Note: Descriptions are shown in the official language in which they were submitted.
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Specification
Device for introducing lubricant into a tubing
The invention concerns a device for introducing a lubricant into a
tubing, especially into a so-called ball tube of a ball measurement
system as part of the instrumentation of a nuclear reactor, such as is
known for example from the publications DE 1 953 605 Al or EP 2
453 443 Al.
Ball measurement systems are regularly used in nuclear facilities,
preferably in nuclear power plants with a pressurized water reactor. It
involves a device for measuring the power density distribution of the
radiation in the reactor core. In this method, balls of a radioactivatable
material, such as vanadium, are sent through the reactor core. The
balls have a characteristic diameter of less than one millimeter to a
few millimeters and are carried in tubes parallel to the nuclear fuel
rods. Thanks to the given positioning within the tubes, the balls are
activated by the emitted radiation within the reactor and allow
inferences as to the local power density distribution within the reactor
due to their known sequence within the tubes.
The radioactivated balls lie against one another in the manner of a
column of balls within the tubing, also known as ball tube or short
tube or tubes, and after a certain time spent in the reactor core they are
taken out onto a measurement table located outside the reactor's
pressure vessel (detection zone). This is accomplished by the
pneumatic post principle through a propellant or transport gas, usually
nitrogen, introduced into the tubing system. Since the tube diameter is
attuned to the ball diameter, the balls maintain their relative position
to one another and after leaving the reactor core they can be matched
up with exact coordinates inside the reactor core. The radiation given
off from the balls is read off by means of detectors on a measurement
table and thus provides definite information as to the radiation
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conditions inside the reactor core.
One drawback of the existing system is the complicated method of
providing the balls with a lubricant, so that they slide through the
tubes during the transport with the fewest possible problems and do
not get stuck. In existing systems, a worker at the measurement table
must open the tubes with the radiation-emitting content and wet the
balls or the inner walls of the tubes with sufficient lubricant.
The problem which the invention solves is to automate this process
by means of a suitable device and thus make possible a lubrication
without the need for a worker at the measurement table and without
the need to open the tubes. The lubrication should be done, in
particular, as needed during the power-producing operation of the
plant and meet the high safety standards for a nuclear power plant.
This problem is solved according to the invention by the features of
claim 1.
The device according to the invention for introducing a lubricant into
a tubing, or lubricant device or lubricating device for short,
accordingly comprises
= a feed line for a transport gas, connected to the tubing, to which is
switched a connection piece configured as a T-piece or cross
piece,
= a transverse line connected to the connection piece, enclosing a
lubricant piston able to move along its lengthwise dimension,
= a lubricant depot connected to the transverse
line, wherein the lubricant piston
= is sealed off against the transverse line at its outer circumference,
= has a recess to receive a portion of the lubricant,
= can be moved from a receiving position to a dispensing
position (and vice versa),
and wherein the recess
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= communicates with the lubricant depot in the receiving position, and
= is arranged inside the connection piece in the dispensing position
and the transport gas flowing to the tubing can flow across or onto
it.
The movable lubricant piston accordingly produces inside a closed
conduit system, sealed against the outside, a discontinuous portionwise
transport of lubricant from the lubricant depot to the feed line into the
tubing being wetted with lubricant. The process can be fully
automated with the aid of suitable driving and control means. Because
the transport gas flows across the recess in the lubricant piston that
receives the lubricant in dispensing position, along with the dispensing
there occurs a swirling or misting and thus an especially good
distribution of the lubricant in the downstream conduit components
being lubricated.
In preferred embodiment, the receiving position and the dispensing
position are each defined by a mechanical end stop for the lubricant
piston, so that a costly position measurement and regulation for the
adjustment of said positions is not necessary.
Advantageously, the lubricating device is configured so that the
transport gas flowing into the feed line upon exceeding a specific gas
pressure brings about a displacement of the lubricant piston from the
receiving position to the dispensing position. In other words, the
transport gas here performs a dual function: first, as a kind of
pneumatic drive unit, it moves the lubricant piston, acting as a
pneumatic cylinder, in the transverse line from the receiving position
to the dispensing position, and secondly in the dispensing position it
blows the lubricant portion previously transported there from the
lubricant piston into the tubing being lubricated. Accordingly, one can
say that the lubricant piston is driven by its own medium.
This functional principle is realized in a preferred embodiment in that
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a branch line branches off from the feed line upstream from the
connection piece, looking in the flow direction of the transport gas,
the other end of which emerges into the transverse line so that the
transport gas flowing into the branch line forces the lubricant piston
into the dispensing position. This automatically accomplishes a
transport of the lubricant piston into the dispensing position once the
transport gas flows into the feed line and from there to the branch line
and strikes the lubricant piston with enough pressure. Accordingly,
the system is not only driven, but also controlled by its own medium.
In general, the recess carrying the lubricant portion can be arranged at
the end of the lubricant piston and the connection piece can be
configured as a T-piece. But it is advantageous for the connection
piece to be configured as a cross piece, wherein the lubricant piston
passes entirely through the cross piece for the total displacement path
between receiving position and dispensing position, and accordingly
the recess is arranged more in a middle area of the lubricant piston.
This ensures in the receiving position and for practically the entire
displacement path to the dispensing position that the lubricant piston
relatively tightly closes the feed line leading to the tubing or at least
constitutes a substantial flow obstacle therein, this has the effect that
the lubricant piston is subjected to relatively high pressure via the
branch line and thus is moved reliably into the dispensing position.
The terms T-piece, cross piece and transverse line are to be
understood here in a broad sense and do not necessarily mean a
perpendicular arrangement of the transverse line in relation to the
feed line, but rather also include other angle relations. In the case of a
rigid lubricant piston, the transverse line must be straight inside the
displacement region. For the feed line, a straight course is not
absolutely required.
In general, the back transport of the lubricant piston from the
dispensing position to the receiving position after the lubricant
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dispensing has occurred could also be accomplished by the transport
gas. However, it has proven to be advantageous to have a return
spring present, which returns the lubricant piston to the receiving
position upon dropping below the specific gas pressure. Thus, the
entire movement is controlled by the transport gas itself in the most
easy conceivable manner. At sufficiently high pressure, the transport
gas sets the lubricant piston in motion in the direction of the
dispensing position; upon falling below the critical pressure value, it
is pulled back by the return spring to the starting position, i.e., the
receiving position, so that the recess is again filled with a portion of
lubricant.
The lubricant depot is preferably located somewhat higher
geodetically than the lubricant piston, so that the lubricant can pass
easily through a short connection piece or a connection line under the
action of gravity downward into the recess of the lubricant piston,
which receives it (by flowing, trickling, creeping, etc., depending on
its consistency), when the latter is found in the receiving position.
In one easily realized and expedient configuration, the lubricant piston
has a cylindrical base body, in which the recess is formed as a
circumferential annular groove. Thanks to an exact fitting of the
diameter of the lubricant piston and the transverse line receiving it
and/or by the use of suitable seal elements (0-rings etc. placed on the
circumference of the lubricant piston), laterally to the recess, it is
ensured that no lubricant can get into the transverse line when the
lubricant piston is located outside the receiving position.
In close coordination with the preferred purpose of use of the
lubricating device for the lubrication of the ball tubes of a ball
measurement system, the lubricant is a pulverized dry lubricant,
which preferably contains molybdenum disulfide as its principal
component. Such lubricants are available on the market, for example,
under the brand name "Molykote" of the Dow Corning Corporation.
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As the propellant or transport gas, inert-acting nitrogen is used, for
example. For other purposes, air (pressurized air) could also be used.
As already mentioned, the lubricating device serves preferably to
introduce a lubricant into the tubings of a ball measurement system,
also known as ball tubes and containing a number of radioactivatable
balls, as part of the core instrumentation of a nuclear reactor.
The lubrication of the ball columns can be done by a corresponding
number of valves in relation to the subsystem or in relation to the ball
tube, being mounted for example in a valve bank and connected to an
external pressurized gas source at the inlet side.
It is advantageous here to use the very same propellant or transport
gas which is being used to drive and control the lubricant piston and
swirl the dispensed lubricant portion as well for the transport of the
balls in the particular tubing (ball tube). However, a lubrication cannot
be done at the same time as the transport of the balls, since no
pressure difference occurs in this case between ball tube and feed line
of the lubricating device. Instead, whenever the balls are in their
designed waiting position, a portion of lubricant can be introduced
automatically as needed into the corresponding tubing by propellant
gas flowing into the feed line and be distributed therein. After the
stoppage of the gas supply, the lubricating device automatically
returns to the starting position and is automatically readied for the
next cycle of use by the filling of the lubricant portion into the recess
of the lubricant piston.
All these processes occur automatically by simple
mechanical/pneumatic interactions and require no electronic
regulation or the like, and except for the supply of gas or vapor under
pressure they need no other energy input. The control of the lubricant
piston by turning on and off the application of pressure can occur
during the power operation from outside the measurement table room,
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so that access of persons to the measurement table room is no longer
required and the exposure dose of personnel can be decisively
reduced.
Even though the device according to the invention has been described
here primarily with a view to the preferred use in a nuclear ball
measurement system, it can generally be used wherever a lubricant or
some other portionable liquid, gel-like or solid substance, especially
one consisting of powderlike or friable solid units or separate or
separable solid units, is supposed to be introduced under the
described boundary conditions with the help of a moving transport
fluid (gas, liquid, vapor or mixture thereof) into a tubing or some
other target volume, especially a volume closed off against the
surroundings. In place of a lubricant depot and a lubricant piston, one
would then speak in general of a substance depot and a transport
piston, and so on.
Further measures characterizing the invention more closely and
improving it shall be presented below, together with the description
of a sample embodiment of the invention, with the aid of the
schematic figures. There are shown:
FIG. 1 a segment of a pressurized water reactor with a ball
measurement system and with a corresponding lubricant
device,
FIG. 2 the structural layout of the lubricant device in detail, here
shown in a first operating state, and
FIG. 3 the lubricant device in a second operating state.
In FIG. 2, the lower part of the lubricant device has been left out,
being visible in FIG. 3, and in FIG. 3 the upper part of the lubricant
device has been left out, being visible in FIG. 2
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In FIG. 1 a segment of a nuclear reactor 1 is shown, here a pressurized
water reactor 2, with a reactor pressure vessel 4, coordinated with a ball
measurement system 6 with a detector arrangement 8. The ball
measurement system 6, shown only schematically, has a system of
closed tubings, also known as ball tubes 10, which are led through the
wall of the reactor pressure vessel 4 into it and past the fuel rods of the
reactor core 12. The ball tubes 10 contain columns of radioactivatable
balls, such as balls of vanadium. The actual measurement unit with the
detector arrangement 8 is located outside the reactor pressure vessel 4.
The balls wetted with a lubricant are delivered by a transport gas under
pressure by the principle of pneumatic post through the ball tubes 10
into the reactor pressure vessel 4 and back again to the detector
arrangement 8. After the balls have completed this circuit once, valid
information about the power density distribution inside the reactor core
12 can be obtained by the measurement at the detector arrangement 8.
In order to introduce the lubricant into the ball tubes 10, a lubricant
device 14 is provided, shown only schematically in FIG. 1, which is
coupled to the tubing system outside the reactor pressure vessel 4.
The lubricant device 14 is shown in detail in FIG. 2 and FIG. 3, and this
in two different operating states, which shall be described at length
hereafter.
The structural makeup of the lubricant device 14 is as follows:
The tubing 18 to be filled with lubricant 16 of the ball measurement
system 6 is connected by means of a T-piece 20 to a feed line 22 for a
pressurized transport gas 24. The transport gas 24 used here is nitrogen,
which is supplied from the outside by a gas bottle 26 and/or a
compressor, shown here only schematically. For the control of the gas
supply, a shutoff valve 28 is arranged in the feed line 22.
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The diameter of the connection bore in the T-piece 20 is so small that
the balls 30 located in the tubing 18 cannot pass through and thus cannot
cross laterally into the feed line 22.
Switched to the feed line 22 is a connection piece 31 in the form of a
cross piece 32, which is also connected to a transverse line 34. Arranged
in the transverse line 34 and able to move lengthwise is a lubricant
piston 36, while the two end stops 38, 40 establish the maximum
displacement path 42 of the lubricant piston 36. The end stops 38, 40 are
positioned such that the lubricant piston 36 passes entirely through the
cross piece 32 for the total displacement path 42. The lubricant piston
36 has a cylindrical base body 44, whose diameter is fitted exactly to the
diameter of the transverse line 34, so that on the one hand the desired
lengthwise movability is assured, and on the other hand a sealing of the
transverse line 34 is achieved. To intensify the sealing action, 0-rings
can be provided on the outer circumference of the lubricant piston 36,
not being otherwise shown in the figures. The two end faces 46, 48 of
the lubricant piston 36 are each provided to bear against the
corresponding end stops 38, 40 in the end position.
The lubricant piston 36 moreover has in its middle region a recess 50 in
the form of a circumferential annular groove 52, which communicates in
the right end position of the lubricant piston 36, as shown in FIG. 2,
with a lubricant depot 56, connected by means of a T-piece 54 to the
transverse line 34. The lubricant 16 stored up in the lubricant depot 56 is
a powderlike dry lubricant based advantageously on molybdenum
disulfide. The storage receptacle of the lubricant depot 56 is located
directly above the connection to the transverse line 34, so that in the
receiving position 58 realized by the right end position of the lubricant
piston there is an automatic filling of the annular groove 52 with a
corresponding portion of lubricant 16, which trickles down from above.
In the left end position, the annular groove 52 of the lubricant piston 36
is situated in the intersection region of feed line 22 and transverse line
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34 within the cross piece 32 and thus the transport gas 24 flowing into
the feed line 22 to the tubing 18 can flow through it when the shutoff
valve 28 is opened. In this process, the lubricant 16 previously
transported in the annular groove 52 is blown into the tubing 18 and
swirled (dispensing position 60).
Upstream from the cross piece 32 and downstream from the shutoff
valve 28, a branch line 64 branches off from the feed line 22 in a T-piece
62, emerging at the other end in a T-piece 66 in the otherwise closed
transverse line 34. The connection is situated to the right of the right end
face 48 of the lubricant piston 36, even when this is located in the right
end position, that is, the receiving position 58. In this way, the right end
face 48 of the lubricant piston 36 is exposed to pressure when transport
gas 24 flows into the feed line 22 with the shutoff valve 28 opened.
Furthermore, at the left end of the transverse line 34 is arranged a return
spring 68, configured as a compression spring, which acts on the left end
face 46 of the lubricant piston 36 as soon as it is swiveled from the
receiving position 58 to the dispensing position 60.
The spring force is dimensioned so that, when a specific gas pressure
intrinsic to the system is crossed in the branch line 64, the transport gas
24 forces the lubricant piston 36 from the receiving position 58 into the
dispensing position 60, while upon dropping below the specific gas
pressure in the branch line 64 the rightward directed restoring force
exerted by the return spring 68 is preponderant and forces the lubricant
piston 36 back into the receiving position 58 and holds it there.
It should be noted, on the one hand, that due to the sealing of the
lubricant piston 36 against the transverse line 34, the transport gas 24
cannot exert any pressure on the left end face 46 of the lubricant piston
46, and on the other hand the lubricant piston 36 passing through the
cross piece 32 closes the feed line 22 at this place, if not totally then
relatively tightly, even when a somewhat larger flow cross section is
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provided through the annular groove 52 located in the cross piece 32.
The movement sequences during the operation of the lubricant device
14 are now on the whole as follows:
The return spring 68 at first with the shutoff valve 28 closed fixes the
lubricant piston 36 in the receiving position 58, whereby the annular
groove 52 is filled with a portion of lubricant 16 from the lubricant
depot 56 (FIG. 2).
Next, by opening the shutoff valve 28, a specific gas pressure is
generated, which produces a leftward directed resultant force on the
lubricant piston 36, forcing it into the dispensing position 60. The
return spring 68 is accordingly compressed. Due to the prevailing
pressure difference, the transport gas 24 can flow through the
annular groove 52 and past it and thus delivers the lubricant portion
collected there into the downstream connected tubing 18. The
lubricant 16 is thus injected into the ball measurement system 6 for
lubrication of the ball columns (FIG. 3).
Once the pressure is shut off by closing the shutoff valve 28, the return
spring 68 moves the lubricant piston 36 back to the receiving position
58 again and the processes start all over.
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List of reference numbers
1 Nuclear reactor 60 Dispensing
position
2 Pressurized water reactor 62 T-piece
4 Reactor pressure vessel 64 Branch line
6 Ball measurement system 66 T-piece
8 Detector arrangement 68 Return spring
Ball tube 70 Flow direction
12 Reactor core
14 Lubricant device
16 Lubricant
18 Tubing
T-piece
22 Feed line
24 Transport gas
26 Gas bottle
28 Shutoff valve
Ball
31 Connection piece
32 Cross piece
34 Transverse line
36 Lubricant piston
38 Left end stop
Right end stop
42 Displacement path
44 Base body
46 Left end face
48 Right end face
Recess
52 Annular groove
54 T-piece
56 Lubricant depot
58 Receiving position
