US3766951A

US3766951A - Topic noncontaminating fuel capsule loading systems

Info

Publication number: US3766951A
Application number: US00046321A
Authority: US
Inventors: H Rexford; D Harvey
Original assignee: Sanders Nuclear Corp
Current assignee: CAMBRIDGE NUCLEAR Corp; Sanders Nuclear Corp
Priority date: 1970-06-15
Filing date: 1970-06-15
Publication date: 1973-10-23
Anticipated expiration: 1990-10-23

Abstract

Fueling systems and methods for loading radioisotopic fuel capsules provide for efficient fuel loading without contaminating the exterior surface of the fuel capsules. The systems comprise clamp means, for holding a capsule during a fueling operation, preferably having cooling means associated with the clamp means. A fueling tool receives radioisotopic fuel in microsphere form and passes the fuel into the fuel chamber through a fill opening provided by the capsule. At least one compression seal is formed between the fueling tool and the capsule to prevent undesired leakage of the microspheres. Preferably the fueling tool has a self sealing plug through which a fill tube can be passed during fueling with the tube later withdrawn to cause sealing of the plug preferably prior to removal of the fueling tool.

Description

United States Patent Rexford et al.

[ 1 Oct. 23, 1973 RADIOISQTOPIC NONCONTAMINATING primary Examiner samuel a Rot-hberg FUEL CAPSULE LOADING SYSTEMS AttorneyL0ulS Etlinger 57 Inventors: Harry E. Rexford; Douglas G. [57j AliSTRACT Harvey both of Nashua NH. F l' s stems and methods for loading radioisotopic *'*r uemg y [73] Asslgnee' $2 13 2; Corporation fuel capsules provide for efficient fuel loading without J contaminating the exterior surface of the fuel cap- [211 App 46321 sules. The systems comprise clamp means, for holding a capsule during a fueling operation, preferably having [52] US. Cl 141/37, 141/11, 141/59, cooling means associated with the clamp means. A fu- 53/25 cling tool receives radioisotopic fuel in microsphere [51] Int. Cl... B2ld 21/00, 823p 19/04, B65b 31/02 form and passes the fuel into the fuel chamber [58] Field of Search 53/25, 127; 141/11, through a fill opemng provided by the capsule. At I 141/59, 82, 98, 329, 369, 370, 383 least one compression seal is formed between the fueling tool and the capsule to prevent undesired leakage [56] References Cited of the microspheres. Preferably the fueling tool has a UNITED STATE PATENTS self sealing plug through which a fill tube can be passed during fueling with the tube later withdrawn to cause sealing of the plug preferably prior to removal 2,475,317 7 1949 Gess 141/82 x of the fuelmg tool- ,513,l 3 6/1950 Carter 141/59 X 3,455,347 7/1969 Lambert 141/65 6 Claims, 8 Drawing Figures l g 1Q I l 54 52 l 36 l l 5 7 L 25 53 i I 56 l l 37 I I0 1 I? I I H l 26 23 2| 27 24 l5 I3 27 I 30 20 25 I 2IA l4 PATENTEU 0B! 2 3 I975 SHEET 10F 4 ATTORNEY PATENTED 0U 23 I973 SHEET 2 [IF 4 lNVE/VTORS HARRY E. REXFORD DOUGLAS G. HARVEY ATTORNEY PAIENIEMnzama 3L766L951 SHEET 3 BF 4 FIG. 6

IN VE N TORS HARRY E. REXFORD DOUGLAS G. HARVEY A TTOR/VE Y PAIENIED 9t! 23 I975 FIG? lNlfENTO/PS HARRY E. REXFORD DOUGLAS G. HARVEY RADIOISOTOPIC NONCONTAMINATING FUEL CAPSULE LOADING SYSTEMS BACKGROUND OF THE INVENTION terior of the capsule by means of a fill hole which is later plugged. Particularly in vented type capsules or those having rough surfaced outer containment walls, some of the particulate radioisotopic material can be entrapped on the capsule exterior or collect there due to dusting from the pouring device used or by airborne particulate matter. The capsule exterior is thus contaminated and various decontamination procedures must be carried out before the capsule is ready for use. Moreover, as the filling proceeds, heat buildup about the capsule increases, causing a hazard unless cooling procedures are used.

It is an object of this invention to provide efficient fueling systems for loading radioisotopic fuel capsules without causing contamination of the exterior surfaces of the capsules.

Another object of this invention is to provide fueling systems in accordance with the preceding object which systems are highly efficient and can be rapidly used.

Still another object of this invention is to provide fuelding systems in accordance with the preceding objects which enable cooling of the capsules during the fueling to maintain the capsules at workable temperatures.

Still another object of this invention is to provide compression seal means for use in fueling radioisotopic fuel capsules without contaminating exterior surfaces of said capsules.

A still further object of this invention is to provide novel and improved elements for use in the fueling systems of this invention.

SUMMARY OF THE INVENTION According to the invention fueling systems for loading a radioisotopic fuel capsule have a fill passageway and a fuel chamber, and comprise a clamp means for holding the capsule during the fueling operation. Means are preferably associated with the clamp means for cooling the capsule during filling. A fueling tool means receives radioisotopic fuel in microsphere form and passes fuel into the fuel chamber through the fill passageway. A compression seal means seals the fueling tool means against unwanted leakage of the fuel to areas other than the fill passageway whereby the fuel is loaded into the capsule without causing unwanted radioisotopic contamination.

Preferably the fueling tool carries a fill tube and a self sealing plug so that the fill tube which carries the mi crospheres can be sealed prior to and after filling of the capsule.

In one embodiment, a compression seal is formed by an inflatable bladder which forms a double seal in conjunction with the clamp means and the fuel capsule. The clamp itself preferably provides a compression seal about the fill opening.

According to the method of this invention a radioisotopic fuel capsule has a fill passageway defining an outer opening on an outer surface of the capsule and a fuel chamber. The capsule is held in a clamping means with a resilient compression seal means isolating the fill opening on the surrounding surface of the capsule. A fueling tool means is introduced for transferring radioisotopic material in microsphere form into operative position within the chamber. A compression seal is formed between the fueling tool means and a surrounding atmosphere so that the capsule can be loaded without contaminating the surrounding atmosphere or the outer capsule surface.

In a preferred embodiment, the fueling tool preferably carries a vent tube for venting while filling the capsule to enhance ease of filling.

It is a feature of this invention that the systems and methods allow sequential filling of capsules of various sizes and shapes without contamination of capsule outer surfaces. Filling can be carried out rapidly and efficiently. The microsphere form of the fuels used is advantageous with a number of different radioisotopic materials. Room temperature filling can be carried out easily by the use of suitable cooling means acting jointly with the clamp means.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be better understood from a reading of the following specification when read in conjunction with the accompanying drawings in which:

FIG. 1 is a semi-diagrammatic illustration of a preferred embodiment of a fueling system in accordance with this invention;

FIG. 2 is a cross sectional view through an element thereof;

FIG. 3 is a semi-diagrammatic cross sectional'view through an alternate embodiment of elements thereof;

FIG. 4 is a semi-diagrammatic view of an alternate embodiment of a fuel system of this invention;

FIG. 5 is a semi-diagrammatic view of an element of the system of FIG. 4 showing fill and vent tubes in an alternate position;

FIG. 6 is a semi-diagrammatic view of an accessory useful with the systems of this invention;

FIG. 7 isa cross sectional view through an alternate embodiment of the filling tool in accordance with this invention; and

FIG. 8 is a cross sectional view through a modified fuel capsule in accordance with this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS With reference now to the drawings and more particularly FIG. I a preferred radioisotopic fueling system is indicated generally at 10 and comprises a fueling tool 11 for loading a fuel capsule 12 maintained in position by

clamp plates

13 and 14 with

compression seals

15 and 16 acting to prevent contamination. The system 10 is preferably enclosed in a dry box (indicated by dotted lines 17 having a controlled atmosphere such as a vacuum or inert gas. Suitable filling and venting means are interconnected with the fueling tool.

The systems of this invention are designed to fuel various sized and geometrical shaped fuel'capsules without contaminating the exterior surface of the capsules. However, spherical fuel capsules such as 12 of small size preferably having outside diameters of from 0.25 to 12 inches, are described herein in order to simplify the description. The particular fuels used can be any emitting isotopes. Biological shielding required will depend on the isotope and quantity used. The radioactive isotopic materials are preferably in microsphere form. Such microspheres are conventionally made by adding fine powders of thulium oxide for example to a plasma arc where the powders are vaporized into liquid form with the liquids later reformed into solids and the liquid surface tension acting to form microspheres. The microspheres preferably have diameters of from 50 to 200 microns. Conventional radioactive isotopes such as thulium 170, thulium 171, P 210, Pm 147, Pu 238 and Tl 204 can be used in the system of this invention.

In the preferred embodiment, the fuel capsule 12 is formed of a conventional fuel capsule material such as Hastealloy to provide structural strength while providing for good heat transfer. A capsule chamber is provided with a cylindrical fill passageway 22 defining an outer opening having a diameter of 0.5 inch. The particular size of the fill opening can vary as known in the art with variation in sizes and types of fuel capsules used.

The clamp means for holding the capsule in position during fueling comprises upper and

lower clamp plates

13 and 14 preferably formed of polished stainless steel having upper and lower spherical recesses 21 and 21A designed for the specific capsule such as 12 to hold it firmly in position. The spherical portion 21 is provided with a through hole 23 to allow passage of the fueling tool as will be described. A smooth soft silicone rubber gasket 24 is positioned between the clamp plate and capsule. The gasket 24 acts as a compression seal between the outer surface 25 of the capsule and the clamp plate. This gasket is also provided with a fill hole 26 preferably of substantially the same size as hole 23. In use, the clamp plates are pressed together, by conventional clamp means indicated diagrammatically at 27, to form a compression seal between the outer surface of the capsule and the clamp plate 21 thus preventing contamination about the fill passageway 22 since the opening of the fill passageway 22 is entirely surrounded by the gasket 24.

The clamp plates further provide a chamber 30 surrounding the capsule which enables a cooling heat transfer fluid to be passed about the capsule during filling. Thus, the temperature of the fuel capsule can be maintained at a workable temperature such as room temperature during filling even as the fuel chamber within the capsule is filled.

The fueling tool 11 is best illustrated in FIG. 2 and comprises a stainless steel or other preferably metallic cylindrical tube 31 having an axially extending through passageway 32 and a recessed end wall 33. Within the end wall 33 is placed a resilient silicone rubber plug or other self-sealing plug 34. In the preferred embodiment, the plug 34 is maintained in position by a metallic ring 35welded to the tube 31. Within the passageway 32 are located fuel fill tube 36 and vent tube 37. The

tubes

36 and 37 are preferably stainless steel hypodermic tubes having pointed tips to enable the tubes to be pushed through the rubber plug 34 during filling and withdrawn therefrom completely into the passageway 32 after filling if desired. The hypodermic tubing can be standard stainless steel hypodermic tubing as for example, using 13 guage tubing (0.059 inch, outside diameter, 0.071 inch inside diameter) for the

fill tube

36 and 31 gauge tubing (0.010 inch outside diameter, 0.005 inch inside diameter for the vent or evacuation tube 37. Preferably the vent or evacuation tube is of a smaller inside diameter than the fill tube to reduce the rate at which gas is displaced from within the fuel capsule to minimize pertubation to microspheres as they exit the fill tube and enter the chamber 20 of the fuel capsule. The tubing sizes can vary depending upon particular materials, capsules and tools used.

In some cases the vent tube can be eliminated particularly where fueling is carried out under vacuum conditions within the chamber of as for example -l0 p.s.i.g.

A compression seal for the fill tool is formed by an extensible and collapsible resilient bladder 40. The bladder 40 is preferably fabricated of resilient soft silicone rubber tubing which has an inside diameter that matches the outside diameter of the stainless steel tube. The tubing of the bladder 40 is slid over the outside of the stainless steel tube for a length extending from the lower end of the tube to preferably at least an inch above the point on the tube that extends beyond the clamp plate 21 as shown in FIG. 1. A small inflation and evacuation port is provided by a tube 41 which may be formed of Teflon or other plastic and extends into the bladder and is hermetically sealed at its point of entrance as with any conventional sealant material. Heat

shrinkable collars

43 and 42 are positioned at ends of the rubber tubing of the bladder with the end of the bladder turned thereover and the collars shrunk in place to define an airtight bladder.

The fuel can be provided to the fill tube 36 by any conventional means such as a microsphere fuel container 50 operated by a vibrator 51 and connected to the fill fuel tube 36 by a standard connector 52. Similarly, conventional evacuation means are connected to the evacuation tube 37 through a standard connector 53. Evacuation means can comprise a manometer 54 for monitoring the vacuum to be created, an absolute filter 55, standard control valve 56 and standard vacuum pump 57. A control valve (not shown) is positioned at the container 50 to enable closing and opening of the flow to'the fill tube when desired.

In carrying out the method of this invention, the system 10 is used with the fuel capsule 12 positioned between the clamp plates which are clamped together to form a support and cooling fixture while sealing the area about the exterior opening of the fill passageway 22. The fueling tool 11 is centered within the fill opening 22 and preferably protrudes into the chamber 20 a sufficient amount for it to enable the bladder 40, when it is inflated, to form a seal both inside and outside the fuel capsule as best shown in FIG. 1. The bladder 40 is then inflated sufficiently for it to balloon out over the top of the clamp plate and over the inside of the fuel capsule to form a good compression seal between the clamp plate and fueling tool, passageway 22 and the filling tube. The hypodermic tubes 36-and 37 are then caused to penetrate the tubber plug 34. Cooling fluid is passed about the fuel capsule within the clamp plates and the capsule is fueled by activation of vibrator 51.- In a specific embodiment, the inside diameter of the capsule is 2 inches, Pu 238 in microsphere form (diameter 10 micron) is used, the tubing hypodermic tubing sizes are as noted above. The vacuum pump 57 creates a vacuum of-lO p.s.i.g. within the capsule as a fuel is passed therein. The entire fueling operation is carried out in a dry box under an inert gas atmosphere. After filling of the capsule, tubing 37 is closed to the chamber by a control valve and moved upwardly with respect to the rubber plug as is tubing 36 to have their ends lying within the passageway 32 which is closed by the self-sealing plug 34. The bladder 40 is deinflated and the fueling tool removed. A conventional plug (not shown) is sealed in the opening 22 as by force fitting or welding to seal the fully fueled capsule. The clamp plates are released and the loaded capsule is ready for use.

It should be noted that the multiple compression seals formed by the bladder 40 and the gasket 24 act to effectively prevent any contamination of the outer surface 25 of the capsule. The movement of the hypodermic needles to the inside of the stainless steel tubing 31 causes the rubber plug to self-seal before the fueling tool 11 is removed and further avoids any possibility of contamination. A further capsule contamination preventitive feature is the upper clamp plate 13 which covers the top surface of the capsule as best seen in FIG. 1.

Turning now to an alternate embodiment of the invention as illustrated in FIG. 3, a modified fuel capsule 12A is used. In this embodiment indicated generally at 60, elements identical to the elements of embodiment 10 are designated by identical numerals.

In this embodiment the fuel capsule 12 has an outer containment wall as previously described also has a conventional fuel capsule inner liner 61 which may be formed of refractory metal or ceramic material. Such inner liners are often used to provide chemical and/or thermal compatibility with the fuel. The capsule is held in a clamping and cooling means comprising clamp plates 13 and 14 'as previously described. However, cooling here is carried out by the provision of a cooling means comprising cooling channel 62 which may be of resilient tubing extending about the capsule.

In the embodiment 60, the fuel capsule 12A has a modified fill passageway comprising a first funnel or frustoconical shapedfill passageway 63 in the liner 61 and a cylindrical threaded bore 64 of larger diameter than the diameter of the passageway 63. The bore 64 is provided with a resilient compressible gasket 65 as of silicon rubber and a polished stainless steel externally threaded sleeve 66. The stainless steel threaded sleeve is provided with a high surface polish tolenable ease of removing any contamination which occurs during fueling. The modified fuel capsule 12A can be used in conjunction with the fueling tool 11 as previously described.

The modified fuel capsule 12A is preferably used in conjunction with a modified fueling tool of this invention as best illustrated in FIGS. 4 and 5. The system of FIG. 4 is generally similar to the system 10. In this system, the fueling tool 70 comprises a brass tube 31 as previously described and a rubber plug 71 functioning as does rubber plug 34. However, the plug 71 has a frustro conical end surface 72 designed to mate with funnel shaped opening 63 of the capsule liner 61. A ring 35 as previously described mounts the plug 72 to seal the lower end of the fueling tool. The upper end of the fueling tool is similarly sealed by a resilient. rubber plug 73.

A second loading chamber or bin 75 is provided preferably filled with a wash material such as zirconium dioxide microspheres. Bin 75 is interconnected with the system by suitable conduits as illustrated and on off

flow control valves

76, 77 and 78 are provided.

In use of the system of FIG. 4, the clamp means is positioned as previously described after first inserting sleeve 66 to form a compression seal by the use of the gasket 65. The cooling channels 62 are activated to provide continuous cooling. The fueling tool 70 is then inserted to compress the plug 71 forming a seal between it and the funnel shaped passageway 63. The fueling tool can be held by hand or by a suitable jig not shown.

Tubes

36 and 37 are then caused to pierce the plug 71 so that the position shown in FIG. 4 results. The

control valves

76, 77 and 78 are then suitably actuated along with the vacuum pump and vibrator to cause a vacuum within the chamber of the fuel capsule and to cause passage of the radioisotopic microspheres into the chamber 20. Shortly before complete filling of the chamber the control valve 77 is opened and the zirconium dioxide microspheres displace the radioisotopic material within the tubing 36 to form a slight coating over the top surface of the microspheres within the chamber 20. This cleans the tubing 36 further avoiding contamination during withdrawal of the fueling tool 70. After filling, all control valves are closed, the pressure in the chamber 20 of the fuel capsule equalized with the pressure of the dry box and the

tubes

36 and 37 are moved to the position shown in FIG. 5 allowing self sealing of the plug 71. The fueling tool is then removed and a suitable plug for the capsule inserted. If desired, the plug used can plug only the liner 61 allowing washing of the inside of sleeve 66 and subsequent plugging of the sleeve or removal of the sleeve and insertion of the suitable threaded plug.

Turning now tothe device of FIG. 6, a cylindrical closed end cap 80 is illustrated carrying a resilient silicon rubber grommet 81 dimensioned to snugly receive the fueling tool 70. The end cap 80 is preferably used when removing the fueling tool 70 or 11 to cover the exposed surface of the plug in order to further avoid any chance of contamination as by microspheres falling off the plug.

Turning now to an alternate embodiment of this invention, (FIG. 7) a fuel capsule such as 12A. is further modified at its fill passageway by the provision of a cylindrical hole coaxial with the frustroconical open ing 63 of the liner. In this embodiment the self sealing plug 71' is adapted to be compressed against the frustroconical portion 63'. A single hypodermic tube 91 is used in the fueling tool 70' without a vent tube and need not be pointed at its lower end. The hypodermic tube 91 is coaxially aligned with element 31 and is designed to form a right cylinder from a swage lock coupling end 92 to its lower filling end 93. The diameter of the tube 91 is selected to have an inside diameter greater than the diameter of fill hole 90. In this embodiment, venting is not used and the microspheres are introduced through the hypodermic-tube 91 without creation of vacuum conditions within the fuel capsule. This embodiment enables passage of a plug 94 through the bore of the hypodermic tube 91 after filling of the capsule to seal the hole 90 prior to removal of the fueling tool 70. Thus, the fueling tool is positioned to form a compression seal by means of the plug 71 and microspheres are passed into the chamber of the fuel capsule until the desired level in chamber 20' is reached. The swage lock coupling 92 is then disconnected from a microsphere bin or reservoir and the plug 94 introduced by means of a suitable ram or chuck which may be a vacuum chuck. The plug 94 is passed through the bore of the hypodermic tube and rammed into place to seal the opening 90. After sealing, the fueling tool 70. is withdrawn. Decontamination of the sleeve 66 can be carried out if desired as by flushing with a suitable solution.

In still another modification of a fuel capsule useful in this invention, a fuel capsule 128 having an outer containment wall and a liner 61" is provided with a fueling port formed of a metallic block 100 welded to the liner 61" as at 101. The block 100 has a threaded circular bore 102, a frustroconical surface 63" as previously described and a fill passageway formed by a bore 90 substantially as previously described. An integral, continuous circular rib 104 extends into the bore 90. Block 100 is preferably of a hard metal such as Hastealloy. The outer containment wall is preferably provided with a gasket seal 65 and acontainment prevention sleeve 66" as previously described. The fuel capsule 123 can be loaded by fueling tools such as 11 and 70 as previously described. After filling and removal of the fueling tool a primary plug seal for the liner is formed by the use of plug 105 which may be of a resilient plastic or soft metal. A secondary fuel capsule seal is formed by a metallic secondary plug 106 threaded to match the threading 64". A further seal can be provided in the fuel capsule by a plug positioned within the sleeve 66" or by removal of the sleeve 66" and insertion of a solid plug if desired. The use of more than one seal plug is desirable since decontamination steps can be carried out as by flushing after each seal plug is positioned to further insure decontamination of the capsule.

While specific embodiments of this invention have been shown and described, many variations are possible. For example, while frustroconical plug sealing surfaces have been described, the fuel capsule and fueling tool plug can have other configuration angled sealing portions which generally mate with each other. Gravity flow aided by vibration is preferably used to cause movement of the microspheres; however, other means such as air pressure can be used to aid flow. While microspheres are preferred for use, any radioisotopic flowable particles can be loaded in accordance with this invention. For example, radioisotopic shpheres up to about 0.25 inch can be used in the methods of this invention. Such spheres can be suitably coated as with vapor deposited metals to give a radioactive contamination-free surface. It is preferred that the fuel capsules filled by the process of this invention have interior chambers corresponding to diameter sizes of no greater than 10 inches and that the filling tubes for passing the als identify identical parts.

What is claimed is:

l. A fueling system for loading a radioisotopic fuel capsule having a fill passageway and a fuel chamber,

said system comprising clamp means for holding a radio-isotopic fuel capsule during a fueling operation,

cooling means associated with said clamp means for cooling said capsule, fueling tool means for receiving radioisotopic fuel in flowable particulate form and passing said fuel into said fuel chamber through said fill passageway,

said fueling tool means comprising a tool tube defining a passageway therethrough and a plug at one end thereof, and a radioisotopic fuel fill tube and a vent tube positioned with said first-mentioned tube and constructed and arranged to be passed through said plug in use and compression seal means for sealing said filling tool means against unwanted leakage of said fuel to areas other than said fuel chamber whereby said fuel can be loaded into said capsule without causing unwanted radioisotopic contamination.

2. A fueling system in accordance with claim 1 and further comprising, means for passing said radioisotopic fuel to said fill tube and means for applying a vacuum to said vent tube,

said plug being formed of a self-sealing material.

3. A fueling system in accordance with claim 1 wherein a portion of said tool tube is surrounded by an inflatable bladder constructed and arranged to form a compression seal about a surrounding portion of said clamp means when said fueling tool is passed through said clamp means.

4. A fueling system in accordance with claim 1 wherein said plug is formed of a self-sealing resilient material and defines an angled sealing portion,

said capsule fill passageway defining generally an angled sealing portion constructed and arranged to mate with said portion of said plug to form a compression seal.

5. A fueling system in accordance with claim 1 wherein said clamp means defines a clamp means passageway therethrough to enable positioning of said fueling tool means in said clamp means passageway in operative relationship with said fill passageway of said capsule,

and a gasket positioned between said clamp means and said capsule whereby a compression seal can be formed therebetween.

6. A fueling system in accordance with claim 4 wherein said clamp means defines a clamp means passageway therethrough to enable positioning of said fueling tool means in said clamp means passageway in operative relationship with said fill passageway of said capsule,

Claims

1. A fueling system for loading a radioisotopic fuel capsule having a fill passageway and a fuel chamber, said system comprising clamp means for holding a radio-isotopic fuel capsule during a fueling operation, cooling means associated with said clamp means for cooling said capsule, fueling tool means for receiving radioisotopic fuel in flowable particulate form and passing said fuel into said fuel chamber through said fill passageway, said fueling tool means comprising a tool tube defining a passageway therethrough and a plug at one end thereof, and a radioisotopic fuel fill tube and a vent tube positioned with said first-mentioned tube and constructed and arranged to be passed through said plug in use and compression seal means for sealing said filling tool means against unwanted leakage of said fuel to areas other than said fuel chamber whereby said fuel can be loaded into said capsule without causing unwanted radioisotopic contamination.

2. A fueling system in accordance with claim 1 and further comprising, means for passing said radioisotopic fuel to said fill tube and means for applying a vacuum to said vent tube, said plug being formed of a self-sealing material.

4. A fueling system in accordance with claim 1 wherein said plug is formed of a self-sealing resilient material and defines an angled sealing portion, said capsule fill passageway defining generally an angled sealing portion constructed and arranged to mate with said portion of said plug to form a compression seal.

5. A fueling system in accordance with claim 1 wherein said clamp means defines a clamp means passageway therethrough to enable positioning of said fueling tool means in said clamp means passageway in operative relationship with said fill passageway of said capsule, and a gasket positioned between said clamp means and said capsule whereby a compression seal can be formed therebetween.

6. A fueling system in accordance with claim 4 wherein said clamp means defines a clamp means passageway therethrough to enable positioning of said fueling tool means in said clamp means passageway in operative relationship with said fill passageway of said capsule, and a gasket positioned between said clamp means and said capsule whereby a compression seal can be formEd therebetween.