License Application Design Selection Enhanced Design Alternative V: Very High Thermal Loading
The major goals of Enhanced Design Alternative (EDA) V are to keep the temperature of the cladding on the spent nuclear fuel (SNF) within the waste package below 350 C (Section 4.2.3), the temperature of the emplacement drift walls below 225 C (Section 4.2.3), and to keep the emplacement drifts dry for several thousand years. In addition, the design would produce relatively consistent heat output from waste package to waste package and ensure that waste package thermal outputs are spread more evenly across the repository. The design would also provide defense in depth (Section 5.3). The goals of this design would be achieved by the combination of design features described below. This EDA would have an areal mass loading (AML) of 150 metric tons of uranium equivalent (MTU) per acre (Section 4.1.16) as opposed to the 85 MTU/acre in the Viability Assessment (VA) reference design. To achieve this loading and the elements necessary to the EDA's overall goals, the design would require approximately 420 acres of emplacement area, within the lower repository block (Appendix A, Section A.2). A conceptual layout was developed for EDA V (Section 5.4.3). The layout, as shown in Figure 2, contains openings that are sized and arranged in a similar configuration as the VA reference design. A total of 54 emplacement drifts will be required for emplacement of the 70,000 MTU of spent nuclear fuel and high level waste packages. A total of four ventilation shafts, one intake and three exhausts are anticipated for the layout in order to provide sufficient air quantities to the emplacement drifts. Two exhaust mains will be located below the level of the emplacement drifts to provide exhaust from the emplacement drifts. In addition, the evaluation has confirmed that the decision to close the repository is possible 50 years after start of emplacement (Section 5.7.5). The licensing and preclosure period encompassed by the Mined Geologic Repository (MGR) extends from the year 2002 through 2066 (Section 6.2.2). This schedule is based on the VA reference design schedule with the monitoring period shortened such that the total preclosure period from the start of emplacement is 50 years. The spent nuclear fuel (SNF) would be blended to produce a targeted average and maximum thermal load. That is, the waste would be specifically sorted according to its type, heat output, and age and then put into packages with other similarly selected waste for the purpose of controlling the heat output of each waste package (WP). Blending would be done to create an average pressurized water reactor (PWR) heat output per waste package of 9.8 kW and a maximum of 11.8 kW. With blending, the heat output from the different waste packages is more consistent from package to package, thus resulting in a more nearly uniform linear heat-generation rate in the drift and from drift to drift for the repository as a whole. This will possibly reduce the waste package cladding temperatures for the hottest waste packages. The inclusion of waste blending in the EDA V conceptual design may increase the amount of surface waste handling and will also increase costs due to an addition of approximately 3,750 MTU of surface storage (Section 5.5).
- Research Organization:
- Yucca Mountain Project, Las Vegas, NV (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC08-91RW00134
- OSTI ID:
- 806858
- Report Number(s):
- B00000000-01717-2200-00224, Rev. 00; MOL.19990625.0231, DC No. 21798; TRN: US0402793
- Resource Relation:
- Other Information: PBD: 22 Jun 1999
- Country of Publication:
- United States
- Language:
- English
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