energy neutrons at enough intensity and irradiation volume for DEMO materials qualification. As part of the Broader Approach (BA) agreement between Japan and EURATOM, the goal of the IFMIF/EVEDA project is to work on the engineering design of IFMIF and to validate the main technological challenges which, among a wide diversity of hardware includes the LIPAc (Linear IFMIF Prototype Accelerator), a 125 mA continuous wave deuteron accelerator up to 9 MeV mainly designed and manufactured in Europe.

The beam is stopped in a copper cone involving a high production of neutron and gamma radiation and activation of its surface. A shield has been designed to attenuate both the radiation produced during accelerator operation and the residual radiation. This shield is made of an inner layer of polyethylene to moderate neutrons and an outer layer of iron to attenuate gammas produced by deuteron interactions with Cu but also those generated by neutrons in the polyethylene.

The present work summarizes the upgraded design of the shielding, as well as its upgraded mechanical analysis following the ASME Boiler and Pressure Vessel Code Division VIII Section 2. It also shows the manufacturing processes and requirements imposed on the shielding along with the acceptance tests performed and the lessons learned.