WO2012168054A2 - Radiation-shielded container - Google Patents

Abstract

The invention relates to a radiation-shielded container, comprising an inner chamber for receiving at least one radioactive source (7), which inner chamber is surrounded on the outside by a material absorbing radioactive radiation, and at least one channel (25, 33, 49), which connects the inner chamber with an opening (27, 31, 53) of the radiation-shielded container and is closable by a rod-shaped element (23, 35, 51). Such a container makes it possible to achieve an all-round, high-quality shielding of the source (7) contained therein in that the rod-shaped element (23, 35, 51) has an external geometric shape that is helically wound about the longitudinal axis thereof at least over the majority of the overall length thereof and the channel (25, 33, 49) comprises an inner space identical thereto in shape, into which the rod-shaped element (23, 35, 51) can be introduced by rotation about the longitudinal axis thereof.

Description

 Source holder

The invention relates to a radiation protection container, with a lined externally with a radioactive material absorbing material

Interior for receiving a radioactive radiator, and at least one of the interior space with an opening of the radiation protection container connecting by a rod-shaped element closable channel.

Radiation protection containers are used in particular for receiving radioactive radiators from radiometric measuring devices. The latter are used in industrial metrology, for example for measuring a filling level of a filling material in a container, for monitoring an exceeding or falling below a predetermined level of a filling material in a container, or for measuring a density of a medium.

The basic principle of the radioactive measuring technique is based on the fact that one or more radioactive radiators, such. COO or CS137 preparations are positioned at a measuring location such that the radiation emitted by them is a region to be measured, e.g. penetrates a part of a container filled with a filling material, and a radiation intensity exiting on a side opposite to the radiators with a corresponding detector, e.g. a scintillation detector. The emitted radiation intensity depends on the geometric radiation

Arrangement and absorption. The latter is in the level measurement depends on the filling level of the filling material located in the beam path and in the density measurement of the density of the filling material located in the beam path. Consequently, the emerging radiation intensity is a measure of the current level or the current density of the contents in the container. For radiation protection reasons, the radioactive radiators used in radiometric measuring instruments are introduced during their transport to the measuring location and in a variety of measuring instruments and applications during the measurement in a radiation protection container, which serves to the To shield the radiator to the outside in such a way that as far as possible no radiation that is not required for measurement penetrates to the outside. To insist

Radiation protection containers regularly made of metal, e.g. out of each other

welded steel moldings, and are internally coated with a radioactive material, e.g. Lead, poured out.

Radiation protection containers inevitably have at least one often but also two or even more openings. It is regularly provided an opening through which the radioactive

 Spotlight introduced into the radiation protection container, and if necessary can be removed again. For this purpose, usually today - as shown in Figures 1 and 2 - rod-shaped specimen holder 1 is used, which opens into a opening into the opening 3 in the interior of the

Radiation container leading tubular channel 5 can be used. This specimen holder 1 have at the end a recess for receiving the radiator 7. To achieve a high-quality shield, the specimen holder 1 is inserted as accurately as possible into the channel 5. However, owing to manufacturing tolerances, a gap 9 extending substantially straight-line over the entire length of specimen holder 1 and channel 5 in the direction of opening 3 remains between specimen holder 1 and channel 5, through which radiation can escape. This is indicated in Figures 1 and 2 by arrows P1. There are specimen holder 1, to which - as shown in Fig. 2 - on whose the

Recess for receiving the radiator 7 opposite end a short threaded piece is formed, which is screwed into a corresponding internal thread in the opening 3. The resulting screw G essentially serves the mechanical attachment of the specimen holder 1 and causes due to their small length only an incomplete

Shielding of the gap 9 to the outside. Accordingly, the reduced

Although screw connection G exits the radiation emerging on the path indicated by the arrow P1, it does not completely prevent it. In addition, many radiation protection containers have a further opening in the form of an output 1 1, which can normally be closed by a closure device, via which outlet 1 1 is open for measuring operation

Closing device radioactive radiation of the positioned in the radiation protection container radiator 7 is emitted via a radiator 7 to the output 1 1 leading radiation channel 13 in the direction of the metrologically detected area.

An unwanted escape of radiation from this output 1 1, e.g.

during transport, is avoided today, for example, in the manner shown in Fig. 1, by the radiator 7 eccentric in the

Specimen holder 1 is arranged so that it by rotation of the

Specimen holder 1 either directly above the specimen holder 1 arranged to the output 1 1 leading radiation channel 13, or via a laterally adjacent to the beam channel 13 shield 15 can be positioned. Again, there is the problem that due to

Manufacturing tolerances and the requirement of the rotation of the specimen holder

I between the specimen holder 1 and the shield 15 in the

Radiation channel 13 remains leading gap on which radiation can escape to a limited extent on the path indicated in Fig. 1 by the arrow P2.

In addition, closure devices are known in which the output

I I can be closed by externally in front of the output 1 1 sliding mechanical shutter. Although theoretically, shutters can be made sufficiently large and massive so that good shielding can be achieved through them. In the implementation, however, it is difficult to obtain these relatively large and heavy components mechanically movable. This is further complicated by the fact that radiometric

Measuring instruments are usually used in extremely harsh environmental conditions that make the use of alternative measurement methods impossible. There they are often very high or strongly changing temperatures and / or Pressed and / or exposed to strong chemical and / or mechanical stress, which consequently also exposed to the movable shutter.

Another alternative known from the prior art forms the closure device shown in FIG. Fig. 2 shows side by side two

Sectional drawings of a corresponding radiation protection container in cutting planes rotated by 90 ° relative to one another. In this

Strahlenschutzbehalter is a the leading from the interior to the output 1 1 beam channel perpendicular durchkreuzender außenseit on

Strahlenschutzbehalter provided in an opening 17 opening another channel 19, in which a rotatably mounted rod-shaped closure element 21 is inserted. The latter has a perpendicular to its longitudinal axis through the closure element 21 through bore B leading. The

Closure element 21 is opened by being brought by rotation into a position in which the jet channel leads via the bore B to the outlet 1 1, and closed, in which it is rotated to the position shown here, in which the rod-shaped closure element 21 the Radiation channel closes. Again, there is a straight gap 25 between the closure member 21 and the other channel 19 in which it is used, can escape through the radiation to a lesser extent due to manufacturing tolerances and the requirement of rotation of the closure element 21.

In addition, radiation protection containers are known from the prior art, in the interior of which a single or a plurality of mutually parallel outwardly shielded guide tubes are provided for receiving a corresponding number of preparation rods. Preparation rods are rod-shaped elements, in each of which, preferably in the middle, a radioactive radiator is used. They are used, for example, in applications in which the emitters are lowered in the measurement mode at predetermined heights into a dip tube located under the radiation protection container in a container. Again, the preparation rods are made

Radiation protection during transport and preferably during longer lasting measurement breaks in the radiation protection container brought in. In radiation protection container emanating from the emitters radiation is the outside by the surrounding the guide tubes

shielded absorbent material. In the longitudinal direction of the specimen rods, the shielding takes place by the segment of the specimen rod itself upstream of the radiator in the respective longitudinal direction. Here, too, there is regularly a straight gap extending between the guide tube and the segments of the guide sleeve displaceably mounted therein in the axial direction

Rods over which radiation can escape. It is an object of the invention to provide a radiation protection container for receiving at least one radioactive emitter, with which an all-round highest possible shielding of the radiators therein is achievable.

For this purpose, the invention consists in a radiation protection container, with

- an externally absorbed by a radioactive radiation

 Material surrounded interior to accommodate at least one

 radioactive emitter, and

 - At least one of the interior with an opening of the

 Radiation container connecting by a rod-shaped element closable channel in which

 - The rod-shaped element over at least a major part of its entire length has a helically rotated along its longitudinal axis outer geometry, and

 - The channel has a form this same interior, in which the rod-shaped element can be introduced by rotation about its longitudinal axis.

According to one embodiment of the invention, the channels are surrounded on the outside by a radiaktiv radiation absorbing material. According to a first variant of the invention, at least one of

rod-shaped elements a specimen holder having a recess for receiving the radioactive radiator end. Furthermore, the invention comprises a second variant in which

 - The interior for receiving the radioactive radiator on a

 Radiation channel is connected to an outlet of the radiation protection container,

- A channel crossing this channel is provided, and

 - The rotatable in this deployable rod-shaped element

 Protective container closure is,

 - Having a perpendicular to the longitudinal axis through the element leading through the beam channel,

- Can be brought by rotation in an open position in which the

 Radiation channel the interior of the radiation protection container with the

 Output of the radiation protection container connects, and

- Which can be brought by rotation in a closed position in which the rod-shaped element leading from the interior to the output

 Radiation channel closes.

According to a preferred embodiment of the first or the second variant, the rod-shaped element is a threaded spindle, esp. A threaded spindle with a round thread, a triangular thread or a trapezoidal thread.

Furthermore, the invention comprises a third variant in which

 - At least one channel arranged in the radiation protection container

 is outside of the absorbent material surrounded guide tube, and

- The insertable into the guide tubes rod-shaped elements

 Preparation rods are, in each of which one of the radioactive emitters can be used at a predetermined height along its longitudinal axis.

According to one embodiment of the third variant are in the

Radiation protection container two or more guide tubes arranged parallel to each other, in each of which one can be used equipped with a radioactive preparation rod. According to a further embodiment of the third variant

 - The guide tubes on one side of the radiation protection container opening openings, and

 a conveyor is provided,

- about which preparation rods, in particular for transportation of

 Radiation protection container, can be introduced into the guide tubes in the radiation protection container by rotation about its longitudinal axis, and

- About the preparation rods by rotation about their longitudinal axis from the radiation protection container out and to a location located under the openings of the guide tubes site, esp. A arranged in a container dip tube, are transportable.

According to a development of the third variant, the preparation rods are along their longitudinal direction about their longitudinal axis turned rods, esp. Rods with rectangular, square, oval, triangular or star-shaped cross-section.

The invention has the advantage that the unavoidable gaps between the channels and the rod-shaped elements closing them do not run in a straight line due to the shaping according to the invention but are also helical. There is no straight line from

Interior through the gap to the opening leading connection to the outside more. However, radioactive radiation can spread only in a straight line. Radiation penetrating from the interior into the gap is thus inevitably scattered several times within the gap and at each scattering on the material of the rod-shaped element or on the channel enclosing

strongly weakening absorbent material. As a result, a drastic reduction of the exiting radiation power is effected. The invention and further advantages will now be explained in more detail with reference to Figures 3 and 4 of the drawing, in which two embodiments are shown; like parts are provided in the figures with the same reference numerals. Fig. 1 shows: a conventional radiation protection container with a

 rotatably mounted specimen holder;

Fig. 2 shows: two sectional drawings of a conventional

 Radiation protection container with a rotatably mounted

Closure element;

Fig. 3 shows: two sectional drawings of an inventive

 Radiation protection container with a specimen holder and a rotatably mounted radiation protection container closure; and

Fig. 4 shows: a radiation protection container according to the invention with

 in preparation parallel to each other guide tubes insertable preparation rods.

The invention relates to a radiation protection container, esp. For a

radiometric measuring device, with an externally surrounded by a radioactive material absorbing material for receiving at least one radioactive radiator having at least one closable by a rod-shaped element, connecting the interior with an opening of the radiation protection container channel.

According to the invention, the rod-shaped element over at least a majority of its entire length, preferably even over its entire length away, a helically rotated along its longitudinal axis outer geometry, and the channel has an inner space for this purpose in which the rod-shaped element by rotation to whose longitudinal axis can be introduced. The latter is equivalent to the fact that a width of a gap between channel and element along the longitudinal axis of the channel is less than that by the helical shape of the channel

Element-related difference between maximum and minimum distance of the lateral surface of the element to its longitudinal axis. Again, as in the prior art, a coaxial to the longitudinal axes of element and channel extending the element

enclosing gap. In contrast to the prior art, however, this gap is not rectilinear, but has in the direction of the longitudinal axis of one of the helical outer shape of the rod-shaped element and the

 Channel interior next spiral geometry. There is thus no straight through this gap leading connection between the interior and the opening. Since radioactive radiation generally propagates only in a straight line, the radiation along the gap can propagate only through multiple scattering at the winding partition walls. However, any scattering causes a significant attenuation of the radiation. In contrast to rectilinear columns in which penetrating radiation in the axial direction can spread practically unhindered, the invention causes

Shaping that the radiation absorbing material surrounding the channel and the radiation absorbing material of the rod-shaped

Elements unfolds its shielding effect over the entire length of the gap with each scattering.

In contrast to the aforementioned screw G for mechanical attachment of rod-shaped elements, the only one

 Form gap gap short length, a shielding effect is achieved here over the entire existing winding length of the gap.

The invention is in connection with a variety of different

Embodiments of communicating with the interior via channels

can be used in standing openings. Some variants for this purpose are described with reference to the embodiments listed below.

Fig. 3 shows two sectional drawings in mutually rotated by 90 ° cutting planes of a first embodiment of a radiation protection container according to the invention, in which two variants of the invention are used. Exactly as in the radiation protection container known from the prior art shown in Fig. 2, also shown here

Radiation protection container according to the invention an interior space for receiving a radioactive emitter 7, which via one of a first

rod-shaped element 23 closed first channel 25 with a first

Opening 27 of the radiation protection container is connected. The first rod-shaped element 23 is also here a specimen holder which has a recess for receiving the radioactive radiator 7 at the end. According to the invention, the rod-shaped element 23 has a helically rotated outer geometry along its longitudinal axis, and the channel 25 has a thereto

identical interior space, in which the specimen holder is introduced by rotation about its longitudinal axis such that the radiator 7 in the

Interior of the radiation protection container is located.

The rod-shaped element 23 is for this purpose at least over a large part of the entire length of time, preferably - as shown here- over its entire length, preferably designed as a threaded spindle. This can be a threaded spindle with a round thread as in the present embodiment. Alternatively, however, other thread forms, such as e.g. Triangular thread or trapezoidal thread, are used.

In the radiation protection container, a radiation channel leading to one of the first openings 27 opposite output 29 of the radiation protection container is connected to the channel 25, via which radiation emanating from the radiator can be emitted in the direction of an area to be detected.

To open and close this beam channel is perpendicular to the longitudinal axis of the first channel 25 in the radiation protection container, the

Radiation channel intersecting in an outside opening 31 of the

Radiation container opening second channel 33 provided in which a second rod-shaped element 35 is arranged. The second rod-shaped element 35 also has a length along at least a large part of its entire length, preferably over its entire length whose longitudinal axis is helically rotated outer geometry, and is screwed into the same inner space of the second channel 33.

The second rod-shaped element 35 forms a rotatable

Protective container closure, and has a perpendicular to its

 Longitudinal axis through the element 35 passing through the beam channel 37. The second rod-shaped element 35 can accordingly be brought into an open position by rotation, in which the beam channel 37 connects the interior of the radiation protection container to the outlet 29 of the radiation protection container. In this position, radiation emitted by the emitter 7 exits the exit 29 through the beam channel 37. Conversely, the second rod-shaped element 35 can be brought into a closed position shown in FIG. 3 by rotation, preferably by 90 ° relative to the opened position, in which the second rod-shaped element 35 closes the outlet 29.

Also, the second the protective container closure forming rod-shaped element 35 is preferably used as a threaded spindle, for. B. as shown here as

Threaded spindle formed with a round thread or as a threaded spindle with a trapezoidal or triangular thread.

The two rod-shaped elements 23, 35 consist of a radioactive material absorbing material. For this they can be considered massive

Be formed steel components. Alternatively, however, they may also be considered to be complete with an absorber such as e.g. Lead, filled spindle-shaped pipes

be educated. This form can, for example, by mechanical

Forming a cylindrical tube can be made that then

then poured with the absorber. Similarly, for the production of the surrounding of the absorbent material channels 25, 33 correspondingly shaped spindle-shaped tubes can be used at the corresponding positions in the radiation protection container, the remaining free interior then then with a Radiation absorbing material, such as lead is poured out. Alternatively, however, the radiation protection container can also initially be completely filled with the absorber, and the channels 25, 33 are then exposed by a corresponding mechanical processing of the absorber material, such as milling, in the radiation protection container.

Preferably, for the two rod-shaped elements 23, 35 a

mechanical attachment 39, 41 are provided, via which the element 23, 35 in the respective channel 25, 33 are each mounted against rotation. For this purpose, for example, a respective the element 23, 35 directly connected to the radiation protection container locking device, such. a bolt passing through a paragraph formed on the respective element 23, 35 located outside the respective opening 27, 31 paragraph in the

Radiation protection container is screwed. Preferably, the

Fastening device 39, 41 for safety reasons additionally with a seal and / or a theft protection, such as. one the bolt

anti-rotation lock 43, equipped.

Because of the inventive shape of the rod-shaped elements 23, 35 and the channels 25, 33 resulting helical shape of each gap between element 23, 35 and channel 25, 33 existing gap from the interior into the respective gap penetrating radiation

Multiple scattering extremely strongly damped. In this case, the absorbing effect of the channels 35, 33 surrounding material and the material of the elements 23, 35 over the entire length of the channels 25, 33 exploited.

Another advantage of the invention is that the shielding

Effect even if the gap, e.g. owing to

different thermal expansions of the individual components of the radiation protection container between channel 25, 33 and element 23, 35th

is relatively wide. Since the element 23, 35 according to the invention only by rotation about its longitudinal axis in the associated channel 25, 33 can be introduced, the width of the gap along the longitudinal axis of the channel 25, 33rd less than the difference between the maximum and minimum distance of the lateral surface of the element 23, 35 to its longitudinal axis. Accordingly, there is no straight connection between the equipped with the radiator 7 interior of the

Radiation protection container and the respective opening 27, 31. Thus, the radiation protection container according to the invention esp. Also in applications can be used in which high temperatures or strong

Temperature fluctuations can occur. Fig. 4 shows a further variant of an inventive

 Radiation protection container, which is used, for example, when one or more radiators 7 are transported in the radiation protection container to a measuring location at which the radiation protection container then, for. is mounted on a container 45, and the emitters 7 for the measurement of the

Radiation container out to a location such. a submerged under the radiation protection container into a container 45 immersed tube 47, are transferred.

In the case, a channel 49 surrounded on the outside by the absorbing material is provided in the radiation protection container for each emitter 7, into each of which a rod-shaped element 51 can be inserted.

The rod-shaped elements 51 are formed in this variant as preparation rods, in each case at a predetermined height along the

Longitudinal axis of the respective specimen rod a radioactive radiator 7 is used. The channels 49 accordingly form guide tubes for the preparation rods.

Depending on the application, location, and the number of required there radioactive emitter 7 can in the radiation protection container a single

Guide tube may be provided, or there may be two or - as shown in Fig. 4 - more guide tubes are arranged parallel to each other, in each of which a preparation rod equipped with a radioactive spot 7 preparation rod can be introduced. Here, too, have the form of a preparation rods rod-shaped

Elements 51 according to the invention over at least a majority of their entire length, preferably over their entire length, a helical outer geometry along the longitudinal axis thereof, and the associated channels 49 forming the guide tubes have identical inner spaces into which the rod-shaped elements 51 penetrate Rotation about the longitudinal axis can be screwed. The production of

Preparation rods are, for example, in the rods, e.g. Made of steel, with a square over the entire length, rectangular, triangular, star-shaped or oval cross section in the longitudinal direction to be rotated about its longitudinal axis. The production of the guide tubes, for example, by appropriately shaped tubes are used in the radiation protection container, which then subsequently with a radioactive radiation

absorbent material, such as e.g. Lead is poured out, so that the

Guide tubes in the radiation protection container over the length of which are surrounded on all sides by the absorbent material.

The channels 49 open on a first side of the radiation protection container in each case in openings 53, through which the preparation rods from the

Radiation protection container can be left out or introduced into this.

In addition, a conveyor 55 is provided on a side of the channels 49 opposite these openings 53, via which the

Preparation rods, esp. For transporting the radiation protection container, introduced into the guide tubes in the radiation protection container under train and rotation thereof about its longitudinal axis in the radiation protection container, and in the reverse direction, esp. For performing measurements, also with rotation about the longitudinal axis of the radiation protection container out a measuring location located under the openings 53, such as, for example, the immersion tube 47 arranged here in the container, can be transported. If the specimen rods, as shown here, lowered to different heights in the dip tube 47, so each radiator 7 radiates through another portion of the container 45. In this way, on the

corresponding to the outside of the container 45 mounted detectors 57 measured from the container 45 exiting radiation intensity, and a level in the container 45 are measured over this from the individual sub-areas composed metrologically detected area.

1 rod-shaped specimen holder

3 opening

 5 channel

 7 spotlights

 9 gap

 1 1 opening

 13 beam channel

 15 shielding

 17 opening

 19 more channel

 21 closure element

 23 first rod-shaped element

25 first channel

 27 first opening

 29 exit

 31 outside opening

33 second channel

 35 second rod-shaped element

37 beam channel

 39 mechanical attachment

41 mechanical attachment

43 Castle

 45 containers

 47 dip tube

 49 channel

 51 rod-shaped element

53 opening

 55 conveyor

 57 detector

Claims

claims 1 . Radiation protection container, with  - An outer side of a radioactive material absorbing material surrounded interior for receiving at least one radioactive emitter (7), and  at least one channel (25, 33, 49) connecting the interior space with an opening (27, 31, 53) of the radiation protection container and closable by a rod-shaped element (23, 35, 51),  characterized in that  - The rod-shaped element (23, 35, 51) has at least over a major part of its entire length along a longitudinal axis wendeiförmig turned outer geometry, and  - The channel (25, 33, 49) has a matching inner space, in which the rod-shaped element (23, 35, 51) can be introduced by rotation about its longitudinal axis. 2. Radiation protection container according to claim 1, characterized in that the channels (25, 33, 49) are surrounded on the outside by a radiaktive radiation absorbing material. 3. Radiation protection container according to claim 1, characterized in that at least one of the rod-shaped elements (23) is a specimen holder, the end has a recess for receiving the radioactive emitter (7). 4. Radiation protection container according to claim 1, characterized in that - The interior for receiving the radioactive emitter (7) via a radiation channel with an output (29) of the radiation protection container is connected,  - That is provided by a jet channel this intersecting channel (33), and - That in this deployable rod-shaped element (35) rotatable Protective container closure is,  - Has a perpendicular to its longitudinal axis through the element (35) passing through the beam channel (37),  - Can be brought by rotation in an open position in which the  Beam channel (37) connects the interior of the radiation protection container with the output (29) of the radiation protection container, and  - Which can be brought by rotation in a closed position in which the rod-shaped element (35) closes the leading from the interior to the output (29) beam channel. Radiation protection container according to claim 3 or 4, characterized in that the rod-shaped element is a threaded spindle, esp. A  Threaded spindle with a round thread, a triangular thread or a trapezoidal thread is. Radiation protection container according to claim 1, characterized in that - At least one channel (49) is arranged in the radiation protection container outside surrounded by the absorbent material guide tube, and  - That the insertable into the guide tubes rod-shaped elements (51) are preparation rods, in which at a predetermined height along the longitudinal axis of each one of the radioactive emitter (7) can be inserted. Radiation protection container according to claim 6, characterized in that in the radiation protection container, two or more guide tubes are arranged parallel to each other, in each of which a preparation rod equipped with a radioactive emitter (7) can be inserted. Radiation protection container according to claim 6 or 7, characterized in that - The guide tubes on one side of the radiation protection container opening openings (53), and a conveyor (55) is provided,  - about which preparation rods, in particular for transportation of  Radiation protection container, can be introduced into the guide tubes in the radiation protection container by rotation about its longitudinal axis, and  - About the preparation rods by rotation about the longitudinal axis of the radiation protection container out to an under the openings (53) of the guide tubes located site, esp. In one  Container (45) arranged dip tube (47) are transportable. 9. Radiation protection container according to claim 6, 7 or 8, characterized  in that the preparation rods are rods rotated along their longitudinal direction about their longitudinal axis, in particular rods with a rectangular, square, oval, triangular or star-shaped cross section.