WO1989012305A1

WO1989012305A1 - Method for decontaminating specially selected and conventional plastic materials which have become radioactively contaminated, and articles

Info

Publication number: WO1989012305A1
Application number: PCT/US1989/001738
Authority: WO
Inventors: William J. Mcconaghy; James M. Wallace
Original assignee: Nutech, Inc.
Priority date: 1988-06-07
Filing date: 1989-04-25
Publication date: 1989-12-14
Also published as: AU3740289A

Abstract

A method for (20) decontaminating plastic products (50, 70, 80) and materials which have become radioactively contaminated. The first treatment method (20) involves dissolving such plastics (50, 70, 80) in an aqueous solvent (34) and treating the resulting solution selectively via filtration (36), ion-exchange (40), and precipitation (44) processes to remove particulate and dissolved radioactive contaminants. The second treatment method (120) involves dissolving such plastics in a dissolution tank (128) in an organic solvent and treating the resulting solution by a solvent extraction technique in column (136) to remove particulate and dissolved radioactive contaminants from the plastic. The separated plastic material can be disposed of in a sanitary landfill or recycled into other plastic products.

Description

METHOD FOR DECONTAMINATING SPECIALLY SELECTED AND CONVENTIONAL PLASTIC MATERIALS WHICH HAVE BECOME RADIOACTIVELY CONTAMINATED, AND ARTICLES

Field of the Invention

The present invention is directed to a method for decontaminating plastic materials which are used as disposable protective surfaces in an environment where the plastic materials can become radioactively contaminated.

Background of the Invention

The nuclear power industry, medical institutions, DOE facilities, and research and academic institutions generate a considerable quantity of low level dry radioactively contaminated trash (low level dry active waste) each year. A good percentage of this trash consists of plastic material or material which could be replaced by plastic. Such plastic material can include polyvinylchloride (PVC) , polyethylene (PE) , polypropylene, polystyrene and others. Polyvinylchloride and polyethylene are of particular interest due to their widespread use in the nuclear industry. Currently, such plastic material which is of a sufficiently low activity level is disposed of by shallow land burial in a controlled facility designed for such waste disposal. Such disposal facilities have become increasingly unpopular, and as a result of the strict regulations regarding the design and operation of such facilities, the cost of burial has escalated tremendously in recent years. Therefore, many strategies and techniques have been devised to incinerate, compact, or otherwise reduce the volume of material which must be disposed of at such low level waste burial facilities.

Plastic materials which are subject to becoming contaminated in the above environment range widely from clothing used to protect personnel, to cloths, drapes and coatings used to protect walls, floors, structures and equipment, and to actual structural elements and equipment.

The methods currently employed for reducing the volume of dry active waste include: (1) Compaction and Supercompaction, (2) Incineration, (3) Segregation, and (4) Miscellaneous washing or laundering processes.

The compaction and segregation processes attempt to physically reduce the volume of a given quantity of waste by the application of high pressure or by segregating individual pieces of the waste which can be identified as having an acceptably low level of radioactivity so as to be considered releasable to the environment.

The incineration process attempts to reduce the volume of waste by oxidizing all of the combustible components in the waste, thereby leaving a condensed and concentrated residue. The washing and laundering processes are used primarily for clothing materials as a method for reducing the contamination levels between uses. Some attempts have been made to launder plastic materials prior to disposal, however, these attempts have met with little success as regards to significant volume reduction.

Much knowledge of the characteristics of dry active waste is available in the literature. Characteristics which are of importance in devising a disposal method include (1) isotope composition, (2) particle size distribution, (3) soluble/insoluble proportions, and (4) chemical forms.

Due to the shipping and burial requirements for radioactive material, a great deal of isotopic distribution data is available in the literature. Although the numbers vary widely from year to year and from plant to plant, the predominant isotopes which account for the majority of the activity are Co-58 and Co-60 (Cobalt isotopes) , Fe-55 (Iron isotopes) and Cs-134 and Cs-137 (Cesium isotopes) . Cobalt-60 alone generally account for 40%-60% of the activity and is by far the most important contributor. Most of these isotopes are found in the form of salts and particulate oxides.

Further data shows that the particle size generally ranges from 0.1 to 5 microns. Of the identified isotopes the cobalt isotopes are generally insoluble while the cesium isotopes are generally soluble.

Summary of the Invention

The present invention is directed toward solving the outstanding problem of reducing the volume of dry plastic active waste which must presently be buried in a licensed waste disposal facility. The present invention utilizes the dissolution of the contaminated plastic materials in order to separate the radioactive material from the substrate plastic material. Dissolution occurs in an aqueous solvent and the plastic materials are specially selected in order to be rapidly dissolved. In another embodiment, dissolution occurs in an organic solvent.

Following dissolution, the effluent steam is operated on in order to segregate contaminants from the plastic materials in order to be able to dispose of the contaminants at a special burial site in an efficient manner with a reduced volume. The plastic material can then be disposed of conventionally or reprocessed into other plastic product for reuse.

Accordingly an object of the present invention is directed to a method of decontaminating plastic materials which have become radioactively contaminated in order to reduce the volume of material which must be disposed of by shallow land burial.

Another object of the present invention is to provide a method for treating contaminated plastic material to reduce the contamination level on the plastic material.

Still another object of the present invention is to provide a method for treating contaminated plastic materials to remove the radioactive substances from the plastic material such that the plastic material is suitable for reuse.

Another object of the invention is to select appropriate plastic materials that are readily dissolved in an aqueous solution such that the resulting effluent stream can be operated on in order to segregate contaminants from the plastic materials.

Another object is to select appropriate plastic materials that are readily dissolved in an organic solution in order to segregate contaminants from the plastic materials.

Another object is to provide for appropriate articles, coatings and the like to be made from the specially selected plastic material.

In accordance with the principles of the present invention, the activity level of low level dry active waste plastic material can be reduced to sufficiently low levels as to be considered releasable to the environment by treatment of such plastics with an organic solvent succeeded by contacting in a solvent extraction process to remove the radioactive material from the organic phase.

Brief Description of the Figures;

Figure 1 depicts an embodiment of the decontamination process of the invention; and

Figures 2 and 3 depict embodiments of the process and articles of the invention.

Figure 4 depicts another embodiment of the decontamination process of the invention.

Figures 5 and 6 depict plastic solvent extraction test results. Detailed Description of the Preferred Embodiment

An embodiment of the method of the invention is depicted in Figure 1 and denoted by the number 20. The method contemplates the use of specially selected plastics for use in clothing, coverings, structures and equipment meant to be used where such plastics will become radioactively contaminated. The method so contemplates, in a preferred embodiment, plastics that are soluble in aqueous solutions. In a preferred embodiment said plastics can comprise a copolymer of ethyl acrylate and methacrylic acid which has physical properties similar to those of conventional plastics such as polyvinylchloride or polyethylene films which are widely used in the nuclear industry for sheathing, personnel clothing, plastic bags, lay-down cloth and the like.

In a preferred embodiment the composition of the copolymer can include, by way of example only, ratios of 4:1, 3:1, 2:1, and 3:2 of ethylacrylate and methacrylic acid respectively.

It is to be understood that other plastic materials which are soluble in aqueous solvent can be used with the method of the invention. For example polyvinylalcohol (PVOH) has similar properties and can be so used in the method of the invention. Polyvinylalcohol, however, has the drawback that it is readily dissolved in an aqueous solution at any time. Thus dissolution could take place prior to when dissolution and subsequent disposal are desired.

A discussion of such plastics that are dissolvable in aqueous solutions can be found in the following references, which are incorporated herein by reference:

Inventor Number Title issue Date

Belz U.S. Pat. 4,467,728 Composite Foil Sept 4, 1984

Particularly A Toilet Seat Support, as Well as Process

Belz U.S. Pat. 4,261,066 Toilet Seat Apr 14, 1981

Cover

Belz U.S. Pat. 4,352,214 Toilet Seat Oct 5, 1982

Cover

Belz U.S. Pat. 4,551,369 Composite Nov 5, 1985

Packaging Material & Process for Making Same

Belz Canada Pat. 1,190,014 Composite Foil July 9, 1985 Generally appropriate plastics are copolymers of unsaturated, organic acids such as acrylic acid, methacrylic acid and particularly maleic acid anhydride. Due to their flexible properties, particular reference is made to copolymers of maleic anhydride and ethyl vinyl ethers, particularly those produced in a ratio of 1:1. Reference is also made to copolymers of maleic anhydride and methacrylate, terpolymers of maleic anhydride, methacrylate and butyl acrylate, as well as copolymers of methacrylic and acrylic acid, especially copolymers of acrylic acid and methacrylate. Additionally hydroxy propyl cellulose can be used.

For purposes of the method 20 of the invention, the specially selected plastic materials that are dissolvable in an aqueous solution are in a preferred embodiment distinctly marked as to be readily identifyable from other plastic materials used in a nuclear power plant environment. An initial step in the method 20 is that of segregating conventional plastics and other materials and specially selected and marked plastics^" at segregating step 22 of the method 20.

Once the specially selected plastic is segregated, it can be shredded as represented at shredding step 24 in order to enhance the efficiency of the remaining method 20 of the invention.

The next step is the washing step 26. At washing step 26 the shredded plastic material is spray washed with a neutral or acidic solution in order to remove any of the loosely attached soluble and insoluble radioactive contaminants from the plastics. The resultant effluent stream can then be treated by filtration step 28 and ion exchange or adsorption step 30 to remove enough of the radioactive contaminant as to make the effluent stream environmentally acceptable for release at step 32. The contaminant removed by filtration step 28 and ion exchange or adsorption step 30 can then be buried in a site suitable for burying low level contaminants. It is to be understood that particulars of the filtration step 28 and the ion exchange or adsorption step 30 are similar to the filtration and ion exchange or adsorption steps described below which form part of method 20.

The washed plastic is subsequently dissolved at step 34 in an aqueous solvent which in a preferred embodiment includes a caustic solvent. Heat is preferrably added to enhance the rate of dissolution and to aid in the digestion of cobalt particulate.

The effluent stream from this stage is subject to one or more filtration operations at step 36 depending on the nature of the waste stream. The filtration stages in step 36 are intended to remove all insoluble material down to the sub-micron size and in so doing remove a significant portion of the radioactive material form the waste stream. The discharge from the filtration step 36 includes a filtered effluent stream and periodically the solid material captured by the filter device. This solid discharge may be disposed of in a licensed nuclear waste disposal facility. The solid discharge is generally in the form of insoluble and particulate contaminants.

After the filtration step 36, the pH of the effluent stream may be adjusted prior to an ion-exchange/adsorption step 40. The ion-exchange/adsorption step 40 will remove the soluble portion of the radioactive contaminants which were not previously removed. The discharge from the ion exchange step 40 includes the treated effluent stream, and periodically the solid ion exhange or adsorption media utilized in the step 40. This material can be dewatered or otherwise treated or contained in order to make it suitable for disposal in a licensed nuclear waste facility. The solid discharge is generally in the form of soluble contaminants and some insoluble contaminants not removed by the filtration step.

Examples of appropriate ion exchange/adsorption media can be acquired through DURATEK Corporation of Greenbelt, Maryland. Durasil 70, Durasil 190 and Durasil 230 are tradenames of such media.

Subsequent to ion—exchange treatment, the effluent stream is monitored for activity level and could potentially be discharged to an effluent stream or biological treatment system. Otherwise, this stream will be treated to remove the plastic from the waste stream and then dischanged to an effluent stream. The plastic is removed from the waste stream by a precipitation reaction (step 44) utilizing the insolubility of the plastic polyelectrolyte in an acidic regime. Once the solution is acidified, the plastic will precipitate out of solution and can be separated from the solution by filtration or other dewatering techniques. The product plastic can be dried and either disposed of as clean waste or recycled into other thermoplastic products (step 46) . The disposable items from the above method 20 include in addition to contaminants, contaminated filtration and ion-exchange media which can be dewatered and incorporated into a solid matrix for shallow land burial or can be placed in a high integrity container (HIC) for similar disposal. DRY ACTIVE WASTE CHARACTERIZATION

The predominant species are cobalt and cesium, the cobalt resulting from activation of structural materials and corrosion products and the cesium from poor fuel performance. The cobalt is anticipated to be present in both soluble and insoluble forms with the insoluble particulate having a wide range of particle size. The cesium is expected to be essentially 100% soluble. EXAMPLE

A plastic which is comprised of a 3:1 copolymer of ethyl acylate and methacrylic acid is used in this example. This plastic has physical properties similar to those of conventional polyvinylchloride or polyethylene film, and can be used in nuclear power facilities for a variety of purposes, some of which include sheathing, personnel clothing, plastic bags, and laydown cloth. Once contaminated, this material is segregated from other plastic materials, shredded and washed, then dissolved in a IN NaOH solution. Low heat addition during the dissolution process will increase the rate of dissolution such that a 3% solution of polymer can be achieved in approximately 30 minutes. The solvent can be preheated for most rapid dissolution. The heat addition process also aids in the formation of insoluble metal ion precipitates such as Co(OH)_ which can be subsequently removed by filtration. This digestion is governed by the reaction:

+2 -1

Co (aq) + 20H (aq) ===> Co(OH)₂(s)

16The reaction with cobalt is used as an example because the cobalt isotopes Co-58, and Co-60 constitute the vast majority of the radioactivity in low level dry active waste streams.

DISSOLUTION REACTION

Ethylacrylate Methacrylic Acid

(-CH₂ - R"C00 _aq) + H₃0⁺

After the dissolution and digestion processes, the plastic waste stream is pumped through a filtration stage which consists of one or more individual filtration units of different pore sizes or media types. This stage removes the insoluble and particulate portion of the waste stream, while allowing the plastic to continue downstream. A decontamination factor between 5 to 10 can be achieved from the filtration stage alone. Subsequent to filtration, the waste stream is passed through an ion-exchange stage which may consist of mixed beds or serial beds of different media. Ion-exchange media are which are selective for cobalt and cesium with a low specificity for common ions such as sodium are the preferred media. Some examples includes Durasil-70, Durasil-190, and Durasil-230, all of which are products of Duratek Corporation. This ion-exchange stage removes to a high degree the specific metal ions which are responsible for the majority of the activity in the stream and for which the ion-exchange media have been selected. Decontamination factors on the order of one hundred (100) or greater can be acheived. After ion-exchange, the waste stream must be acidified using, for example, hydrochloric acid, in order to precipitate the polymer from solution. This precipitate is filtered or dewatered using a device such as a centrifugal decanter or similar polymer filtering device, then extruded into a form suitable for drying. The plastic can then be disposed of or recycled into reusable plastic products. The effluent liquid from the precipitation and filtering stage may be discharged to the environment at a properly licensed facility.

DISSOLUTION TESTS

Tests have been performed to characterize the dissolution properties of the two plastic materials, copolymers of ethylacrylate and methacrylic acid.

With ratios of 4:1 and 3:1, respectively, the 3:1 copolymer has dissolved faster and with more clarity than the 4:1 under all conditions tested. Solvents tested include: AQUEOUS SOLVENTS

1% NaOH

4% (IN) NaOH

5% Na₂C03

IN NH_ΛOH 4

The most rapid dissolution rate has been observed with (IN) NH.OH; however, this solvent has not been pursued due to its potentially hazardous nature and more importantly due to its interference with cobalt removal. The most promising solvent is 4% (IN) NaOH. Dissolution rates with low heat additon range from 1.3-2.0 g/liter.min and result in clear solutions which although viscous, are filterable. ION EXCHANGE

Cs Removal

3% w/w solutions of plastic containing 20 ppm Cs in IN NaOH showed no sign of breakthrough after 600 bed volumes with Durasil 190 and 230 media. This means a minimum of 7Kg of plastic can be processed with 1 liter of the media.

Co Removal

The high pH generated by dissolution in IN or 1% NaOH causes precipitation of Co in solution. The precipitation process requires time for the particles to agglomerate. In early experiments where this time was not allowed, Co removal appeared very poor, most likely because fine precipitated Co(OH) 2 passed through the column. An experiment where a 1% plastic, 1% NaOH, 20 ppm Co solution was allowed to stand for 24 hours, filtered and then passed through a Durasil 70 media Co column gave excellent results. Eighty percent of this Co came out on the filter. After 300 bed volumes, there was no sign of Co breakthrough in the test column. Thus, a minimum of 3 Kg of plastic can be processed of 1 liter of the media.

Cobalt and Cesium are expected to be the major contaminants which will be removed by the method 20 of the invention.

The method of the invention can be used in several manners. The method can be built into the operation of any particular and desired nuclear power plant. Further the method can be provided on a portable facility so that it may be selectively positioned at a nuclear power plant site for periodic processing of the required plastics. Further the method can be established in a central facility and the plastics shipped to the central facility from a number of regional locations.

The invention further encompasses the production and fabrication of a number of articles which can be processed according to the method 20. As can be seen in Figure 2, the invention includes the use of a dispersion 50 of plastic materials as identified above which are soluble in aqueous solutions for structural coatings 52 which can lock in existing contamination and which can ease future decontamination procedures. Further dispersion 50 can be applied initially and directly to structures 54 such as containment walls and floors, reactor walls and floors and gratings and ladders. Additionally, temporary equipment 56 such as scaffolding, shielding and tools can be covered by the dispersion. Further, permanent equipment 58 such as valve operators, cabling casks, refueling equipment and piping can be covered with a dispersion of a plastic material which is soluble in an aqueous solution. Additionally, dispersions can be used selectively to protect personnel 60 such as, for example, in hand coatings.

Additional uses of the invention can be made by placing the plastic material in the form of a film 70. Such film 70 can be used as disposable protection 72 as plastic suits, gloves, boots, bags, sleevings, laydown cloths, and drapes and the like. Further such plastic film can be used for bags 74 for containing waste products. A granulate form 80 of the plastic materials as identified above, can be used for producing other disposals 82 such as rope, step-off pads and face-shields.

From the above, it can be seen that the present invention is directed to a method and articles which have significant advantage in the nuclear power industry. Such invention allows for appropriate protection from contamination while easing the problem of disposal and storage of the contaminated plastic materials. The plastic materials according to the invention are processed by the method of the invention by dissolution in an aqueous solution with the contaminants removed and buried, and the plastic, recycled and reformed again into items used for protection in the nuclear environment.

Another embodiment of the method of the invention is depicted in Figure 4 and denoted by the number 120. The method contemplates the use of plastics for use in clothing, coverings, structures and equipment meant to be used where such plastics will become radioactively contaminated. The method also contemplates, in a preferred embodiment, plastics that are soluble in organic solvents.

Before proceeding to the full description of the method as depicted in Figure 4, it is to be understood that the method of the invention includes reducing the activity level of low level dry active waste plastic materials to sufficiently low levels as to be considered releasable to the environment by treatment of such plastics with an organic solvent followed by a solvent extraction process to remove the radioactive materials from the organic phase. The distribution of the radioactive materials between the organic and aqueous phases is sufficiently weighted toward the aqueous phase that by contacting the solutions in one or more batch-wise stages or in a continuous contacting apparatus , the organic phase will become sufficiently low in activity level as to be considered releasable to the environment with regards to the radioactive isotope concentration levels. The resulting aqueous phase (ie. extract, Figure 4) can be treated by conventional, state of the art water treatment technology in order to concentrate the radioactivity for disposal in, for example, a shallow land-burial facility. Treatment methods can include filtration, ion exchange, and evaporation followed by incorporation in a bitumen or concrete matrix or disposal in a high-integrity container. The product organic phase (ie. raffinate, Figure 4), may be treated to recover and separate the organic solvent and plastic. The recovered plastic may be disposed of as non-contaminated material or further processed into plastic articles and materials for reuse.

Turning to Figure 4, the method 120 of the invention is depicted. The method includes initially collecting the contaminated plastic materials at collection point 122. These plastic materials will include for the most part polyvinylchloride, polyethylene, polypropylene and polystyrene products. Other plastic materials may also become contaminated and require disposal. Once these materials are collected, they are provided to a segregator 124 which by various techniques separates the plastic components from the non-plastic components. The non-plastic components are disposed of by other means known in the nuclear industry. The plastic material is then shredded at shredder 126 and provided to a heated dissolution tank 128. Into dissolution tank 128 an appropriate organic solvent is introduced by solvent dispenser 132. This solvent is mixed with the shredded plastic and the mixture is heated by heater 130 in order to dissolve the plastic in the solvent and provide a feed stream to a solvent extraction column 136. In the solvent extraction column 136, the plastic material, being dissolved in an organic solvent, can be contacted with an aqueous solvent in order to remove the solute or extract (radioactive particulate and soluble matter) from the organic phase, thus leaving a contamination-free plastic in the organic phase. Since most of the particulate matter is a combination of ordinary dirt, dust and iron oxides, this material, being of relatively high density, will tend toward the heavier or aqueous phase. The dissolved radioactive species, being virtually all metal cations will have a much high affinity for the more polar or aqueous phase as well.

In a preferred embodiment, the solvent extraction column 136 will include a continuous column solvent extraction unit with counter-current flow of the continuous aqueous phase feed from the top and the organic discontinuous phase feed from the bottom. This arrangement gives the advantage of having the heavy particulate settle out to the bottom of the column where they would be carried away with the aqueous phase for treatment by conventional water-treatment techniques as discussed below. As can be seen in Figure 4, the extract or radioactive solute can be provided to filtration stage 138 and an ion exchange stage or adsorption stage 140. These stages remove insoluble and soluble contaminate respectively, discharging a concentrated contaminate which can be disposed of properly, and water which can be released to the environment. This extract can also be provided to an evaporator 142 where the water is boiled off and condensed for reuse, in condensor 146 and the bottoms are disposed in a low level disposal facility as is known in the industry.

The product organic phase from the solvent extraction column 136, otherwise known as a raffinate, is provided to a solvent recovery station 144 where the plastic is recovered and disposed of in a sanitary land-fill or recycled, and the solvent is recycled back to the dissolution tank 128 and used with make— p solvent as required in order to dissolve additional raw plastic.

EXAMPLE

Polyvinylchloride, PVC, is a common thermoplastic material which is used in the nuclear power industry and elsewhere in the forms of plastic bags, laydown cloth, sheathing material and others. PVC is dissolved in an organic solvent such as methyl isobutyl ketone, MiBK, to produce an opaque but relatively non-viscous solution. This solution is contacted stagewise in a mixer-settler with an aqueous solvent such as a mild hydrochloric acid or other acid solution. With adequate mixing, mass transfer occurs between the two phases such that any dissolved ionic material which was initially on the plastic material, and became dissolved in the organic phase, is redistributed between the two phases according to the preference of the particular ionic species for the more polar aqueous phase.

The above example indicates one selected organic solvent which can be used with polyvinylchloride. Other solvents which can be used are listed below in Table 1. Table 2 below lists plastics solubility test results when these organic solvents are used on polyvinylchloride and polyethylene, which as indicated above are two of the most common plastics used in the nuclear industry. TABLE 1

SOLVENT GROUP SOLVENT

Aromatic compounds Benzene, toluene Chlorinated hydrocarbons CC1, 4 Aliphatic hydrocarbons N-dodecane, cyclohexane

Ketones Methyl Ethyl Ketone (MEK) ,

Methyl Isobutyl Ketone (MiBK) , and other higher order ketones

TABLE 2

PLASTIC SAMPLES

SOLVENT GROUP SOLVENT POLYETHYLENE PVC

Aromatic Benzene Yes No

Compounds Toluene NO

Aliphatic Cyclohexane^' Yes No

Hydrocarbons N-dodecane No _____-.

Chlorinated CC1 Yes No

Hydrocarbons

Ketones MEK No Yes MIBK Yes

The "Yes" and "No" Table 2 refers to whether the plastic did or did not dissolve in the solvent.

Table 2, polyethylene dissolved in three different solvents in three different categories, while the PVC dissolved in only one of the solvent categories tested. The most promising of these is the cyclohexane for polyethylene and the ketones for PVC. The other two solvents, benzene and carbon tetrachloride, which were successful at dissolving polyethylene, are both hazardous chemicals and are preferably avoided when possible in industrial applications.

Solvent extraction tests were performed using simple mixer-settler type equipment utilizing separatory funnels. Solutions of plastic dissolved in an organic solvent along with traces of soluble cobalt were contacted with aqueous solvents. Atomic absorption analysis was performed on the extract and raffinate samples to determine the effectiveness of the extraction process. The results of this test are depicted in Figures 5 and 6. The data on these figures indicates that there is a significant decontamination factor which can be realized from this process wherein the decontamination factor or, DF is defined as the ratio of the initial radioactivity level divided by the final radioactivity level. Figure 5 depicts a two-stage extraction test and Figure 6 depicts a three-stage extraction test.

Other objects and advantages of the invention can be obtained through a review of the claims and the Figures.

It is to be understood that other embodiments of the invention can be devised which come within the scope and breadth of the claims appended hereto.

Claims

We Claim:

1. A method of reducing radioactive contamination from plastic materials comprising the steps of: dissolving the plastic materials in an aqueous solvent to produce an effluent stream; and operating on the effluent stream to remove contaminated materials.

2. The method of claim 1 wherein the operating step includes: filtering the effluent stream to remove insoluble materials, at least some of which are contaminated.

3. The method of claim 1 wherein the operating step includes: providing for ion exchange whereby the soluble materials, at least some of which are contaminated, are removed from the effluent stream.

4. The method of claim 1 wherein the operating step includes: providing for adsorption whereby the soluble materials, at least some of which are contaminated, are removed from the effluent stream.

5. The method of claim 1 including the step of: precipitating the plastic from the effluent stream.

6. The method of claim 1 wherein the dissolving step includes the step of: heating the aqueous solvent to enhance the rate of dissolution.

7. The method of claim 1 wherein said dissolving step includes: using sodium hydroxide as the aqueous solvent.

8. The method of claim 1 wherein the dissolving step includes: using a caustic solvent as the aqueous solvent.

9. The method of claim 2 including the step of: adjusting the pH of the effluent stream after the filtration step.

10. The method of claim 5 wherein said precipitating step includes: providing an acidic regime in order to precipitate the plastic material out of the effluent stream.

11. The method of claim 5 including the steps of: dewatering the precipitated plastic material; drying the plastic material; and disposing of the plastic material.

12. The method of claim 1 including the preparatory step of separating plastic materials that can be dissolved in an aqueous solution from plastic materials that cannot be dissolved in an aqueous solution; shredding the dissolvable plastic materials; and washing the shredded dissolvable plastic materials with a washing solution to remove loosely attached soluble and insoluble materials, at least some of which can be radioactively contaminated, from the plastic materials.

13. The method of claim 12 wherein the washing step includes: using a neutral solution to wash the shredded plastic material.

14. The method of claim 12 wherein the washing step includes: using an acidic solution to wash the shredded soluble plastic materials.

15. The method of claim 10 including the step of providing for a dewatering step to separate out the loosely attached soluble and insoluble materials from the washing solution; disposing of the soluble and insoluble materials; discharging washing solution.

16. The method of_.claim 5 wherein hydrochloric acid is used in the precipitation step to precipitate the plastic material from solution.

17. The method of claim 1 including the step of: using a copolymer of ethyl acrylate and methacrylic acid as the plastic material.

18. A method of reducing radioactive contamination from plastic materials comprising the steps of: dissolving the plastic materials in an aqueous solvent to produce an effluent stream; filtering the effluent stream to remove insoluble materials, at least some of which are contaminated; providing for, selectively, an ion exchange or adsorption step whereby the soluble materials, at least some of which are contaminated, are removed from the effluent stream; discharging the effluent stream.

19. A method of protecting permanent and temporary structures or equipment for use in a radioactive environment from radioactive contamination including the steps of: coating the structure or equipment with a plastic material that is at least in part soluble in an aqueous solvent.

20. The method of claim 19 wherein the coating step includes: applying a copolymer of ethyl acrylate and methacrylic acid to the structure or equipment.

21. A method of locking in existing radioactive contaminates on permament and temporary structures or equipment used in radioactive environments and for protecting from further radioactive contamination including the step of: coating the structure or equipment with a plastic material that is at least in part soluble in an aqueous solvent.

22. The method of claim 21 wherein the coating step includes: applying a copolymer of ethyl acrylate and methacrylic acid to the structure or equipment.

23. A method of making protective clothing for individuals, and coverings for equipment and structures for use in radioactive environments, where such clothing and coverings will become radioactively contaminated: providing plastic material that is at least in part soluble in an aqueous solvent; fabricating the plastic material into the desired clothing and coverings.

24. The method of claim 23 including the step of: providing the plastic material in the form of a film.

25. The method of. claim 23 including the steps of: making the plastic material at least in part of a copolymer of ethyl acrylate and methacrylic acid.

26. A method of making disposable goods for use in an environment where such goods may become radioactively contaminated, including the step of: forming the goods with a plastic material that is at least in part soluble in an aqueous solvent.

27. The method of claim 26 wherein the forming step includes: using a copolymer of ethyl acrylate and methacrylic acid as the plastic material.

28. The method of claim 26 including the step of: providing the plastic material in a granulate form.

29. A method of protecting personnel that work in an environment that would subject such personnel to radioactive contamination including the step of: coating at least some portion of the body of the personnel with a plastic material that is at least in part soluble in an aqueous solvent.

30. The method of claim 1 including the step of: providing identifying markings on the plastic material which is dissolvable in an aqueous solvent such the plastic material can be segregated from other types of materials for processing.

31. The method of claim 1 including the step of: using plastic polyvinylalcohol (PVOH) as the plastic material.

32. The method of claim 1 including the step of: using plastic material which is a 4:1 copolymer of ethyl acrylate and methacrylic acid.

33. The method of claim 1 including the step of: using plastic material which is a- 3:1 copolymer of ethyl acrylate and methacrylic acid.

34. The method of claim 1 including the step of: using plastic material which is a 2:1 copolymer of ethyl acrylate and methacrylic acid.

35. The method of claim 1 including the step of: using plastic material which is a 3:2 copolymer of ethyl acrylate and methacrylic acid.

36. The method of claim 1 including the step of: using a polymer of an unsaturated organic acid as the plastic material.

37. The method of claim 19 wherein the coating step includes: applying a polymer of an unsaturated organic acid to the structure or equipment.

38. The method of claim 21 wherein the coating step includes: applying a polymer of an unsaturated organic acid to the structure or equipment.

39. The method of claim 23 including the step of: making the plastic material, at least in part, of a polymer of an unsaturated organic acid.

40. The method of claim 26 wherein the forming step includes: using a polymer of an unsaturated organic acid as the plastic material.

41. An article for use in a radioactive environment and which article will become radioactively contaminated and which article allows for efficient radioactive decontamination comprising: a plastic material that is dissolvable in an aqueous solvent.

42. The article of claim 41 wherein: the plastic material is comprised of a copolymer of ethyl acrylate and methacrylic acid.

43. The article of claim 41 wherein: the plastic material is comprised of a polymer of an unsaturated organic acid.

44. A method of reducing and removing radioactive contaminants from plastic materials comprising the steps of: dissolving the .plastic materials in an organic solvent to produce a feed stream; operating on the feed stream in order to separate the dissolved plastic materials from the radioactive contaminates.

45. The method of claim 44 wherein the dissolving step includes the step of: using an aromatic compound to dissolve the plastic materials.

46. The method of claim 44 wherein the dissolving step includes the step of: using an aliphatic hydrocarbon to dissolve the plastic materials.

47. The method of claim 44 wherein the dissolving step includes the step of: using a chlorinated hydrocarbon to dissolve the plastic material.

48. The method of claim 44 wherein the dissolving step includes the step of: using a ketone to dissolve the plastic material.

49. The method of claim 44 wherein the operating step includes using the step of: using solvent extraction to remove contaminants from the feed stream.

50. The method of claim 49 wherein the solvent extraction step includes: contacting an aqueous solvent with the feed stream in order to cause the contaminants to be transferred from the organic solvent to the aqueous solvent.

51. The method of claim 44 including the step of: recovering the organic solvent after the radioactive contaminants have been removed.

52. The method of claim 49 including the step of: recovering the organic solvent from the dissolved plastic after the contaminants have been removed by the solvent extraction step.

53. The method of claim 44 including the step of: segregating the plastic material from other nonplastic material prior to the dissolving step.

54. The method of. claim 44 including the step of: shredding the plastic material prior to the dissolving step.

55. The method of claim 44 including the step of: using methyl isobutyl ketone to dissolve the plastic materials.

56. The method of claim 44 including the step of: using methyl ethyl ketone to dissolve the plastic materials.

57. The method of claim 44 including the step of: using cyclohexane to dissolve the plastic materials.

58. A method of reducing and removing radioactive contaminants from plastic materials comprising the steps of: dissolving the plastic materials in an organic solvent to produce a feed stream; contacting the feed stream in a solvent extraction device with an aqueous solvent to cause the contaminants to transfer from an organic phase to an aqueous phase.

59. The method of claim 58 including the step of: using a solvent extraction column with the feed stream, from the dissolving step entering the bottom of the column and the aqueous solvent entering the top of the column.

60. The method of claim 58 including the step of: recovering the organic solvent from the solution of the organic solvent and the plastic material, and recovering the plastic material.