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Estimating Surface Facility Throughput During the Preclosure Emplacement Period at Yucca Mountain

Leah Spradley, Mark Abkowitz, James H. Clarke

Nuclear Technology / Volume 169 / Number 2 / February 2010 / Pages 180-194

Technical Paper / Radioactive Waste Management and Disposal /

This paper focuses on how variations in commercial spent nuclear fuel shipment schedules have the potential to impact preclosure operations at the proposed repository for high-level waste at Yucca Mountain (YM) in Nevada. The analysis employs a simulation tool developed by the authors for modeling the packaging and thermal characteristics of the waste stream arriving at Yucca Mountain and is related to a study on the safety of the surface facilities that was also conducted by the authors using the simulation tool. The objective of the research is to gain a better understanding of how waste-stream variations affect surface facility throughput, defined as the rate at which packages are prepared for aging or emplacement in the surface facilities at YM. The basis for and adequacy of the preliminary surface facility throughput requirements are reviewed by evaluating throughput performance subject to various preclosure operating scenarios.

Results indicate that under most scenarios, the preliminary design adequately accommodates the mean demand over the operating lifetime for the canister receipt and closure facility (CRCF) and receipt facility (RF) but not the wet handling facility (WHF). While results indicate that WHF demand is likely to be higher than capacity in many scenarios, it seems reasonable that dual-purpose cask and truck deliveries could be deferred to maintain WHF operations at near-capacity levels.

Results also show a high potential for variability in annual throughput demand at the CRCF and RF that might result in system backups. In the event of bottlenecks, the facility with less demand can fulfill functional roles of one that is overburdened. The overlap of functional capability in facilities incorporates flexibility into the system. However, since throughput targets are named per facility, as opposed to functions of the system, the design goals of the system as a whole are obscured. An alternative design is proposed that is based on functional goals within the facilities, along with other recommendations.

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