VI. Safe Uses of Sources of Ionizing Radiation
Since the guiding philosophy of the radiation safety program is characterized by ALARA, it is obvious that all sources of ionizing radiation must be used as safely as possible. In this section the focus will be requirements for safe procedures and practices in using radioactive materials and radiation machines, with peripheral attention devoted to various other hazardous materials encountered in laboratories.
VI.A. Radioactive Materials
The rules for working with radioisotopes and radiation fields in a safe manner are governed by good judgment and common sense for safe laboratory practices and by a thorough knowledge of the nature of the experiment and the equipment being used. Experiments require careful planning from the first to last step. It is inevitable that certain steps in the experimental procedure, more accident-prone than other steps, result in spillage and spread of radioactive material. These problems must be anticipated in designing the experiments. Some "excessive" caution is necessary in dealing with radioisotopes. A set of guidelines is tabulated in the next subsection in order to minimize external radiation exposure, to minimize internal radiation exposure by avoiding ingestion, inhalation, and absorption of radioactive material, and to prevent the spread of contamination in the event of a spill or other accident.
VI.A.1. General Laboratory Requirements
The laboratory requirements for the safe utilization of radioactive materials are not fundamentally different from those for use of other potentially hazardous materials. A properly designed laboratory gives due consideration to the movement of personnel and materials, the comfort and convenience of personnel, the required utilities, waste disposal, illumination, fire prevention and security, as well as to the minimization of potential hazards and to minimizing the probability of the creation of hazardous working conditions. The potential hazards that are unique to the utilization of radioactive materials in a laboratory are those of external radiation exposure, internal radiation exposure, and the spreading of radioactive contamination to other areas. Thus a radioisotope laboratory must, in addition to the usual safety considerations, provide due consideration for adequate shielding against external radiation, containment of volatile radioactive materials, minimization of contamination, and provision for ease of decontamination. The Radiation Safety Committee, in granting authorization to use radioactive materials, will consider the laboratory facilities in relation to the proposed use. The specific laboratory requirements are dependent upon the type of experiment, quantity of radioactive material to be used, and the hazard rating of the radionuclides being used. It is difficult to establish precise laboratory requirements for the wide varieties of utilization that occur at a university. However, radionuclides are classified into hazard groups, and a laboratory classification scheme for purposes of monitoring is predicated on these hazard groupings (see Section IX, Table I).
VI.A.2. Basic Laboratory Practices
It is essential that all personnel who work with radioactive materials become familiar with the radiation protection program at WSU as set forth in this manual. (A radioactive materials laboratory is defined in Section XIV.) The guidelines for proper procedures as well as requirements in handling radioactive materials are summarized in this section. It is essential to point out that these guidelines pertain to all use of radioactive materials. It is expected that the individual will use the utmost care always to ensure safe use of radioisotopes in order to avoid endangering his or her colleagues in the laboratories. All experimenters must
a. Wear personal dosimeters (e.g., film badge, ring badge, or pocket dosimeter).
b. Wear protective clothing, such as lab coats, full-length slacks, overshoes, and safety glasses or goggles.
c. Protect the hands by wearing plastic gloves. (Consider the outer part of the gloves to be contaminated and limit the use of gloves to the immediate experimental area. Do not use gloves in the "inactive" regions of the laboratory,
where it is normally allowed to use bare hands (e.g., doorknobs, light switches, fume hood doors, and telephones)).
d. Prohibit drinking, eating, smoking, and application of cosmetics in a radioactive materials laboratory. (Even if parts of the laboratory are "inactive," it is necessary to depart from the laboratory for drinking, eating, smoking, or application of cosmetics.) The presence of empty food or drink containers will be considered a violation of these regulations, since it will be inferred that consumption occurred on the premises. Food or drink may be transported (expeditiously) through a radioactive materials laboratory only if in a completely closed container.
e. Prohibit pipetting radioactive solutions using mouth, licking gummed labels, or combing hair, in a radioactive materials laboratory.
f. Monitor hands, feet, clothing, and shoes, before leaving the laboratory.
g. Use suitable monitoring equipment such as portable survey meters in laboratories. (These instruments give exposure rate to radiation in mR/hr, or the observed rate of decay of radioisotopes in counts/min.)
h. Survey the laboratory area before commencing an experiment using radioisotopes. (This precaution will ensure that the laboratory is uncontaminated when starting the work. Allocate a smaller portion of the surveyed area for experimental work. In case of an accident, it will be relatively easy to contain the radioactivity and to decontaminate that area.)
i. When using volatile materials, always work in fume hoods. (For extremely high activity levels, a glove box is preferred. Inasmuch as feasible, avoid open bench-top experiments.)
j. Ensure that the fume hood is in satisfactory condition (e.g., strippable or washable paint on exposed area, proper air-flow, and unclogged drains). Physical Plant personnel are required to conduct an annual inspection of each fume hood to ensure proper operational characteristics. (It is preferable to use glove boxes with pressure inside the box slightly less than atmospheric pressure.)
k. Use a large porcelain or stainless steel tray lined with absorbent paper and carry out the experiments on top of this tray. (In case of an accident it is an easy matter to decontaminate the tray.)
l. Line adjacent porous surfaces with absorbent paper or equivalent material.
m. Store and transport radioactive material in closed containers. (Do not transport open containers from one part of the laboratory to another.)
n. Label all containers of radioactivity properly with date, radioisotope, quantity of radioactivity, and your name. (Regulations require that each container be clearly marked as to its contents.)
o. Use radiation shields if measured radiation levels at the body will result in a dose equivalent in excess of about 20 mrem (0.20 mSv) (Remember that the maximum permitted radiation exposure is 100 mrem/week (1.0 mSv/week). In shielding samples, do not forget that the back or sides of the hood may face an adjacent laboratory; it will be necessary to consider exposure to this area as well.)
p. Survey the work area. Decontaminate the work area as necessary and clean up all equipment immediately after use. (Check the area with survey equipment to ensure the adequacy of the cleanup. Consult with the Radiation Safety Office if you are not able successfully to clean up the area.)
q. Properly post notices to designate areas containing radioactive materials. (Areas where radiation exposure rates would result in a dose equivalent in excess of
5 mrem (0.05 mSv) in one hour should be posted as a Radiation Area and those in excess of 0.1 rem (1 mSv) in one hour as a High Radiation Area. Signs are available for these designations. Remove all signs or markings when the hazard is removed.)
r. Rope off radiation areas and contaminated areas to restrict access and post signs to indicate the hazard. (The barriers should not be removed without prior consultation with the Radiation Safety Office.)
s. Report all accidents promptly to the Radiation Safety Office on the Radioactive Materials Incident and/or Accident Report (SPPM S.90.55.7). (Accidents can occur in the best-planned experiments.)
VI.A.3. Security and Control
a. Stored radioactive materials must be secured from, or controlled in such a manner as to prevent, unauthorized removal from the place of storage.
b. Radioactive materials which are neither in storage nor in an unrestricted area must be tended under the constant surveillance and immediate control of the authorized user.
VI.A.4. Safe Handling
The basic approach to safe handling of radioactive materials is to focus on avoidance of spills, escapes, or other avenues to contamination by the material being handled. Thus the container must be suitable for the material contained, both from the integrity standpoint and the shielding standpoint. In all types of handling, which usually involves a change in position or location of the radioactive materials, one must never allow his or her attention to wander from the procedure at hand. Moreover, because of the nature of radioactive materials and the attendant dangers of exposure or contamination, extra precautions for safe handling must be adopted. For example, in transporting radioactive materials from one laboratory space to another, even in the same building and on the same floor, the mode of transport must include (at least) double containment, so that there is a second barrier to dispersion should the first barrier fail.
VI.A.5. Contamination Control
The rules for contamination control possess considerable overlap with those enumerated in Subsection VI.A.2. above.
a. Wear fully protective clothing, including gloves, a laboratory coat, wrist guards, full-length slacks, shoes (preferably overshoes) that cover the feet and possibly the ankles, and safety glasses or goggles.
b. Designate a specific area for work with radioactive materials.
c. Label all containers and tools properly.
d. Use trays and absorbent papers.
e. Prohibit smoking, drinking, eating, or application of cosmetics in the radioactive materials laboratory.
f. Change gloves frequently so as to avoid contaminating various laboratory articles, fixtures, and surfaces.
g. Use transfer pipettes and prohibit any mouth-pipetting.
h. Work with volatile compounds only in operational fume hoods.
i. Use traps to absorb volatiles. (Guidance on disposal of chemical traps should be obtained from the RSO.)
j. Provide for regular monitoring of clothing, shoes, and the work area.
k. Avoid all interruptions and distractions once the procedure has been commenced, and especially those which might cause contamination of laboratory articles or furniture (e.g., telephone calls).
VI.A.6. Time, Distance, and Shielding
Exposure can be minimized by minimizing the time spent near radioactive materials. In this spirit, one should plan and set up the experiment, including the conduct of dry runs, before actually using radioactive materials. One should also practice handling techniques such as pipetting and aliquotting so that the procedures can be performed with alacrity.
Exposure can be minimized by maximizing the distance between the source of radiation and the experimenter. If a characteristic source dimension is much smaller than the distance between source and observer, then the radiation exposure for the experimenter (observer) is inversely proportional to the square of the distance separating source and observer.
Exposure can be minimized by proper use of appropriate shielding. The type of shielding needed is a function of the type of radiation employed. Both the shielding material to be used and its thickness will vary considerably with the type of radiation source. Properly chosen shielding can either stop or sharply attenuate the radiation that otherwise would strike the experimenter.
VI.B. Radiation Machines
Safe operation of these devices is the responsibility of the authorized user, of the operator, and in its supervisory capacity, of the Radiation Safety Office.
VI.B.1. Authorized User Responsibilities
Each authorized user of a radiation machine is required to
a. Use the device in strict compliance with the provisions of an approved application to the Radiation Safety Committee,
b. Attend radiation safety training,
c. Wear a film badge, issued by the Radiation Safety Office,
d. Apprise the Radiation Safety Office of changes in personnel, machine location, and machine repair,
e. Obtain Radiation Safety Office approval prior to effecting machine modifications, and
f. Forbid activation of safety interlocks for the purpose of deliberate termination of machine operation (except for the case of a test),
g. Prepare and provide written procedures explaining the use of each item of radiation machine in the laboratory, with one copy positioned in the laboratory and another on file in the Radiation Safety Office,
h. Maintain a record of use of each piece of equipment, to include the name of the user, exposure time and intensity, and the date and time of use, with this record available for inspection, and
i. Ensure that each operator of the radiation machine is adequately trained in all aspects of machine operation, with emphasis on safety requirements, with a log of all training maintained and available for inspection at any time, and
j. Ensure that operators comply with all applicable regulations.
VI.B.2. Operator Responsibilities
Each operator of a radiation machine is required to
a. Demonstrate for the authorized user adequate knowledge and ability for safe use of the machine in order to be listed on the Authorization to Use Radioactive Materials as an approved operator,
b. Wear a film badge issued by the Radiation Safety Office,
c. Ensure that shielding and safety devices are in place and functioning properly before operating the machine,
d. Survey the machine for radiation leakage as specified by current regulations, and
e. Maintain awareness of all specific safety requirements for the machines operated.
An exception to these requirements is that a machine may be operated by an authorized repairman during setup, testing, or repair as long as prior permission has been obtained from the Radiation Safety Office for each such use.
VI.B.3. Radiation Safety Office Responsibilities
The Radiation Safety Office is required to
a. Notify the State of Washington Department of Health at least 30 days prior to receipt, transfer, or disposal of any radiation machine,
b. Renew registration of all university-owned or related radiation machine as required by the Department of Health,
c. Maintain a complete inventory of all university-owned or related radiation machines,
d. Retain on file a complete set of written procedures for each radiation machine in the inventory,
e. Conduct inspections of radiation machine facilities to ensure compliance with all pertinent regulations, and report items of non-compliance to the appropriate authorized users,
f. Appraise requests for modifications to machines, and give permission as appropriate,
g. Provide a radiation survey of each facility prior to initiation of routine use and at least once annually thereafter, retaining a copy of results in the use log,
h. Provide advance approval of any radiation survey meter to be purchased by authorized users of radiation machines,
i. Provide appropriate dosimetry for users and operators of radiation machines, and
j. Provide basic training in radiation protection for facility personnel through offerings of the Radiation Safety Course.
VI.C. General Safety Practices
Provisions for radiation safety are often commingled with more general safety requirements and appropriate precautions. In this spirit, reference will be given to pertinent documents governing university policies and procedures in other areas.
VI.C.1. Chemical Hazards
VI.C.2. Biological Hazards
Safety policies and procedures for this area are found in the WSU Safety Policies and Procedures Manual S80 (Occupational Health), and in the Laboratory Safety Manual.
VI.C.3. Other Hazards
Safety policies and procedures for this more general category are found in the WSU Safety Policies and Procedures Manual S20 (Accident Prevention), S25 (Accident Reporting and Follow-up), S30 (Personal Protective Equipment), S35 (Motor Vehicle Safety ), S40 (Equipment Safety), S45 (General Safety), S50 (Area Safety), and S60 (Fire Safety).