SP34 Contains a presentation from the International Symposium "Concrete for Nuclear Reactors," held in Berlin in 1970 plus additional selected papers and discussions, and a 365-entry annotated bibliography on concrete for radiation shielding. Subjects include: what the designer needs to know; concrete strength under different states of stress; behavior under long-term thermal influences; effects of neutron irradiation; and future research and development.

Cracks in concrete, porosity, and lack of bond with fittings cause air leakage in concrete. The paper presents the results of tests to determine the leakage rate of a concrete reactor building without a leakproof lining. Cracked concrete proved unsuitable for meeting safety requirements of leakage.

A research program sponsered by EURATOM to develop a concrete made of readily available components capable of being used at high temperatures as structural material for nuclear reactor pressure vessels is presented.

Shrinkage and creep strains, thermal conductivity and also deformation behavior under load are more or less affected by the moisture content of a concrete structure. The following study of moisture migration under a sustained temperature gradient along the axis of 300 mm long and 80 mm diameter concrete cylinders was undertaken on 1968 by CITRA to obtain some information on the possible moisture movement in the 5.50 m thick cylindrical wall of BUGEY I P.C.R.v. (see P. Launay, annales de l'I.T.B.T.P., May 1970). The corresponding tests were prepared and performed by the Centre d'Etudes Scientifiques et Techniques (CEST) of Grenoble under the supervision of tehcnical department of CITRA, and completed in June 1969.

As concrete pressure vessels are intended to have a working life of 30 years or more it is of prime importance to know the effect of operating temperatures on the properties of concrete at all ages. . .The results so far obtained indicate that, in general, a decrease in strength and modulus of elasticity occurs on the first heating and for practical purposes subsequent heating to the same temperature does not cause further losses.