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The Environment Today
Published in Anco S. Blazev, Power Generation and the Environment, 2021
Reprocessing of spent nuclear fuels also, and very importantly so, reduces the volume of high-level waste. This, however, does not by itself reduce the final radioactivity or heat generation, so a geological waste repository is still needed. So, the challenges of waste repository site location and cost apply here too.
Radioactive Waste
Published in William H. Hallenbeck, Radiation Protection, 2020
High-level waste (HLW) refers to spent fuel assemblies generated by commercial power reactors and liquid reprocessing waste (fission products and transuranics) generated at civilian and defense nuclear fuel reprocessing facilities. There are 108 operating civilian power reactors in the U.S. (see Table 8.1). Spent fuel assemblies are being stored at 70 of these facilities.
High-Level Waste Management
Published in James H. Saling, Audeen W. Fentiman, Radioactive Waste Management, 2018
James H. Saling, Audeen W. Fentiman
High-level waste (HLW), by definition, includes liquid wastes from the first-cycle solvent extraction of fuel reprocessing and solids into which such liquid wastes have been converted. Also included are concentrated liquid wastes from subsequent extraction cycles. When the spent nuclear fuel (SNF) is not processed, as discussed in Chapter 3, it is also considered as HLW. Because of the high radioactivity of such waste, its management has become a matter of great public concern.
Using the swelling rate calculated from the swelling index test to evaluate the influence of concrete alkali concentration and temperature on bentonite swelling properties
Published in Journal of the Chinese Institute of Engineers, 2023
Wei-Chien Wang, Jia-Chen Xue, Chung-Hao Wu, Kao-Hao Chang
For high-level waste (HLW), the most recognized global disposal method is to build an enclosed geologic disposal system underground for deep geologic repositories (Pusch and Svemar 2004). International disposal facilities mostly utilize engineered barrier systems (EBS), including artificial and natural barrier structures (Haaramo and Lehtonen 2009). In the conceptual design of HLW disposal facilities, cementitious material is extensively used for repairing cracks, building concrete passageways, fixing the rock’s fracture of the main tunnel and disposal tunnel, and plugging concrete (SKB 2006). Parts of the structures built of cementitious material contact the bentonite as a buffer material. Portland cement continuously generates Na+ and K+ during its hydration, and a large amount of Ca(OH)2 forms in the cement hydration product. Therefore, as highly alkaline substances such as Na+, K+, Ca2+, and OH− exist in the pore solution of normal concrete, this pore solution shows high alkalinity, with pH values generally larger than 12 (Alonso et al. 2010).