Louisiana State University Radiation Safety Office Module 12 General Rules for Irradiator Use

Operating the Irradiators Shepherd Co-60 Irradiator Safety Features The Shepherd Co-60 Irradiator is equipped with an Interlock System which prevents the opening of the chamber door when the radioactive source is in the exposed position. To operate the interlock system, a special key is needed. A radiation monitoring system (placed on top of the irradiator) continuously measures the radiation level in the vicinity of the irradiator and will set off an alarm whenever the radiation level exceeds the limit.

Operating the Irradiators Shepherd Co-60 Irradiator Operating Procedures Unlock the irradiator door padlock and place the padlock on top of the power panel With the other (interlock system) key, turn the panel POWER on Check that the INTERLOCK light is on. Check that the LOW PRESSURE light is off. Verify both sources are in SAFE position, i.e. the source position indicators are at the bottom of the columns.

Operating the Irradiators Shepherd Co-60 Irradiator Open the door by pressing the red DOOR SWITCH button and at the same time opening the door latch. If the door does not open, release the DOOR SWITCH and press against the door to make sure the door sensor is activated. Then, immediately press the DOOR SWITCH and open the door latch at the same time. Place the sample in the chamber at a pre-determined position. Refer to the chamber dose rate graphs to determine the proper sample positioning and exposure time. The graphs indicate the percent of dose rate in different areas of the chamber.

Operating the Irradiators Shepherd Co-60 Irradiator Close the door by pushing on the handle. The door is very heavy, so make sure your other hand is away from the opening. Select the source activity, (i.e. 5 Ci or 3000 Ci) by setting the source toggle switch accordingly.

Operating the Irradiators Shepherd Co-60 Irradiator Set the sample exposure time: PRESET or MANUAL. (A) For PRESET time operation: 1. Set the time toggle switch to PRESET 2. Based on your calculated exposure time, set the timer to the nearest 1/100 minute 3. Push the RESET button to clear previous setting and accept the new setting. (B) For MANUAL time operation: Set the time toggle switch to MANUAL

Operating the Irradiators Shepherd Co-60 Irradiator To start the irradiation, press the RED source button. Immediatley, the selected source will raise to the exposed position, shown by the source position indicator position at the top of the column. Check that the timer is showing the elapsed time. The irradiation can be paused or terminated at anytime by pressing the GREEN source button. For preset time operation, the timer will stop when the source is returned to SAFE position, and will continue when you press the RED source button and the source raises to the exposed position.

Operating the Irradiators Shepherd Co-60 Irradiator For preset time operation, the irradiation is automatically terminated at the preset time and the source automatically returns to its SAFE position. Before opening the chamber door, verify both sources are in the SAFE position. Remove the sample from the chamber and close the chamber door. Turn the Power off and lock the padlock

Operating the Irradiators Shepherd Co-60 Irradiator Safety and Emergency Procedures Do not put explosive or pressurized materials in the chamber. Never attempt to defect the chamber door interlock. This is a condition of our license to operate the irradiator. Always notify Radiation Safety Office personnel if the door does not open when the sources are in the safe position. The chamber door is very heavy. When closing the door, push on the handle and make sure you other hand is away from the opening. If the radiation monitor alarms, immediately close the chamber door, exit the basement area and notify Radiation Safety Office personnel.

Operating the Irradiators Pool Irradiator Co-60 Safety Features High activity Co-60 radioactive sources are placed at the bottom of the pool, and the water in the pool is the main radiation shielding to keep the radiation level in the room below an acceptable limit. A locked metal grid covers the pool surface to prevent access into the pool. Only a small opening (with a metal grid cover) is provided for transferring a special container into the pool. A radiation monitoring system is placed in the room. The system is placed at one corner of the room and monitors the ambient radiation level.

Operating the Irradiators Pool Irradiator Co-60 Operating Procedures Turn on the light in the pool. The switch box is located on the wall next to the room radiation monitoring system. Unlock the pool padlock, remove the metal bar and the grid cover over the small opening. Put the sample(s) in the special container located on the preparation bench next to the pool. Secure the top of the container (which is already attached to the hoist) to the container with the three C-clamps provided.

Operating the Irradiators Pool Irradiator Co-60 Using the hoist system, carefully transfer the container through the opening into the pool until the container sits in the hole at the bottom of the pool. Use your own timer/watch to register the start of irradiation. Cover the opening with the metal grill and the metal bar, lock the pool padlock, and turn off the pool light. At the end of the irradiation period, recover the container by unlocking the security grill, lift with the hoist and then transfer the container back to the preparation bench. Recover the sample(s), leave the container on the bench, cover the opening with the metal grill and the metal bar, lock the pool padlock, and turn off the pool light.

Operating the Irradiators Pool Irradiator Co-60 Safety and Emergency Procedures Upon entering the room, check if the pool is filled with water. The material to be irradiated has to be placed in the special container. Do not put explosives or dry-ice in the sample container. Make sure you do not drop anything in the pool. Report to Radiation Safety Office personnel if you accidentally do so. If the radiation monitor alarms, immediately exit the basement area and notify the Radiation Safety Office.