Article 3. Design and Performance Requirements for Irradiators
12VAC5-481-2720. Performance criteria for sealed sources.
Article 3
Design and Performance Requirements for Irradiators
A. Sealed sources installed after July 1, 1993, shall:
1. Have a certificate of registration issued by the NRC or another agreement state;
2. Be doubly encapsulated;
3. Use radioactive material that is as nondispersible as practical and that is as insoluble as practical if the source is used in a wet-source-storage or wet-source-change irradiator;
4. Be encapsulated in a material resistant to general corrosion and to localized corrosion, such as 316L stainless steel or other material with equivalent resistance if the sources are for use in irradiator pools; and
5. In prototype testing of the sealed source, have been leak tested and found leak-free after each of the tests described in subsections B through G of this section.
B. The test source shall be held at -40ºC for 20 minutes, 600ºC for one hour, then be subjected to a thermal shock test with a temperature drop from 600ºC to 20ºC within 15 seconds.
C. The test source shall be twice subjected for at least five minutes to an external pressure (absolute) of 2 million newtons per square meter.
D. A 2-kilogram steel weight (2.5. centimeters in diameter) shall be dropped from a height of 1 meter onto the test source.
E. The test source shall be subjected three times for 10 minutes each to vibrations sweeping from 25 hertz to 500 hertz with a peak amplitude of five times the acceleration of gravity. In addition, each test source shall be vibrated for 30 minutes at each resonant frequency found.
F. A 50-gram weight and a pin (0.3 centimeter pin diameter) shall be dropped from a height of 1 meter onto the test source.
G. If the length of the source is more than 15 times larger than the minimum cross-sectional dimension, the test source shall be subjected to a force of 2000 newtons at its center equidistant from two support cylinders, the distance between which is 10 times the minimum cross-sectional dimension of the source.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2730. Access control.
A. Each entrance to a radiation room at a panoramic irradiator shall have a door or other physical barrier to prevent inadvertent entry of personnel if the sources are not in the shielded position. Product conveyor systems may serve as barriers as long as they reliably and consistently function as a barrier. It shall not be possible to move the sources out of their shielded position if the door or barrier is open. Opening the door or barrier while the sources are exposed shall cause the sources to return promptly to their shielded position. The personnel entrance door or barrier shall have a lock that is operated by the same key used to move the sources. The doors and barriers shall not prevent any individual in the radiation room from leaving.
B. In addition, each entrance to a radiation room at a panoramic irradiator shall have an independent backup access control to detect personnel entry while the sources are exposed. Detection of entry while the sources are exposed shall cause the sources to return to their fully shielded position and shall also activate a visible and audible alarm to make the individual entering the room aware of the hazard. The alarm shall also alert at least one other individual who is onsite of the entry. That individual shall be trained on how to respond to the alarm and prepared to promptly render or summon assistance.
C. A radiation monitor shall be provided to detect the presence of high radiation levels in the radiation room of a panoramic irradiator before personnel entry. The monitor shall be integrated with personnel access door locks to prevent room access when radiation levels are high. Attempted personnel entry while the monitor measures high radiation levels, shall activate the alarm described in subsection B of this section. The monitor may be located in the entrance (normally referred to as the maze) but not in the direct radiation beam.
D. Before the sources move from their shielded position in a panoramic irradiator, the source control shall automatically activate conspicuous visible and audible alarms to alert personnel in the radiation room that the sources will be moved from their shielded position. The alarms shall give individuals enough time to leave the room before the sources leave the shielded position.
E. Each radiation room at a panoramic irradiator shall have a clearly visible and readily accessible control that would allow an individual in the room to make the sources return to their fully shielded position.
F. Each radiation room of a panoramic irradiator shall contain a control that prevents the sources from moving from the shielded position unless the control has been activated and the door or barrier to the radiation room has been closed within a preset time after activation of the control.
G. Each entrance to the radiation room of a panoramic irradiator and each entrance to the area within the personnel access barrier of an underwater irradiator shall be posted as required by 12VAC5-481-860. Radiation postings for panoramic irradiators shall comply with the posting requirements of 12VAC5-481-860, except that signs may be removed, covered, or otherwise made inoperative when the sources are fully shielded.
H. If the radiation room of a panoramic irradiator has roof plugs or other movable shielding, it shall not be possible to operate the irradiator unless the shielding is in its proper location. This requirement may be met by interlocks that prevent operation if shielding is not placed properly or by an operating procedure requiring inspection of shielding before operating.
I. Underwater irradiators shall have a personnel access barrier around the pool which shall be locked to prevent access when the irradiator is not attended. Only operators and facility management may have access to keys to the personnel access barrier. There shall be an intrusion alarm to detect unauthorized entry when the personnel access barrier is locked. Activation of the intrusion alarm shall alert an individual (not necessarily on site) who is prepared to respond or summon assistance.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2740. Shielding.
A. The radiation dose rate in areas that are normally occupied during operation of a panoramic irradiator may not exceed 2 mrem (0.02 mSv) per hour at any location 30 centimeters or more from the wall of the room when the sources are exposed. The dose rate shall be averaged over an area not to exceed 100 square cm having no linear dimension greater than 20 centimeters. Areas where the radiation dose rate exceeds 2 mrem (0.02 mSv) per hour shall be locked, roped off, or posted.
B. The radiation dose at 30 centimeters over the edge of the pool of a pool irradiator may not exceed 2 mrem (0.02 mSv) per hour when the sources are in the fully shielded position.
C. The radiation dose rate at 1 meter from the shield of a dry-source-storage panoramic irradiator may not exceed 2 mrem (0.02 mSv) per hour and at 5 centimeters from the shield may not exceed 20 mrem (0.2 mSv) per hour.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2750. Fire protection.
A. The radiation room at panoramic irradiator shall have heat and smoke detectors. The detectors shall activate an audible alarm. The alarm shall be capable of alerting a person who is prepared to summon assistance promptly. The sources shall automatically become fully shielded if a fire is detected.
B. The radiation room at a panoramic irradiator shall be equipped with a fire extinguishing system capable of extinguishing a fire without the entry of personnel into the room. The system for the radiation room shall have a shut-off valve to control flooding into unrestricted areas.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2760. Radiation monitors.
A. Irradiators with automatic product conveyor systems shall have a radiation monitor with an audible alarm located to detect loose radioactive sources that are carried toward the product exit. If the monitor detects a source, an alarm shall sound and product conveyors shall stop automatically. The alarm shall be capable of alerting an individual in the facility who is prepared to summon assistance. Underwater irradiators in which the product moves within an enclosed stationary tube are exempt from this requirement.
B. Underwater irradiators that are not in a shielded radiation room shall have a radiation monitor over the pool to detect abnormal radiation levels. The monitor shall have an audible alarm and a visible indicator at entrances to the personnel access barrier around the pool. The alarm shall be capable of alerting an individual who is prepared to respond promptly.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2770. Control of source movement.
A. The mechanism that moves the sources of a panoramic irradiator shall require a key to actuate. Actuation of the mechanism shall cause an audible signal to indicate that the sources are leaving the shielded position. Only one key may be in use at any time, and only operators or facility management may possess it. The key shall be attached to a portable radiation survey meter by a chain or cable. The lock for source control shall be designed so that the key may not be removed if the sources are in an unshielded position. The door to the radiation room shall require the same key.
B. The console of a panoramic irradiator shall have source position indicator that indicates when the sources are in the fully shielded position, when they are in transit, and when the sources are exposed.
C. The control console of a panoramic irradiator shall have a control that promptly returns the sources to the shielded position.
D. Each control for a panoramic irradiator shall be clearly marked as to its function.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2780. Irradiator pools.
A. For licenses initially issued after July 1, 1993, irradiator pools shall have a method to safely store the sources during repairs of the pool and either:
1. Have a watertight stainless steel liner or a liner metallurgically compatible with other components in the pools; or
2. Be constructed so that there is a low likelihood of substantial leakage and have a surface designed to facilitate decontamination.
B. For licenses initially issued after July 1, 1993, irradiator pools shall have no outlets more than 0.5 meter below the normal low water level that could allow water to drain out of the pool. Pipes that have intakes more than 0.5 meter below the normal low water level and that could act as siphons shall have siphon breakers to prevent siphoning of pool water.
C. A means shall be provided to replenish water losses from the pool.
D. A visible indicator shall be provided in a clearly visible location to indicate if the pool water level is below the normal low water level or above the normal high water level.
E. Irradiator pools shall be equipped with a purification system designed to be capable of maintaining the water during normal operation at a conductivity of 20 microsiemens per centimeter or less and with a clarity so that the sources can be seen clearly.
F. A physical barrier, such as a railing or cover, shall be used around or over irradiator pools during normal operation to prevent personnel from accidentally falling into the pool. The barrier may be removed during maintenance, inspection, and service operations.
G. If long-handled tools or poles are used in irradiator pools, the radiation dose rate on the handling areas of the tools may not exceed 2 mrem (0.02 mSv) per hour.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2790. Source rack protection.
If the product to be irradiated moves on a product conveyor system, the source rack and the mechanism that moves the rack shall be protected by a barrier or guides to prevent products and product carriers from hitting or touching the rack or mechanism.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2800. Power failures.
A. If electrical power at a panoramic irradiator is lost for longer than 10 seconds, the sources shall automatically return to the shielded position.
B. The lock on the door of the radiation room of a panoramic irradiator may not be deactivated by a power failure.
C. During a power failure, the area of any irradiator where sources are located may be entered only when using an operable and calibrated radiation survey meter.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2810. Design requirements.
A. For all irradiators, licensees shall evaluate the location and sensitivity of the monitor to detect sources carried by the product conveyor system as required by 12VAC5-481-2760 A. Licensees shall verify that the product conveyor is designed to stop before a source on the product conveyor would cause a radiation overexposure to any person.
B. For panoramic irradiators:
1. Licensees shall design shielding walls to meet generally accepted building code requirements for reinforced concrete and design the walls, wall penetrations, and entrance ways to meet the radiation shielding requirements of 12VAC5-481-2740. If the irradiator will use more than 5 million curies (2 x 1017 Bq) of activity, licensees shall evaluate the effects of heating of the shielding walls by the irradiator sources.
2. Licensees shall design the foundation, with consideration given to soil characteristics, to ensure it is adequate to support the weight of the facility shield walls.
3. Licensees shall verify from the design and logic diagram that the access control system will meet the requirements of 12VAC5-481-2730.
4. Licensees shall verify that the number, locations, and spacing of the smoke and heat detectors are appropriate to detect fires and that the detectors are protected from mechanical and radiation damage. Licensees shall verify that the design of the fire extinguishing system provides the necessary discharge patterns, densities, and flow characteristics for complete coverage of the radiation room and that the system is protected from mechanical and radiation damage.
5. Licensees shall verify that the source rack will automatically return to the fully shielded position if offsite power is lost for more than 10 seconds.
6. Licensees shall verify that electrical wiring and electrical equipment in the radiation room are selected to minimize failures due to prolonged exposure to radiation.
7. Licensees shall determine that source rack drops due to loss of power will not damage the source rack and that source rack drops due to failure of cables (or alternate means of support) will not cause loss of integrity of sealed sources.
8. Licensees shall review the design of the mechanism that moves the sources to assure that the likelihood of a struck source is low and that, if the rack sticks, a means exists to free it with minimal risk to personnel.
9. For panoramic irradiators to be built in seismic areas, licensees shall design the reinforced concrete radiation shields to retain their integrity in the event of an earthquake by designing to the seismic requirements of an appropriate source or local building codes, if current.
D. For pool irradiators:
1. Licensees shall design the pool to assure that it is leak resistant, that it is strong enough to bear the weight of the pool water and shipping casks, that a dropped cask would not fall on sealed sources, that all outlets or pipes meet the requirements of 12VAC5-481-2780 C, and that metal components are metallurgically compatible with other components in the pool.
2. Licensees shall verify that the design of the water purification system is adequate to meet the requirements of 12VAC5-481-2780 E. The system shall be designed so that water leaking from the system does not drain to unrestricted areas without being monitored.
3. Licensees shall verify that there are no crevices on the source or between the source and the source holders that would promote corrosion on a critical area of the source.
4. If licensees use radiation monitors to detect contamination under 12VAC5-481-2870 B, they shall verify that the design of radiation monitoring systems to detect pool contamination includes sensitive detectors located close to where contamination is likely to concentrate.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.
12VAC5-481-2820. Construction monitoring and acceptance testing.
A. For all irradiators, licensees shall verify the proper operation of the monitor to detect sources carried on the product conveyor system and the related alarms and interlocks required by 12VAC5-481-2760 A.
B. For all irradiators with product conveyor systems, the licensee shall observe and test the operation of the conveyor system to assure that the requirements in 12VAC5-481-2790 are met for protection of the source rack and the mechanism that moves the rack; testing shall include tests of any limit switches and interlocks used to protect the source rack and mechanism that moves the rack from moving product carriers.
C. For panoramic irradiators:
1. Licensees shall monitor the construction of the shielding to verify that its construction meets design specifications and generally accepted building code requirements for reinforced concrete.
2. Licensees shall monitor the construction of the foundations to verify that their construction meets design specifications.
3. Licensees shall test the movement of the source racks for proper operation prior to source loading; testing shall include source rack lowering due to simulated loss of power.
4. Licensees shall test the completed access control system to assure that it functions as designed and that all alarms, controls, and interlocks work properly.
5. Licensees shall test the ability of the heat and smoke detectors to detect a fire, to activate alarms, and to cause the source rack to automatically become fully shielded. Licensees shall test the operability of the fire extinguishing system.
6. Licensees shall demonstrate that the source racks can be returned to their fully shielded positions without offsite power.
7. For panoramic irradiators that use a computer system to control the access control system, licensees shall verify that the access control system will operate properly if offsite power is lost and shall verify that the computer has security features that prevent an irradiator operator from commanding the computer to override the access control system when it is required to be operable.
8. Licensees shall verify that the electrical wiring and electrical equipment that were installed meet the design specifications.
D. For pool irradiators:
1. Licensees shall verify that the pool meets design specifications and shall test the integrity of the pool. Licensees shall verify that outlets and pipes meet the requirements of 12VAC5-481-2780 B.
2. Licensees shall verify that the water purification system, the conductivity meter, and the water level indicators operate properly.
3. Licensees shall verify the proper operation of the radiation monitors and the related alarm if used to meet 12VAC5-481-2870 B.
E. For underwater irradiators, licensees shall verify the proper operation of the over-the-pool monitor, alarms, and interlocks required by 12VAC5-481-2760 B.
Statutory Authority
§ 32.1-229 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 22, Issue 25, eff. September 20, 2006; amended, Virginia Register Volume 24, Issue 18, eff. June 12, 2008; Volume 32, Issue 24, eff. August 25, 2016.