Radiation Safety Requirements for Analytical X-Ray Producing Equipment

Table of Contents

1. Purpose
2. Equipment Requirements
3. Area Requirements
4. Operating Requirements
5. Personnel Requirements
6. Emergency Procedures
7. References

• Appendix A.  Analytical X-Ray Producing Equipment Lab Based Training Form


• Appendix B.  Analytical X-Ray Producing Equipment Training Program

1. Purpose

   The following requirements are applicable to equipment utilized for x-ray diffraction or fluorescence analysis. Analytical x-ray producing equipment in the possession of the University of Connecticut is subject to registration with the State of Connecticut and applicable state and federal regulations. The University of Connecticut Radiation Safety Office must be notified of the possession of such equipment prior to utilization. Individuals in charge of the installation and all equipment operators shall be familiar with applicable operating procedures and regulations governing the x-ray installation. The Radiation Safety Officer is empowered by the Radiation Safety Committee to immediately terminate the operation of analytical x-ray equipment found to be a threat to health, safety, or property until the violation is corrected.

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2. Equipment Requirements

Requirements For An Enclosed Beam X-Ray System:

1. The radiation source, beam paths, sample, detector and/or other devices e.g. analyzing crystal, filters, etc. shall be enclosed in a chamber, coupled chambers, beam pipes, whole system enclosure, etc. that cannot be entered by any part of the body during normal operation.
   
   
2. The inherent shielding of the chamber/enclosure walls shall be sufficient to limit the dose rate in all regions 5 centimeters (cm) from its outer surface to 0.25 mrem/hr during normal operations.
   
   
3. The system enclosure, sample chamber, etc. closure shall be interlocked with the x-ray tube high voltage supply and/or a shutter in the primary beam so that no x-ray beam can enter the sample chamber while it is open unless the interlock has been consciously and deliberately defeated. The interlock shall be of fail-safe design.
   
   A fail-safe characteristic means a design feature that causes beam port shutters to close upon failure of a safety or warning device.
   


4. If there is more than one port in the radiation source housing or more than one radiation source, all requirements must be satisfied for each port in every source housing associated with the system.
   



 
Safety Device: A safety device is that which prevents entry of any portion of the individual's body into the primary x-ray beam path or which causes the beam to be shut off upon entry into its path shall be provided on all open-beam configurations.

An open beam system is defined as an analytical x-ray system in which an individual could accidentally place some part of his/her body into the primary beam path during normal operation. An analytical x-ray system is considered to be an open-beam system unless the requirements for an enclosed beam system outlined in Section I of this document are met.

The primary beam is the radiation that passes through an aperture of the source housing by a direct path from the x-ray tube or a radioactive source located in the source housing.

An analytical x-ray equipment supervisor may apply for an exemption from the requirement of a safety device if compliance with the requirement is not feasible. The application shall be submitted to the University of Connecticut's Radiation Safety Officer for review and shall include the following:



a. A description of the various safety devices that have been evaluated;



b. The reason each of these devices cannot be used; and



c. A description of the alternative methods that will be employed to minimize the possibility of an accidental exposure, including procedures to assure that operators and others in the area will be informed of the absence of safety devices.


An exemption is dependant upon review and formal approval from the University of Connecticut's Radiation Safety Officer. The x-ray equipment shall not be utilized until approval of the exemption.

Warning Devices:

1. An open-beam configuration shall be provided with a readily discernible indication of:

a. X-ray tube "on-off" status located near the radiation source housing, if the primary beam is controlled in this manner; and/or


b. Shutter "open-closed" status located near each on the radiation source housing, if the primary beam is controlled in this manner.


2. An easily visible warning light labeled with the words "X-RAY ON", or words having similar intent shall be located near any switch that energizes an x-ray tube and shall be illuminated only when the tube is energized.

3. Warning devices shall be labeled so that their purpose is easily identified. The warning devices shall have fail-safe characteristics.

Ports:

Unused ports on radiation source housings shall be secured in the closed position in a manner that will prevent casual opening.

Labeling:

All analytical x-ray equipment shall be labeled with a readily discernible sign or signs bearing the radiation symbol and the words:


a. "CAUTION-HIGH INTENSITY X-RAY BEAM", or words having a similar intent, on the x-ray source housing; and
b. "CAUTION RADIATION-THIS EQUIPMENT PRODUCES RADIATION WHEN ENERGIZED", or words having a similar intent, near any switch that energizes an x-ray tube if the radiation source is an x-ray tube; or
c. "CAUTION-RADIOACTIVE MATERIAL", or words having a similar intent, on the source-housing if the radiation source is a radionuclide.



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Shutters:
On open-beam configurations, each port on the radiation source housing shall be equipped with a shutter that cannot be opened unless a collimator or coupling has been connected to the port.

Radiation Source Housing:
Each radiation source housing shall be subject to the following requirements:


a. Each x-ray tube housing shall be equipped with an interlock that shuts off the tube if it is removed from the radiation source housing or if the housing is disassembled.
b. Each radioactive source housing or port cover or each x-ray tube housing shall be so constructed that, when all shutters are closed, the radiation measured at a distance of 5 cm from its surface is not capable of producing a dose in excess of 2.5 mrem (0.025 mSv) in any one hour. For systems utilizing x-ray tubes, this limit shall be met at any specified tube rating.

Generator Cabinet:
Each x-ray generator shall be supplied with a protective cabinet that limits leakage radiation measured at a distance of 5 cm from its surface such that it is not capable of producing a dose in excess of 0.25 mrem (2.5 µSv) in any one hour.

 




3. Area Requirements

   Radiation Levels:
   The local components of an analytical x-ray system shall be located and arranged and shall include sufficient shielding or access control such that no radiation levels exist in any area surrounding the local component group which could result in a dose to any individual that may be present therein in excess of the dose limits specified in applicable University of Connecticut, state, and/or federal regulations. For systems utilizing x-ray tubes, these levels shall be met at any specified tube rating.
   
   

   A local component is defined as part of an analytical x-ray system and includes areas that are struck by x-rays during operation. Examples of such components include radiation source housings, port and shutter assemblies, collimators, sample holders, cameras, detectors, and shielding but do not include power supplies, transformers, amplifiers, readout devices, and control panels.
   
   Radiation Surveys The Radiation Safety staff shall perform radiation surveys of all analytical x-ray systems sufficient to demonstrate compliance:
   
   
   • Upon installation of the equipment, and at least once every 12 months thereafter. Annual radiation measurements shall not be required if the Radiation Safety staff can demonstrate compliance with applicable state and/or federal regulations;
   • Following any change in the initial arrangement, number, or type of local components in the system;
   • Following any maintenance requiring the disassembly or removal of a local component in the system;
   • During the performance of maintenance or alignment procedures if the procedures require the presence of a primary x-ray beam when any local component in the system is disassembled or removed;
   • Any time a visual inspection of the local components in the system reveals an abnormal condition; and
   • Whenever a personnel monitoring device shows a significant increase over the previous monitoring period or the readings are approaching the limits specified in applicable University of Connecticut, state, and/or federal regulations.
   
   
   Radiation Safety staff shall be notified immediately when the designated laboratory supervisor of analytical x-ray equipment becomes aware of any of the above conditions. The equipment shall not be utilized until Radiation Safety demonstrates compliance with these requirements.
   
   A survey meter should be kept near the equipment at all times so that the operator may perform casual surveys frequently. It should never be assumed that another operator or a service person left the equipment in a safe condition.
   
   Posting:
   Each area or room containing analytical x-ray equipment shall be conspicuously posted with a sign or signs bearing the radiation symbol and the words "CAUTION - X-RAY EQUIPMENT" or words having a similar intent.

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4. Operating Requirements

   Procedures:
   
   Normal operating procedures shall be written by the laboratory supervisor for the analytical x-ray equipment and be made available to all analytical x-ray equipment workers. No individual shall be permitted to operate analytical x-ray equipment in any manner other than that specified in the procedures unless such individual has received written approval directly from the University of Connecticut's Radiation Safety Officer.
   
   
   Normal operating procedures means step-by-step instructions necessary to accomplish the analysis. These procedures shall include sample insertion and manipulation, equipment alignment, routine maintenance, and data recording procedures, which are all related to radiation safety.
   
   The radiation producing equipment supervisor shall ensure that a usage log is maintained for each x-ray producing machine. An entry shall be recorded on the usage log for each time the equipment is utilized. A period of use is defined as a consecutive period of time when x-rays are being generated. At a minimum, the following information shall be recorded for each period of use:
   
   
   • Operator Name
   • Date
   • Start Time
   • End Time
   • X-Ray Unit Make, Model, and Serial Number
   • Equipment Supervisor
   • Operating Parameters (voltage and current)
   
   The equipment supervisor shall utilize either key control or other administrative controls in order to prevent unauthorized use of the x-ray equipment. Additionally, when the x-ray unit is unattended, steps shall be taken to prevent entry to the x-ray beam.
   
   
   Bypassing:
   
   No individual shall bypass a safety device or interlock unless such individual has obtained prior approval from the University of Connecticut's Radiation Safety Officer. Such approval, if granted, shall only be made for a specified period of time. During the approved time that the safety device or interlocks are bypassed, a readily discernible sign bearing the words "SAFETY DEVICE NOT WORKING", or words having a similar intent, shall be placed on the radiation source housing.
   
   Repair or Modification of X-Ray Tube Systems:
   
   Most severe injuries have occurred during non-routine operations such as repair and alignment. Alignment procedures recommended by the manufacturer of the x-ray system shall be utilized if available.
   
   Except as specified in the section pertaining to bypassing, no operation involving the removal of covers, shielding materials, or tube housings or modifications to shutters, collimators, or beam stops shall be performed without ascertaining that the tube is off and will remain off until safe conditions have been restored. The main switch, rather than the interlocks, shall be utilized for routine shutdown in preparation for repairs.
   
   If the entire system, including the x-ray tube, is under one contiguous vacuum, and radiation leakage is less than 0.25 mrem/hr at 5 cm, and a change in any part of the system will not increase the radiation level, then the entire system shall be considered to be an enclosed beam system.
   
   
   Radioactive Source Replacement, Testing, or Repair:
   
   Radioactive source housings shall be opened for source replacement, leak testing, or other maintenance or repair procedures only by individuals authorized to specifically conduct such procedures under a license issued by the U.S. Nuclear Regulatory Commission (NRC) or the applicable Agreement State.
   

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