A general rule for nuclear reactor biological shielding materials is that an ordinary concrete or high-density concrete using an aggregate such as magnnetite, limonite, etc., is the most reasonable for a thermal neutron reactor. . .This paper consists of two parts: first, an experiment on magnetite aggregate concrete and ordinary concrete at elevated temperatures from 20 C to 600 C is reported, and second an experiment on serpentine aggregate concrete and ophicalcite aggregate concrete subjected to different degrees of heating is reported.

A criticism of the present philosophy in concrete research is presented.

In this paper are presented results of geological prospecting and of testing physical and mechanical properties of serpentinite and ordinary concretes.

The efffects of the thermal conditions imposed on a prestressed concrete pressure vessel (PCRV) present a major uncertainty in predicting long-term vessel behavior. In current vessel deesigns insulating and cooling are provided to limit concrete temperatures to 200 F (93 C) or less; however, the time-dependent behavior of the structures may be significantly affected by this relatively low temperature.

Twenty-five different types of concrete, including mortar and grout, were used in the construction of shielding structures for the Hanford Nuclear Power Reactor. . .Data are presented which described physical properties of shielding aggregates and concrete used during shield concstruction.