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Experiment Chamber opening safety procedure

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Date: July 29, 2002

The following instructions are intended to elucidate the target chamber access requirements for experimenters working at ISAC. Access to any other part of the RIB beam line for maintenance work is govern by an ISAC work permit.

 

The presence of airborne radioactivity depends on the nature of the radioactive beam delivered to the target station. Only when the RIB or its progeny are volatile or gaseous species will there be a risk of airborne or radioactivity when opening a vacuum enclosure. Therefor, opening of a target chamber for ISAC experiments not using any volatile or gaseous radioactive beam does not require an air sample.

 

The potential hazard of airborne activity can be identified during Safety Approval process for each experiment individually. Once there is a hazard identified, an initial opening of the vacuum enclosure would  require a respirator and an air sample to establish the level of airborne contamination. If nothing is found on that first sample, and given no other changes in operating conditions, air samples on subsequent openings would not be necessary.Note: Measurements done recently at LTNO with short lived  Rb-79 from the crystal in which decays to Kr-79, found no evidence for migration or loss of Kr-79 from the crystal in which the Rb-79 had been implanted, over a period of week.

 

Other than relaxing the requirement for an air sampling, the procedure for opening a target chamber in the ISAC experimental hall remains as described earlier.

 

  •     Once an experiment has begun to receive radioactive ion beam, a work permit is required for the first break of the vacuum enclosure or target chamber.
  • A respirator needs to be worn on the initial opening to protect against a respiratory hazard associated  with high level of removable contamination. Once the contamination levels are measured to be less than 1500 cpm on a pancake probe or high energy gamma probe, there is no further need for respiratory protection.
  • Provided the levels of removable contamination on the first opening are below 1500 cpm, subsequent openings of the RIB beamline at the same location does not require a work permit nor a respirator. Gloves should be worn and a swipe taken and checked on both beta and gamma meters. Experimenters should record any nonzero level of contamination found.

 

A radiation protection surveyor or an ISAC operator should do the initial contamination survey upon opening the vacuum enclosure. This individual should already have been issued a respirator and should be familiar with the use of pancake probe and high energy gamma probe for checking removable contamination levels.

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