EPRI rethinks rebar standards in nuclear plant construction

The Electric Power Research Institute (EPRI) is examining the strength of rebar as the group designs concrete codes and specifications for new nuclear plant construction.

The use of higher-strength rebar in the design and construction of safety-related concrete structures and containment structures has been examined as an option to reduce costs and improve concrete quality for new nuclear power plants.

The EPRI said enlarging the space between steel rebar rods would greatly reduce the quantity of rebar required and avoid the formation of honeycombs and voids, and that replacing standard hooks with higher-strength headed rebar anchors would diminish wall congestion, and simplify and allow for the pre-assembly of rebar form fabrication.

As it stands now, the modern nuclear industry's reinforced concrete design standards call for 60 ksi rebar for both hooked and headed rebar, as well as bars with yield strengths up to 120 ksi.

EPRI research is advancing its understanding of the variation in hook and head strength as a function of bar size, concrete strength, group configuration, geometry, and transverse reinforcement. Testing emphasis will be placed on bar stresses of 60, 80 and 100 ksi. In addition, a limited number of bars will be tested at stresses as high as 120 ksi.