Radiation Control (RadCon) Group
Special Survey Instructions - RSS Experiment
September 12, 2003
General guidance for surveys in hall C during G-0 Experiment
This document is intended to clarify radiation survey requirements and precautions around the G0 detector setup.
The following precautions are specific to radiation surveys. There may be other general safety precautions to be adhered to in association with the target/detectors. ARMs are expected to be familiar with all EH&S requirements for the areas they survey.
Survey guidelines:
- Only use the YELLOW teletector. Due to the high magnetic field, the other instrument models are subject to failure and damage.
- Use extreme caution when surveying around the magnet - do not bring the probe any closer than 30 cm from the magnet.
- The upstream side of the magnet should not
pose any special problems, just use caution not to let the magnetic field pull
the detector into contact with the chamber. It may damage the detector if the
magnetic field is too high.
Upstream of Target - There should not be a need to survey the upper platform of the target/magnet, unless a radiation area appears to extend up onto the platform area. This is not really expected, but you can judge the extent of any radiation area upward by its extent downward. Obviously if it is less than 5 mR/hr a few feet away from the beamline below, it will be less than 5 mR/hr up on the platform.
- If there is a radiation area at the target/magnet, rope it off at the floor.
- The magnet should be powered down for access to the upper platform.
- If there appears to be a radiation area extending up to the platform, and access to the platform is necessary, either carry the instrument with a strap, or use the lanyard that is near the ladder to hoist the instrument up to the platform after climbing up. Do NOT try to climb the ladder with the meter in your hand.
- On the back side of the magnet, there are large vacuum windows — NEVER place the detector directly behind a vacuum window when the plexiglass guard is removed from the window. The photo below is misleading - it appears that the probe is in front of the window, but it is not. You can get get the probe within a couple feet of the beam centerline at this point, but you will not be able to get it as close as you would like to beam centerline, and technically may not be able to do a whole body survey in this area (because you would have to have the probe where it jeopardizes the vacuum window). Use the following guidance for posting, if the levels are elevated in this area....
If the dose rate in this location is greater than 2 mR/hr at the closest point you can get the probe without endangering a window, post the area as a Radiation Area. If access is needed, the magnet will have to be powered down, and a followup survey can be done to verify levels at 30 cm.
Downstream of Target
Of course the rest of the beamline in the hall needs to be surveyed as usual. Don't forget the locations like the "old" target pivot. As always, if you have any questions about the survey call the Radcon on-call cell phone.