US3883441A - Apparatus for fixing radioactive waste - Google Patents

Abstract

Fixing radioactive waste is disclosed in which the waste is collected as a slurry in aqueous media in a metering tank located within the nuclear facilities. Collection of waste is continued from time to time until a sufficient quantity of material to make up a full shipment to a burial ground has been collected. The slurry is then cast in shipping containers for shipment to a burial ground or the like by metering through a mixer into which fixing materials are simultaneously metered at a rate to yield the desired proportions of materials.

Description

United States Patent 1 Murphy et al.

1 May 13, 1975 l l APPARATUS FOR FIXING RADIOACTIVE WASTE [75] Inventors: John D. Murphy, Bedford Hills;

John Pirro, Jr., Rutland; Monsey Lawrence; Stanley F. Wisla, both of Yorktown Heights, all of N.Y.

[73] Assignee: Atcor lnc., Park Mall, Peekskill,

[22] Filed: July 20, I970 [211 Appl. No.: 56,625

[52] U.S. C1 252/30Ll W [51] Int. Cl C09k 3/00 [58] Field 01' Search 252/301.l R, 301.1 W

[56] References Cited UNITED STATES PATENTS 3,012,385 l2/l96l Hufft 252/301.1 W 3.142648 7/1964 Lefillatre et al. 252/301.1 W 3,507,801 4/1970 Kausz et al 252/301.1 W $513,100 5/1970 Stogner 252/3011 OTH ER PUBLICATIONS Stoller et al., Reactor Handbook, Vol. 11, Fuel Reprossing, 1961, p. 498

Lawroski et al., Reactor Fuel Processing, Vol. 8, No. 3, 1965, pp. 172473, USAEC-Argonne National Lab.

Flagg, Chemical Processing of Reactor Fuels. Academic Press, New York, 1961, p. 467.

Martin et al., Chemical Processing of Nuclear Fuels, Academic Press. New York, 1958, p. 198.

Primary E.raminerBenjamin R. Padgett Assistant Examiner-R. L. Tate [57] ABSTRACT 3 Claims, 4 Drawing Figures SLURRY PUM P INVENTORS JOHN D.MURPHY JOHN P|RRO,JR. LAWRENCE RUTLAND STANLEY F.W|SLA 29 J0 SHIPPING CONTAINER AUGER FEED HOPPER b a O BY I %smgMazl Mei @6141 ATTORNEYS APPARATUS FOR FIXING RADIOACTIVE WASTE This invention relates to disposal of radioactive waste and, in particular, to such disposal by fixing the waste for shipment to a burial ground or the like.

BACKGROUND OF THE lNVENTlON Radioactive wastes accumulate in nuclear power generating stations and are, for example, contaminated bead ion exchange resin, powdered resin, filter aid, filter precoat and evaporator bottoms which are contaminated typically with corrosion and fission products.

The present practice in disposal of radioactive wastes is to mix the wastes with cement and water, if required, and to cast these in drums for shipment to a burial ground. Fixing is required by most burial grounds in order that the radioactive waste not be available to the environment and is also desirable, as it prevents spread of radioactive material which might occur incidental to an accident in shipment. The present practice of fixing radioactive wastes at a nuclear facility is cumbersome and presents potential contamination problems.

GENERAL SUMMARY OF THE INVENTION This invention is generally applicable to the disposal of any radioactive wastes which can be slurried in an aqueous medium and has for its general purpose fixing of such wastes on a production line basis avoiding the difficulties of atmospheric contamination and nonuniform mixture characterizing prior fixing methods.

In accordance with this invention radioactive wastes are collected from time to time, and slurried in an aqueous medium in a metering tank which is contained in a shielded enclosure. The metering tank is adapted to meter the collected slurry, when required, through a mixer which is also connected simultaneously to receive cement or other fixing materials in metered quantities proportionate to the metering rate of the slurry. The mixer is shielded and arranged continuously to discharge metered and mixed fixing material and slurry into a shipping container for shipment to a burial ground when the mixture has set.

Ordinarily in accordance with this invention the furing process is carried out only when a sufficient quantity of radioactive waste has been collected to constitute a suitable quantity for shipment to a burial ground. This quantity may involve one or several shipping casks or other containers and the fixing process is carried out continuously until the desired number of casks have been charged. Thus expensive shipping casks are tied up at the particular plant only for that time necessary for the fixing operation and need not be kept on hand as storage vessels until an adequate quantity for shipment has been made up.

Another advantage of this invention is that it is flexible in terms of achieving the proper ratio of water to fixing material in the mixture. Thus if the radioactive wastes are in slurry fonn containing excess water they can readily be dewatered by decanting or filtering from the metering tank prior to fixing. If they are solid wastes additional water can be added as required. The proportions of fixing material, water and waste materials are a function of density, shielding requirements, moisture content and ultimate disposition of the fixed waste.

For a more complete understanding of the practical application of this invention reference is made to the accompanying drawings in which:

FIG. 1 is a fragmentary elevation partly in section of the waste processing facility of a nuclear power plant;

FIG. 2 is a plan view partly in section of the facility shown in FIG. 1;

FIG. 3 is an end view partly in section of the same facility; and

HG. 4 is a schematic diagram of certain apparatus shown in FIGS. 1, 2 and 3.

Referring to the drawings the reference numeral l0 designates a building, housing a waste processing facility at a nuclear power plant. The waste processing facility itself includes a metering tank ll, hopper l2 and.a mixer 13. Both metering tank It and its associated equipment and hopper l2 and its associated equipment are located on a platform 16 in the processing area of the power plant such that a portable shipping container, such as a movable shipping cask 14 or lCC approved drum mounted, for example, on a dolly 15 can be positioned beneath platform 16 to receive the contents of metering tank I] and hopper 12 through mixer 13 which is mounted on the underside of platform l6.

Exemplary of the portable containers used in this invention are a shielded nuclear cask licensed in accordance with ABC regulations, Title 10, Chapter 71, Code of Federal Regulations for large quantities" of radioactive materials or Department of Transportation regulations for Group B shipments or Group A or low specific activity. In addition lCC approved single trip containers for radioactive materials, e.g., ICC-17H, 55 gallon steel, open head, typify the drums used herein.

The processing area in building 10 is entirely enclosed in concrete, including an outside wall 17, a rear wall 18 and a ceiling 19 which are shown in the drawings. Platform 16 is mounted beneath ceiling 19 in the comer where rear wall 18 and outside wall 17 join, and metering tank 11 is positioned in such corner with hopper 12 mounted further out on the platform. Walls 17 and 18 and ceiling 19 are of thick concrete and thus serve partially to shield tank ll. Metering tank 11 is shielded further by providing a thick concrete floor 20 on platform 16 beneath tank 11 and by providing an outside wall 21 of thick concrete on platform l6 rising to ceiling l9 and extending from outer wall 17 in front of metering tank 11. The shielded enclosure for metering tank 11 is completed by a U-shaped partition 22 and baffle 23 formed of concrete and extending across platform 16 from floor 20 to ceiling l9 and from front wall 21 to rear wall 18 defining a U-shaped access to service metering tank 11 when required. Arrangements not shown are provided for charging metering tank It with slurried radioactive waste and water, as required, through ceiling l9.

Hopper I2 is located on platfonn l6 outside of the enclosure in which metering tank 11 is mounted and is provided with a downward, gravity feed into an auger 24 leading to mixer 13 mounted on the underside of platform 16 beneath floor 20. Mixer 13 is also provided with a connection 25 through a slurry pump 26 from the underside of metering tank ll. Pump 26 is located in the shielded enclosure in which tank 11 is housed and is provided with suitable valving to discharge directly into mixer 13 or to discharge into a line 27 recirculating the discharge of slurry pump 26 to the upper end of tank 11. Mixer 13 itself, while located on the un derside of platform 16, is housed in a steel shielded compartment 28 and is provided internally with a power driven agitator such that fixing material and waste discharged from hopper l2 and tank 11 into the upper end of mixer 13 feed by gravity to the lower end of mixer 13 while being thoroughly mixed, such that they are discharged through outlet 29 in a suitably mixed condition for casting.

Finally, it will be noted, referring particularly to FIG. 4 that water can be withdrawn through a filter 30 and line 31 from tank 11 when it is desired to dewater the contents. Also a radiation detector 32 is located in line 27 to measure the radioactivity of the contents during recirculation. An agitator 33 is also provided in metering tank 11 to provide thoroughly mixed slurry of uniform consistency.

in operation radioactive waste is collected from time to time and slurried and delivered to metering tank 11, for example, through a line 34. Spent resin in a demineralizer, for example, can be backflushed and fed as a slurry through line 34 to metering tank 11. The operation of agitator 33 assures that the mixture is uniform without hot spots. Recirculation through line 27 enables radiation measurements to be made to verify that the Curie capacity of the shipping cask or casks to be used is not exceeded. Radiation measurements could be made on the surface of the metering tank alternatively.

As wastes are accumulated in tank 11, the radiation level rises to the maximum of the desired shipment. A shipping cask l4 fitted with a tank liner or ICC approved drums is then transferred and positioned, for example, by dolly under platform 16 beneath mixer 13. At this point, with a knowledge of the volume of liquid contents in metering tank 11 and of the volume of shipping cask or casks 14 and with the knowledge of the proportion of water to fixing materials required, excess water present in the slurry in tank 11 is removed through filter 30 and line 3]. On the other hand, if additional water is required, it is supplied through line 35 followed by sufficient agitation utilizing agitator 33 to insure a uniform mixture. Slurry pump 26 is then oper ated to discharge the contents of tank 11 into mixer 13 at a regulated rate. At the same time auger 24 is operated to supply fixing materials from hopper [2 into mixer 13 in the proper proportion for the slurry introduced from tank 11. Mixer 13 is also operated to agitate the mix so that, as it is discharged from outlet 29 into the shipping cask, the mix is properly uniform. After cask I4 is filled it is sealed and the top secured, and the cask is shipped to the burial site typically on a flat bed trailer. Depending on the means of transportation, one or more shipping casks 14 may be filled during the course of the operation.

We claim:

1. A waste processing facility for preparing radioactive wastes for disposal which includes means defining a shielded enclosure, a metering tank positioned in said enclosure, said metering tank including metering means for removing liquid contents therefrom at a metered rate and measuring means for measuring the radioactivity of liquid contents thereof, mixing means for continuously receiving, mixing and discharging fixing materials and liquids said mixing means being con nected to said metering means to receive the contents of said tank through said metering means, fixing materials feed means connected to said mixing means to deliver fixing materials thereto at a regulated rate, means defining a space in which to position a container relative to said mixing means to receive the discharged contents therefrom.

2. A waste processing facility according to claim I which further includes means for storing fixing materials adjacent said enclosure defining means.

3. A waste processing facility according to claim I in which said means defining an enclosure is located on a platform in which said mixing means is positioned on the underside of said platform, the space beneath said platform thereby constituting said space in which to position a container.

4! l t i i

Claims (3)

1. A WASTE PROCESSING FACILITY FOR PREPARING RADIOACTIVE WASTES FOR DISPOSAL WHICH INCLUDES MEANS DEFINING A SHIELDED ENCLOSURE, A METERING TANK POSITIONED IN SAID ENCLOSURE, SAID METERING TANK INCLUDING METERING MEANS FOR REMOVING LIQUID CONTENTS THEREFROM AT A METERED RATE AND MEASURING MEANS FOR MEASURING THE RADIOACTIVITY OF LIQUID CONTENTS THEREOF, MIXING MEANS FOR CONTINUOUSLY RECEIVING, MIXING AND DISCHARGING FIXING MATERIALS AND LIQUIDS SAID MIXING MEANS BEING CONNECTED TO SAID METERING MEANS TO RECEIVE THE CONTENTS OF SAID TANK THROUGH SAID METERING MEANS, FIXING MATERIALS FEED MEANS CONNECTED TO SAID MIXING MEANS TO DELIVER FIXING MATERIALS THERETO AT A REGULATED RATE, MEANS DEFINING A SPACE IN WHICH TO POSITION A CONTAINER RELATIVE TO SAID MIXING MEANS TO RECEIVE THE DISCHARGED CONTENTS THEREFROM.

2. A waste processing facility according to claim 1 which further includes means for storing fixing materials adjacent said enclosure defining means.

3. A waste processing facility according to claim 1 in which said means defining an enclosure is located on a platform in which said mixing means is positioned on the underside of said platform, the space beneath said platform thereby constituting said space in which to position a container.

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