Repository Modular Design Concepts

Modular design concepts are being considered for the license application during the surface facility design phase of the Monitored Geologic Repository (MGR). The viability assessment (VA) design is used as the reference design for the study. The primary objectives of the study are to spread construction of the WHB and the subsurface repository over time to reduce annual project costs, and to provide a cost-effective design for the surface facilities that supports waste emplacement starting in the year 2010. A waste receipt, waste handling, and emplacement rate throughput analysis is included by refer- ence to determine when facilities must be constructed just in time to meet throughput requirements. Ten different modular design and/or phased construction options are developed for the Waste Handling Building (WHB) and other supporting surface facilities. Alternative configurations studied include the reference design and other WHB configurations employing separate identical structures, separate nonidentical structures, and phased construction of single or multiple structures. Two final alternative design concepts are selected for detailed analysis and comparison to the VA design. A detailed study and comparison of the alternatives using specified evaluation criteria is made to select the preferred design concept. The study provides estimates of construction and operation cost including a total system life cycle cost analysis for each alternative. The results of the study indicate that modular building design provides improved flexibility for construction, operation, main- tenance, and better engineering and regulatory acceptance. However, these benefits come at a higher cost than that for an integrated building design. The modular design concept has a total life cycle cost $416 million higher than the VA reference design cost of $19,100 million (2.2 percent increase). Based on net present value of the total life cycle cost, the modular design concept has a cost $130 million higher than the VA reference design cost of $10,200 million (1.3 percent increase).