(i) The use of steel reinforcement must be minimized in concrete structures that form the essential components of the disposal units. Steel reinforcement may be utilized to control shrinkage and thermal stresses to minimize cracking of concrete during the construction and operation periods, but must not be relied upon for long-term stability following facility closure.

(ii) The load-bearing capacity for any structural component must be at least 1.5 times the maximum design load assuming the concrete cover to the reinforcement and the reinforcement itself are not effective.

(iii) In minimizing the reinforcing steel required, the concrete members of the components essential to the stability of the disposal units must be designed to place as much of the structure as possible in compression throughout the design life of the disposal units while meeting the other design requirements and providing reasonable assurance that the performance objectives will be met. The design must be accomplished without the use of pre-stressing mechanisms such as rods or wires.

(iv) The use of alternative, corrosion-resistant reinforcing materials that can meet the design requirements may be proposed in the permit application.

(i) Construction materials used in all structures and components of the disposal units must be of adequate composition, quality and quantity to provide reasonable assurance that the structures and components will function as designed and that the performance objectives will be met. The materials must be tested and shown to meet the standards of quality and durability as specified in the plans and specifications approved in the permit, to be compatible with all other components of the disposal unit, and to provide reasonable assurance of long-term performance. All materials must be monitored for radioactive contamination prior to use. An operating portal monitoring system approved by the department will be sufficient to satisfy this requirement.

(ii) Where no codes or standards exist, or the recognized codes and standards do not adequately address the properties required, the applicant must submit documentation in the application describing the rationale of choice, test methods and data, and/or the in-service history that substantiates the selection and the use of the material for the intended application.

(iii) All synthetic and manufactured materials must be installed in accordance with the engineering plans and specifications approved in the permit and, unless otherwise authorized by the department, in accordance with the manufacturer's recommendations.

(i) Concrete material types and proportioning, concrete placement, and curing must be specified to achieve the required design strength, minimize shrinkage and heat of hydration, and maximize density, impermeability, durability, and resistance to chemical attack. Admixtures and constituent materials the sole purpose of which is construction convenience and which may have a possible long-term detrimental effect on the concrete must not be used.

(ii) The materials used in the concrete, including admixtures and the concrete constituents, must be tested and approved as compatible, nonreactive, and acceptable for the application. The testing methods must be identified in the application.

(iii) Concrete constituents must be selected to avoid possible reactivity between the cement alkalis and the aggregate and any potential reactivity of the materials with the disposed waste.

(i) Structural steel and miscellaneous metals utilized in the construction of the disposal units must be protected against corrosion. The use of corrosion-resistant metals must be evaluated and may be used if approved by the department.

(ii) Reinforcing steel and other metals embedded in concrete must be protected against corrosion. The design of concrete disposal units must compensate for protective methods that affect concrete bonding.