Management of Commercially Generated Radioactive Waste - U.S. ...

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appears not to significantly impact the cost of electrical power, a cost comparison should
not currently be assigned significant weight in this analysis. It should be noted that the
cost estimates for all concepts essentially assume that no currently unanticipated questions
will arise, which is probably an unlikely assumption.
6.2.4.7 Potential for Corrective or Mitigating Action
Prior to closure and sealing of access tunnels and shafts, mined repositories (includ-
ing those utilized in the island disposal concept) would allow failure detection and permit
retrieval of waste canisters. This system allows flexibility to future generations as to
how long they might choose to leave the facilities open to inspection. Following closure,
failure detection would be more difficult, although remote instrumentation could be
installed for this purpose. Corrective action would be difficult (though possible) as the
location of the waste would be known and access tunnels could be reopened. Detection of
repository failure exemplified by unexpected concentrations of radionuclides could allow the
mitigating actions of restriction of access to contaminated aquifers and other measures
including evacuation of affected areas.
Complete corrective action capability for the island mined repository concept would
require development of systems for locating and retrieving casks lost at sea in the case of
the sinking of a transfer ship. A similar system would be required for the subseabed con-
cept. Transponder devices would be fitted to the casks while enroute, and location and
retrieval of an individual cask from the seafloor is considered feasible using existing
equipment. However, loss of a ship with waste within the hull would severely complicate
retrieval operations. Retrieval of emplaced canisters is considered to be feasible using
existing overcoring technology, although retrieval of a large number of canisters would
likely be very expensive.
Full corrective action capability for space disposal would require a deep-ocean payload
retrieval system if system failure released radionuclides to the atmosphere. No corrective
action would be possible. If failure of the space disposal system were to occur after
achieving orbit, backup launch and orbit transfer vehicles, and some means for correction
of improper orbit would be required. Each of these is under consideration as part of the
space disposal concept, and if successfully developed (along with appropriate monitoring
systems), would provide corrective action capability for most situations.
Corrective action with the very deep hole concept is thought possible only while the
package is attached to the emplacement cable.
In summary, mined repositories appear to offer the greatest potential for corrective
action. Subseabed appears also to provide reasonable potential for corrective action with
the principal problem being retrieval of waste from a transport ship lost at sea. Island
mined repositories present the combined difficulties and assets of the subseabed and mined
repository concepts. Full corrective action potential appears to be achievable with space
disposal for all situations except failure of the waste packaging system during launch or
pre-orbital operations. Corrective action is thought not to be possible with the very deer