Salt Disposal of Heat-Generating Nuclear Waste

5 SUMMARY AND RECOMMENDATIONS
Deep geologic disposal of heat-generating nuclear waste (HLW) requires an
explicitly stated methodology to link the various completed, ongoing, and
proposed investigations to a meaningful examination of the suitability of a
specific geologic medium. This review document on HLW disposal in salt is one
of a series of SNL reports examining disposal of HLW in various geologic media.
Brady et al. (2009) looked at disposal in very deep boreholes. Hansen et al. (2010)
also looked at HLW disposal in clay or shale media.
The methodology for assessing repository viability includes clearly defining the
objectives, boundary conditions, and safety strategies. A top-down approach helps
define gaps in the technical basis that should be resolved if a salt HLW repository
program is pursued as an option for the U.S. This document summarizes the
information currently available to identify research activities needed to strengthen
the basis for salt disposal. Future regulations could impose other, key
requirements on characterization and research activities.
This report first documents that the U.S. has vast land areas with salt formations
of sufficient thickness and lateral extent to accommodate a nuclear waste
repository. Second, that international nuclear waste repository programs have
advanced the engineering and science sufficiently to impart confidence that such a
repository could be safely constructed, operated, and sealed. Third, that the
performance function of a salt repository would readily satisfy expected
regulatory criteria for the safety case. And fourth, that sophisticated multiphysics
analysis techniques are poised to investigate features, events, and processes that
determine salt repository performance.
5.1 Summary of Findings
Use of salt formations for nuclear waste disposal
has been a widely embraced concept for more
than 50 years. Salt is impermeable and deforms
plastically around the waste. There is no natural
water flow through a salt repository. Disposal of
nuclear waste in salt remains a viable concept in
the U.S., as has been successfully demonstrated
by more than ten years of successful operations at
the WIPP repository for TRU waste near
Carlsbad, New Mexico. The suitability of salt as
a medium for HLW has been recognized by
national and international repository programs,
which have developed advanced engineering,
scientific, and operational concepts. A high-level
review of this progress and of previous
investigations of salt media is provided in
Sections 1 and 2. From this publicly available
Key study findings
Thermal, hydrologic, and geochemical
considerations suggest that radionuclides
in a salt repository for HLW would not
migrate from the disposal horizon.
Current knowledge of thermal effects
supports a viable concept of repository
operations.
Three-dimensional multiphysics
capabilities offer advanced capabilities for
performance assessment modeling and
field test development.
The suitability of salt as a medium for
HLW disposal has been recognized by
national and international repository
programs.
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