Note: Descriptions are shown in the official language in which they were submitted.
il53365
SYSTEM FOR MIXING PUMPABLE RADIOACTIVE WASTES
The invention relates generally to an installation far mixing pumpable
radioactive wastes with a solidifier substance in a storage container. "Pump-
able" radioactive waste i9 herein also to be understood to mean waste whlch
has been rendered pumpable.
Installations of this type are already known and in DE-OS 27 20 342
published 9 November 1978 in the name Steag Kernenergie GmbH radioactive wastes
and a solidifler are introduced into a storage container in which the mixing
process is to take place; the container may already be mounted in a storage
container stand. At this point, or subsequently, the stand and the storage
container installed in it are swung through an angle of 90 , so that the con-
tainer axis and thus the axis of rotation of the container are parallel for
- the purpose of mixing the components contained thereinO This has proved satis-
factory and works well provided there is sufficient unfilled space inside the
storage container after the materials to be mixed have been introduced. The
known system suffers from the disadvantages that the mixture dispersion is not
always satisfactory, and the mixing time is unnecessarily long to achieve a
specific mixing effect.
An ob~ect of the invention is to improve upon known installations of
this type so that very intensive mixing can be achieved in reduced mixing time,
with concomitant reduction of unfilled space.
The apparatus here described includes a tilting motion arrangement in
the form of a swing or rocking drive which can be activated during rotation of
the storage container. In a preferred embodiment of the invention the swing
drive can move freely through an arc from O to a minlmum of 90 , O corres-
ponding to the position of the storage container stand with the axis of the
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lnstalled storage contalner vertlcal, and 90 to the posltion wlth the axis
horlzontal. In order to adapt the lnstallatlon of the wldest varlety of condl-
tlons and to
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various mlx components, ~he system Eor rotating the storage container has means
for varying the speed of rotation during operation and the swing drive system
includes means for adjusting the oscillation frequency of swlng and/or the
swing amplitude during operation. In general, the rotntlonal speed of the
storage container is high in relation to the swing frequency. ~djustment during
operation means that these settings or adjustments can be made when rotation
is taking place. Suitable systems for providing such ad~ustment are already
familiar in power train technology and require no detailed description here.
~ We have discovered that the mixing effect achieved in the mix
components during rotational motion of the container using the prior art systems
can be greatly improved if diagonally directed mixing forces can be superposed
on the single direction circumferential mixing forces. This is achieved in our
apparatus by the additional swinging or rocking motion. The mixing effect achieved
by the combination of rotational movement and swinging movement is so intensive
' that a very homogenous mixture results; in the solidified state this mixture
is almost completely free of undesirable pore voids. In addition, the unfilled
space in the container referred to above is reduced by this procedure.
A typical installation as described above permits a process for
solidifying pumpable radioactive wastes in a storage container, in which the
radioactive wastes and cement as a solidifier are measured into a storage
container and then mixed in the container. Typically the radioactive wastes
are drawn into the storage container by partial vacuum.
- Thus dry cement is introduced into the container, next a partial
vacuum is created in the storage container, the storage container is then
isolated from the vacuum system; next a quantity of radioactive wastes,
determined by the level of vacuum in the storage container, is drawn into the
storage container; and finally the storage container is tilted and caused to
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- rotate and rock, to mix the radioactive wastes and the cement.
More particularly in accordance with the invention there is provided
- apparatus for mixing pumpable radioactive wastes with a solidifier substance,
which comprises;
a storage container for receiving said wastes and said solidifier,
a retaining stand for said storage container,
means on ssid stand for rotating the storage container about a
fir~t axis,
means for imparting a tilting motion to the storage container
about an axis orthogonal to said first axis,
said tilting motion means being characterised by providing
repetitive swinging motion to said container about said orthogonal axis
during rotation of the storage container, and having a freedom of swing of~
0 to-et ~ 90 wherein 0 represents the position of the stand in
which the first axis is vertical, and 90 represents the position of the
stand in which the first axis is horizontal,
and said means on said stand for rotating the storage container
comprising driven roller means, the container being received by and supported
- against said roller means during tilting motion imparted by said tilting
;~ 20 motion means. The apparatus may include means for setting the speed of
;' rotation of the container during operation and the tilting motion means may
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include a control device for setting swing oscillation frequency and/or
;~ amplitude during operation.,`'.
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Specific embodiments of the invention wlll now be described having
reference to the accompanying drawings in which;
Figure 1 is a side view partly in section of a stora~e contalner and
stand with the rotation axis of the container arranged vertically;
Figure 2 is a vlew similar to that of Figure 1, with the container
axis horizontal; and
Figure 3 is a view similar to that of Figures 1 and 2 with the con-
tainer axis in an intermediate position.
The apparatus illustrated in the drawings is employed for mixing
radioactive material, which is pumpable or has been prepared so as to be pump-
able, with a solidlfier in a storage container 1. The substances may already
be present in the storage container 1 or they may be introduced into the con-
tainer 1 ~ust prlor to the subsequent steps of mixing. The container 1 is
received in a stand 2, and a system 3 is provided for rotating the container 1
about its axis 4, colinear wlth shaft 15, in the stand 2. A mechanism 5 imparts
a tilting motlon to the stand 2 about an axis 6 orthogonal to the container
axis 4.
A feed system for the radioactive wastes can be included at 13 and an
evacuating system for producing the partial vacuum in the storage container for
drawing in the radioactive wastes included at 14. It can be seen that the
installation is configured in such a way that the feed system for the radio-
; active wastes can also serve to evacuate the storage container and is provided
with at least one twist-type coupling which is axially connected to the con-
tainer shaft at the storage container. ~ixing paddles or devices can be
arranged or formed in the interior of the storage container.
The tilt motion drive mechanism comprises a motor and a drive train 9.
Rotation drive for the container 1 is applied by driven rollers, driven by means
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not show~ and upon whlch the storage contalner 1 rests when in any inclined
state as shown typically by Figures 2 and 3. The container 1 is also mounted
by supports 8, provided with suitable bearings at 12, for hollow filling shaEt
15. The container can thus be rotated about axis 4 upon ~ilting and resting
against rollers 7.
The tilting drive provides a rocking or swinging motion during
rotation of the storage container 1 by rollers 7. Comparison of Figure 1 with
Figure 2 reveals that--as indicated by the arrow 10--the tilting drive has a
freedom of swing from O tc at least 90 for the container axis 4, 0
corresponding to the position of the stand 2 with the axis of the container 1
vertical, and 90 to the position wi~h the axis 4 horizontal. Figure 3
indicates that within the range from O to at least 90 it is possible to select
a sub-range for tilting motion as indicated by the arrow 11 in between the
extremes of 0 and 90.
The system 3 includes means, not shown, for settin& the rate of
rotation of the container 1 at a chosen value, and the tilting drive 9 also
includes a control device for setting the swing oscillation frequency and/or
amplitude during operation.
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