Safety protection of irradiation
Writer: Sterilization Time: 2020-09-02 Browse: 796 ℃
Safety of radiation sources
The Permit Holder shall consider fire, explosion, corrosion and any other matters related to the continuous use of sealed radiation sources.
It is affected by the following factors:
Activity of radioactive material in sealed source
Radiation toxicity, leaching and solubility of materials
Chemical properties and physical forms
Source usage environment
The Permit Holder shall keep records related to sealed sources. especially:
Serial number of model and logo / source
Nuclide, activity and date
Special form certificate
Leak test certificate
Pollution test certificate
Source rack security
The sealed source should be firmly fixed on the source rack and cannot be moved easily.
The device used for source positioning and moving purposes should be able to use the source lifting system outside the radiation shield.
If the source support or source rack fails, if the source cannot be moved to the designated position, it may lead to radiation accident.
Effective mechanical protection should be provided for radiation sources to prevent interference and damage from items such as product packaging boxes or transport containers.
Whether directly or indirectly, the product positioning system cannot contact the radiation source. This can be achieved by using protective partitions, guide rods or floor guides in the product positioning system.
Source water well
An automatic water level controller will be installed to keep the water level above the predetermined level.
The tank must be impervious to water and designed to retain water under all foreseeable conditions.
It must be able to withstand the weight of the radiation source container used in transportation without affecting the integrity of the pool.
Pool protection and cover
Physical barriers such as fences and / or metal covers will be installed to prevent personnel from accidentally falling into the source storage pool.
Water treatment system monitor
A fixed radiation monitor with audible alarm is installed on the deionization column to detect contamination due to source leakage. This monitor will be interlocked with the radiation control system, and if the contamination reaches the preset alarm level, the source will return to its shielding position and the water circulation will stop.
Zoning of radiation workplaces
Control area an area divided in a radiation workplace in which special protective measures and safety measures are or may be required to:
(1) Control normal exposure or prevent contamination expansion under normal working conditions
(2) Prevent or limit potential exposure.
For the gamma irradiation device, the irradiation chamber and labyrinth are the control areas. Therefore, obvious signs of ionizing radiation should be set up at the entrance of the irradiation room, and administrative procedures and physical barriers (including door locks and interlocking devices) should be used to restrict personnel access to the control area.
zone of inspection
Any area that is not identified as a controlled area and does not normally require special protective measures and safety measures, but whose occupational exposure conditions are subject to continuous inspection. Operation area, control room, ventilation room, equipment room, inverted source room, water treatment room and other areas are supervision areas. Ionizing radiation signs should also be set up in this area.
A workplace monitoring plan is required. The permit holder must have an appropriate number of portable radiation monitoring instruments, including some spare ones, to replace those being verified or repaired (neutron monitoring needs to be considered for electron beam facilities with energy ≥ 10 MeV).
The monitoring instrument must have appropriate energy response, be in good working conditions, be able to measure the dose rate under normal and accident conditions without saturation or distortion, have directly available batteries and check the built-in batteries.
Monitoring instruments must be verified by an organization recognized by the audit and management department before the first use, immediately after repair, or according to the time interval specified by the audit and management department.
Even if it is believed that the environmental radiation level is normal, no one can enter the irradiation room without carrying the monitoring instrument in operation.