Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
  • G21C3/30—Assemblies of a number of fuel elements in the form of a rigid unit
  • G21C3/32—Bundles of parallel pin-, rod-, or tube-shaped fuel elements
  • G21C3/334—Assembling, maintenance or repair of the bundles
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B21/00—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings
  • F16B21/10—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts
  • F16B21/16—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts with grooves or notches in the pin or shaft
  • F16B21/18—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts with grooves or notches in the pin or shaft with circlips or like resilient retaining devices, i.e. resilient in the plane of the ring or the like; Details
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• the interfaces must support axial tensile and compressive loads during normal operation, such as those loads from assembly holddown springs or lifting of the fuel assembly during handling.
• the interfaces must also support bending loads during abnormal conditions, such as loads from fuel assembly lateral deflections induced by seismic conditions.
• these joints must also permit removal of the nozzles for fuel reconstitution, preclude a possibility of generating loose parts during operation, and withstand the effects of the reactor operating environment for the fuel lifetime. Many designs exist which satisfy these requirements.
• a screwed connection at the joint that contains a deformable feature to prevent its "backing out” or counter-rotation during operation.
• a second category includes the type of joint that relies on grooves and projections in mating pieces which are slid together and then locked with a separate sleeve.
• the third category of joint involves a quarter-turn type having quick-disconnect components using a spring and moving parts.
• a second aspect of the present invention resides in a joint comprising: a first member having a throughhole in which a first circumferential groove and an axial slot are formed, the axial slot leading to and merging with the first circumferential groove; a shaft-like member which is disposed through the throughhole, the shaft-like member having a second circumferential groove formed thereabout; and a retaining ring having lugs at the end thereof, the retaining ring being disposed in the first and second circumferential groove with the lugs received in the axial slot, the retaining ring being partially received in the first circumferential groove and partially received in the second circumferential groove so as to interlock the shaft-like member in the first member.
• Fig. 1 is a sectional elevation of a female part of a preferred embodiment of the present invention
• Fig. 5 is a side elevation of a male portion of the preferred embodiment.
• Fig. 6 is a partially sectioned elevation showing the male and female portions connected with one another.
• Fig. 7 is a front elevational view of a conventional fuel assembly with inserted control rod assembly to which the joint, which characterizes the present invention, is applicable.
• Figs. 1 and 2 show details of a nozzle 1 which includes a throughhole 2 and a circumferential groove 4 which is formed partway along the axial height of the throughhole.
• An axial access slot 6 is milled along the wall of the throughhole 2 and is formed so as to extend axially slightly beyond the circumferential groove 4.
• Figs. 3 and 4 show a retaining ring 8 inserted into the circumferential slot 4.
• the ring is essentially C-shaped and has a lug 10 at each of its free ends.
• the ring 8 is inserted by forcing the two lugs 10, 10 together, lowering it into the throughhole 2 of the nozzle 1, and then releasing the lugs 10, 10.
• this procedure results in the retaining ring 8 being partially received in the groove 4, and azimuthally constrained by the access slot 6.
• the ring I.D. is designed to be smaller than that of the nozzle throughhole 2 (and the O. D. of a thimble 12 which is disposed in the throughhole) when the ring 8 is in an unstressed condition and assumes its original configuration.
• Initial connection of the joint is accomplished by lowering the nozzle 1 onto the chamfered upper tip 12a of the guide thimble 12.
• the I.D. of the retaining ring 8 is smaller than the O.D. of the guide thimble 12 at this stage.
• a tool (not shown) is positioned above the joint such that a tool extension enters and is centered by the I.D. of the throughhole 2.
• an outlying feature engages the lugs 10, 10 of the retaining ring 8.
• this tool extension can be adapted to enter the holes 10a, 10a formed in each of the lugs 10, 10.
• this tool feature is such that it both spreads the ring lugs 10, 10 and expands the ring O.D. out against the inner peripheral edge 4a of the groove 4 which is opposite the nozzle access slot 6.
• the I.D. of the retaining ring 8 is larger than the O.D. of the end of the guide thimble 12. Accordingly, the nozzle 1 can be lowered onto the guide thimble 12 without interference between the ring and the thimble until the nozzle seats against the shoulder 16. At this point the tool is withdrawn and the retaining ring 8 returns toward its original configuration. As the I.D. decreases, it engages the circumferential groove 14 formed in the ends of the guide thimble 12.
• the parts are sized to ' ensure no more than a light radial contact force between the ring 8 and the groove 14 is established.
• the nozzle 1 is now secured to the thimble 12. If the nozzle 1 is pressed axially toward the thimble 12, all force is transmitted by way of the nozzle flow plate to the thimble shoulder 16. No axial force is transmitted through the retaining ring 8. Since this is the typical condition during reactor operation for both the top and bottom nozzles, no creep or stress relaxation will occur in the joint components during operation. When the fuel assembly is lifted, a load path, however, passes through the retaining rings 8. A comparison of the magnitude of these forces to the allowed thrust forces for commercially available rings demonstrates that their capacity is many times higher than the anticipated loads.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• High Energy & Nuclear Physics (AREA)
• Mechanical Engineering (AREA)
• Fuel-Injection Apparatus (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Citations (10)

• 1994
  • 1994-01-26 TW TW083100650A patent/TW240319B/zh active
  • 1994-06-20 AU AU72480/94A patent/AU7248094A/en not_active Abandoned
  • 1994-06-20 WO PCT/US1994/006924 patent/WO1995003613A1/en active Application Filing

Patent Citations (10)

Non-Patent Citations (1)

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