Method and apparatus for storing nuclear fuel rods

• US 5,274,682 A
• Filed: 01/19/1993
• Issued: 12/28/1993
• Est. Priority Date: 08/22/1990
• Status: Expired due to Term

• Current Assignee: NAC International Inc. (Hitachi Zosen Corporation)
• Original Assignee: Nuclear Assurance Corporation, Inc.
• Inventors: McDaniels, John D. Jr.
• Primary Examiner(s): Wasil, Daniel D.
• Application Number:
  US08/006,034
• Time in Patent Office: 343 Days
• Field of Search: 376/261, 376/272, 376/313
• US Class Current: 376/261
• CPC Class Codes: G21C 19/32 Apparatus for removing radioactive objects or materials from the reactor discharge area, e.g. to a storage place; Apparatus for handling radioactive objects or materials within a storage place or removing them therefrom disposal of waste material G21F9/00
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors
• CPC Class Codes: Y10S 100/915 Fixed upper ram, lower movable receptacle

Abstract

A storage canister for spent nuclear fuel rods, having loading and storage configurations, has an open end and an apertured end wall, and means therein defining a plurality of rod locations. The canister also has movable means therein for vertically offsetting adjacent rods within the canister so that any pair of adjacent rods are vertically offset from each other. The movable means is positioned during loading to permit fluid flow into and out of the canister through the apertured end wall and in the storage configuration blocks at least one of the apertures in the end wall. The movable means may also be used to lift the fuel rods such that their tops extend above the canister body to permit removal of one or more rods. A closure member for the open end has a locking mechanism for locking it to the canister and a tamper indicating mechanism.

Claims

1. A rod storage canister for use in a rod consolidation system wherein individual elongated rods, at least some of which have elongated tips on one end thereof, are withdrawn from an array of rods in a first fuel rod holder having a plurality of rod locations therein by means of a pulling tool having a distal, rod grasping end and are transferred to the storage canister, said storage canister having a loading configuration and a storage configuration and comprising;

an end wall and elongated side walls extending therefrom and defining an open ended container,

means defining an array of a plurality of rod locations in said container,

means within said container for vertically offsetting substantially all adjacent rods within said container, said means for offsetting being movable longitudinally relative to said end wall and adapted to rest against said end wall in said storage configuration, and

closure means for said container for closing the open end thereof.

2. The rod storage canister as claimed in claim 1 wherein said end wall has at least one aperture therein for permitting ingress and egress of fluid to and from said container.

3. The rod storage canister as claimed in claim 2 wherein at least one aperture has fluid filter means located therein.

4. The rod storage canister as claimed in claim 2 wherein said means for offsetting adjacent rods includes means for blocking at least some of the apertures in said end wall when said canister is in said storage configuration.

5. The rod storage canister as claimed in claim 1 wherein said means for offsetting adjacent rods comprises a first apertured plate adapted to rest against said end wall in the canister storage configuration, and

a plurality of apertured plates forming a stack of plates resting on said first plate.

6. A rod storage canister as claimed in claim 5 wherein the plates of said stack of plates are spaced from each other and from said first plate.

7. A rod storage canister as claimed in claim 5 wherein said stack of plates comprises a lower plate, an upper plate, and at least one intermediate plate, said lower plate being adjacent said first plate.

8. A rod storage canister as claimed in claim 7 wherein said plates are made of stainless steel.

9. A rod storage canister as claimed in claim 7 wherein said lower plate has a plurality of spaced apertures therein sized to allow a first group of rod tips to pass therethrough;

said intermediate plate has a first group of spaced apertures therein sized to allow the first group of rod tips to pass therethrough and aligned with the apertures in said lower plate, and a second group of spaced apertures each of which is offset from the apertures of said first group and sized to allow a second group of rod tips to pass therethrough; and

said top plate has a first group of spaced apertures therein sized to allow the first group of rod tips to pass therethrough and aligned with the apertures of said first group of apertures in said intermediate plate, a second group of spaced apertures sized to allow the second group of rod tips to pass therethrough and aligned with the apertures of said second group of apertures in said intermediate plate; and

a third group of spaced apertures, each of which is offset from the apertures of said first and second groups and sized to allow a third group of rod tips to pass therethrough.

whereby, when rods are loaded into the canister, the rods of each of said first, second and third groups are vertically offset from the rods of the other groups and adjacent rods are vertically offset from each other.

10. A rod storage canister as claimed in claim 1 wherein said means defining an array of rod locations comprises first and second sets of longitudinally extending corrugated plates mounted in said container in spaced relationship with adjacent plates belonging to different sets, the corrugations of the plates of the first set forming, with the corrugations of the plates adjacent thereto, a plurality of rod locations.

11. A rod storage canister as claimed in claim 10 wherein the corrugated plates of said second set extend longitudinally toward the open end of said container a greater distance than the corrugated plates of said first set.

12. A rod storage canister as claimed in claim 10 wherein said corrugated plates are of stainless steel.

13. A rod storage canister as claimed in claim 10 wherein adjacent plates form a row of rod locations, the rod locations in any one row being offset laterally from the rod locations in the next adjacent row.

14. A rod storage canister as claimed in claim 1 wherein said closure means comprises means for locking said closure means to said container.

15. A rod storage canister as claimed in claim 14 wherein said closure means comprises means for actuating said means for locking.

16. A rod storage means as claimed in claim 14 and further including tamper indicating means on said closure means.

17. A rod storage canister as claimed in claim 14 wherein said container has at least one slot in a side wall thereof adjacent said open end, said means for locking comprising projecting means insertable in said slot when said closure means is in place on said open end of said container.

18. A storage canister as claimed in claim 17 wherein said actuating means comprises means for forcing said projecting means into said slot.

19. A rod consolidation system for removing nuclear fuel rods from a container and placing them in a storage canister, said system comprising;

a storage canister having a loading configuration and a storage configuration, said storage canister having an end wall and elongated side walls extending therefrom defining an open ended container,

means within said container for vertically offsetting substantially all adjacent rods within said container when the rods are loaded into the container, said means for offsetting being movable longitudinally relative to said end wall and being adapted to rest against said end wall in said storage configuration,

holder means for holding said canister in its loading configuration, said holder means including means for moving said means for offsetting within said container longitudinally away from said end wall.

20. A rod consolidation system as claimed in claim 19 wherein said means for moving elevates said means for offsetting to a position wherein a rod inserted in said means for offsetting extends beyond the open end of said canister.

21. A rod consolidation system as claimed in claim 19 wherein said end wall has a plurality of apertures for permitting ingress and egress of fluid to and from said container, and said holder means comprises means for permitting passage of fluid through said apertures in said end wall.

22. A rod consolidation as claimed in claim 21 wherein said means for permitting passage of fluid comprises duct means within said holder.

23. A rod consolidation system as claimed in claim 21 wherein said means for vertically offsetting rods within said container comprises means for blocking at least some of said apertures in said end wall when said canister is removed from said holder.

24. A rod storage canister having a loading configuration and a storage configuration and comprising:

an end wall,

means forming an open ended container comprising side

walls extending longitudinally from said end wall,

locating means within said container defining a plurality of vertically offset rod locations wherein substantially all adjacent rods, when loaded into said canister, are vertically offset from each other, at least a portion of said locating means having a first rod loading position and a second rod storage position relative to said end wall,

a closure member for closing the open end of said container,

first locking means for affixing said closure member to said container, said container having means for receiving a portion of said first locking means in the locked position,

and tamper indicating means for indicating when an attempt has been made to unlock said first locking means after said closure has been locked to said container.

25. A rod storage canister as claimed in claim 24 wherein said means for receiving a portion of said first locking means comprises at least one slot in a side wall of said container adjacent the open end thereof.

26. A rod storage canister as claimed in claim 25 wherein said first locking means comprises a rotatable member having a first projecting means adapted to fit within said slot to bear against an edge thereof in the locked position.

27. A rod storage canister as claimed in claim 26 wherein said rotatable member has a second projecting means, and said closure member has actuating means therein adapted to bear against said second projecting means for rotating said rotatable member.

28. A rod storage canister as claimed in claim 27 wherein said actuating means comprise a rotatable threaded member threaded through a portion of said closure member.

29. A rod storage canister as claimed in claim 28 wherein said tamper indicating means is affixed to said actuating means.

30. A rod storage canister as claimed in claim 29 and further including second locking means in said closure means for preventing rotation of said actuating means when said first locking means is in the locked position.

31. A rod storage canister as claimed in claim 30 wherein said tamper indicating means comprises a disc shaped member having first and second sides, and a detent recess on said first side, and said second locking means comprises a spring biased pin member adapted to fit into said detent recess when said first locking means is in the locked position.

32. The method of loading rods into a storage canister having a plurality of defined individual rod locations therein comprising the steps of

removing individual rods from a rod assembly by means of a long reach tool,

inserting each rod into the storage canister in one of the defined rod locations therein,

vertically offsetting substantially all adjacent rods from each other within the storage canister,

flowing fluid into the canister while the rods are being inserted therein,

closing the canister with a closure means after the canister has been loaded,

locking the closure means to the canister, and

positioning a tamper indicator in a tamper indicating position on the closure means after it has been locked to the canister.

33. The method of loading rods into a canister as claimed in claim 32 and further including the steps of

placing the canister in a holder prior to inserting the rods therein, and

reducing the fluid flow into the canister after it has been loaded and closed.

34. The method of loading rods into a canister as claimed in claim 33 wherein the step of reducing the fluid flow into the canister comprises removing the canister from the holder.