Participants: David Rodriguez, Guillaume Cnudde, Claudia Ahdida, Pablo Santos Diaz, Oriol Rios, Arnaud Kolzer, Gemma Humphreys, James Currie, Rahul Kallada

Agenda:

1. Sanity check of water retention solution for TCC8 and upstream TCC8
2. Explore water retention solutions for ECN3

Guillaume described the existing networks at the surface

• Gravitational network of pipes at the surface until EHN1
  • Industrial water discharged to Lion river.
• TCC8 target area has retention tank
  • It is important to have a level monitoring for the retention tanks
  • CV alarms should be shared with the CFRS

• • Retention basin for the target area should have an additional retention basin
  • Position of the drainage network is not defined in TCC8.

Open Action: Drainage model of the TCC8 and ECN3 to be shared with Gemma - Resp: Guillaume Cnudde, David Rodriguez, Deadline: August 12, 2026

Open action: The placement of retention basin to be decided. Jura or Saleve side. Conflicts with other equipment to be checked. Shape of tanks, number of tanks etc. - Resp: Guillaume Cnudde, David Rodriguez, Deadline: August 12, 2026

Open Action: Who does the monitoring of the volume of the retention basin? Answer: EN-CV installs the level monitoring alarm. The alarm is handled by EN-AA (CSAM alarm) and produces a Level 3 alarm which goes to the CFRS.    We can suggest the monitoring level required. Ideally, one RP alarm and one level indicator for firefighting. - Answered by Henrik Nissen

• Cooling water leaks will also go into 4 m3 retention tank. Cooling water leakage has not been accounted for in the current volume.
  • MHS and Muon shield magnets are water cooled. Leak can occur at the MHS or before. Cooling water comes from BA82.

Open Action: The control of water leakage for cooling water coming from BA82 to be checked.  - Resp. Claudia Ahdida, Gemma Humphreys?? , Deadline: August 12, 2026

• For TCC8 upstream part - Conventional water has negligible activation - Flows towards the pump room in ECN3
• Chemical or other pollution is unknown

Open Action: Pavol to be invited to the next meeting to provide insight into contamination levels - Resp. Rahul Kallada - Done

ECN3 retention discussion:

• Liquid scintillator is the main pollutant identified. Retention basin provided - https://indico.cern.ch/event/1620152/
  • Muon shield is water cooled. Prone to leakage. 
• Water leakage more probable than fire in ECN3.

Open Action: Firefighting water to be estimated. - Resp. Rahul Kallada, Deadline: August 12, 2026

• Spectrometer magnet pit = 9 m x 8 m x 0.1 m = 7.2 m3
• 3 options available for water retention in ECn3
  • Use the floor of the cavern
  • Pump it to surface and goes through the industrial water network
  • Use the magnet pit as the retention
•  
• Retention basin to be dimensioned according to the operational water rate used for cooling.

Open action: Check if double walled pipes are needed for the pipes of the proximity shielding. - Resp: Claudia Ahdida, Gemma Humphreys??, Deadline: August 12, 2026

• For TCC8 upstream part - Conventional water has negligible activation - Flows towards the pump room in ECN3