FR2582231A1 - FILTER FOR LIQUIDS CONTAINING RADIOACTIVE SUBSTANCES - Google Patents

Abstract

THE INVENTION RELATES TO A FILTER FOR LIQUIDS CONTAINING RADIOACTIVE SUBSTANCES. THIS DEVICE INCLUDES A PLURALITY OF HORIZONTAL AND SUPERIMPOSED FILTER PLATES 31 EACH INCLUDING A FILTERING MEDIUM 32; THE ADMISSION OF THE SLUDGE IS CARRIED OUT AT THE CENTER OF THE PILE THROUGH A VERTICAL CENTRAL CHANNEL 24 WHICH CONNECTS THE INTERCAL SPACES LOCATED BETWEEN THE FILTER PLATES, WHICH ARE SEALED WITH RESPECT TO OTHERS ON THEIR PERIOD AND HAVE RADIAL OPENINGS 34 FOR EVACUATION OF THE FILTRATE TO THE EXTERIOR. APPLICATION IN PARTICULAR TO THE TREATMENT OF NUCLEAR FUEL.

Description

1. Filter for liquids containing radioactive substances The invention

  relates to a device for filtering radioactive liquids loaded with solid substances and which comprises a pressure-filled housing provided with a lid and an inlet for the sludge and comprises a collection space provided in the bottom of the housing and an evacuation for the filtrate, the casing comprising

a filter cartridge.

  When reprocessing irradiated nuclear fuel, fuel solutions appear that are cloudy and contain a few thousandths of the fuel weight in the form of insoluble particles in suspension. With regard to solid substances

  which must be separated from the fuel solution ,.

  namely, dissolution residues, these are zirconia and insoluble sludge particles having a variable composition.

  For the continuation of the treatment it is neces-

  to remove these parts of solids before proceeding to extraction. This is achieved either by

  centrifugation, or by filtration.

  It is known to use for filtration, so-called bag filters with plastic filter media. These bag filters, however, have no holding action in the micron and sub-micron size range and have only a small filter area per unit volume, which does not allow

  an economical use. In addition, the stability

  The bag filter is not sufficient in all cases.

  Another proposal for wire devices

  for the stated purpose of use relates to candle filters made of treated steel,

  be washed against the current. Similarly, these filters in

  of candlesexercent insufficient restraint

  solid substances in the lower size range

  micron. In addition, a disadvantage of

  form-of candle must be seen in the fact that they do

  only a limited service life, since clogged pores in the filter can not be cleaned

  only partially by backwashing.

  From DE-OS-31 36 905 a filter is known

  press allowing the separation of residues formed at

  firing of obtaining wet ash from

  of Pu, and which includes a casement equipped with a neck-

  vercle and an admission for the solution. The solids and the filtrate are separated in the box. It is expected a filter pot, in which a

  sieving basket is mounted tightly. Between the

  as the sieve base of the sieving basket and the bottom of the filter pot, there is a collection space for the filtrate which can be evacuated in a sealed manner,

  through a discharge pipe of the fil-

  trat, through the bottom of the housing, by means of the pressure load applied to the interior space of the cabinet or

  by establishing a vacuum in the tubular

  lure of evacuation of the filtrate. This filter represents a

  one-disc horizontal filter and has a low flow rate.

  The filtering devices described in the state

  technical problems are problematic in the case of

  placement of a charged filter cartridge as concentrated radioactive solids

  may lead to an increase in radioactivity.

  Since the replacement of a filter cartridge must be carried out by means of a remote controlled device by means of the remote handling technique, the risk of entrainment of the radioactive substances

is particularly important.

  With the aid of the filtering devices according to the state of the art, solid substances are obtained.

  filtered, which for their further processing

  require the implementation of operational phases

  additional complex devices.

  The object of the invention is to provide a filtering device of the type described above so that it is suitable for use in installations

  nuclear weapons, can easily be replaced by telemanipu-

  tion, reduce the entrainment of radioactive particles

  and allows for high throughput while retaining very

  the finest particles of solids.

  This problem is solved according to the invention

  thanks to the fact that the filter cartridge is

  killed by a plurality of horizontal filter trays

  stacked on top of each other and wear each

  each a thick film filter medium acting in the sub-micron range, that the sludge inlet is centrally located in the stack of filter trays via

  a central vertical channel, between them the spaces

  these dividers located above the layers respectively

  of the filter medium, between the filter trays, that these trays are sealed with respect to

  others on their outer circumference and

  radially evacuatioin outward directed, for the filtrate, that the central channel is sealed by a plate at its lower end and that the filtrate can be removed, in a manner known per se, via a filtrate pipeline in

the base of the enclosure.

  The radioactive liquid loaded with solid substances arrives in the filter box from the top via the inlet located in the lid

  of the shoemaker and is distributed, from the center, by the

  intermediary of the central canal, in

  laires located between the trays of the filter. On the half

  filtering place of the trays of the filter is formed, under the effect of a retention of solids, a filter cake thin and thanks to the choice of filter medium is obtained additional depth filtration. The

  The filtrate passes through the filter media and is discharged radially.

  outward. The filtrate collects in the lower part of the filter housing and is sent to

  destination through a channel

  evacuation of filtrate. If, after a period of

  quite a long time, loading the cartridge

  Filter media is signaled by an increase in upstream pressure, the filter stack should be replaced by a new filter cartridge. For this purpose, the lid of the filter housing is remotely opened and the filter cartridge is removed from the filter housing by means of a hoist. Radioactive waste is safely retained in the

  filter stack and can be packaged in

  appropriate containers and then be sent to a

  definitive storage. We introduce, in the

  pour a new filter cartridge into the filter housing and close the filtering device again

  so that he is ready to function.

  According to an advantageous variant of the invention, the stacked filter trays are welded together so as to form a unit. The welding is performed on the outer periphery and sealingly closes the stack of filter trays outwardly, with the exception of the radial discharge openings for the purified filtrate. This ensures that the retained solids remain securely inserted into the battery of the

  filtered. Welding gives the filter stack a stable

  increased mechanical flexibility which proves to be particularly advantageous

  in the case of remote handling.

  According to another embodiment of the invention, the filter cartridge is constituted by several superimposed units formed of filter trays. The different

  filter trays or multiple stacked units

  filter trays are fixed between two clamping plates by means of a clamping bolt arranged in

  centered position. This produces a filter cartridge

  easy to handle. The lower clamping plate may advantageously serve to seal the central channel. If the lower clamping plate is detachably joined to the clamping bolt, it is possible to reuse the filter support constituted by

  by clamping plates and clamping bolts.

  According to another embodiment, the plate

  clamping ring is provided with a handling ring

  This simplifies the remote handling of the cartridge.

filtering.

  According to an advantageous embodiment of

  the invention, the upper clamping plate is suspended

  loosely, by its edge on a part

  peripheral annular luer by means of the interposition of a seal in the filter casing and is loaded by a pressing pressure spring

  on the cover and has at least one piercing at

  the central canal running vertically through the car-

  filter button. The loosely suspended filter cartridge can then be removed in a simple manner from the filter housing by means of the handle of the upper clamping plate. Thanks to the organ

  annular projection and on the annular surface of the

  that upper clamping, which is supported on this projecting portion, the upper space of supply of the boot

  is sealed away from the rest of the bowl space.

  tier. According to another advantageous embodiment of the invention, the cover of the casing is provided with a housing, serving to house according to a connection by complementary shapes, a locking head of a threaded compression pin which is guided in a stirrup clamping device mounted so as to be laterally rotatable on the casing and that the clamping caliper comprises clamping members intended to engage below

a flange of the boxer.

  This embodiment makes it possible, by

  easy handling, locking and unlocking

  and sure of the lid on the filter housing.

  In order to avoid losses of materials in the filter cake, such as uranium or plutonium, the filter cartridge can be washed.

  using appropriate solvents. Residual liquid

  killed in the filter cartridge can be discharged by discharge through a gas through a pipe

  corresponding supply before the cover of the

  filter is open and that the filter cartridge

removed from you.

  Thanks to the invention there is obtained a compact filter cartridge which is traversed from the inside towards

  outside by the liquid to be filtered and

  holds in it the solid substances. Radioactivity is not increased. There is no separate manipulation

  concentrated sludge of solid substances.

  The invention creates a filtering device

  having an increased mechanical stability and which is

  endured by a long service life. The high flow rate

  v at the same time, fine filtering must be considered as an essential additional benefit

  of the device according to the invention.

  The invention makes it possible to solve globally the

  different technical problems of a thread device

  for the stated purpose of use, and this in a

building unit.

  Other features and benefits of the

  present invention will emerge from the description given

  hereinafter taken with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic representation;

  a filter cartridge used in a filament box

  be and constituted by a multiplicity of superimposed filter trays; FIG. 2 is a sectional view on a larger scale of a part of a stack of filter trays.

  superimposed, the admission of which is in a central position

  and whose evacuation is at the outer periphery; and Fig. 3 shows an embodiment

  modification of a device incorporating a filter cartridge

  trante constituted by three units formed of trays

of filter.

  In Figure 1, there is shown a filter housing 6 which is closed by a cover 7 by means of screws 8 mounted on flanges. The lid 7 has a

  manipulation ring 9 and is connected through the intermediary

  re of an intake 11 to an inlet pipe 12 for the fuel solution containing substances

  solid. The arrival line 12 comprises a maneuver

  meter 13 and is connected to a branch line 14

2582Z31

  which is connected to a source of compressed gas that is not

presented here.

  In the box 6 is arranged a cartridge

  filter 15 which is suspended freely by the

  of an upper clamping plate 16 in

  the filter housing 6 and which is supported on a part

  peripheral annular protrusion 17. At the end

  bottom of the filter cartridge 15 is located

  a closed clamping plate 18 which is connected directly

  with a tightening bolt 19. The trays of the

  15 of the filter are held together by means of

  this clamping bolt 19 between the two plates

clamping 16 and 18.

  The upper clamping plate 16 has a

  manipulator ring 22 loaded by a pressure spring

  21 and is provided with holes 23 arranged concentrically

  with respect to the clamping bolt 19 and connected to

  a vertical supply channel 24, which is arranged in a posi-

  centered in the filter stack 15.

  A collection area.25 for the filtrate is

  present below the clamping plate 18. The thread

  trat reaches his place of destination by borrowing

  a pipe 26 of the filtrate outlet.

  FIG. 2 shows superposed filter trays 31 of the filter cartridge 15, which carry the filtering medium 32. The filtering medium 32 is tightened by locking on the outer periphery and on the outside.

  vicinity of the vertical supply line 24.

  Between this supply line and the outer circumference

  are located below each half

  filtering place 32, a number of evaluation channels

  33 These drain channels 33 open into radial discharge openings 34 arranged in the filter trays.

  the outer peripheral surface of the filament cartridge

trante 15.

  Each filter plate 31 located above a filter medium comprises supply channels 35 made by machining on the lower face 32 of the plate and which are connected at their end facing

the center, to the supply canal 24.

  The upper filter plate 31 has two concentric sealing rings 37 which seal

  the filter cartridge 15 with respect to the service plate

superior rabies 16.

  The operating mode of the device described above is as follows: the mud loaded with solid substances arrives at the filter housing 6, above the upper clamping plate 16, through the bores 23 formed in

  this clamping plate and reaches the central channel

  The fuel solution is distributed, from the center, on the filter medium 32 of the filter trays 31. As a result of the retention of the solid substances, it is formed on the filter medium 32. filter medium 32 a thin filter cake, while the filtrate enters, after passing through the filter medium 32, into the discharge channels 33 and is

  evacuated radially outwards. The filtrate is collected

  lecte in the lower collection space 26 of the boot

  filter 6 and is evacuated to its destination

  through the Evacuation Line 26

filtrate.

  The filtering medium 32 consists of a fabric

It is made of fiberglass.

  If the inlet pressure increases at the manometer 13 of the supply line 12 this indicates a charge of the filter cartridge 15. When a

  predetermined limit pressure is reached in the

  supply 12, the admission is closed and the

  residual material located in the filter cartridge 15 is discharged through the bypass line 14, consequently

sending a gas.

  After this washing or drying process, the casing lid 7 is opened by remote manipulation.

  filter 6 and completely remove the filament box.

  the filter cartridge 15, suspended freely, at

  with the aid of a hoist grasping the ring of

  22. The particles, consisting of highly corrosion-resistant steel, filter cake and

  that the clamping plates 16 and 18 and the service bolt

  Rage 19 can be removed remotely in a separate workstation and can be mounted in a new filter stack to form a

new filter cartridge 15.

  After inserting a new filter cartridge

  15 in the filter box 6, the lid is closed

  7, and the filter is ready for operation again.

  The filtering device of FIG.

  a box 41 which is closed by a lid 43 can

  to be locked. The locking is achieved by means of a locking mechanism 45 mounted

  centrally above the lid 43 and which possesses

  of a T-shaped housing 46, in which engages

  a locking head 47 of a threaded spindle of

  pressure 48 of a clamping bracket 49 mounted to be able to tilt on the casing 41. The clamping bracket 49 comprises two clamping members 51 and 53 which, in the locked state, engage below the

  flange 55 located on the filter housing 41. At the

  The upper part of the clamping flange 49 is located

  placed a guide 59 which is intended to guide the screwdriver

  to be used to actuate the threaded spindle

pressure 48.

  The filter housing 41 has, laterally, a fixed claw 60 for its mounting in a structure and, in its upper part, an intake manifold 61 for the sludge to be filtered. In

  the filter casing 41 is provided a part sail-

  peripheral annular louse 63, on which the edge

  an upper clamping plate 65 is supported

  the interposition of a peripheral sealing ring

  The clamping plate 65 is rigidly connected to a handling ring 69 and is urged downwardly by means of a compression head 71 loaded by a spring against the annular projecting portion 63. The ring manipulator 69 constitutes the end of a clamping bolt 73 which has, at its lower end, a tapping 75 in which is

  screwed a threaded bolt 77 with a lower clamping plate

  79. Three units 81,83,85 constituted by stacks of filter trays are fixedly mounted by being compressed between the two clamping plates 65 and 79, the different units enclosing rings between them.

respective sealing elements 87.

  The clamp bolt 73 passes through a central channel

  vertical intake tral 89 which extends vertically through the filter cartridge 91. The clamping plate

  65 has, in the vicinity of the admission channel,

  89, holes 93 which connect the space of admission

  95 to the inlet channel 89. The filter cartridge 91 is surrounded, over most of its length, by a grid-shaped housing 97 provided with openings,

  which represents an additional mechanical protection.

  A collection area 99 for the filtrate is

  provided below the filter cartridge 91.

  filtrate evacuation 101 is arranged

  in the bottom of the filter housing 41.

  How to replace the filament cartridge

  91 of Figure 3 is as follows: As the inlet pressure increases,

  close the admission. By introducing a screwdriver

  per, it is rotated in ascending motion

  compression threaded spindle 48 by grasping it at the right

  calf of its hexagon maneuvering outline. The tightening tension of the lid 43 is suppressed. The clamp 49 is tilted to the side, which has

  effect of suppressing the meshing of the parts

  clamping lugs 51 and 53 with the flange 55 and disengaging the locking head 47, making a connection through

  complementary shapes, the threaded spindle of compres-

  48, out of the T-groove of the locking mechanism

  45 is located on the cover 43. The cover 43 is free and can be removed from the filter box 41 in

  being seized by a hoist. As a result, the cartridge

  The filter cartridge 91 is released and is ready to be

  entry. The hoist clings to the hoist ring

* nipulation 69, remove the filter cartridge 91 and pla-

  this latter in a conditioning device.

  The insertion of a new filter cartridge 91 becomes

in the opposite direction.

  The cover 43 of the housing is placed by

  manipulation on the filter box 41.

  the clamping bracket 149 is supported over the cover 43, so that the locking head 47, forming a connection by complementary shapes, of the threaded spindle of the compression 48 engages the T-shaped groove of the mechanism 45 and that the projecting clamping portions 51 and 53 engage above the flange 145 of the casing 41. By means of a

  screwdriver to strike, tighten the threaded spindle

  pressure 48, according to a downward movement so that

  the cover 43 of the housing is firmly tightened.

Claims (7)

  1. Device for filtering radioactive liquids   solids-laden assets with a pressure-loaded housing with a lid and an inlet for the sludge and   planned collection in the bottom of the box and an evacuation   for the filtrate, the casing comprising a filter cartridge, characterized in that the filter cartridge (15) is constituted by a plurality of horizontal filter trays (31) which are stacked on each other and each carry a filter medium in thick layer   (32) acting in the range of   micron, that the sludge is fed centrally into the stack of filter trays (31) via a central vertical channel (24), which interconnects the interspace above the respective layers of the filter medium, between   the filter trays (31), that these trays are   cherished against each other on their perimeter   exterior and have radial openings for   (34) for the filtrate, that the central channel (24) is sealingly closed by a plate at its lower end and that the filtrate   can be removed, in a manner known per se, through   of a filtrate line (26,101) in the of the enclosure (6).   2. Device according to claim 1, characterized   characterized in that the stacked filter trays (31)   are welded together in the form of a unit.   5. 3. Device according to claim 2,   characterized by the fact that the filter cartridge (15)   consists of several superimposed units (81,83, -   ) which are formed of filter trays and are   cherished against each other.   4. Device according to one of the claims   1 or 3, characterized in that the filter cartridge   trante (15) is arranged between two clamping plates   (16,18) connected to each other by means of tightening lons (19).   5. Device according to claim 4,   characterized in that the clamping plate (16) is   provided with a handling ring (22).   6. Device according to claim 4,   characterized by the fact that the upper clamping plate   re (16) is suspended, loosely, by its edge on   a peripheral annular protruding portion (17)   the interposition of a packing (67)   in the filter box (6) and is loaded by a   pressure spout (21) pressing on the cover   (7) and has at least one hole (23,93) in the vicinity of   of the central channel (24) crossing vertically filter cartridge (15).   7. Device according to claim 1, characterized   characterized in that the cover (43) of the casing (41) is provided with a housing (46) for accommodating a   connection by complementary forms a locking head   lage (47) of a threaded compression pin (47) which is guided in a clamp (49) mounted so as to be pivotable laterally on the casing (41) and   that the clamping bracket (49) comprises   rage (51-53) intended to engage below a flange (55) of the housing.