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Tools and equipment: From nuclear waste to reuseable items
NUCLEAR AND CHEMICAL WASTE Printed in the USA. All rights reserved.
MANAGEMENT,
Vol. 2,
pp.
197-200, 198 I
TOOLS AND EQUIPMENT: TO REUSEABLE ITEMS
0191-815X:81,030197-04$02.00/O Copyright @ 1981 Pergamon Press Ltd
FROM NUCLEAR
WASTE
J. T. MC Vey* C. Campuzano** D.E. Fowler* *Health Physics Systems, Inc., 2727 N. W. 43rd Street, Gainesville, **Palhades Nuclear Plant, Covert, Michigan 49043, USA
Florida 32601, USA
ABSTRACT. High pressure Freon cleaning and electropolishing techniques were employed to clean radioactively contaminated metallic items, including pumps, cables, electric motors, hand tools, and assorted porous items. The techniques produced minimal waste in the decontamination processes due to advances in distillation and filtration of the cleaning fluids to permit their reuse. The volume of waste for burial was reduced by a factor of 40. Ninety-five percent (95%) of the radioactive contaminants were removed and condensed to a minimal volume for disposal, thereby permitting the return of approximately 6000 articles, worth $1.5 million, to active reuse.
(trademarked RADKLEEN-TD) ishing system.
INTRODUCTION
The typical operation and maintenance of nuclear power plants unavoidably results in various tools and devices with both fixed and loose surface radioactivity. This contamination is often in sufficient quantities to prohibit the use of these items, due both to the external exposure levels that may be encountered and the possibility of internal deposition. Practices for handling these contaminted items normally are limited to conventional decontamination (by washing and/or wiping) and/or ‘storage for subsequent disposal. These practices are not satisfactory due to the following problems: 1. Inadequate cleaning achieved; 2. Unacceptable application (electric motdrs, delicate items); 3. The large volume of liquid radioactive waste generated; 4. The space required to store large volumes of previously uncleanable tools; 5. The expense of destroying costly items. This paper presents the results of a tool and equipment decontamination service using a high pressure Freon-Based Tool Decontamination Unit
MATERIALS
AND
and an electropol-
METHODS
A self-contained Mobile Decontamination Unit (Fig. 1) was deployed at a nuclear power plant to decontaminate an inventory of items accumulated during a recent outage. These items included steam generator dams and tracks, brackets, cables, pumps, electrical tools, motors, and assorted hand tools (Table 1). An estimated 12,000 pounds (5500 kg) of aluminum, stainless steel, and other materials constituting 4000 cubic feet (110 m3) of radioactively contaminated equipment worth approximately $1.5 million was decontaminated by Freon cleaning and electropolishing techniques (Figs. 2 and 3). The levels of smearable activity prior to decontamination varied from 200 dpm (disintegrations per minute) to 1.2 x 106 dpm. Fixed contamination was of similar levels. The primary objective was to render the power plant’s contaminated equipment reuseable. By definition, “reuseable” status required that smearable levels be reduced to 200 dpm/ 100 cm2 for use in controlled areas; if the fixed contamination could be reduced to 300 dpm/ 100 cm*, the items were considered suitable for use in uncontrolled areas as well. In each case, the type of material along with its designated area of use often predetermined the levels of contamination that would be encountered and the levels of removal that were acceptable. The physical composition of the item
RECEIVED11/6/30; ACCEPTED614181. **Present address: C. Campuzano, P.O. Box 341, Lusby, MD 20657, USA. Acknowledgemenrs-The authors express their appreciation to Mr. Jerry Cunningham and to Mr. Michael Laycock for their technical input to this paper. 197
J.T. McVEY, C. CAMPUZANO,
198
FIGURE 1.
Schematic diagram of Mobile Decontamination
AND D.E. FOWLER
Unit.
TABLE 1. Items Decontaminated
Item
Quantity
by High-Pressure
Freon and ElectropoliihingProcesses
Activity Level (smaarable) DPMHOO cm Before After
Decontamination
Dacontamination Factors Maximum Minlmum
1. Aluminum Dams
Generator
32
200,000 to 1,200,000
Background to 3,000
99.97 %
1.2 mil:l
250:1
2. Aluminum Generator
Steam Tracks
16
5,000 to 70,000
Background to 400
98.6%
45,OOO:l
2O:l
100
4,000 to 75,000
Background to 500
99.5%
16O:l
93:l
3. Dam Clamps 4. Stainless Strongback - Steam Generator
4
40,000 to 95,000
Less than 400
99.4%
23&l
1OO:l
5. Stainless
Turnbuckles
6
20,000 to 60,000
Background to 400
99.8%
50,000: 1
1OO:l
6. Stainless Braces
S.G.
29
5,000 to 50,000
Background to 400
99.3%
13&l
138:1
1
300,000
Background
100%
-
300,000:1
6. NDT Test Equipment
10
150 to 3,500
95.6%
14O:l
7:l
9. Probe Pusher
6
3,200 to 42,000 1,800 to 425,000
300 to 4,000 (on motor)
94.8%
106:l
8:1
2,500
200
7. S.G. Dam Brace
-
13:1
82.2%
11:1
3:l
Less than 200
87.5%
8:1
8:1
500,000
800
99.8%
-
625: 1
100 to 500
97.9%
-
47:l
Pump
1
11. Electric Drills and Grinders
48
200 to 4,500
Less than 200
7
200 to 3,000
1
10. Electric
12. Electric
Adapters
13. Large Stainless
Shaft
(1)’
14,000
Cable
(1)’
3,500
Background to 150
97.9%
-
47:1
Cord
(1)’
3,000
Background to 150
98.3%
-
6O:l
(2)’
up to 15,000
Less than 200
88.5%
23:1
2:1
17,000 to 800,000
Less than 400
99.2%
67,OOO:l
43:l
1
300,000
100
99.9%
-
3,OOO:l
32
200 to 3,900
Less than 200
84.3%
14:l
3:1
14. 1” Hose 15. Welding 16. Electrical
17. Miscellaneous Hand Tools 16. Stainless Brackets
92%
Generator
19. Relief Valve 20. Miscellaneous Equipment
Electric
23
NOTE: (1) Cleaned
in the Tool Decon Hose Cleaning
attachment.
Record of actual
feet not maintained.
(2) Records available on approximately 1,400 Bechtel and 200 Palisades hand tools such as: drill bits, putty knives, files, levels, hammers, channel locks, scissors, saw blades, crowbars, crescent wrenches, rotary hammers, wire wheels, hand saws, “C” _ clamps, pliers, torque gauges, torque wrenches, 3 ton chain falls, come alongs (%, % and 1% ton) pulleys, pipe cutters. etc.
199
TOOLS AND EQUIPMENT
A-7 FllM 1
AlY 1, = 57 7
Freon 8 2000 psi 1
-----
High Pressure System
L_____ I
T
---J
Freon & Contaminants
e
Cleaning
.
Chamber
Freon Processer
FIGURE 2.
Schematic
diagram
of high-pressure
Freon
system.
was always considered so that the cleaning technique employed resulted in a cleaned item with its operational functions intact as in the cases of electric pumps, grinders, drills, and saws. Routinely the items to be cleaned were delivered in containers where an inventory and radiation survey to determine the initial level of activity present was conducted. All items were initially spray cleaned with Freon and surveyed to determine the effectiveness of this decontamination step. Those items with remaining high levels of fixed contamination were then electropolished. Periodically, items required reprocessing due to their initially high level of contamination. However, the vast majority of items required only one cleaning to achieve the desired objective of unlimited reuse in controlled or uncontrolled areas. Throughout the entire process, precautions were taken for personnel protection. These included the wearing of protective apparel (gloves, clothing, and respirators as necessary) and periodic surveillance of the work area with portable survey meters and swabs to maintain radiation levels within limits set by regulatory agencies. Freon Technique The techniques used to decontaminate items included both high pressure Freon spraying and modified electropolishing. The use of freon cleaning had been previously evaluated and determined to be an effective method of cleaning cloth, plastic, and rubber apparel (1,2,3). Its application to tool decontamination was accomplished by a specially designed, self-
contained unit which allowed the operator to manipulate a high-pressure spray nozzle directed at specific, hard-to-reach portions of the radioactive item. The contamination-laden Freon was then passed through a filtration system (soluble contaminants were removed daily by integrated distillation) so that a continuously recycled, clean fluid was utilized in the cleaning process. The Freon Tool Decontamination Unit measured approximately 66 x 69 x 72 in. (168 x 175 x 183 cm) and operated at a nominal pressure of 2000 psi (1.03 x 105 mm Hg). The spray nozzle and item to be cleaned were manipulated through the glove ports of the unit. Cleaning times varied depending on the size and intricacy of the item, but ranged from 2 to 5 min. Electropoiishing Techniques Like the Freon technique, the electropolishing technique employed a self-contained and continuously filtered operation. This procedure was most applicable to items which could withstand the passage of the required electric current while submersed in the electropolishing solution. The contamination (both loose and fixed) is electrically, chemically, and mechanically suspended in the solution. This technique is a subtly difficult procedure requiring a thorough knowledge of the principles employed to effectively perform the task for various types of materials, This process required two tanks each 28 x 28 x 80 in. (71 x 71 x 203 cm): one for the actual electropolishing and another for rinsing the item in water. The first process required 20-30 min and space was available for handling numerous items at the same time. The rinse process required less than one minute to flush residual acid from the item. RESULTS During the three weeks (1000 man hours) of on-site services, 6000 articles were decontaminated. Loose surface and fixed dpm data were obtained for a representative sampling (l/3) of the articles. The
-
-
0
cathode
Object to be Decontaminated
Polishing Tank
Polishing Solutmn
FIGURE 3.
Schematic
diagram
of electropolishing
system.
2Qo
decontamination record and final disposition status, indicated that 100% of the items were reclaimed and useable. All samples were analyzed by the health physics staff using a Ludlum Model 20 instrument with a HP-210 detector. One minute counting times provided statistically accurate measurements (uncertainty + 10% at 95% C.L.) with a counting efficiency for the system of 13%. Table 1 indicates that the degree of decontamination achieved for each category of equipment was significant, with no category retaining more than 17% of its original radioactivity. It is significant to note that those categories with the lowest level of decontamination included extremely difficult items such as electric motors, wooden-handled tools, and various other porous material. The large metallic (often the most expensive and hard to replace) items, cleaned extremely well (greater than 95% of initial activity removed). The calculated decontamination factors averaged 31:l with a range from 1.2 million: 1 to 2:l. Considering the criteria for “clean” release of 200 dpm/ 100 cm2,95% of the items decontaminated were found to be in compliance. The remaining 5% had extremely high levels of initial activity, but after decontamination were reuseable on a modified basis in specific areas of the plant. Additionally, 94(% passed the criterion to permit their use in uncontrolled areas, indicating the item was also cleaned of most of its fixed contamination. A comparative analysis of these methods of tool and equipment decontamination with the conventional water-based techniques reveals significant reductions in the final volumes of radioactive waste. The resultant waste from the Mobile Decontamination Unit amounted to 1. Water-50 gallons (189 liters); 2. Phosphoric acid (85%)-200 gallons (757 liters) required; 3. Filters (110-5 cm diam x 25 cm long)-two 55gallon barrels (208 liters); 4. Gloves, suits, and other compactable supplies-three 55-gallon barrels (208 liters). When compared to the original 4000 cubic feet (110 m3) of contaminated items, these volumes indicate a reduction in radioactive waste by a factor of 40. The estimated volume of waste resulting from water/detergent decontamination is large compared to the amount resulting from the Freon/ electropolishing process. An estimated 100 gallons (379 liters) of
J.T. McVEY, C. CAMPUZANO,
AND D.E. FOWLER
detergent (for a 5% solution) and an estimated 5000 gallons (1.9 x 104 liters) of water would be required to cleanse the items plus an additional lO,OOO-20,000 gallons (3.8-7.6 x 104 liters) for rinse. Processing this waste by filtration, evaporation, and solidification for disposal would require additional expenditures and manpower of 3 to 4 times the 1000 hours reported for Freon cleaning. Furthermore, an estimated 1/3 of the items would not be cleanable by water, resulting in at least $500,000 worth of items remaining unuseable. Finally, plant experience indicates that of those items that could be cleaned by water processing, only half would meet the “reuseable” criteria. CONCLUSION
AND
SUMMARY
The techniques and equipment described in this paper produced waste volume reductions, cost savings in the form of both reduced storage dollars per cubic foot and capital replacement, and quicker turn-around times, compared to the conventional decontamination methods. The fact that virtually all equipment was returned as “reuseable” highlights the efficiency of the decontamination system. Maximum decontamination was attained while the volume of waste was reduced to approximately 1/ 40th of its original volume. It would have been impossible to perform this same degree of decontamination with water/ detergent-type cleaners for several reasons. First, the electrical, porous,’ and some of the intricate items would not easily lend themselves to conventional cleaning. Electrical malfunctions, increased fixed activity, and oxidation would have occurred. Secondly, it is estimated that conventional cleaning techniques would not typically be able to remove more than 50%75% of the removeable contamination. Finally water/detergent type cleaners have little, if any, effect on the fixed contamination.
REFERENCES Capella, J. Dry cleaning of protective clothing. Trans. Am. Sot. 30: 675 (1978). Francis, C. J. Solid waste uranium recovery by Freon-base extraction. XN-NF-PTA-280, Exxon Nuclear Company, Inc., Richland, Washington (1980). Active Dry Cleaning Test Program for Protective Garments and Equipment at Bruce GS “A.” Report Number 79345, Ontario Hydro, Ontario, Canada (1979).
MANAGEMENT,
Vol. 2,
pp.
197-200, 198 I
TOOLS AND EQUIPMENT: TO REUSEABLE ITEMS
0191-815X:81,030197-04$02.00/O Copyright @ 1981 Pergamon Press Ltd
FROM NUCLEAR
WASTE
J. T. MC Vey* C. Campuzano** D.E. Fowler* *Health Physics Systems, Inc., 2727 N. W. 43rd Street, Gainesville, **Palhades Nuclear Plant, Covert, Michigan 49043, USA
Florida 32601, USA
ABSTRACT. High pressure Freon cleaning and electropolishing techniques were employed to clean radioactively contaminated metallic items, including pumps, cables, electric motors, hand tools, and assorted porous items. The techniques produced minimal waste in the decontamination processes due to advances in distillation and filtration of the cleaning fluids to permit their reuse. The volume of waste for burial was reduced by a factor of 40. Ninety-five percent (95%) of the radioactive contaminants were removed and condensed to a minimal volume for disposal, thereby permitting the return of approximately 6000 articles, worth $1.5 million, to active reuse.
(trademarked RADKLEEN-TD) ishing system.
INTRODUCTION
The typical operation and maintenance of nuclear power plants unavoidably results in various tools and devices with both fixed and loose surface radioactivity. This contamination is often in sufficient quantities to prohibit the use of these items, due both to the external exposure levels that may be encountered and the possibility of internal deposition. Practices for handling these contaminted items normally are limited to conventional decontamination (by washing and/or wiping) and/or ‘storage for subsequent disposal. These practices are not satisfactory due to the following problems: 1. Inadequate cleaning achieved; 2. Unacceptable application (electric motdrs, delicate items); 3. The large volume of liquid radioactive waste generated; 4. The space required to store large volumes of previously uncleanable tools; 5. The expense of destroying costly items. This paper presents the results of a tool and equipment decontamination service using a high pressure Freon-Based Tool Decontamination Unit
MATERIALS
AND
and an electropol-
METHODS
A self-contained Mobile Decontamination Unit (Fig. 1) was deployed at a nuclear power plant to decontaminate an inventory of items accumulated during a recent outage. These items included steam generator dams and tracks, brackets, cables, pumps, electrical tools, motors, and assorted hand tools (Table 1). An estimated 12,000 pounds (5500 kg) of aluminum, stainless steel, and other materials constituting 4000 cubic feet (110 m3) of radioactively contaminated equipment worth approximately $1.5 million was decontaminated by Freon cleaning and electropolishing techniques (Figs. 2 and 3). The levels of smearable activity prior to decontamination varied from 200 dpm (disintegrations per minute) to 1.2 x 106 dpm. Fixed contamination was of similar levels. The primary objective was to render the power plant’s contaminated equipment reuseable. By definition, “reuseable” status required that smearable levels be reduced to 200 dpm/ 100 cm2 for use in controlled areas; if the fixed contamination could be reduced to 300 dpm/ 100 cm*, the items were considered suitable for use in uncontrolled areas as well. In each case, the type of material along with its designated area of use often predetermined the levels of contamination that would be encountered and the levels of removal that were acceptable. The physical composition of the item
RECEIVED11/6/30; ACCEPTED614181. **Present address: C. Campuzano, P.O. Box 341, Lusby, MD 20657, USA. Acknowledgemenrs-The authors express their appreciation to Mr. Jerry Cunningham and to Mr. Michael Laycock for their technical input to this paper. 197
J.T. McVEY, C. CAMPUZANO,
198
FIGURE 1.
Schematic diagram of Mobile Decontamination
AND D.E. FOWLER
Unit.
TABLE 1. Items Decontaminated
Item
Quantity
by High-Pressure
Freon and ElectropoliihingProcesses
Activity Level (smaarable) DPMHOO cm Before After
Decontamination
Dacontamination Factors Maximum Minlmum
1. Aluminum Dams
Generator
32
200,000 to 1,200,000
Background to 3,000
99.97 %
1.2 mil:l
250:1
2. Aluminum Generator
Steam Tracks
16
5,000 to 70,000
Background to 400
98.6%
45,OOO:l
2O:l
100
4,000 to 75,000
Background to 500
99.5%
16O:l
93:l
3. Dam Clamps 4. Stainless Strongback - Steam Generator
4
40,000 to 95,000
Less than 400
99.4%
23&l
1OO:l
5. Stainless
Turnbuckles
6
20,000 to 60,000
Background to 400
99.8%
50,000: 1
1OO:l
6. Stainless Braces
S.G.
29
5,000 to 50,000
Background to 400
99.3%
13&l
138:1
1
300,000
Background
100%
-
300,000:1
6. NDT Test Equipment
10
150 to 3,500
95.6%
14O:l
7:l
9. Probe Pusher
6
3,200 to 42,000 1,800 to 425,000
300 to 4,000 (on motor)
94.8%
106:l
8:1
2,500
200
7. S.G. Dam Brace
-
13:1
82.2%
11:1
3:l
Less than 200
87.5%
8:1
8:1
500,000
800
99.8%
-
625: 1
100 to 500
97.9%
-
47:l
Pump
1
11. Electric Drills and Grinders
48
200 to 4,500
Less than 200
7
200 to 3,000
1
10. Electric
12. Electric
Adapters
13. Large Stainless
Shaft
(1)’
14,000
Cable
(1)’
3,500
Background to 150
97.9%
-
47:1
Cord
(1)’
3,000
Background to 150
98.3%
-
6O:l
(2)’
up to 15,000
Less than 200
88.5%
23:1
2:1
17,000 to 800,000
Less than 400
99.2%
67,OOO:l
43:l
1
300,000
100
99.9%
-
3,OOO:l
32
200 to 3,900
Less than 200
84.3%
14:l
3:1
14. 1” Hose 15. Welding 16. Electrical
17. Miscellaneous Hand Tools 16. Stainless Brackets
92%
Generator
19. Relief Valve 20. Miscellaneous Equipment
Electric
23
NOTE: (1) Cleaned
in the Tool Decon Hose Cleaning
attachment.
Record of actual
feet not maintained.
(2) Records available on approximately 1,400 Bechtel and 200 Palisades hand tools such as: drill bits, putty knives, files, levels, hammers, channel locks, scissors, saw blades, crowbars, crescent wrenches, rotary hammers, wire wheels, hand saws, “C” _ clamps, pliers, torque gauges, torque wrenches, 3 ton chain falls, come alongs (%, % and 1% ton) pulleys, pipe cutters. etc.
199
TOOLS AND EQUIPMENT
A-7 FllM 1
AlY 1, = 57 7
Freon 8 2000 psi 1
-----
High Pressure System
L_____ I
T
---J
Freon & Contaminants
e
Cleaning
.
Chamber
Freon Processer
FIGURE 2.
Schematic
diagram
of high-pressure
Freon
system.
was always considered so that the cleaning technique employed resulted in a cleaned item with its operational functions intact as in the cases of electric pumps, grinders, drills, and saws. Routinely the items to be cleaned were delivered in containers where an inventory and radiation survey to determine the initial level of activity present was conducted. All items were initially spray cleaned with Freon and surveyed to determine the effectiveness of this decontamination step. Those items with remaining high levels of fixed contamination were then electropolished. Periodically, items required reprocessing due to their initially high level of contamination. However, the vast majority of items required only one cleaning to achieve the desired objective of unlimited reuse in controlled or uncontrolled areas. Throughout the entire process, precautions were taken for personnel protection. These included the wearing of protective apparel (gloves, clothing, and respirators as necessary) and periodic surveillance of the work area with portable survey meters and swabs to maintain radiation levels within limits set by regulatory agencies. Freon Technique The techniques used to decontaminate items included both high pressure Freon spraying and modified electropolishing. The use of freon cleaning had been previously evaluated and determined to be an effective method of cleaning cloth, plastic, and rubber apparel (1,2,3). Its application to tool decontamination was accomplished by a specially designed, self-
contained unit which allowed the operator to manipulate a high-pressure spray nozzle directed at specific, hard-to-reach portions of the radioactive item. The contamination-laden Freon was then passed through a filtration system (soluble contaminants were removed daily by integrated distillation) so that a continuously recycled, clean fluid was utilized in the cleaning process. The Freon Tool Decontamination Unit measured approximately 66 x 69 x 72 in. (168 x 175 x 183 cm) and operated at a nominal pressure of 2000 psi (1.03 x 105 mm Hg). The spray nozzle and item to be cleaned were manipulated through the glove ports of the unit. Cleaning times varied depending on the size and intricacy of the item, but ranged from 2 to 5 min. Electropoiishing Techniques Like the Freon technique, the electropolishing technique employed a self-contained and continuously filtered operation. This procedure was most applicable to items which could withstand the passage of the required electric current while submersed in the electropolishing solution. The contamination (both loose and fixed) is electrically, chemically, and mechanically suspended in the solution. This technique is a subtly difficult procedure requiring a thorough knowledge of the principles employed to effectively perform the task for various types of materials, This process required two tanks each 28 x 28 x 80 in. (71 x 71 x 203 cm): one for the actual electropolishing and another for rinsing the item in water. The first process required 20-30 min and space was available for handling numerous items at the same time. The rinse process required less than one minute to flush residual acid from the item. RESULTS During the three weeks (1000 man hours) of on-site services, 6000 articles were decontaminated. Loose surface and fixed dpm data were obtained for a representative sampling (l/3) of the articles. The
-
-
0
cathode
Object to be Decontaminated
Polishing Tank
Polishing Solutmn
FIGURE 3.
Schematic
diagram
of electropolishing
system.
2Qo
decontamination record and final disposition status, indicated that 100% of the items were reclaimed and useable. All samples were analyzed by the health physics staff using a Ludlum Model 20 instrument with a HP-210 detector. One minute counting times provided statistically accurate measurements (uncertainty + 10% at 95% C.L.) with a counting efficiency for the system of 13%. Table 1 indicates that the degree of decontamination achieved for each category of equipment was significant, with no category retaining more than 17% of its original radioactivity. It is significant to note that those categories with the lowest level of decontamination included extremely difficult items such as electric motors, wooden-handled tools, and various other porous material. The large metallic (often the most expensive and hard to replace) items, cleaned extremely well (greater than 95% of initial activity removed). The calculated decontamination factors averaged 31:l with a range from 1.2 million: 1 to 2:l. Considering the criteria for “clean” release of 200 dpm/ 100 cm2,95% of the items decontaminated were found to be in compliance. The remaining 5% had extremely high levels of initial activity, but after decontamination were reuseable on a modified basis in specific areas of the plant. Additionally, 94(% passed the criterion to permit their use in uncontrolled areas, indicating the item was also cleaned of most of its fixed contamination. A comparative analysis of these methods of tool and equipment decontamination with the conventional water-based techniques reveals significant reductions in the final volumes of radioactive waste. The resultant waste from the Mobile Decontamination Unit amounted to 1. Water-50 gallons (189 liters); 2. Phosphoric acid (85%)-200 gallons (757 liters) required; 3. Filters (110-5 cm diam x 25 cm long)-two 55gallon barrels (208 liters); 4. Gloves, suits, and other compactable supplies-three 55-gallon barrels (208 liters). When compared to the original 4000 cubic feet (110 m3) of contaminated items, these volumes indicate a reduction in radioactive waste by a factor of 40. The estimated volume of waste resulting from water/detergent decontamination is large compared to the amount resulting from the Freon/ electropolishing process. An estimated 100 gallons (379 liters) of
J.T. McVEY, C. CAMPUZANO,
AND D.E. FOWLER
detergent (for a 5% solution) and an estimated 5000 gallons (1.9 x 104 liters) of water would be required to cleanse the items plus an additional lO,OOO-20,000 gallons (3.8-7.6 x 104 liters) for rinse. Processing this waste by filtration, evaporation, and solidification for disposal would require additional expenditures and manpower of 3 to 4 times the 1000 hours reported for Freon cleaning. Furthermore, an estimated 1/3 of the items would not be cleanable by water, resulting in at least $500,000 worth of items remaining unuseable. Finally, plant experience indicates that of those items that could be cleaned by water processing, only half would meet the “reuseable” criteria. CONCLUSION
AND
SUMMARY
The techniques and equipment described in this paper produced waste volume reductions, cost savings in the form of both reduced storage dollars per cubic foot and capital replacement, and quicker turn-around times, compared to the conventional decontamination methods. The fact that virtually all equipment was returned as “reuseable” highlights the efficiency of the decontamination system. Maximum decontamination was attained while the volume of waste was reduced to approximately 1/ 40th of its original volume. It would have been impossible to perform this same degree of decontamination with water/ detergent-type cleaners for several reasons. First, the electrical, porous,’ and some of the intricate items would not easily lend themselves to conventional cleaning. Electrical malfunctions, increased fixed activity, and oxidation would have occurred. Secondly, it is estimated that conventional cleaning techniques would not typically be able to remove more than 50%75% of the removeable contamination. Finally water/detergent type cleaners have little, if any, effect on the fixed contamination.
REFERENCES Capella, J. Dry cleaning of protective clothing. Trans. Am. Sot. 30: 675 (1978). Francis, C. J. Solid waste uranium recovery by Freon-base extraction. XN-NF-PTA-280, Exxon Nuclear Company, Inc., Richland, Washington (1980). Active Dry Cleaning Test Program for Protective Garments and Equipment at Bruce GS “A.” Report Number 79345, Ontario Hydro, Ontario, Canada (1979).