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

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3-11
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conventional or suspended on roof mounted tracks; manually operated or .c.12 p. K.5, Appendix K
remote controlled. Rooms could be in the traditional orthogonal pattern
3-12
The design of the repository used in the GEIS is a single level room and
as presented or they could take on different configurations. The alternative
repository layout possibilities in granite are not addressed in TM-36. In
general, the preconceptual repository design procedure is not clear, and
lacks a logical, consistent argument. Little attempt is made to evaluate
pillar mine for all media and waste types. Thermal criteria are then used
to set capacities for each medium and fuel cycle. Optimization of the
design for a given waste type in a particular medium would likely result
in different capacity estimates.
the design either in part or in total, in terms of the risks associated
with nuclear waste storage, particularly the long-term containment aspects.
Therefore, it is difficult to judge the adequacy of proposed design measures
Ssafety featres
and safety featuressalt
3.c.13 P. K.8
Figure K.6 shows a smaller temperature increase after emplacement of waste
for a repository in shale (Figure K.6, page K.8) than for a repository in
(Figure K.2). The opposite should be true because the temperature
increase should be inversely proportional to the thermal conductivity and
.c i icult to coent on the resource requirements presented in Table shale has a lower thermal conductivity than salt as shown in Tables 7.2.6
It is difficult to comment on the resource requirements presen
3.1.11 without having access to their back-up. It is, however, strange and 7.2.3, respectively.
that construction steel, lumber and concrete costs per MTHM for granite
are greater than those for salt. Granite is structurally far superior to
salt, has no creep characteristics and relatively lower risk of being
Inundated by water from an overlying aquifer. Retrievability in granite
u d b aebasalt
3.c.14 p. K.19, Appendix K
It is stated that 25-year retrievability requires lower thermal.densities.
For salt and shale the decrease is a factor of 2 while for granite and
it is 2.5. Hence costs increase by the same factor. The reason
should be easier. given is the need to maintain room and pillar stability for 25 years. Why
Support requirements in salt, in order to maintain access to the storage
rooms during the retrievable period is expected to be considerably greater
is the effect greater for granite and basalt?
than In granite and basalt. The problem in salt is compounded by a high 3.c.15 p. 7.1.2 and 7.2.18, DOE/ET-0028
level of uncertainty regarding the behavior of the salt rock mass when
"...there were no immediate detrimental effects on the stability of salt
Sas a result of exposure to heat or radiation"
subjected to thermal and mechanical loading.
It.appears that the resource requirements are biased in favor of salt due
to poor design of repositories in other media. The differences between
the unit resource figures for salt and those for granite and basalt are
"The physical behavior of salt is drastically affected by temperature.
... for a rise in temperature from 20°C to 100°C the strain increased by a
factor of seven."
not adequately justified. The GEIS should discuss whether retrievability in salt can be guaranteed
under the expected thermal loadings. It should also discuss whether the
The statement that "granite unit costs are less than those fr shale" s ntegrity of seals in the salt repository can be maintained following
inconThe statemnt wth the datanite unit costs are le 3.1.28 on those 3.1134.
closure.
inconsistent with the data presented in Table 3.1.28 on page 3.1.134.
Closure.