GB2073030A - Agitating mixtures - Google Patents

Abstract

A mixture comprising a liquid and a multiplicity of solids is introduced into a declivitous chamber 11 having a baffle 15 at its lower end, the baffle 15 having a drainage aperture 21 and a discharge aperture 22 angularly displaced from the drainage aperture 21. A drive unit 130 is arranged to rock the chamber 11 to agitate the mixture, and subsequently to turn the chamber 11, initially to drain the liquid through the drainage aperture 21 and then to spill the solids through the discharge aperture 22. A plurality of the chambers 11 may be joined together in a declivitous series with adjacent discharge apertures thereof displaced through 180 DEG so that the solids spill progressively from one chamber 11 into an adjacent chamber 11 along the series. <IMAGE>

Description

SPECIFICATION A method of and an apparatus for agitating a mixture This invention relates to a method of and an apparatus for agitating a mixture, and more particularly but not exclusively for agitating a mixture of solids in a solvent so as to assist in the dissolution of the solids by the solvent.

The aforementioned mixture might contain chopped pieces of a nuclear fuel pin, the pieces comprising lengths (hulls) of a nuclear fuel can containing irradiated mixed oxide nuclear fuel and typically 25 mm long and 6 mm diameter, and the solvent might be nitric acid for leaching the nuclear fuel out of the hulls. In addition, particulate fines of some of the lighter fission products arising from irradiation of the nuclear fuel might be suspended in the liquid, and heavy fines could be present in the mixture, for example from the can material (e.g. stainless steel), from alloys of plutonium and some of the heavier fission products, and from plutonium rich residues of the nuclear fuel, the alloys and the residues being relatively insoluble.

Because of the radioactive nature of the irradiated nuclear fuel and the fission products, it is highly desirable to be able to reprocess the irradiated fuel elements to separate the nuclear fuel from the fission products and from the fuel can with the minimum of transfer operations from one equipment to another and from one stage of the reprocessing operation to another.

The invention in a first aspect therefore provides an apparatus for agitating a mixture comprising a liquid and a multiplicity of solids, the apparatus comprising a chamber rotatably supported at a selected declivity, an inlet means for the mixture at the upper end of the chamber, radially displaced port means at the lower end of the chamber, and means for turning the chamber initially to rock the chamber so as to agitate the mixture and subsequently to spill at least some of the mixture or the liquid or the solids thereof through the port means.

According to a second aspect of the present invention, there is provided an apparatus for agitating a mixture comprising a liquid and a multiplicity of solids, the apparatus comprising an elongate compartment, means rotatably supporting the compartment at a selected declivity, a plurality of baffles axially displaced inside and along the compartment so as to define therebetween a plurality of axially spaced chambers in the compartment, port means in each baffle so as to intercommunicate adjacent chambers, adjacent baffles having the port means thereof in angularly displaced relationship, an inlet means for the mixture at the uppermost of the chambers, an outlet means from the compartment, and means for turning the compartment initially to rock the compartment so as to agitate said mixture therein and subsequently so as to spill at least some of the mixture or the liquid or the solids thereof through alternate port means along the compartment.

Preferably, adjacent port means are displaced through 1 800 with respect to each other, and drain means having a restricted outlet may be provided in at least one or more of the baffles so that the liquid spills through the drain means before the mixture or the solids thereof can spill through the port means of the or each said baffle having a drain means therethrough.

Additional inlet means for liquid may be provided to one or more intermediate chambers, and means may be necessary for heating or cooling one or more of the chambers.

It is desirable that sealing means be provided between members in rotational relationship, and such sealing means may comprise a labyrinth compartment adapted to contain a trapped quantity of a liquid seal therein.

The invention also provides in a third aspect, a method of agitating a mixture comprising a liquid and multiplicity of solids, the method comprising introducing the mixture into a declivitous chamber having a radially displaced port means at the lower end of the chamber, rocking the chamber to agitate the mixture in a manner to maintain the port means above the mixture, and subsequently turning the chamber to submerge the port means or a portion thereof below the level of the mixture to cause at least some of the mixture or the liquid or the solids thereof to spill through the port means out of the chamber.

In the preferred form of the third aspect of the invention, the mixture is introduced into an uppermost of a plurality of said declivitous chambers connected together in a declivitous series thereof with adjacent said port means angularly displaced, desirably displaced through 1800, with respect to each other.

The invention will now be further described by way of example only with reference to the accompanying drawings in which:~ Figure 1 shows diagrammatically and in median section a side view of a single stage apparatus for agitating a mixture; Figure 1 a shows a view on the line la-la of Figure 1; Figure 2 shows dIagrammatically and in median section a side view #of a multi-stage apparatus for agitating a mixture; Figure 3 shows diagrammatically a side view of a drive means for the apparatus of Figure 2; Figure 4 shows a modification to the apparatus of Figure 2; and Figure 5 shows a lute seal for the apparatus of Figure 2.

Referring now to Figure 1, a single stage apparatus 10 is shown and comprises a declivitous annular compartment 11 defined by an outer cylindrical casing 1 2 and an inner cylindrical casing 13, the compartment 1 1 having an upper conical inlet 14 and a baffle 15 at the junction with an annular conical chamber 16 so as to contain a mixture of an acid 17 and of hulls 18 comprising nuclear fuel to be dissolved by the acid 17 inside a partially open metal can. The baffle 15 as shown in Figure 1 a has a radially displaced drainage aperture 21 spaced from the inner casing 13 of the compartment 11, and is cut-away locally to provide a discharge aperture 22 having a radially directed side 23 displaced approximately 900 from the drainage aperture 21 and a side 24 extending in a direction perpendicular to that of the side 23.Referring again to Figure 1 , a tubular housing 27 extending from the upper conical inlet 14 forms part of an upper sleeve bearing 28 about an inlet pipe 29 connected by a flanged connection 31 to an entry port 32. A discharge tube 33 extends from the baffle 1 5 at the drainage aperture 21, and extends through the annular conical chamber 16 and a discharge pipe 34, and through a bend 35 of a transfer pipe 36 to discharge the acid 17 through an outlet 37 in the transfer pipe 36, the transfer pipe 36 having an end sleeve portion 40 which forms part of a lower sleeve bearing 41 with the discharge pipe 34.

Suitable lute seals (not shown) are incorporated in the upper and in the lower sleeve bearings 28, 41.

A feed tube 42 in the inlet pipe 29 provides an inlet for the acid 17 into the inlet pipe 29, and a tube 43 extending from the transfer pipe 36 provides a vent for any gases evolved from the acid 17. A cylindrical chest 46 surrounds the compartment 11 and extends from a position above the upper sleeve bearing 28 to the sleeve portion 40.

In use of the apparatus 10 with the discharge aperture 22 in its upper position, steam is injected onto the chest 46 to heat the apparatus to an operating temperature, the acid 17 is fed through the feed tube 42 and the hulls 18 are dropped through the entry port 32, to fall into the compartment 11 so that the hulls 18 rest in a pool of the acid 17. The compartment 11 is then rocked continuously about the sleeve bearings 28, 41 through an included angle of about 600 by drive means (not shown). The agitation produced by the rocking action assists dissolution of the nuclearfuel in the hulls 18 to form a product liquor, and also assists in dispersing any heavy fines from the hulls 18 to assist in the dissolution of the more soluble of these fines.The product liquor is withdrawn from the compartment 11 by turning the outer casing 12 slowly about the sleeve bearings 28, 41 so as to bring the drainage aperture 21 to the bottom of the compartment 11 to allow the product liquor to flow through the discharge tube 33. The outer casing 12 is then turned slowly to bring the discharge aperture 22 near the bottom of the compartment 11 to allow the hulls 18 to tumble firstly into the conical chamber 16 and from there into the transfer pipe 36. Some undissolved heavy fines remain on the outer casing 12 in the compartment 11 thus ensuring an adequate dissolution time in the compartment 11, although light fines might be carried by the product liquor through the drainage aperture 21.The outer casing 12 is then turned to restore it to its original position with the discharge aperture 22 uppermost, and fresh acid 17 and more hulls 18 are fed into the compartment 11.

If desired product liquor may be withdrawn as aforedescribed and the outer casing 12 restored to its original position without discharging the hulls 18 so that fresh acid 17 can be introduced into the compartment 11 to continue the dissolution of the original nuclear fuel and the fines.

The declivitous angle of the compartment 11 may be selected to suit a particular application to ensure that the material to be agitated slips readily along the apparatus 10, and an angle of declivity of about 350 from the horizontal has been found adequate for applications in which metal hulls 18 containing nuclear fuel are to be fed into the apparatus 10. The angle through which the apparatus 10 is rocked may be varied although an angle which leads to an appreciable movement of material such as the hulls 18 on that part of the outer casing 12 forming the floor of the compartment 11 might lead to erosion of the outer casing 12.

Although the invention has been described in relation to the single stage apparatus of Figure 1, several such apparatus may be arranged in series relationship. Alternatively the invention may be incorporated in a multi-stage apparatus, and referring to Figure 2 a multi-stage apparatus 50 is shown having a declivitous annular compartment 51 at the same angle of declivity as the compartment 11 of Figure 1.The annular compartment 51 is divided by seven baffles 52, 53, 54, 55, 56, 57 and 58 respectively similar to the baffle 15 of Figure 1 into a first dissolution chamber 62, a transfer chamber 63a and a second dissolution chamber 63b, a transfer chamber 64a and a rinse chamber 64b, and a transfer chamber 65a and a separation chamber 656. Each baffle 52 to 58 has a discharge aperture 67 similar to the discharge aperture 22 of Figure 1, and adjacent baffles 52 to 58 have the discharge apertures 67 thereof displaced through 1 800 with respect to each other.The annular compartment 51 is defined between an outer cylindrical casing 70 and an inner cylindrical casing 71 , the outer casing 70 at the upper end thereof having a tubular housing 72 which fits over an angled inlet pipe 73 to provide an upper sleeve bearing 77, the inlet pipe 73 extending to an entry port 84. The lower end of the outer casing 70 extends inside a housing 74 having a bearing portion 75 which provides a lower sleeve bearing 78 with the outer casing 70. Suitable lute seals (not shown) are incorporated in the upper and in the lower sleeve bearings 77, 78. The upper end and the lower end of the inner casing 71 are closed, and the outer casing 70 in the transfer chamber 65a and the separation chamber 65b has a multiplicity of perforations 76 therethrough. A feed pipe 79 for a rinse acid 80 runs downwardly outside the tubular housing 72 and the outer casing 70, and extends at the lower end thereof through the outer casing 70 into the rinse chamber 64b. The upper end of the feed pipe 79 is connected to a flexible pipe 82 itself connected through an electrically operated flow control valve 81 to a source (not shown) of the rinse acid 80. An injection pipe 85 for cold dilute wash acid extends through the lower end and near the top of the housing 74, and terminates adjacent to the baffle 58 so as to inject the wash acid through the discharge aperture 67 of the baffle 58 when the discharge aperture 67 is at or near the top of the separation chamber 65b.

A discharge tube 87 extends from a drainage aperture 88 in the baffle 54, then through the baffle 55 and through a drainage aperture 89 in the baffle 56 and inside a discharge pipe 91 extending from the baffle 56, the discharge pipe 91 extending through the baffles 57 and 58 and at its lower end having a drain tube 92 for discharging into a return pipe 93 from the housing 74. The discharge tube 87 at the lower end thereof extends through a closure 95 of the discharge pipe 91 to discharge into a product liquor drain 96 from the housing 74. A relatively large bore transfer pipe 99 extends downwardly from the lower end of the housing 74 and has a vent branch pipe 102 therefrom, and a drain tube 103 extends declivitously from the underside of the housing 74 at a position above the transfer pipe 99.An annular ridge 105 at the lower end of the outer casing 70 is located inside a protuberance 106 which extends around the periphery of the outer casing 74. The return pipe 93 connects via an ejector (not shown), or a fluidic pump (not shown) such as the fluidic pump of British Patent Specification No. 1480484, to a reservoir 108 which is connected to the inlet pipe 73 by a feed pipe 109 having an electrically operated control valve 110 therein.

In operation, a batch of hulls 18 containing nuclear fuel and with some adherent fines thereon, is fed through the entry port 84 into the top of the inlet pipe 73 and acid 80 from the reservoir 108 is fed through the feed pipe 109 to fall into the first dissolution chamber 62 with the discharge aperture 67 thereof in its upper position as shown. A drive means (not shown) is actuated to rock the outer casing 70 and thereby the first dissolution chamber 62 through an included angle of about 600. The agitation produced by the rocking action assists the dissolution of the nuclear fuel by the acid 80 in the hulls 18 in a similar manner to that described in relation to Figure 1.After a suitable period the outer casing 70 is rotated slowly through about 1 800 to bring the discharge aperture 67 in the baffle 52 to the bottom of the first dissolution chamber 62 so that the acid 120 and the hulls 18 spill into the transfer chamber 63a when the transfer aperture 67 of the baffle 53 is in the upper position thereof.The outer casing 70 is then returned through 1800 to its original position so that the acid 80 and the hulls 18 can spill through the discharge aperture 67 of the baffle 53 into the second dissolution chamber 636. A further batch of the hulls 18 and the acid 80 is fed through the entry port 84 into the inlet pipe 73 to fall into the first dissolution chamber 62, and the outer casing 70 is then rocked again through the same included angle of 600 so as to agitate the hulls 18 and the acid 80 in the first and in the second dissolution chambers 62 and 63b respectively.When the outer casing 70 is next turned slowly through 1 800, a product liquor formed by the dissolution of the nuclear fuel in the acid 80 drains from the second dissolution chamber 63b through the drainage aperture 88 in the discharge tube 87, and is discharged therefrom into the product liquor drain 96. When the discharge aperture 67 in the baffle 54 approaches the bottom of the second dissolution chamber 63b the hulls 1 8 and some of the light undissolved fines from the nuclear fuel in the second dissolution chamber 63b spill therethrough into the transfer chamber 64a, whilst at the same time the acid 80 and the hulls 1 8 with some of the undissolved heavy fines spill from the first dissolution chamber 62 into the transfer chamber 63a.On the outer casing 70 being returned by about 1 800 to its original position, the hulls 1 8 and some of the heavy fines in the transfer chamber 64a spill through the discharge aperture 67 in the baffle 55 into the rinse chamber 64b, and at the same time the acid 80 and the hulls 18 spill from the transfer chamber 63a into the second dissolution chamber 63b.

Rinse acid 80 is fed through the feed pipe 79 into the bottom of the rinse chamber 64b to well up against the settling heavy fines and wash any residual product liquor from the hulls 1 8 and from the heavy fines as the outer casing 70 is rocked through 600 whilst at the same time providing a further dissolution period for any residual nuclear fuel. When the outer casing 70 is again turned slowly through about 1 800, the rinse acid 80 drains through the drainage aperture 89 into the discharge pipe 91, and is discharged from the drain tube 92 into the return pipe 93 where it is returned to the reservoir 108 for recycling through the apparatus 50.When the discharge aperture 67 in the baffle 56 approaches the bottom of the rinse chamber 64b, the hulls 18 and some of the heavy fines in the rinse chamber 64b spill through this discharge aperture 67 into the transfer chamber 65a. Simultaneously the aforementioned transfers take place into the transfer chambers 63a and 64a. Subsequently when the outer casing 70 is turned in the reverse direction to restore it to its original position, the hulls 18 and the heavy fines spill from the transfer chamber 65a into the separation chamber 65b, and simultaneously the aforementioned transfers take place from the transfer chambers 63a and 64a into the second dissolution chamber 63b and the rinse chamber 64b respectively.Cold dilute wash acid is ejected from the feed pipe 85 through the discharge aperture 67 in the baffle 58 into the separation chamber 65b to wash heavy fines through the perforations 76 into the housing 74 from which the heavy fines and the wash acid are discharged through the drain tube 103 as the outer casing 70 is rocked by the drive means. On the outer casing 70 again being turned through about 1800, the hulls 18 in the separation chamber 65b spill through the discharge aperture 67 in the baffle 58 and tumble along the outer casing 70 to drop into the transfer pipe 99, any gases from acid on the hulls 18 being vented to a large extent through the vent branch pipe 102.

The above sequence of movement of the hulls 18 through the apparatus 50 is repeated as the outer casing 70 is continuously rocked through 600 for a period, and subsequently turned slowly through about 1 800 and then returned to its original angular position.

The rotation of the apparatus of Figures 1 and 2 may be effected by a conventional drive arrangement, and in Figure 3 one such drive arrangement 130 is shown and comprises a direct current reversible electric motor 132 on which is mounted a toothed pulley 134. A larger toothed pulley 136 is mounted on the tubular housing 72 of Figure 2, and a timing belt 135 extends around both the pulleys 134, 136 so that rotation of the pulley 134 drives the pulley 136 and thus turns the tubular housing 72. A lug 137 on the pulley 136 is set midway between two limit switches 138, 139 when the apparatus 50 is in the mean position shown in Figure 2.A signal from either one of the limit switches 138, 139 can be ignored when desired so that the pulley 136 overruns, and a limit switch 140 at the other side of the pulley 136 is provided to limit the overrun of the pulley 136 to about 1800 and thus inverts the apparatus 50 from the position shown in Figure 2. The limit switches 138, 139 are set apart at a distance to limit the angular movement of the pulley 136 to about 600, thus producing the rocking action of the apparatus 50. The limit switches 138, 139, 140 are connected to an electric circuit (not shown) linked to the electric motor 132 such that signals from the limit switches 138, 1 39, 140 reverse the direction of rotation of the drive from the electric motor 132.

The drive arrangement 130 may be used with the apparatus 10 of Figure 1, the pulley 136 being mounted on the housing 27 (not shown in Figure 3) instead of the tubular housing 72. If desired additional limit switches (not shown) may be provided to reverse or momentarily halt the rotation of the pulley 136 at some intermediate position, for example to allow the bulk of the product liquor to be drained from the second dissolution chamber 63b before the hulls 18 are allowed to spill therefrom.

In some applications of the invention it may be desirable to prevent fumes from the acids used in the apparatus from escaping from the apparatus through the entry port 84, and furthermore the constant flexing of the flexible pipe 82 may lead to long term maintenance difficulties when the apparatus is situated in a radioactive environment.

In such circumstances the modifications shown in Figure 4 may be used, and referring to Figure 4, part of an apparatus 150 is shown which in most respects is similar to the apparatus 50 of Figure 1, but before the first dissolution chamber 62, the apparatus 150 has an additional transfer chamber 152 and two seal chambers 1 54a, 1 54b defined by baffles 156, 157 and 158 each having a discharge aperture 67 therein displaced alternately at 1 800 with respect to each other. A feed pipe 160 for acid 80 extends through the inlet pipe 73 and terminates in a cup 162 connected to an inlet pipe 164 which extends into the transfer chamber 1 52, a shroud 165 about the cup 162 providing a splash cover therefor. An inlet tube 167 extends into the inlet pipe 73 to enable the seal chamber 154b to be filled with water.

In use of the apparatus of Figure 4, the feed ofacid 80 into the apparatus through the feed pipe 160 and into the cup 162 is effected without a solid connection between the feed pipe 160 and the cup 162, and the seal chambers 1 54a, 1 54b contain water to trap acid fumes rising in the apparatus. When the apparatus is turned through 1800 the water and hulls 18 in the seal chamber 154b spill into the transfer chamber 152, and on the subsequent reversal of the apparatus, the hulls 18 and the water in the transfer chamber 1 52 spill into the first dissolution chamber 62 then fed through the feed pipe 160 and the inlet pipe 164 into the first dissolution chamber 62 to produce the required acidity therein, and fresh water is fed through the inlet tube 167 into the seal chambers 1 54a, 1 54b.

An example of a lute seal for use with the apparatus of Figures 1 and 2 is shown in Figure 5 to which reference is now made. In Figure 5 the outline of the apparatus 50 of Figure 2 is shown but the housing 74 extends inside a labyrinth compartment 172 which provides two concentric chambers 174, 176 defined either side of a hollow cylinder 177 and intercommunicating through an aperture 178. A hollow cylinder 180 defines the outer periphery of the chamber 176 and is joined by an inturned flange 182 to the housing 74, and the cylinder 177 is joined to the outer casing 70 by an inturned flange 184. The chamber 176 is open to the environment to permit a liquid 186 such as water to be fed into the labyrinth compartment 172.Another labyrinth compartment 172 but of smaller cross-section is provided at the upper end of the apparatus 50, the flange 182 being joined to the tubular housing 72 and the flange 184 being joined to the inlet pipe 73. A labyrinth seal similar to that shown in Figure 5 may be provided for the apparatus of Figure 1.

The apparatus of Figure 2 may be heated, for example locally in the vicinity of the first and the second dissolution chambers 62, 63b. In some applications of the apparatus, because of the heat from fission product decay in the nuclear fuel, it may be necessary to remove heat from these chambers 62, 63h, for example by providing a cooling jacket (not shown) about the chambers 62, 63h. Alternatively a steam chest (not shown) could be disposed about the chambers 62, 63b to bring about a limited amount of cooling if the temperature should rise above the saturation temperature of the steam.

Although the invention has been described in relation to the reprocessing of irradiated nuclear fuel, it will be understood that it may be used for agitating a mixture comprising non-nuclear material. It will also be appreciated that the chambers may be of alternative shape to those aforedescribed, although the annular shape has advantages in inhibiting the aggregation of a critical mass of fissile material.

Claims (17)

1. An apparatus for agitating a mixture comprising a liquid and a multiplicity of solids, the apparatus comprising a chamber rotatably supported at a selected declivity, an inlet means for the mixture at the upper end of the chamber, radially displaced port means at the lower end of the chamber, and means for turning the chamber initially to rock the chamber so as to agitate the mixture and subsequently to spill at least some of the mixture or the liquid or the solids thereof through the port means.

2. An apparatus for agitating a mixture comprising a liquid and a multiplicity of solids, the apparatus comprising an elongate compartment, means rotatably supporting the compartment at a selected declivity, a plurality of baffles axially displaced inside and along the compartment so as to define therebetween a plurality of axially spaced chambers in the compartment, port means in each baffle so as to intercommunicate adjacent chambers, adjacent baffles having the port means thereof in angularly displaced relationship, an inlet means for the mixture at the uppermost of the chambers, an outlet means from the compartment, and means for turning the compartment initially to rock the compartment so as to agitate said mixture therein and subsequently so as to spill at least some of the mixture or the liquid or the solids thereof through alternate port means along the compartment.

3. An apparatus as claimed in Claim 2, wherein adjacent said port means are displaced through about 1800 with respect to each other.

4. An apparatus as claimed in Claim 2 or Claim 3, wherein additional inlet means for liquid are provided to one or more intermediate said chambers.

5. An apparatus as claimed in any one of the preceding Claims, wherein drain means are provided for the chamber or at least some of the chambers, the drain means having a restricted outlet and being positioned so that the liquid in the respective chamber spills through the drain means before the mixture or the solids thereof can spill through the port means.

6. An apparatus as claimed in Claim 5, wherein the drain means is angularly displaced about 900 from the port means.

7. An apparatus as claimed in any one of the preceding Claims, wherein the selected declivity is about 350 from the horizontal.

8. An apparatus as claimed in any one of the preceding Claims, wherein the or each chamber is of annular form.

9. An apparatus as claimed in any one of the preceding Claims, wherein there are provided means for heating or for cooling a said chamber.

10. An apparatus as claimed in any one of the preceding Claims, wherein sealing means are provided between those members of the apparatus in rotational relationship, the sealing means comprising a labyrinth compartment adapted to contain a trapped quantity of a liquid seal therein.

11. A method of agitating a mixture comprising a liquid and a multiplicity of solids, the method comprising introducing the mixture into a declivitous chamber having a radially displaced port means at the lower end of the chamber, rocking the chamber to agitate the mixture in a manner to maintain the port means above the mixture, and subsequently turning the chamber to submerge the port means or a portion thereof below the level of the mixture to cause at least some of the mixture or the liquids or the solids thereof to spill through the port means out of the chamber.

12. A method as claimed in Claim 11, including introducing the mixture into an uppermost of a plurality of said declivitous chambers connected together in a declivitous series thereof with adjacent said port means angularly displaced with respect to each other.

13. A method as claimed in Claim 12, wherein adjacent said port means are angularly displaced through about 1800.

14. A method as claimed in any one of Claims 11 to 13, wherein rocking of the chamber or chambers is through an included angle of about 600.

1 5. A method as claimed in any one of Claims 11 to 14, including turning the chamber or chambers initially to drain some of the liquid from the chamber or chambers through a drain means before the liquid, the mixture, or the solids can spill through the port means.

16. An apparatus substantially as hereinbefore described with reference to Figures 1 and 1 a, or Figures 2. 3 and 5, or Figures 2, 3, 4 and 5 of the accompanying drawings.

17. A method of agitating a mixture substantially as hereinbefore described with reference to Figures 1 and 1 a, or Figures 2. 3 and 5, or Figures 2, 3, 4 and 5 of the accompanying drawings.