Note: Descriptions are shown in the official language in which they were submitted.
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SIN1 E001 WOCAlu103s29/Dr.LIu1/02.09.2003
Method and device for the decontamination of a surface
Description
The invention relates to a method for a decontamination of a surface, in which
the
surface is treated with a treatment tool, the treatment tool being guided by a
robot
over said surface, as well as a device for conducting this method.
When shutting down or dismantling nuclear installations, a final
decontamination
of these installations has got to be performed after the dismounting of its
devices
and equipment. In particular in older installations, contaminations not only
exist
on the surface of floors, walls, and ceilings, but also in deeper layers of
these
floors, walls, and ceilings, as e. g. contamination protection layers have not
been
fully operational or cracks therein have occured. For this reason, it is
presently
required to remove material layers in order to remove contaminations. Up to
now,
this has been done with various methods, each of them having a large demand of
personel and, in addition, are characterized by bad working conditions (noise,
de-
bris, aspiration protection). Additionally, the irregular surface structures
being the
result of a manual removement of the material layers create technical problems
regarding the clearance measurement of the contamination of the rooms, which
is
required in order to prove that the contamination is below legally fixed
values so
that these rooms or parts of buildings no longer fall under the provisions of
the re-
spective nuclear regulations.
A further disadvantage of known methods is that substantially independent of
the
degree of contamination of partial surface areas of the whole surface the same
amount of material has to be removed even if this wouldn't be necessary in
partial
surface areas where the contamination is below given limit values.
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Proceeding in this way does not only have the disadvantage that the known me-
thods are very time consuming, but also that a huge amount of waste is
created.
This is particularity disadvantageous in the case of surfaces having
radioactive
decontamination, as the disposal of radioactively decontaminated material is
ex-
tremely expensive.
The German patent application laid open DE-A1 195 21 236 discloses a method
for the cleaning of barriers like walls and/or ceilings and/or floors
especially of
closed areas as rooms, in particular laboratories, in which a contamination
has
occured mainly by airborn contaminants. For cleaning the surface of a barrier
the
known method provides that the material of the whole surface is removed comple-
teiy or almost completely, without any regard to the decontamination level of
cer-
tain partial areas of the surface in order to provide a new surface. A feature
con-
sidered of special importance by the known method is that, prior to the
removing
of the material of the old surface, recesses in the old surface such as cracks
and
holes, are pre-treated and then filled with filling material such that the
resulting
surface is planar or at least substantially planar. This pre-treatment is
preferrably
done by boring, cheiseling-out or scraping-out. After the pre-treatment has
been
completed and a intact surface has been created in this way, material from
this
intact surface is removed over the entire area of the surface in an amount of
approximately 1 to 3 mm in depth. fn order to minimize the depth of the layer
to
be removed and thus the amount of work, the known method provides that orien-
tated surface contamination measurements are performed in order to determine
the depth of the layer of the existing surface which has to be removed. By
procee-
ding in this way the known method tries to achieve that only as much surtace
ma-
terial is removed as is required in order to render the new surface reliably
decontamination-free.
The known method has also the disadvantage that material from the entire sur-
face area is removed regardless of the contamination level of partial surtace
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areas. The known method too creates a high amount of waste, resulting in high
disposal costs.
It is therefore the object of the present invention to provide a method and a
de-
vice for the decontamination of surfaces, in particular of surfaces being
radioacti-
vely contaminated, in which the amount of waste to be disposed is reduced and
which is capable of being performed automatically.
This object is achieved in that a measuring device is successively moved over
a
measuring field correlated with the surface to be decontaminated, such that in
a
first measuring sequence the measuring device is positioned over a first measu-
ring region of the measuring field, that a measuring value measured by the mea-
surfing device representing the contamination value of this first measuring
region
is stored together with the coordinates of the first measurement region in a
con-
trot unit, that in a subsequent series of n-1 measuring sequences the
measuring
device is positioned over each of further n-1 measuring regions, that the
corre-
sponding measuring values are stored along with the coordinates of the
respecti-
ve measuring regions in the control unit, that in a subsequent step each of
the n
measuring values obtained in this way is evaluated by the control unit for
whether
it is below a given threshold value, and that the treatment tool is moved by
the ro-
bot to that, or those, areas of the surface to be treated correlated to that,
or those,
of the measuring regions having a measuring value being above the threshold
value.
The invention creates a method having the advantage that a time saving de-
contamination of surfaces can be achieved, since the measurements according to
the invention allow in an advantageous manner to selectively choose the
partial
areas of the surface to be decontaminated.
Furthermore, the invention provides a device for the decontamination of a
surtace
having a robot on the arm of which a treatmtent tool can be mounted and a
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measuring device can be arranged and moved by the robot arm over the surtace
to be decontaminated, that the measuring device is positioned by the robot in
a
first measuring sequence over a first measuring region of the measuring field,
that the robot has a control unit in which a measuring value meassured by the
measuring device representing the contamination value of this first measuring
re-
gion can be stored along with the coordinates of the first measuring region,
that in
the control unit of the device further n-1 measuring values of n-1 measuring
regi-
ons can be stored along with the coordinates of the corresponding measuring re-
gions, that the control unit evaluates each of the n measuring values for
whether
a measuring value is below a certain threshold value, and that the treatment
tool
can be moved by the robot to the that, or those, of the surtace areas of the
sur-
face to be treated correlated to that, or those, of the measuring regions
having a
measuring value being above the threshold value.
The device according to the invention has got the advantage that it allows in
a
simple manner a selective treatment of that areas of the surface to be
decontami-
nated having a decontamination above the threshold value.
Further advantageous embodiments of the invention are the subject matter of
the
depending claims.
Further details and advantages of the invention are disclosed in the
description
and the drawing of a specific embodiment. !t shows:
Figure 1 an exemplary embodiment of a device for conducting the method.
Figure 1 shows a device, generally designated with 1, for the decontamination
of
a surface F by means of a surface treatment, in particular of a surtace
removal.
This surface F is in particular the surface of a room, e. g. a wall surface or
a cei-
ling surface. The device 1 has a robot 2, which is known per se and is hence
not
described in detail any more. The robot 2 has a robot arm 3, the front end of
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which bears a treatment tool 4. The treatment tool 4 is in the case described
here
a knocking tool and has several pressure operated knocking elements being pro-
vided in such a way in a housing having several compartments so that each knok-
king element is in operational connection with its compartment. The treatment
tool
4 further has an air pressure compartment, an air pressure expansion compart-
ment, a suction compartment and a collection compartment. The pressurized air
being required for the operation of the treatment tool 4 is provided by a
pressuri-
zed air generation device 5 and is led to the treatment tool 4 via a
corresponding
line 6. In order to prevent a contamination of the surrounding areas, the
device 1
provides that the compartments, in which the knocking elements of the
treatment
tool operate, are air-tight sealed from the enviroment and that the removed
par-
ticles are led away by the suction device 7.
ft must be noted that it is also possible to employ instead of a knocking tool
a
grinding tool or a milling tool. The method described below is not limited to
a cer-
tain kind of tool or a certain tool type. The described method as well as the
device
1 therefore allow in an advantageous way to adapt the treatment tool 4 born by
the robot 2 to the specific surface treatment process required in a specific
case.
In the following it is assumed that the surtace F to be treated is
radioactively de-
contaminated and has got to be decontaminated by means of a surface removal
of one or several material layers. It does not require any further explanation
far
the person skilled in the art that the case of a radioactive contamination
descri-
bed below is only one single exemplary embodiment, as the method described al-
so can be employed in an advantageous way for the treatment of other kinds of
contaminations of the surface F.
The method described know provides that in a first step a removal of a first
mate-
rial layer is performed by the treatment tool 4. In order to guide the
treatment tool
4 by the robot 2 over the surtace F automatically, it is provided that in this
first
step of the method the surface F to be treated is defined for the device 1.
This is
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preferably achieved in that the robot 2 moves the treatment tool 4 to a first
corner
point F1. In the case described here this first corner point F1 is the first
out of four
corner points F1-F4 defining the surface F being rectangular in this case. The
coordinates of this corner point F1 are stored in a control unit (not shown)
of the
device 1. Then the robot 2 moves the treatment tool 4 to a second corner point
F2
of the surface F and the coordinates of the corner point F2 are stored in the
con-
trol unit of the device 1. in a corresponding way the treatment tool 4 is
moved by
the robot 2 to the third corner point F3 and to the fourth corner point F4 and
the
coordinates of the corresponding positions are stored in the control unit of
the de-
vice 1. It need not to be noted that the case described here, which is the one
of a
rectangular surface F, is not compulsory. The surface F to be treated can of
cour-
se have a random shape F', so that in this case the definition of the shape F'
is
done by storing coordinates of an appropriate number of corner points F1-F4 in
the control unit of the device 1. It also can be provided that the teaching-
process
described afore is performed by a separate teaching-tool.
After the shape F' of the surface F to be treated has been defined as
described
above, the treatment tool 4 is moved by the robot 2 successively over the
surface
F and the first material layer is removed and transported away by the suction
de-
vice 7.
In a second step following the first step a measurement of the contamination
valu-
es of the surface F to be treated is performed. For this purpose a measuring
de-
vice known per se is employed, which can be moved by the robot 2 over the sur-
face F to be treated. This measuring device can be a part of the treatment
tool 4.
It is also possible, that the robot 2 performs a tool change, in such a way
that it
puts the treatment tool 4 after the treatment step of the first method step in
an sui-
table tool box (not shown) and picks up from this tool box the measuring
device.
Since the measuring device has generally a different configuration as the
treat-
ment tool 4, the method described provides - if required - that the measuring
field
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being correlated with the surface F, which is to be scanned by the measuring
de-
vice, is defined once again: The measuring device is moved by the robot arm 3
of
the robot 2 to the corner points F 1-F4 of the surtace F and the shape F' of
the
measuring field is defined in this way. It is also possible that, due to known
geo-
metrical correlation between the treatment tool 4 and the measuring device,
this
teaching step can be omitted.
For the measuring of the remaining contamination of the surface F to be
treated it
is provided that the robot 2 moves the measuring device to a first measuring
regi-
on of the surface F to be measured, i. e. to the measurement field being
defined
by the corner points F1-F4 of the surtace F and the shape F', and a first
contami-
nation measurement is performed according to a pre-defined measuring rule. The
first measuring value of this first measurement region is then stored in the
control
unit of the device 1 along with the coordinates of the first measuring region,
which
can preferably be derived in a simple way by evaluating the position of the
mea-
surfing device.
Then the robot 2 moves the measuring device to a second measuring region. It
is
preferred that the second measuring region is immediately adjacent to the
first
measuring region. A second measuring value is measured and stored along with
the coordinates of the second measurement region in the control unit of the de-
vice 1.
After the measuring of the second measurement region the measuring device is
moved by the robot 2 to a third measuring region. It is once more preferred
that
the third measuring region is adjacent to the second measurement region. A
third
measuring value representing the contamination value of the third measuring re-
gion is then stored in the control unit of the device along with the
coordinates of
the third measuring region. This process is continued until in a series of n-3
consecutive measuring sequences the entire measuring field consisting of n mea-
suring regions has been covered.
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It is prefered that the surface F and hance the measuring field is scanned by
an
appropriate movement of the robot arm 3 in a coloumn-like way. It is also
possible
to scan the surface F line-like. Furthermore, the robot 2 allows to scan the
sur-
face F in a random way.
The description above assumes that the single measuring regions are immediate-
ly adjacent. But it is also possible that the individual measuring regions are
di-
stant from each other, or are overlapping. The use of the robot 2 for the move-
ment of the measuring device over the surface F has the advantage that the
gathering of the measuring values can be done in various ways, each way espe-
cially adapted to the specific circumstances being then present.
After the completion of this method step, in the control unit a number of n
measu-
ring values along with the coordinates of the measuring regions correlated to
the
measuring values are stored. A measuring value matrix is achieved in this way,
representing the distribution of the contamination values over the measuring
field.
This allows in advantageous way the spatial correlation of each individual
measu-
rement value with a certain area of the surface F.
In a consecutive method step each measuring value is evaluated for whether it
is
below a threshold level. If each measuring value is below this threshold
level, a
further decontamination treatment is not required and the measuring values
gathered can be used for documenting that the surtace F only has contamination
values being below the ones prescribed by law.
If one or several measuring values are above the pre-set threshold, it is now
pos-
sible, due to the spatial assignment of the individual measuring values to
well-de-
fined measuring regions, and hence to well-defined areas of the surface F, to
se-
lectively treat the respective partical areas of the surface F in that the
robot 2
puts the measuring device back in a tool box and picks up the treatment tool 4
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_g_
from the tool box, to move the treatment tool 4 to the one or the ones of the
areas
of the surface F to be treated which are correlated with the measurement
regions
having a to high measuring value, and to perform a further surface treatment
of
these areas of the surface F. After all surface areas of the surtace F having
a to
high measuring value have been treated correspondingly, the robot 2 puts the
treatment tool 4 back in the tool box, takes once more the measuring device
and
performs a further measurement of all or - what is preferred - only of the
selecti-
vely treated partial areas of the surtace F. The measurment values gathered in
this way are once more stored in the control unit and are once more compared
with the pre-set threshold value. If now these measuring values are below this
pre-set level, the decontamination process is completed and the surtace F is
cle-
aned. If at least one measurement value is above the threshold value, a
further
post-treatment is pertormed in the way described above.
As already mentioned at the beginning, the method described is not only well-
sui-
ted for the decontamination of surfaces, in particular of the ones of a room,
being
radioactively contaminated, by the removal of material layers from the
surface.
Beyond that, the method also can be employed in an advantageous way for other
decontaminations than radioactive ones, so that the term "decontamination" em-
ployed here must be understood in its broadest sense. The method furthermore
is
suited for the decontamination of mercury or heavy metal containing surfaces.
For the sake of completeness it must be noted that it is preferred that the
measu-
ring value matrix is visualized by a display means of the device 1. In order
to
achieve a simple visualization of the measuring value distribution it can be
provi-
ded that the measuring values beyond the threshold are displayed in a first co-
lour, e. g. in red, and that the measurement values below this pre-set level
are
displayed in a second colour, e. g. in green. Proceeding in this Way has got
the
advantage that in a very simple manner a rapid perception of the distribution
of
the measuring values of the surtace F to be decontaminated can be achieved. it
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goes without saying that the measuring value matrix cannot only be displayed,
but also can be printed or stored or can be outputted, preferrably in a
digital way.
It must be noted that the first method step being described in the above-men-
boned embodiment, i. e. the first material removal, is not compulsory. !t is
also
possible that the measurements are performed as described before a first
surtace
treatment of the surface F is performed.
