Louisiana State University Radiation Safety Office

1
Louisiana State UniversityRadiation Safety Office

• Module 12
• General Rules for Irradiator Use

2
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.

3
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.

4
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.

5
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.
• 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

6
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.

7
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

8
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.

9
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.

10
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.

11
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.

12
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.