Date: April 30, 2002
Editor: NSLS ESH / RCD Staff
A recent occurrence during the commissioning of one of our X-ray beamlines indicates that we need to improve our program for configuration control of the equipment and safety devices that make up the beamlines. A shielding cover was removed from a glass view port and not returned when the beam line was enabled. There was no significant exposure, but the beam was not adequately shielded and under different circumstances the exposure potential could have been far higher. A critique of this incident resulted in a finding that inadequate configuration control was the root cause. Distributing this Highlight is one of the measures we are taking to call attention to this issue and to inform you of anticipated changes that will affect the beamlines.
Beamline safety and the padlock checklists are critical tools for maintaining configuration control. Both lists are used at the start of each experiment to assure that each beamline is in the proper configuration before light is delivered to a sample. We are working to improve this program and anticipate several changes to come over the next year as we work with the beamline staffs to review and update our configuration control requirements. Expected improvements include:
Each hard X-ray beamline view port must be covered by leaded glass (typically 1/16" thick lead equivalent; may be thicker for certain applications) to control X-ray scatter through the glass port. The position of these covers must be confirmed using the safety checklist when the beamline is enabled for each experiment. We prefer to have the leaded glass cover bolted into place so that it can be incorporated into the padlock system; however, lead tape or lead sheet/hose clamp arrangements may be acceptable.
The Radiological Control Division staff will soon begin formal, documented annual radiation surveys of each beamline. This will be done as a collaborative effort with the beamline staff so as to impact users as little as possible while developing a record of beamline radiation levels in as many standard operating configurations as possible.