zoom:
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).
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