US 3471826 A
Description (OCR text may contain errors)
Oct. 7, 1969 HUTTER ETAL 3,471,826
ELECTRICAL CONNECTOR FOR USE IN LIQUID METAL Filed April 4, 1966 42 334 11 25 F1 5 a 3i i W 5 Z; 5254/ 23k Z 2;]
d ,J 59 05 ,a Z8 3 6 12 1a 25w 2% jfl United States Patent 3,471,826 ELECTRICAL CONNECTOR FOR,USE IN LIQUID IVETAL Ernest Hutter, Chicago, and Harris H. Hooker, Naperville, 11]., assignors to the United States of America as represented by the United States Atomic Energy Commission Filed Apr. 4, 1966, Ser. No. 540,092
Int. Cl. Htllr 3/04, .7/02 US. Cl. 339-94 4 Claims The invention described herein was made in the course of, or under, a contract with the United States Atomic Energy Commission.
This invention relates to a sealing arrangement. More particularly, the invention relates to a seal for keeping liquid metal away from electrical connectors for preventing shorting-out.
In certain types of nuclear reactors using sodium as a coolant, it is very desirable to obtain accurate information on operating conditions in the reactor, by means of electrical leads extending down into the reactor well below the sodium level. Disconnectible electric connectors are needed below the sodium level in order that easy access may be had to fuel units in the reactor requiring replacement. The seal of the present invention may, inter alia, be employed to keep sodium away from these electrical connectors.
In the drawing:
FIG. 1 is a longitudinal sectional view of an assembly to which the novel sealing arrangement of the present invention is applied;
FIG. 2 is a transverse sectional View taken on the line 2-2 of FIG. 1; and
FIG. 3 is a transverse sectional view taken on the line 3-3 of FIG. 1.
As shown in FIG. 1, an outer member comprises a tube 11 having an internal shoulder 12 provided on its upper side with a flange 13 having a conical end 13a and an annular groove 14 outward of the flange. A plurality of passages 15 extends downwardly and outwardly from the bottom of the groove 14 to the outside of the tube 11. The outer member 10 also has an inner post 16, whose top is about at the level of the end of the flange 13, and which extends downwardly an appreciable distance to its base. At said base a transverse wall 17 extends radially outward to join the inner post 16 with the tube 11 and is spaced an appreciable amount from a lower side 18 of the shoulder 12. The post 16 has an external peripheral rib 18a near its base. The post 16 is radially spaced from the tube 11 at regions between the wall 17 and the lower side 18 of the shoulder 12 a greater amount than from the shoulder 12. Thus a sodium trap is formed in the annular space bounded by the post 16, the wall 17, the tube 11, and the lower side 18 of the shoulder 12.
An inner member 19 has an external conical surface 20, an annular flange 21 extending therefrom, a thin tubular portion 22 adjoining the conical surface 20, and a thick tubular portion 23 adjoining the conical surface 20 and extending therefrom in the opposite direction from the thin tubular portion 22.
The conical surface 20 of the inner member 19 has mechanical sealing engagement with the conical end 13a of the flange 13 on the shoulder 12 of the outer member 3,471,826 Patented Oct. 7, 1969 "ice 10, and the flange 21 projects into the groove 14. The thin tubular portion 22 of the inner member 19 extends along and closely around the inner post 16 of the outer member 10 past the shoulder to a point near the transverse wall 17 of the outer member and engages the rib 18a on the post 16. The thin tubular portion 22 is appreciably spaced radially from the tube 11 of the outer member 10 between the wall 17 and the shoulder 12. The thick tubular portion 23 of the inner member 19 extends along and within the tube 11 of the outer member 10 and has axially spaced external peripheral ribs 23a engaging the interior of the tube 11. Each rib 23a is made discontinuous by a plurality of peripherally spaced slots 23b, as is illustrated in FIG. 3 for the lower of the two ribs 23a.
The inner member 19 is held in the outer member 10 by means of a spring 24 and a retainer 25 which has a bayonet connection with the outer member. The spring 24, which acts against a nut 25a adjustably positioned in retainer 25, yieldingly urges the conical surface 20 of the inner member 19 against the conical end 13a of the flange 13 on the shoulder 12 of the outer member 10.
The post 16 of the outer member 10 is hollow and carries an insulator 26, which is retained in the post by a snap ring 27. Mounted in the insulator 26 are a set of male electrical connectors 28, which slidably engage a set of female electrical connectors 29 mounted in an insulator 30. The latter insulator is carried by the inner member 19 and is retained therein by a snap ring 31. Electrical leads 32 coated with ceramic insulation extend from the connectors 29 through the inner member 19 and a conduit 33.
A pump 34 is connected to the conduit 33 for supplying argon at a slight pressure through the conduit, the inner member 19, and openings 35 in the insulator 30 between the thin tubular portion 22 of the inner member 19 and the post 16 of the outer member 10, between the thin tubular portion and the tube 11, between the thin tubular portion and the shoulder 12, between the thin tubular portion and the flange 13, and between the conical surface 20 of the inner member 19 and the conical end 13a of the flange 13 to the groove 14. The purpose of the pressurized argon thus fed is to prevent sodium located outside the outer member 10 from finding its way into the space between the insulators 26 and 30, where it might short out the electrical connectors 28 and 29.
The assembly of parts just described may be used for measuring temperatures in a sodium-cooled nuclear reactor (not shown) having closely packed parallel fuel units each consisting of an hexagonal casing and a plurality of clad fissile rod-like elements positioned therein. The sodium is pumped through the reactor in a plurality of parallel paths, one to each unit through the casing thereof and over the elements. For temperature studies in the reactgr core, thermocouples are inserted in one or more of the units, and the apparatus of the present invention may be used for connection of the thermocouples. The outer member 11 is an integral or separate axial extension of a unit where thermocouples are placed. Thus, like the casing of a fuel unit, the outer member 10 has the exterior shape of a hexagon. Two thermocouple wires 36 and 37 of different metals coated with ceramic insulation, are connected to two electrical connectors 28 and extend therefrom through a tube 38 down to the nuclear-reactor core in a manner not shown where they have a junction (not shown). Two more thermocouple wires 36 and 37 are illustrated as connected to two more electrical connectors and extending down through another tube 38 to another junction in the reactor core. It is to be understood that there may be other sets of thermocouple wires 36 and 37 to the extent that the size of the insulators 26 and 30 will permit. A single wire may also be provided in each tube 38 to test for a leak in a given fuel element. In this arrangement, there may be 7 to 19 of such single wires, because in one fuel unit there may be 19 fuel elements arranged as one element, a first ring of 6 elements, and a second or outer ring of 12 elements.
The tubes 38, which are of stainless steel, are sealwelded to openings in a wall 39 extending transversely across the inner post 16 near its lower end. The outer member 10, the inner member 19, the spring 24, the retainer 25 and the conduit 33 are formed of stainless steel.
During operation of the nuclear reactor, sodium is pumped into the fuel units at their lower ends and leaves these units at upper regions thereof at the top of the reactor core. This goes on below the level of the parts shown in FIG. 1. During reactor operation the level of the body of sodium being pumped is as indicated by a dash-dot line 40, above the lower end of the conduit 33. Because sodium extends up to line 40, it might conceivably reach the mechanical seal formed between the conical surface 20 on the inner member 19 and the conical end 13a of the flange on the shoulder 12 of the outer member 10, by way of the drain holes 15 and groove 14 and by way of the small spaces between the outer member 10, the retainer 25, and the inner member 19. Yet. the sodium cannot reach the aforesaid mechanical seal, because the argon collected in the annular pocket formed between the bottom of the annular groove 14 and the flange 21 keeps it out and the very narrow space between the groove 14 and the sides of the flange 21 help to impede the sodium.
When one or more fuel assemblies of the reactor are to be replaced, the reactor is shut down, and the pumping of sodium through the fuel units is stopped. The level of the sodium is lowered from the line 40 through the conduit 33 to a dash-dot line 41 about at the level of the transverse wall 17. If the fuel unit to be removed has the parts of FIG. 1 formed as its upper extension, it is of course imperative that the conduit 33 be removed before a lifting device can be applied to the fuel unit for removing it from the reactor. If the fuel assembly to be removed lies elsewhere than directly below the parts of FIG. 1, it is highly desirable to remove the conduit 33 in order to take it out of the way of the lifting tool as it is being lowered to the fuel assembly to be replaced.
When the conduit 33 is removed, the inner member 19, spring 24, and retainer 25, which are connected With the conduit, are also removed. When the inner member 19 and retainer 25 are removed, any residual sodium on the outer member may find its way to the inside thereof by way of the open top thereof of grappling holes 42, one of which appears in FIG. 1. The sodium thus reaching the inside of the outer member 10 will flow into the groove 14 and out through the drain holes 15 or into the large trap formed between the tube 11 and the post 16 and between the transverse wall 17 and the lower side 18 of the shoulder 12. Thus there is little, if any, chance that the residual sodium reaching the inside of the outer member 10 will find its way to the top of the insulator 26 and the electrical connectors 28 either by flowing down thereto or by accumulating sufiiciently in the aforesaid trap as to overflow it.
The purpose of the ribs 23a on the inner member 19 is to center it in the outer member 10 and thus to insure that the flange 13 of the inner member readily enters the space within the flange 21 of the outer member. The purpose of the slots 23b in the ribs 23a is to prevent them from acting like pistons in pushing sodium .7 4 clinging to the inside of the outer .member 10 toward the sealing surfaces 13a and 20 upon reassembling of the members 10 and 19.
It is understood that the invention is not to be limited by the details given herein but that it may be modified within the scope of the appended claims.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. An assembly comprising (1) an outer member comprising a (a) tube,
(b) an internal shoulder attached interiorly to the tube and provided at one side with an annular flange and an annular groove directly radially outward of the flange, the flange having a conical end, the outer member :further comprising (c) an internal post having a top about at the level of the end of the flange, the post being radially inwardly spaced from the shoulder and the flange and extending axially to a base located an appreciable distance beyond the other side of the shoulder opposite the said one side, the post having near its base an external peripheral rib, the outer member also having (d) a transverse wall extending radially inwardly from the tube to the post at the base thereof, the post being radially spaced from the tube at the regions between said wall and the said other side of the shoulder a greater amount than from the shoulder, whereby a sodium trap is formed in the annular space bounded by the post, the wall, the tube, and the said other side of the shoulder,
(2) an inner member having (a) a conical surface located in mating engagement with the conical end of theflange on the shoulder of the outer member and (b) an annular flange radially outward of the conical surface and extending into the groove on the shoulder, the inner member having (c) a thin tubular portion adjoining the conical surface and extending axially in one direction along and around the inner post of the outer member to a point near the transverse wall thereof so as to arrange the rib on the post, the thin portion being radially spaced from the interior of the tube between the shoulder and the wall, the inner member also having (d) a thick tubular portion extending from the conical surface in the opposite direction to the thin tubular portion within the tube and having axially spaced peripheral ribs engaging the interior of the tube,
(3) a first set of electrical connectors mounted in the post,
(4) a second set of electrical connectors mounted in the inner member and being engaged with the electrical connectors of the first set upon engagement of the conical surface of the inner member with the conical end of the flange on the shoulder of the outer member,
(5) a conduit connected with the inner member,
(6) leads to the electrical connectors of the second set extending through the conduit, and
(7) means :for supplying gas under pressure through the conduit between the thin tubular portion of the inner member and the post, between the thin tubular portion and the tube of the outer member, between the thin tubular portion and the shoulder, and between the conical surface of the inner member and the conical end of the flange on the shoulder to the bottom of the annular groove in the outer member outward of the flange.
2. The assembly specified in claim 1 and further comprising a first insulator mounting the first set of electrical connectors in the post, and a second insulator mounting the second set of electrical connectors in the inner member and having openings for passing the gas under pressure.
3. The assembly specified in claim 2, the outer member being provided with drain openings leading to the exterior of the outer member from the annular groove in the said one side of the shoulder.
4. The assembly specified in claim 3, the members being held together in a bayonet connection, the assembly :further comprising a spring for yieldingly urging the conical surface of the inner member against the said one side of the shoulder of the outer member.
References Cited UNITED STATES PATENTS 2,248,588 7/1941 Shanklin et a1. 174---21 2,376,265 5/1945 Meredith 17421 2,620,029 12/1952 Turechek et al. 33996 MARVIN A. CHAMPION, Primary Examiner I. H. MCGLYNN, Assistant Examiner US. Cl. X.R. 339-117