Image: Princeton University Logo
EHS Banner collage (safety manual, men wearing hardhats) EHS Banner collage (radiation symbol, two scientists) EHS Banner collage (biohazard symbol, geiger counter)
Home | Workplace Safety | Laboratory Safety | Radiation Safety | Biological Safety | Emergencies
Radiation Safety Guide


Radiation Safety Guide

SECTION 16: Requirements and Precautions For the Use of "Radiation Producing Machines and Devices"

Radiation can be produced by certain pieces of electronic apparatus, including high voltage power supplies and other high voltage equipment with an associated vacuum, as a by-product of operation. Questions concerning the suspected emission of radiation from equipment should be directed to the "Health Physicist."

Analytical X-ray Installations (top)

The State of New Jersey has set forth requirements for "analytical x-ray equipment" in Subchapter 21 of N.J.A.C. 7:28, and the "Authorized User" is responsible to insure that these requirements are met.

1. Definition

"Analytical x-ray equipment" means any device or combination of devices utilizing x-rays to determine the microscopic structure or composition of material, including but not limited to, x-ray diffraction, x-ray spectroscopy, x-ray fluorescence or fluorescence x-ray spectroscopy equipment. Electron microscopes are not regarded as analytical x-ray equipment.

2. General Requirements

a. Warning Signs and Lights

All "analytical x-ray equipment" must have the following items:

  1. A clearly visible label, near any switch energizing an x-ray tube, which bears the radiation symbol and the words: "Caution: This Equipment Produces X-rays When Energized. To Be Operated Only By Authorized Personnel."
  2. A clearly visible label, near the x-ray tube housing, which bears the radiation symbol and the words: "Caution: High Intensity X-ray Beam."
  3. A clearly visible fail-safe* warning light, near any switch energizing an x-ray tube, labeled with these words: "X-ray On."
  4. A clearly visible fail-safe warning light in a conspicuous place near the x-ray tube which indicates when the x-ray tube is producing x-rays.

*As used for the purposes of Section 16, "fail-safe" means that all failures of warning and safety systems that can reasonably be anticipated will cause the equipment to fail in a mode such that personnel are safe from exposure to radiation.

b. Operating Procedures and Dose Limits

All analytical x-ray equipment must have the following items and meet the following requirements:

  1. Written operating and alignment procedures provided by the manufacturer or the person in charge of the unit.
  2. Procedures such that the dose received by the operator during operation and alignment does not exceed 37.5 mrem in one hour to the hands and forearms and 2.5 mrem in one hour to the whole body or lens of the eye.
  3. A radiation survey to insure that the dose rates transmitted through the beam stop or from other components of the unit, such as high voltage rectifiers, do not exceed the limits set forth in Subchapter 21 of the N.J. Radiation Protection Code.
  4. Finger or wrist personnel monitors for all persons who operate, repair or align this equipment.
  5. A radiation survey each time a new installation is placed into operation or each time changes are made that could affect the degree of radiation protection.
  6. All safety devices, either required by the regulations or provided at the time of the equipment's installation, must be maintained in a fully functional condition.
  7. Safety devices must be tested at least once every six months and records kept of the testing.

3. Requirements for Open Beam X-ray Systems

An open beam system is a system for which it is possible to place any part of the body in any possible x-ray path. In addition to the general requirements found in paragraph 2 below, the following requirements must be met:

a. Safety Devices

The following items are required:

  1. A clearly visible warning indicator near each x-ray tube shutter, which indicates when the shutter is open.
  2. A barrier between the "Radiation Area" and the "Restricted Area."
  3. For new x-ray equipment acquired after February 1, 1980, and for older equipment transferred from one user to another after February 1, 1980, there must be:
    • A guard or interlock to prevent entry of any part of the body into the primary beam
    • A beam shutter for each port of the tube housing. The shutter must be interlocked so that the port will be open only when the collimator or apparatus coupling is in place. Shutters at unused ports must be secured.

b. Dose Rates

  • All parts of the system, except the tube housing, shall be constructed so that, with all shutters closed, the stray radiation measured 5 cm from any surface does not exceed 0.25 mrem/hour.
  • The x-ray tube housing shall be constructed so that, with all shutters closed, the leakage radiation measured 5 cm from its surface does not exceed 2.5 mrem/hour.

4. Requirements for Enclosed Beam X-ray Systems

An enclosed beam system is a system in which all possible x-ray paths are fully enclosed so that any part of the body cannot enter the enclosure. In addition to the general requirements found in paragraph 2 above, the following requirements must be met:

a. Safety Devices

There must be:

  • Enough interlocks to prevent the generation of x-rays or the emergence of the primary beam when any section of the enclosure is opened during routine operation, alignment or maintenance.
  • A chamber or coupled chambers enclosing the radiation source, sample, detector and analyzing crystal, which cannot be entered by any part of the body during normal operation.
  • A sample chamber closure with a fail-safe interlock so that no x-ray beam can enter an open sample chamber.

b. Dose Limits

The equipment must be so constructed that the dose rate due to leakage radiation at 5 cm from any accessible surface does not exceed 0.25 mrem/hour during normal operation.

General Labeling and Warning Sign Requirements (top)

    1. Any "Radiation Producing Machine or Device," even if the production of radiation is incidental to the device or machine's purpose, must be labeled on the control panel or a conspicuous surface with a label stating that ionizing radiation is produced when the machine or device is in operation. Labels may be obtained from the Office of Environmental Health and Safety.
    2. The provisions of Section 9 apply to all "Radiation Producing Machines and Devices."

General Precautions (top)

    1. Analytical x-ray equipment is capable of producing primary or diffracted beams of radiation that are hazardous because of the extremely high exposure rates. Data on the radiation hazards from such equipment is included in Appendix I.
    2. Analytical x-ray equipment should be placed in a room separate from other work areas whenever possible.
    3. When not in operation, equipment whose primary purpose is the production of radiation should be secured in such a way as to be accessible to, or operable by, authorized personnel only.
    4. Equipment whose primary purpose is the production of radiation should not be left operating unattended unless there are suitable indicators present to show that the equipment is switched on. Open beam equipment should never be left unattended during operation without adequate safeguards.
    5. Tampering with interlocks is strongly discouraged, but it is recognized that there may be times when such tampering is unavoidable. Explicit steps must be taken to inform all "Users" of the machine or device that the particular interlock is inoperable, and a sign with the individual's name and description of the status of the interlock must be placed on the equipment.
    6. When "Radiation Producing Machines or Devices" are used by several people, there must be effective communication on the status of the machine or device, particularly during repair and modification operations.
    7. Radiation surveys should be made after each modification of apparatus.
    8. It is strongly recommended that a suitable ratemeter with audible output be present in any area in which open beam analytical x-ray equipment is used. A properly placed ratemeter may provide an audible warning that such equipment is producing radiation.



For a disclaimer and information regarding the use of this page, see the disclaimer notice.
Web page comments:

Link: EHS Homepage Princeton University Home Page