Washington State University
SAFETY POLICIES AND PROCEDURES MANUAL

RADIATION SAFETY
9.40
Revised 3-02
Radiation Safety Office
335-8916

Decontamination Procedures

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RESPONSIBILITY

WSU radiation workers follow decontamination procedures when an incident causes radioactive contamination of persons or work areas. Workers must consult with the Radiation Safety Office before proceeding beyond simple decontamination of objects or facilities.

SEQUENCE

After a spill, the proper sequence of steps is:

EXTERNAL PERSONAL DECONTAMINATION PROCEDURES

General Procedures

The general procedures for external personal decontamination in cases involving no injury or other need for first aid must include the following steps:

If the exact nature of the contaminant is known, it may be more effective to immerse the hands in a suitable reagent immediately after contamination. Consult the Laboratory Safety Manual for a suitable reagent; otherwise, a physician or qualified Environmental Health and Safety (EH&S) personnel must identify a suitable reagent.

Follow this step by washing and thoroughly rinsing with water.

Skin Decontamination

First Step

The initial step is to gently wash the affected area thoroughly for two
to three minutes with a mild soap and lukewarm water. Rinse thoroughly, dry, and monitor.

Repeat washings as deemed necessary. Conduct a radiation survey after each washing.

Second Step

If the contamination is not removed by the first step, lightly scrub the affected area with a soft brush using a heavy lather and lukewarm water for two minutes. Rinse thoroughly, dry, and monitor.

Repeat this step as deemed necessary. However, avoid any skin abrasion in the process.

Consultation

Workers must consult with the Radiation Safety Office before making any more stringent efforts to decontaminate the skin.

Considerations

The following considerations must govern subsequent skin decontamination measures:

If the skin is broken in an accident with radioactive substances, take immediate action to remove possible contamination. Immediately wash the wound under large volumes of running water. Open the gash to permit flushing action of the water unless the severity of the wound and blood loss indicate the need to contain blood and close the wound.

The health of the skin must be maintained to minimize absorption and internal deposition. If necessary, carefully cover the contaminated area with bandages so that the radioactivity does not spread to other parts of the body.

The RSO approves any resumption of decontamination efforts when symptoms of roughness and reddening have essentially vanished.

Report all wounds to the responsible supervisor and the Radiation Safety Office as soon as emergency precautions have been taken and prior to cleaning. See 9.35.

Eye Decontamination

Flooding with water may remove most of the contamination. Use an eye wash station or eye cup if necessary. Do not use any other eye wash or ointment unless it is prescribed by a physician.

Seek prompt medical attention from a personal physician or WSU Student Health Services. Report eye contamination to the Radiation Safety Office immediately.

Hair Decontamination

Decontaminate hair by repeated application of liquid soap and rinse water, using towels to keep water from running onto face and shoulders.

Remove facial hair by shaving. Partial or total removal of other hair may be necessary. (Consult with the RSO concerning any hair contamination.)

Nose Decontamination

If the contamination is in the nose, clean with wet cotton swab sticks and blow nose frequently. Test the swabs for contamination.

INTERNAL PERSONAL DECONTAMINATION PROCEDURES

Departments must report to the Radiation Safety Office (RSO) any incident involving the potential or suspected internal contamination of personnel.

Coordinate the decontamination efforts with the RSO. A licensed physician must directly supervise all internal decontamination efforts. See 9.48 concerning bioassays.

See "Skin Decontamination-Considerations" above for information about decontamination of cuts or puncture wounds.

DECONTAMINATION OF FACILITY OR EQUIPMENT

Short-Lived Isotopes

If the isotope is relatively short-lived (e.g., less than three weeks) and the initial activity level is low, it may be expedient to isolate the area and allow radioactivity to decay to a negligible level.

Contact the RSO prior to such action. Request that the RSO perform confirming surveys and proper marking or posting of the area.

Longer-Lived Isotopes

For longer-lived isotopes, do the following:

If the contamination cannot be removed, the RSO determines whether administrative controls or postings are necessary.

Area Decontamination Agents

Decontamination is accomplished by usual cleaning methods. The decontamination agent is applied, agitated by swabbing or scrubbing, and finally flushed with clean water. The weaker agents should be tried first. The agents are listed below in suggested order of use.

Consult Environmental Health and Safety before performing decontamination with corrosive cleaning agents.

Exercise care so that the radioactive material does not react with the acid to produce airborne contamination (e.g., iodine vapor, CO2). Wear appropriate gloves, a face shield, and an apron or lab coat to protect skin, tissue, and personal clothing.

Surfaces and Cleaning Agents

See the table below for a list of acceptable cleaning agents for specific surfaces. (FDA 83-8211, 1983)

The RSO must supervise decontamination of these surfaces. There may be a potential for airborne radioactivity and any radioactive waste must be handled properly.

SUMMARY OF SURFACE DECONTAMINATION METHODS
Used Under Radiation Safety Office Supervision

Cleaning Method or Agent Surfaces Action Technique Advantages Disadvantages
(Material must be properly disposed)
Vacuum Cleaning Dry contaminated surfaces. Removal of contaminated dust by suction. Use conventional vacuum technique with HEPA filter only. Good on dry porous surfaces. Avoids water reactions. All dust must be filtered out of exhaust. Machine is contaminated.
Water All nonporous surfaces (metal. paint, plastic, etc.). Not suitable for porous materials such as wood, concrete, canvas, etc. Solution and erosion. Use gross decontamination employing water shot from high pressure hoses. Work from top to bottom to avoid recontamination; from upwind to avoid spray; 15 to 20 feet from the surface is the optimum operating distance. Vertical surface should be hosed at an incident angle of 30 to 45 degrees. Determine cleaning rate experimentally if possible. Otherwise use a rate of 4 square feet per minute. All water equipment may be utilized. Allows operation to be carried out from a distance. Contamination may be reduced by 50%. Water solutions of other decontaminating agents may utilize water equipment. Drainage must be controlled. Porous materials will absorb contaminants. Oiled surfaces cannot be decontaminated. Not to be applied to dry contaminated surfaces (use vacuum). Spray will be contaminated.
Steam Nonporous surfaces (especially painted or oiled surfaces). Solution and erosion. Work from top to bottom and from upwind. Clean surface at a rate of 4 square feet per minute. The cleaning efficiency of steam may be greatly increased by using detergents. Steam reduces contamination by approximately 90% on painted surfaces. Steam subject to same limitations as water. Spray hazard makes the wearing of waterproof outfits necessary.
Detergents (e.g. Lestoil or Tide) Nonporous surfaces (especially industrial film). Emulsifying agent.
Wetting agent.
Rub surface for 1 minute and wipe with dry rag. Use clean surface of the rag for each application. A powered rotary brush (with pressure feed) is more efficient. Moist application is all that is desired. Solution should not be allowed to drip onto other surfaces. Solution may be applied from a distance with a pressure proportioner. Dissolves industrial film which holds contamination. Contamination may be reduced by 90%. May require contact with surface. Mild method not efficient on long-standing contamination.
Complexing Agents
   Oxalates
   Carbonates
   Citrates
Nonporous surfaces (especially unweathered surfaces; i.e., no rust or calcareous growth). Forms soluble complexes with contaminated material. Solution should contain 3% (by weight) of agent. Spray surface with solution. Keep surface moist for 30 minutes by spraying with solution periodically. After allotted time flush material off with water. Agents may be used on vertical and overhead surfaces by employing mechanical foam. Holds contamination in solution. Contamination (unweathered surfaces) reduced 75% in 4 minutes. Easily stored. Carbonates and citrates are non-toxic non-corrosive. Requires application from 5 to 30 minutes. Little penetrating power; of small value on weathered surfaces.
Organic Solvents Nonporous surfaces (e.g. greasy or waxed surfaces paint or plastic finishes). Solution of organic materials (e.g., oil, paint). Entire unit may be immersed in solvent. Also may be applied by standard wiping procedures. (See Detergents.) Quick dissolving action. Recovery of solvent possible by distillation. Requires good ventilation and fire precautions. Toxic to personnel. Material bulky.
Inorganic Acids Metal surfaces especially those with porous deposits (i.e., rust or calcareous growth.) Circulatory pipe systems. Strong dissolving power on metals and porous deposits. Dip-bath technique is advisable for movable items. Acid should be kept at a concentration of from 1 to 2 Normal (9 to 18% hydrochloric. 3 to 6% sulfuric acid). Reaction time on weathered surfaces should be 1 hour. Pipe systems 2 to 4 hours. Afterwards surface should be neutralized and rinsed. Corrosive action on metal and porous deposits. Corrosive action may be moderated by addition of corrosion inhibitors to solution. Good ventilation required because of toxicity and explosive gases. Acid mixtures should not be heated. Possibility of excessive corrosion if used without inhibitors. Sulfuric acid not effective on calcareous deposits.
Acid Mixtures
   Hydrochloric
   Sulfuric
   Acetic Acid
   Citric Acid
   Acetates
   Citrates
Nonporous surfaces (especially those having porous deposits). Circulatory pipe systems. Dissolving action. Applied in same manner as inorganic acids. Mixture consists of 0.1 gal. hydrochloric. 0.2 lb. sodium acetate 1.0 gal of water. Dissolving action may reduce contamination 90% in 1 hour (unweathered surfaces). Weathered surfaces may require prolonged treatment.
Caustics
   Lye (sodium hydroxide)
   Calcium Hydroxide
   Potassium Hydroxide
Painted surfaces (horizontal). Dissolving power softens paint (harsh method). Lye paint-removal mixture: 10 gal. water 4 lb lye 6 lb. boiler compound. 0.75 lb cornstarch. Allow lye paint remover solution to remain on surface until paint is softened to the point where it may be washed off with water. Remove remaining paint with long-handled scrapers. Minimum contact with contaminated surfaces. Easily stored. Personnel danger (painful burns). Reaction slow: thus it is not efficient on vertical surfaces or overheads. Should not be used on aluminum or magnesium. Method is difficult on vertical or overhead surfaces.
Tri Sodium Phosphate Painted surfaces (vertical, overhead). Dissolving power (mild method). Hot 10% solution applied by standard wiping technique. (See Detergents.) One minute rub. Reduces activity to tolerance in one or two applications. Destructive effect on paint. Not to be used on aluminum or magnesium.
Abrasion




   Wet Sandblasting

 


   Vacuum Blasting


Nonporous surfaces.


 

Nonporous surfaces.




Porous and nonporous surfaces.

Surface removal.

 

 

 



Abrasion with controlled removal by vacuum suction.

Use conventional procedures but keep surface damp to avoid dust hazard.

Wet sandblasting is most practical on large surface areas. Collect used abrasive.

Hold tool flush to surface to prevent escape of contamination.

Activity may be reduced to as low a level as may be desired.

 

 



Controlled disposal.


Impracticable for porous surfaces because of surface penetration by moisture. Contamination spread over area must be recovered.

 


Contamination of equipment.