US3838289A

US3838289A - Radioactive waste filter removal system

Info

Publication number: US3838289A
Application number: US00284672A
Authority: US
Inventors: D White
Original assignee: GILBERT ASSOCIATES
Current assignee: GILBERT ASS INC US; GILBERT ASSOCIATES
Priority date: 1972-08-29
Filing date: 1972-08-29
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24

Abstract

A radioactive waste filter cartridge removal apparatus comprising a shielding cask having removable top and bottom lids and a support collar integrally secured to the outer wall of the cask for support on a shouldered and shimmed support. Two lowering assemblies comprising rods extending vertically through said support collar at diametrically opposite sides of the cask are provided for effecting lowering movements of the bottom lid. One of said rods has its lower end welded to the peripheral portion of the bottom lid whereby such lid may be rotated about the axis of the rod and thus clear the bottom opening of the cask to permit vertical downward movement of the filter cartridge through such opening. A grappling tool and viewer are mounted on the top lid.

Description

llnite States White atent [1 1 [451 Sept. 24, 1974 [75] Inventor: Donald P. White, Reading, Pa.

[73] Assignee: Gilbert Associates, Inc., Reading,

[22] Filed: Aug. 29, 1972 [21] Appl. No.: 284,672

FOREIGN PATENTS OR APPLICATIONS 1,192,128 5/1970 Great Britain 250/515 Primary Examiner-Harold A. Dixon [57] ABSTRACT A radioactive waste filter cartridge removal apparatus comprising a shielding cask having removable top and bottom lids and a support collar integrally secured to the outer wall of the cask for support on a shouldered and shimmed support. Two lowering assemblies comprising rods extending vertically through said support collar at diametrically opposite sides of the cask are provided for effecting lowering movements of the bottom lid. One of said rods has its lower end welded to the peripheral portion of the bottom lid whereby such lid may be rotated about the axis of the rod and thus clear the bottom opening of the cask to permit vertical downward movement of the filter cartridge through such opening. A grappling tool and viewer are mounted on the top lid.

8 Claims, 8 Drawing Figures PAIENTEDSEPMISH Fgo RADIOACTIVE WASTE FILTER REMOVAL SYSTEM This invention relates to a radioactive waste removal system and, more particularly, to a radioactive shielding assembly for enabling safe removal of radioactive waste filter cartridges.

An outstanding disadvantage of presently used shielding systems for removing radioactive waste filter cartridges has been that they are not totally reliable in operation in assuring complete shielding at all stages of the removal process, also they involve complicated time consumingexpensive procedures for performing the removal operation.

An object of the present invention is to provide a novel radioactive waste filter cartridge removal system that will overcome the above named disadvantages and which will be capable of removing and transporting, from the filter vessel to a drumming station, a plurality of radioactive (spent) filter cartridges, handling one filter cage assembly at a time, which cartridges will then be deposited in a suitable container for shipping.

Other objects and advantages will become more apparent from a study of the following description taken with the accompanying drawings wherein:

FIG. 1 is a top view and FIG. 2 is a vertical, cross-sectional view taken along line IIII of FIG. 1 of a cask assembly used for removal of a radioactive waste filter cartridge 1 shown in dotted outline;

FIG. 3 is an enlarged, vertical, top cross-sectional view of the grappling tool assembly shown in FIG. 1, the dot and dash outline showing the grappling tool in open or expanded position;

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a top view of the locking mechanism and taken along line V-V of FIG. 3;

FIG. 6 is an enlarged, cross-sectional view taken along line VIVI of FIG. 3;

FIG. 7 is an enlarged, fragmentary, cross-sectional view of a stop for the cask lid; and,

FIG. 8 is an enlarged, cross-sectional view of a drainage connection attachable to the bottom of the cask.

Referring more particularly to FIGS. 1 and 2 of the drawing, numeral 1 denotes a radioactive waste filter cartridge which has been spent from use in a nuclear power station. Numeral 2 denotes, generally, a radioactive shielding cask of such construction as to enable removal and shielding of the cartridge 1.

In operation, a 5 ton monorail crane will remove the concrete hatch plug. The filter removal apparatus will be lowered into the open hatch by the crane where it will rest firmly on the access hatch ledge (see FIG. 2). Shims 8a will have been previously installed (preferably welded in place) during plant construction, after the filters l have been installed, to guide the apparatus and assure proper alignment.

The top and

bottom cask lids

6 and 7, respectively, are stepped to prevent radiation streaming. They are preferably made of lead having a thickness exceeding 3 inches. All parts of the cask 2 which may come in contact with the filter cartridge 1 or its drippings are preferably made of stainless steel. Other parts of the cask and lids may be clad in carbon steel as mechanical strength requires. The support collar 8 is preferably For /8 inch bolt 250 ft-lb The lowering rod 11 and support gusset 7a are welded to the bottom cask lid 7. All stresses do not exceed 18,000 psi.

The top cask lid 6 has mounted thereon three tool access plugs 6a, 6b, 60, one grappling tool hole in the center, and a viewing apparatus 15. In addition, rotatability is incorporated. Hold-down bolts are provided to serve the top lid 6 during movement of the cask.

The bottom cask lid 7 has remote lowering and raising capability as well as rotatability provided by two rod and nut assemblies 9 and 11 (one affixed). The bottom cask lid 7 is gasketed for leak-tight integrity. The viewing apparatus 15 provides the equivalent of 3.3 in. lead minimum. The viewer scan will cover the three different bolt locations and the filter centerline which will require approximately a 15 cone of view. A removable section 17 comprising extension rod 19 surrounded by shield 18 is provided.

The bottom cask lid 7 will be lowered by the two rod and nut assemblies 9 and l 1 extending through support collar 8 and through ball bushings and retaining

rings

10, 12, 10a, and 12a, all of which are welded to cask cover 3. This will be accomplished with the use of a ratchet wrench and socket or equivalent.

When the bottom cask lid 7 has been lowered to a depth at which the top of the lid clears the filter cubicle ceiling (about 5 inches), it may be rotated up to about about the axis of the affixed rod and nut lowering assembly 11 to the position shown in dot and dash lines in FIG. 2 such that the cylindrical cask 2 is completely open at the bottom. Hook portion 76 unhooks from rod 9 to permit such swing. A limit is imposed on the depth to which the bottom lid 7 may be lowered by the stop collars 9a and 11a of the lowering rods.

The filter cover bolts 44a are loosened by a ratchet wrench 43 with a socket extension 42. The top cask lid 6 provides the tool access to the filter cover bolts 44a. Tool access plugs 6a, 6b, and 6c, located in the top lid, preferably at 3 inch, 3 3/4 inch, and 5 3/4 inch radius about the centerline, allow access to the three'different filter cover bolt patterns. Three evenly spaced lifting lugs 13 are welded onto the top lid 6. The appropriate access plug is removed and the ratchet wrench extension 42 is inserted. Proper tool alignment is achieved by rotating the top cask lid 6 over each vessel head bolt and observing alignment with the viewing apparatus 15.

After loosening of the filter cover bolts 44a has been completed, the ratchet wrench extension 42 will be withdrawn and the tool access plug 60 re-inserted in the cask lid. The filter cover bolts 44a will then be pushed away with the use of a rod inserted through the viewing port. The filter cover 44 may then be lifted aside remotely by a pulley line arrangement.

A grappling tool 21 with

parts

23, 24, 25, 26 (see FIG. 3) located in the center of the cask lid 6, is provided for the lifting of the filter cartridge 1 into the

main cask body

3, 5; The upper section 17 is removable and serves as an extension. It is attached (and removed) from the permanently installed lower section with a spanner wrench. The

grappling tool

23, 24, 26, 26, may be lowered manually to securely hook onto the filter cage assembly with its ice tong design. Use of a ratchet wrench on the hexagonal (top) end of shaft 19 will open or close the

jaws

23, 24, of grappling tool 21. Three ball bushings and retaining ring assemblies 19a, 19b and 19c are provided, also drill hole 18a for a spanner wrench, as well as a hexagonal shaped socket 20 to receive the hexagonal lower end of rod 19 enclosed by shield 18.

When the filter 1 is securely hooked, it may be lifted into the main cask body as shown in dotted lines in FIG. 2. The bottom cask lid 7 will then be closed securely by reversing the above described lowering procedure. The

upper sections

16 and 17 of the viewing apparatus and grappling tool, respectively, may be removed. A locking mechanism (see FIG. is provided for the lower section of the grappling tool. It comprises a slide bolt or plate 28 with flat sections 27 fitting flat sections of the rod and being slidable by a pin and slot connection 30 and locked in place by a ball plunger 30A. The top cask lid 6 is secured by tightening the hold-down bolts provided. The cask assembly will then be removed from the access hatch by the monorail crane.

A forklift or equivalent will be necessary for the transportation of the cask assembly to the drumming station. A portable stand will be provided in the drumming station for the transfer of the spent filter from the cask to a 55 gallon concrete-lined shipping drum. The drumming station crane will place the cask on the stand. Before filter transfer, the valve 39 extending below the bottom cask lid 7 will be opened to drain any drippings accumulated through the

quick connect line

37, 38, 40, 41, to the shipping drum or other suitable container. The filter is lowered into the drum with the grappling tool. The drum may be capped and secured manually, then transferred to the drum storage area by the drumming station crane.

The appropriate filter cubicle and the filter removal apparatus should be washed down after each use to eliminate any residual radioactive drippings. After washdown, a new filter cartridge may be installed directly.

Thus it will be seen that I have provided a highly reliable and efficient radioactive waste filter removal system for safely shielding spent filter cartridges while removing and transporting from the filter vessel to the drumming station; moreover, l have provided a novel and efficient cask assembly for handling a cartridge in a safe and reliable manner.

I claim:

1. A cask for shielding radioactive waste filter cartridges comprising a cylindrical container with open ends and having removable circular top and bottom lids for detachably covering said open ends, a support collar integrally secured to the outer wall of said cylindrical container, a lowering rod mounted on said support collar for effecting lowering of said bottom lid and pivotal movement of said bottom lid about the axis of said lowering rod, whereby the bottom lid may be moved aside from the lower opening of said cask to permit vertical lowering therethrough of the radioactive waste filter cartridge.

2. A cask as recited in claim 1 together with a grappling tool mounted on and extending through said top lid and including a vertical rod, the turning of which in one direction or in an opposite direction will effect opening and closing movements of the grappling tool.

3. A cask as recited in claim 1 together with a second lowering rod mounted on said support collar diametrically opposite said first mentioned lowering rod for detachably supporting a hook shaped extension from said bottom lid which is adapted to hook about said second lowering rod to permit detachment and lateral swinging movement of said bottom lid about the axis of said first mentioned lowering rod.

4. A cask as recited in claim 1 together with a plurality of plugs at different radii on said top lid through which an extension for a wrench may be inserted and projected throughout the entire height and beyond the lower end of said cask to permit unscrewing of bolts on the cartridge when located below the cask.

5. A cask as recited in claim 1 together with a viewing apparatus mounted in said top lid to permit viewing of the interior of said cask.

6. A cask as recited in claim 2 wherein said grappling tool is provided with an elongated removable extension projecting upwardly from said top cask lid, and a shield enclosing said removable extension.

7. A cask as recited in claim 1 together with a second support rod diametrically opposite said first-mentioned support rod and extending vertically through said support collar, a plurality of vertically disposed ball bushings and retaining rings for mounting said rods and which are attached to diametrical opposite outer surface portions of said cask, the said first-mentioned support rod having its lower end welded to said bottom lid so that rotation thereof about its axis will swing said bottom lid away from the lower opening of said cask.

and supported by said shoulder.

Claims

8. A cask as recited in claim 1 together with a base having a circular shoulder for supporting said support collar, and shim means surrounding said support collar and supported by said shoulder.