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29
of the dome, may be near “equilibrium” since it is close to ti
extension of the near subsurface beachrock
(Byron Ristvet, let
the committee, November 1981).
The coamittee believes that the probability of dome brea
to storm wave and typhoon activity is quite low.
However, to
tate early detection of typiocn-tnduced effects it recommends
visual inspection of the dome structure, the surrounding mole,
beach on the lagoon side be performed at regular intervals (as
minimum, after each major typhoon).
Some settling with time in response to loading is concei
Furthermore, vegetation such as tree limbs included within the
can be expected to undergo bacteriological reduction, result
Slight amounts of settlement within the dome.
access to the contained
dome cap in response to
vided by the key-wall.
slightly in response to
cap functions simply as
Such settlement,} how-
material.
Resistance against movement Bf the
settlement of the contents of the dome
Although the key-wall may spread outwar
stresses produced by settlement, the
a series of cover slabs, not a true com
tial settlement or settle without any impairment of the dome's
formance.
that the tremie and the soil-cement operations were not fully
cessful.
Within the tremie region there are zones of oversized[debris
and unconsolidated tremie material that provide channels for wa
movement.
The rapid tidal response in the boreholes indicates
water in the structure is closely coupled to the island's gro
Therefore, at least part of the radioactivity contained in the
ture is available for transport to the groundwater and, subsequ
to the lagoon, and it is important to determine whether this pa
may be a significant one.
It is not clear whether Cactus Crater (and its vicinity) is
greater or lesser source of transuranic movement to the lagoon
was before the cleanup.
Before Cactus Crater was filled it was
the gources cf transuranics being remobilized to the waters of
lagoon.
Noshkin estimates that about 0.4 percent of the dissoiv
plutonium present in the lagoon originated from the material at
bottom of the crater (V.E. Noshkin, personal communication to 2.
Morse, October 23, 1981).
Several conditions, however, were cha
by the cleanup operations:
the fresh water run-off to the water
was changed by the construction of the dome; the cleanup of soil
island has reduced movement of transurznics to the groundwater;
filling of the crater has modified the amount of transuranics be
transported from the crater.
It is possible to demonstrate that leaching from the dome
create a significant new hazard by use of simple inventory arg
without having to speculate aL.out possible remobilization proces
taking place within the structure.
It was indicated in sectior
tha* there is about 1.5 Ci of plutonium continuously in solution
lag
> and that 3.0 Ci are lost to th
ocean annually.
The amou
: