**1. Introduction**

Aluminum alloys have a higher tolerance to radiation effects than most other metals when irradiated at ambient temperatures due to its low melting point (*Tm*). This is because, at room

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temperature, the homologous temperature of Al alloys is around 0.32*Tm*, when compared to, forinstance,~0.175*Tm* foraustenitic steel,~0.17*Tm* forferritic steel,and~0.14*Tm* for*α*-Zr.Inmetals, it is known that noticeable thermal diffusion of vacancies occurs at homologous temperatures above0.3*Tm*.Thisthermallyinducedmovementofvacanciesatroomtemperature(RT)promotes mutual recombination of vacancies and interstitials, resulting in a lower density of point defect clusters, which are seeds for the damage microstructure.

In particular, 5*xxx* and 6*xxx* series Al alloys exhibit a good combination of mechanical, thermal, corrosion resistance, and irradiation swelling resistance properties in a research reactor environment, which make these alloys a suitable choice for in-core structures and reactor vessel components of research reactors. The reactor vessel of the high flux reactor (HFR) in Petten has been fabricated from the aluminum alloy ASTM B209 [1], specification Al 5154–O with a restriction on Mg content to a maximum of 3.5 wt.%.

The components of these reactors can experience a large amount of neutron fluences, up to several 1027 n/m2 , during their operational life. For the HFR hotspot,a a maximum thermal fluence of ~20 × 1026 n/m2 is expected by the end of 2025.b Substantial damage to the material's microstructure and mechanical properties can occur at these high fluence conditions. To this end, a dedicated SURveillance Program (SURP) is executed to understand, predict, and measure the influence of neutron radiation damage on the mechanical properties of the vessel material. As a part of SURP, a literature survey on irradiated Al alloys that are relevant for HFR vessel material is conducted to obtain fundamental understanding on expected mechan‐ ical property changes in relation with microstructural damage mechanisms, which forms the goal of this work.

This article is organized as follows. First, a brief review of various irradiation-induced damage mechanisms in Al alloys is presented. Next, the tensile data collected from the literature is analyzed to understand the contributions of various irradiation-induced damage mechanisms to the changes in the mechanical properties of these materials up to high irradiation fluences. Finally, the fracture toughness data from HFR SURP is compared with that of the literature, and the underlying damage mechanisms influencing fracture toughness properties are discussed to explain the suitability of literature data for the prediction of HFR SURP data beyond the current surveillance data.
