Guidelines for safe work with sealed materials

Safety Procedure – Working with Sealed Radioactive Sources

Understand the nature of the hazard of the radioactive material (radioisotopes) you intend to use and get practical training from the Radiation Safety Officer for proper handling and work. Source use is limited only to those defined as radiation workers.

  1. Plan your actions ahead to minimize time spent handling of the radioactive material. The shorter the time, the smaller the radiation dose. Run a “cold” trial to acquire skills.
  2. Work at the maximum distance from the radiation source. Doubling the distance from the radiation source reduces the radiation dose significantly (the inverse square law).
  3. Use an appropriate anti-radiation shield. Perspex for beta ()-emitters; lead (in the appropriate thickness) for gamma () emitters; paraffin for neutron radiation.
  4. Use a personal dosimeter (radiation tag) and protective gear as required.
    1. personal protective gear: A closed lab coat, latex or nitrile gloves, safety glasses.
    2. Gloves must be worn at all times and replaced at the required frequency. Use tweezers or tongs and avoid direct hand contact with the source. Use only designated instruments bearing “radioactive” labels.
  5. Concentrate the work in a defined, clearly marked area. Work only on a work surface designated for radioactive work. The surface must be covered with a cloth.
  6. Monitor the work area frequently using an intact Geiger counter or a liquid scintillation counter for smear test, depending on radiation type and intensity, for early detection of a possible contamination.
  7. Follow the safety rules and instructions. 
    1. All equipment and devices intended for use with a radioactive source must be marked with a standard label.
    2. A radioactive source must be under constant supervision. The source must be returned to the safe promptly after use. 
    3. Computerized tracking of source use must be conducted, with the following details: Source name, its activity and serial number, user’s name, date of source removal from the safe and the date of its return.
    4. It is prohibited to transfer a radioactive source without reporting to the Radiation Safety Officer.
    5. It is strictly forbidden to heat, cut, break the sealed source shell, or apply to it any pressure by mechanical means. Any modification to the experiment requires reporting to and obtaining the approval of the Radiation Safety Officer.
    6. Do not eat, drink, smoke, or apply makeup in the laboratory.
    7. Sealed radioactive sources shall be stored in a designated safe, locked and marked with a “radioactive” warning label. An updated list of sources (with the update date) must be placed on the safe door.
  8. In the event of a suspected breach of the source, e.g., source was dropped, inform the service center promptly (extension 2999), evacuate all persons from the room, close the room’s door and await for the arrival of security and safety personnel.

Work with sealed radioactive sources

 The small radioactive sources will be kept in a locked safe if they are not in use.

  • The list of sources will be displayed on the door of the safe and a "Radioactive Caution" sticker.
  • Only authorized radiation employees or students are allowed to open the safe.
  • Gloves must be used when handling the radiation source.
  • At the end of use, the sealed radioactive sources must be returned to a safe.
  • Any transfer of a source from room to room will be reported to the radiation safety officer. 
  • It is mandatory to immediately report to the radiation safety officer any malfunction or accident with the source.

Checking devices before repair

Laboratory instruments that need repair must be monitored before they are removed from the laboratory and make sure they are not contaminated with any radioactive material. A clean device will bear a label signed by the safety officer.

Tests to detect exposure to ionizing radiation

Every authorized worker who appears on the list of radiation workers, determined by the radiation safety officer, is required to undergo personal monitoring. For the purpose of monitoring external exposure to radioactive radiation, dosimetry badges attached to the chest are used. Internal exposure monitoring, as a result of contamination by open sources will be done by a radio-toxicological urine test.

External dosimetry - a chest tag is required for

  • Workers who use high-energy radioactive materials such as certain isotopes that emit gamma radiation. Work in machines that emit radiation such as accelerators and X-ray machine operators.
  • Dosimetry badges for environmental monitoring are placed in the vicinity of radiation emitting devices according to the guidance of the radiation section of the Ministry of Environmental Protection, as well as according to the discretion of the radiation safety officer at the institute.
  • Radio-toxicological urine test - Institute employees who use open radioactive sources are required to undergo a urine test for possible detection of internal contamination. The radiation safety officer at the institute determines which of the employees must undergo this test and accordingly invites the employees to fulfill this obligation. The test is usually performed several times a year for all radiation workers. The test process is as follows:
    • The employee receives a summons for inspection, a plastic container with a sticker on it with his personal information and a biohazard plastic bag. The employee must fill the container with urine (at least 400 ml), write on the sticker the name of the isotope or isotopes he has recently used, put the container in the biohazard plastic bag and hand it to the radiation safety supervisor.
    • The safety unit is responsible for sending the container for testing at the National Radio-Toxicological Laboratory at the Sorek Nuclear Research Center.
  • Examination by an occupational physician - the radiation employee will undergo a medical examination once a year by an occupational physician on behalf of the health organization to which they belong. This test is mandatory and includes a general test and blood and urine. According to the physician’s discretion, the employee will be sent for examination by an ophthalmologist (once every three years or five years). Only the physician is authorized to indicate in the employee's health record whether he is fit to work with ionizing radiation.

How to detect radiation and protect yourself

The entrance to the working area and the radiation work equipment will be marked with a "radiation caution" sticker and appropriate warning signs and/or an audible or visual alarm system. It is strictly forbidden to enter to the work area during operation of radiation emitting equipment.

The recommended safety measures and procedures depend on the type of experiment, the methods and the waste. Special considerations are needed when handling animals. 

The principle underlying radiation safety is monitoring radiation risks and ensuring that exposure is reduced to the lowest possible level, by:

  • Minimizing the duration of exposure.
  • Keeping as much distance as possible from the radiation source.
  • Use of radiation masking.

The equipment or sources that generate radiation may also involve risks other than radiation, such as: chemical, biological and electrical risks. 

Radiation dose standards

The limit dose for the exposure of various tissues and organs (from the occupational safety regulations "Occupational and health regulations for those dealing with ionizing radiation" 1992)

The organ/tissue The borderline dose (REM) The borderline dose (mSv)
Whole body 5 50
Eye lenses 15 150
genitalia 20 200
Breasts 30 300
Bone marrow 40 400
Lungs 40 400
Any other organ or tissue when only one organ or tissue is exposed to radiation 50 500
When more than one organ or algal tissue was exposed to radiation, the total weighted radiation doses according to the calculation below 5 50


Pregnant women - an exposure of one tenth of the dose allowed for an adult is allowed, i.e. 0.5 rem per year. Exposure of more than 0.15 rem per month should be avoided and the dose should not exceed 1 rem for the entire period of pregnancy. A pregnant woman means a woman who herself declared her pregnancy to the employer immediately after receiving the notification.

The radiation doses to which the worker may be exposed will be as low as possible (ALARA - As Low As Reasonably Achievable). It is the responsibility of all radiation workers, including the heads of the research groups to cooperate in order to work in the field of ALARA.  This can be achieved by safety guidelines for a work environment with ionizing radiation and by monitoring and supervision, in order to limit exposure as a result of radioactive contamination.