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lead material in SHiP CCC - HSE chat

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CERN
Gunn Khatri (CERN), James Storey (CERN), Jocelyn Tan (CERN)
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https://cern.zoom.us/j/62550889335?pwd=Z7Qji7QEMsZK7KX2lbS1UUP14j40cY.1&from=addon

Meeting ID: 625 5088 9335
Passcode: 257043

Draft minutes:

Present: Gunn, Alex, Jonathan, Jocelyn

Discussion

  • Gunn presented slides showing the CCC instrument layout and the location of the lead/niobium magnetic shield.

  • CCC performance is not dependent on the choice of shielding material (niobium or lead).
    However, lead is significantly more cost-effective and easier to manufacture, and has already been successfully tested in Jena and at GSI.

  • CERN will purchase the CCC as a turnkey system from GSI, including the lead shielding.
    Therefore, no handling or machining of lead will occur at CERN.
    Expected delivery: 2031, for installation in the CERN North Area (SHiP experiment).

  • The lead shielding is mounted inside the liquid-helium vessel, further enclosed within the insulation vacuum and MLI layers.

  • Potential exposure to lead at CERN would only occur during maintenance, estimated at once every ~5 years (based on AD CCC operational experience).

  • Even during maintenance, direct interaction with the lead component is minimal, as it is a passive part. Typical interventions relate to failures such as a broken SQUID wire or ceramic braze leaks.

  • End-of-life / waste management:

    • Although not expected for many years, a preliminary plan will be prepared.

    • Lead material will be segregated from non-hazardous parts and sent for recycling or compliant disposal.

    • The lead mandrel weighs ~40 kg, cylindrical, with approx. dimensions: L = 350 mm, ID = 200 mm, OD = 350 mm. (for single squid), multiply by 2 if dual squid

  • Concerns regarding lead dust or surface contamination:

    • Upon delivery from GSI, CERN will perform a surface cleanliness assessment, e.g., via colorimetric or wipe tests (cotton swabs sent to a lab).

    • The cryostat will be delivered empty (no LHe).

    • Cryogenic temperatures preclude any risk of lead vapour formation.

    • Occasional warmup/bakeout to ~70 °C is foreseen for moisture removal; this temperature is far below the threshold for lead vaporisation.

  • PPE and maintenance procedure:

    • If the CCC is opened, standard minimum PPE should be used: gloves, long sleeves or appropriate work clothing, and safety glasses.

    • Masks are not mandatory unless visible dust is present.

    • A clear and detailed maintenance procedure must be prepared, describing all interventions and associated safety measures.

    • Responsibilities must be defined (instrument owner, maintenance lead).

    • CERN personnel involved will visit Jena and GSI to gain hands-on understanding during the construction phase.

  • Chemical safety team recommends reviewing CERN lead-handling guidelines (link: https://edms.cern.ch/file/1050102/LAST_RELEASED/SG-C-0-0-3_EN.pdf).

  • General safety doc by Alex: https://edms.cern.ch/ui/file/1113405/LAST_RELEASED/GSI-C-1_EN.pdf

 

Conclusion

  • HSE gives a green light for the use of lead as the shielding material for the SHiP CCC.

  • A concise, validated maintenance procedure must be written and reviewed with HSE, including:

    • PPE requirements

    • Maintenance steps and access conditions

    • End-of-life handling and waste-management principles

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