IAEA International Atomic Energy Agency Personal Protection Day 9 – Lecture 5

IAEA Objective To discuss about personal protection by utilizing barriers to isolate people from the hazard. 2

IAEA Content Contamination control Work place shielding Shielding for personal protection Respiratory Protection Program Personal Protective Equipment 3

IAEA Personal Protection Protection of personnel utilizes barriers to isolate people from the hazard. Techniques for isolation of hazards from personnel are: Physical and engineered controls to contain the source, Administrative procedures-instructions for use of material by personnel to protect them, Contain personnel and isolate them from the sources of contamination, this is the least desirable means of control. 4

IAEA Concepts - Unconfined Sources Containment at the source location (Physical barriers and engineered controls) Glove boxes Ventilation control – negative pressure at location of source Isolate the source (Physical and administrative barriers Restrict access to areas Ventilation control 5

IAEA Contamination Control It is preferable to control the use of materials by restricting access and developing and implementing appropriate procedures which includes personnel training. By controlling and limiting contamination, that is, loose and uncontrolled radioactive material, you reduce the dose to workers. This is effectively accomplished by using both engineering and management controls. Management controls include restricting access to radioactive materials, appropriate procedures for handling, storing, and disposal of materials, and training of personnel who work with the materials. It is a better practice and more cost effective to implement control of radioactive materials by engineering controls, for example by restricting the area of use to a laboratory fume hood when possible; than to need implement an airborne control program which requires the use of a respiratory protection program. 6

IAEA Personal Protection - Industrial Radiography Continuous observation of the area by trained radiography personnel. Use of survey meters to ensure identification of location of the sources so they do not become a hazard to workers or the public. Failure to properly use a survey meter is the primary reason for radiation exposure accidents in industrial radiography. Use of remote cables to achieve ALARA by means of distance from the radioactive source. Guide cables direct the source to the material being radiographed. Collimators provide shielding to reduce the dose to personnel and any areas accessible to the public. 7

IAEA Personal Protection – Medical Applications Shielding materials are used to reduce the dose to both practitioners and patients. “L-Block” and tabletop shields are used for preparation of materials as well as dispensing radiopharmaceuticals. Shielding materials are used to storage as well as disposal of “sharps” and other radioactive waste materials.

IAEA   Shields are used in the preparation of radioactive isotopes. Examples of these type shields are “L-Block” shields using in preparing unit doses for administration.   Table top shields with lead acrylic are used for low energy photon emitters. Plexiglass is used for beta emitters to avoid the production of bremsstrahlung. Work Place Shielding 9

IAEA   To protect medical practitioners, shields are used on syringes used to dispense radioactive isotopes and on unit dose containers. Syringe Shields 10

IAEA   Shielding materials worn by practitioners include glasses with lead incorporated in the lens to reduce the dose to the lens of the eye, and shielded gloves to reduce the dose to the extremities. Shielding for Personal Protection 11

IAEA   Shielding materials are used for radioactive waste, such as “sharp shields,” and “waste shields.” Shielded Waste Containers 12

IAEA .  Shielding materials are used to shield patient organs. Examples of these type shields are those for the thyroid and the gonads. Lead aprons are use to shield patients during dental X-ray procedures. They typically provide shielding equivalent to 0.5 mm of lead. Filtration and collimators are used to reduce unnecessary exposure. Patient Shielding 13

IAEA   Sources of contamination are those radioactive materials which are not encapsulated. Consequently, those applications which do not utilize sealed sources present the greatest concern for contamination.   Control of contamination requires a rigorous program which includes management support, procedures, training of practitioners, and use of appropriate radiations detectors for the radionuclides of concern. Contamination Control: Objectives 14

IAEA   Contamination is a concern because the material may spread and contaminate other materials or areas. This contaminated material presents is costly because material with have to be surveyed to ascertain if it is contaminated or not.   Contaminated material may have to be disposed as radioactive waste which is also expensive. Additionally, contaminated materials present a concern for the spread of contamination and the resulting doses.   Dose concerns include internal contamination which requires an internal dosimetry program and equipment and trained personnel. For these reasons it is important to control the use of radioactive materials and to promptly identify, isolate, and dispose of contaminated materials. Contamination Control: Objectives 15

IAEA   Sources of contamination include radioisotopes used in the healing arts, both for diagnostic as well as therapeutic applications.   Use of these materials may require concern for contamination as well as shielding from direct exposure to radiation. Contamination Control: Medical Applications 16

IAEA   Treatment modalities which use large quantities of radionuclides, such as therapeutic doses of radioactive iodine of thyroid conditions, may require the patient to be isolated to control the spread of contamination.   It must be recognized that their hospital room will become contaminated and that any waste materials, including the toilet, will contain radioactive materials.   Solid waste materials used by the patient may be effectively handled by isolating the materials so storage for radioactive decay.   Handling radionuclides with a short half-life is facilitated by radioactive decay. After seven half-lives, approximately 1% of the radioactivity remains; while after 10 half-lives, only 0.1% of the initial activity is present. Contamination Control: Medical Applications 17

IAEA   Gas chromatography utilizing electron capture detectors often use a nickel-63 source. The radiation protection program includes conducting leak tests to ensure the integrity of this radioactive source. Since nickel-63 has a 66 keV electron, the leak test smears will need to be counted using appropriately calibrated equipment that has the required sensitivity.   Liquid scintillation instrumentation used to evaluate smear samples for contamination must be calibrated using Ni-63 sources; use of tritium (H-3) and C-14 calibrations will result in over or under estimating the activity due to the differences in the beta energy compared with Ni-63. Contamination Control: Laboratory Applications 18

IAEA   There are a variety of radioactive sources used in industry that are encapsulated. Examples are:   industrial radiography which utilize iridium-192, a metal;   moisture density gauges which use cesium-137 and americium-241, and;   process flow gauges which use cesium-137.   Leak tests are utilized to ensure the integrity of the source capsule has not been compromised. Contamination Control: Industrial Applications 19

IAEA   Additional leak tests should be conducted if there are any accidents or incidents which may have damaged the source capsule.   The presence of removable contamination on the smear survey may indicate that either the source capsule may have been compromised.   Leak test procedures should include appropriate limits to ensure compliance with transportation and waste disposal requirements. Contamination Control: Industrial Applications 20

IAEA   For industrial radiography, the presence of removable contamination from leak tests of the “camera,” used to shield the iridium source may indicate that the “S” shaped guide tube in the camera has worn through and that depleted uranium, U- 238, which is used as a shielding material because it is denser than lead, has been detected on the leak test survey. Contamination Control: Industrial Applications 21

IAEA Respiratory Protection Program Elements of a respiratory protection program include: Administrative procedures, Workspace surveillance program, Equipment control program, User certification, Safety program, and Training

IAEA Respiratory Protection Program Element: Administrative Procedures Administrative procedures must include written instructions for: Monitoring airborne radiological conditions, Supervision of the respiratory program, Training requirements for program personnel, Respirator selection, fitting, fit testing, storage, and repair, Medical evaluation of personnel, Records documenting the program.

IAEA Respiratory Protection Program Element: Workspace Surveillance Workspace surveillance must include: Identification of radionuclides and concentrations to ensure that respirators are used when and where they are necessary as specified in procedures, Identification of ancillary hazards such as toxic airborne chemicals and low oxygen concentrations are properly identified,

IAEA Respiratory Protection Program Element: Workspace Surveillance Workspace surveillance must include: Changing airborne radiological conditions are promptly and properly identified, Respiratory protection requirements are updated for the existing conditions, and Information is available for determining dose to personnel

IAEA Respiratory Protection Program: User Certification User certification must include: Fit-testing to ensure that face sealing respirators fit properly, Ensure workers know how to conduct a seal check each time prior to use of the respirator, Retesting of the workers fit test is conducted annually,

IAEA Respiratory Protection Program: User Certification User certification must include: The workers ability to communicate by talking is not excessively impaired by the respirator that it could create a safety hazard, and Vision is maintained by the use of spectacle appliances or contact lenses and is not impaired by fogging, Valves do not freeze open in low temperature environments.

IAEA Respiratory Protection: Equipment Control Equipment control must include: Procurement of the proper respiratory protection equipment including monitoring equipment needed to assess hazards, Inspection of equipment after each use,

IAEA Respiratory Protection: Equipment Control Equipment control must include: Maintenance of respiratory protection equipment including cleaning and decontamination of non-disposable equipment after each use, and Repair of equipment by qualified and properly trained personnel.

IAEA Respiratory Protection Safety A respiratory protection safety program must include: Stand-by rescue personnel for workers who are using respirators that are difficult to remove without assistance. Rescue personnel must be immediately available to assist workers in the event of a failure of supplied air or any other reason that requires relief from distress.

IAEA Respiratory Protection Powered air purifying respirators are used in contaminated areas. The air is pumped into the respirator through a filter. The filter removes particulate material.

IAEA Respiratory Protection Use of respirators requires that workers have a medical evaluation conducted to ensure they do not have health problems that would prohibit them from using respirators. In addition, workers must receive training on the use of respiratory protection equipment and the facility must have procedures and qualified training personnel. For highly contaminated areas, complete “bubble hoods” may be used. An airline supplies filtered air to the unit. Rescue personnel must be present in the event of air supply system failure.

IAEA Air Supplied Suits   Positive pressure air supplied suits help remedy heat stress as well as provide high protection factors for contaminated areas where airborne radioactive materials are a concern. These type suits may also afford protection against other airborne toxic materials. 33

IAEA Personal Protective Equipment Personal Protective Equipment (PPE) Concern should also include hazards other than radiological. Procedures and training should include the appropriate personal protective equipment (PPE). PPE may include laboratory glasses or eye and face shields, lab coats and, in industrial applications, equipment such as hearing protection, hard hats and safety shoes. 34