Concrete for Radiation Shielding

The use of concrete, whether ordinary or special, remains a solution generally chosen when large-scale radiation protection is required, with or without a structural role. In fact, the applications of radiation protection concrete go far beyond nuclear reactors, since these materials are used in facilities as varied as reprocessing plants, storage sites, particle gas pedals, hospitals (radiation-based imaging and therapy), food ionization centers, etc.

Among the nuclear applications of concrete, radiation protection is one of the most important, after the construction of structures (reactor enclosures and other basic nuclear installations) and ahead of radioactivity containment (filling or containerization material for waste in storage centers).

Concrete's relevance to radiation protection stems from a unique set of properties that no other material can offer. Its composite nature allows for a wide range of compositional variations, depending on the performance required. With few exceptions, the basic constituents are readily available and moderately priced. Finally, there is generally a good compromise between mechanical and attenuation properties.

Since the 1980s, various conceptual and technological advances have been made in the field of civil engineering concretes. Many of these advances are now applicable to radiation protection concretes. These include :

• the emergence of the concept of sustainability, which focuses on maintaining performance over time, with the aim of extending the life of certain structures;

• new formulation methods, based on optimization of the granular skeleton and adjuvant technology, enabling the use of increasingly compact and durable concretes.

From the 2010s onwards, with a view to extending the operating life of nuclear power plants, major efforts are being made to understand the mechanisms of ageing under neutron irradiation beyond 40 years, and to derive useful feedback for the design of future reactor concretes.

In keeping with the latest developments, this article presents the basic principles required for the prescription of radiation protection concretes, as well as the typological and technological aspects associated with them. It devotes considerable space to their intrinsic properties, and discusses their behavior under specific irradiation and temperature conditions. For information on concrete manufacture and construction, please refer in particular to the section on Hydraulic Concrete in the "Construction" treatise.