Geochemical optimisation of a disposal system for high-level radioactive waste

McKinley, Ian G.; Neall, F. B.; Kawamura, Hideki; Umeki, Hiroyuki

doi:10.1016/j.gexplo.2005.09.012

Cited by 12 publications

(6 citation statements)

References 7 publications

(5 reference statements)

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“…Considerable cost savings are possible using a simple design with common materials and prefabrication. Development of the concept continues to the present (McKinley et al 2006). The concept is applicable to waste disposal in various media in the U.S. including crystalline rock.…”

Section: Engineered Barrier Systemmentioning

confidence: 96%

Forecasting stability of well bore zones holding radioactive waste containers

Morozov¹,

Kagan²

2015

gzh

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This report evaluates the feasibility of disposing U.S. high-level radioactive waste in granite several hundred meters below the surface of the earth. The U.S. has many granite formations with positive attributes for permanent disposal. Similar crystalline formations have been extensively studied by international programs, two of which, in Sweden and Finland, are the host rocks of submitted or imminent repository license applications. This report is enabled by the advanced work of the international community to establish functional and operational requirements for disposal of a range of waste forms in granite media. In this report we develop scoping performance analyses, based on the applicable features, events, and processes (FEPs) identified by international investigators, to support generic conclusions regarding post-closure safety.Unlike the safety analyses for disposal in salt, shale/clay, or deep boreholes, the safety analysis for a mined granite repository depends largely on waste package preservation. In crystalline rock, waste packages are preserved by the high mechanical stability of the excavations, the diffusive barrier of the buffer, and favorable chemical conditions. The buffer is preserved by low groundwater fluxes, favorable chemical conditions, backfill, and the rigid confines of the host rock. An added advantage of a mined granite repository is that waste packages would be fairly easy to retrieve, should retrievability be an important objective.The results of the safety analyses performed in this study are consistent with the results of comprehensive safety assessments performed for sites in Sweden, Finland, and Canada. They indicate that a granite repository would satisfy established safety criteria and suggest that a small number of FEPs would largely control the release and transport of radionuclides. In the event the U.S. decides to pursue a potential repository in granite, a detailed evaluation of these FEPs would be needed to inform site selection and safety assessment.

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Section: Engineered Barrier Systemmentioning

confidence: 96%

Forecasting stability of well bore zones holding radioactive waste containers

Morozov¹,

Kagan²

2015

gzh

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“…Specific dimensions of the features discussed here are given in Table 4-1, and in the thermal analysis (Section 5.1). Construction may be expedited by use of prefabricated assemblies consisting of a single waste package and the surrounding clay buffer in compacted dry form, held together by a steel envelope (McKinley et al 2006). …”

Section: 51mentioning

confidence: 99%

Generic repository design concepts and thermal analysis (FY11).

Howard

Dupont

Blink

et al. 2011

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(U)Reference concepts for geologic disposal of used nuclear fuel and high-level radioactive waste in the U.S. are developed, including geologic settings and engineered barriers. Repository thermal analysis is demonstrated for a range of waste types from projected future, advanced nuclear fuel cycles. The results show significant differences among geologic media considered (clay/shale, crystalline rock, salt), and also that waste package size and waste loading must be limited to meet targeted maximum temperature values. TABLES Executive SummaryIn this study, the UFD R&D Campaign has developed a set of reference geologic disposal concepts for a range of waste types that could potentially be generated in advanced nuclear FCs. A disposal concept consists of three components: waste inventory, geologic setting, and concept of operations. Mature repository concepts have been developed in other countries for disposal of spent LWR fuel and HLW from reprocessing UNF, and these serve as starting points for developing this set. Additional design details and EBS concepts will be considered as the reference disposal concepts evolve.The waste inventory considered in this study includes: 1) direct disposal of SNF from the LWR fleet, including Gen III+ advanced LWRs being developed through the Nuclear Power 2010 Program, operating in a once-through cycle; 2) waste generated from reprocessing of LWR UOX UNF to recover U and Pu, and subsequent direct disposal of used Pu-MOX fuel (also used in LWRs) in a modified-open cycle; and 3) waste generated by continuous recycling of metal fuel from fast reactors operating in a TRU burner configuration, with additional TRU material input supplied from reprocessing of LWR UOX fuel.The geologic setting provides the natural barriers, and establishes the boundary conditions for performance of engineered barriers. The composition and physical properties of the host medium dictate design and construction approaches, and determine hydrologic and thermal responses of the disposal system. Clay/shale, salt, and crystalline rock media are selected as the basis for reference mined geologic disposal concepts in this study, consistent with advanced international repository programs, and previous investigations in the U.S. The U.S. pursued deep geologic disposal programs in crystalline rock, shale, salt, and volcanic rock in the years leading up to the Nuclear Waste Policy Act, or NWPA (Rechard et al. 2011). The 1987 NWPA amendment act focused the U.S. program on unsaturated, volcanic rock at the Yucca Mountain site, culminating in the 2008 license application. Additional work on unsaturated, crystalline rock settings (e.g., volcanic tuff) is not required to support this generic study. Reference disposal concepts are selected for the media listed above and for deep borehole disposal, drawing from recent work in the U.S. and internationally. The main features of the repository concepts are discussed in Section 4.5 and summarized in Table ES-1. Temperature histories at the waste packag...

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“…In this context the actinides uranium, neptunium, plutonium, americium and curium play an important role mainly due to their high radiotoxicity. The behavior, especially the migration, of these metals in a potential host rock formation after their release from the waste container into the aquifer has to be known to assess possible host formations such as clay, salt and granite for their suitability as host rock and to provide the necessary information needed for the required safety case . The migration of toxic heavy metals such as actinides through the geological barrier of a nuclear waste disposal to the biosphere can be affected by a wide variety of chemical reactions, some of them involving natural organic matter (NOM) .…”

Section: Introductionmentioning

confidence: 99%

Europium (III) and Uranium (VI) complexation by natural organic matter (NOM): Effect of source

2016

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For the safe long-term storage of high-level radioactive waste (HLW), detailed information about geo-chemical behavior of radioactive and toxic metal ions under environmental conditions is important. Natural organic matter (NOM) can play a crucial role in the immobilization or mobilization of these metal ions due to its complexation and colloid formation tendency. In this study, the complexation of europium (as chemical homologue of trivalent actinides such as americium) and uranium (as main component of HLW) by ten humic acids (HA) from different sources and Suwannee NOM river extract has been analyzed. Capillary electrophoresis in combination with inductively coupled plasma mass spectrometry has been used for the evaluation of complex stability constants log β. In order to determine the complex stability constants a conservative single site model was used in this study. In dependence of their source and thus of NOM structure the log β values for the analyzed humic acids are in the range of 6.1-7.0 for Eu(III) and 5.2-6.4 for U(VI) (UO ), respectively. In contrast to the results for HA the used Suwannee river NOM reveals log β values in the range of nearly two orders of magnitude lower (4.6 for Eu and 4.5 for UO ) under the geochemical conditions applied in this study.

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Geochemical optimisation of a disposal system for high-level radioactive waste

Cited by 12 publications

References 7 publications

Forecasting stability of well bore zones holding radioactive waste containers

Forecasting stability of well bore zones holding radioactive waste containers

Generic repository design concepts and thermal analysis (FY11).

Europium (III) and Uranium (VI) complexation by natural organic matter (NOM): Effect of source

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