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Safety evaluation – transport and use of LHe in TCC8 for ECN3-SHiP

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CERN
Gunn Khatri (CERN), Olivier Pirotte (CERN), Philippe Boisseaux-Bourgeois (CERN), Simon Marsh (CERN)
CCC
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62594065271
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Gunn Khatri
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Draft:

Participants: Philippe, Simon, Olivier, Gunn

  • Gunn introduced the future CCC installation for the SHiP experiment, its planned location upstream of TCC8, and its operating principle based on the existing CCC systems in AD. The instrument requires a liquid helium cryostat.
  • During operation, a mobile liquid helium dewar will be brought underground to fill the cryostat, after which the cold head and compressor maintain normal operation in "stand alone mode".
  • Simon and Olivier confirmed that transport of liquid helium underground is standard practice (including experience in EHN1/EHN2 and the SPS tunnel). The dewar can be transported using the elevator, with no personnel inside the lift during transport.
  • The transport route, elevator dimensions, and load capacity need to be verified. An on-site visit will be organised once Torsten returns from holiday.
  • Two possible access routes were identified:
    • via the Building 912 access shaft,
    • via the elevator located directly upstream of the planned CCC location in TCC8.
  • An ODH assessment should be performed, including estimating the effect of a complete release of a full (~500 L) liquid helium dewar into TCC8. Installation of ODH monitoring should be considered.
  • Radiation Protection should be consulted regarding any potential tritium production from liquid helium during operation.
  • A dedicated helium recovery line is not available in ECN3. An extension from the existing cryogenic infrastructure should be investigated. Contact the North Area cryogenic operation team: Ludovic Alaux.
  • Filling the cryostat will require working at approximately 2.5 m height. A safety-approved working platform will therefore be required in addition to the cryogenic safety measures.

Conclusion

The use of mobile liquid helium dewars in TCC8 is considered acceptable from a safety perspective. The remaining work is to identify the optimal transport route, verify the elevator constraints, confirm the helium recovery solution, and perform the required ODH and Radiation Protection assessments.

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