1. Septum 16 shielding increase: result of phase 2 of “Avant projet” S. Gilardoni (BE/ABP) In collaboration with S. Roesler, D. Forkel-Wirth, S. Damjanovic, J. Vollaire, G. Dumont (DGS/RP) H. Damerau, A. Lopez-Hernandez (GS/SE) IEFC – 29 June 2012

2. Phase 2 of “Avant projet” Goal of the study: -Revise CE design after shielding increase to recover margin (61st IEFC) of factor of 3 in term radiation field (hp: 1.1e13 pot/s and MTE losses) -Optimize shielding to reduce risk for existing structure and optimize cost

3. RP presentation from 61 st IEFC (S. Damjanovic) The extra-concrete shielding required following HSE recommendations has been converted in earth shielding New max ground level: 442.6 m

4. Proposed solution I/III Install pre-stressed concrete beams to support the earth shielding Beams supported by tunnel walls on one side and eventually on micro- pillars on the other side

5. Proposed solution II/III Section completely supported by tunnel walls

6. Where samples will be taken (Septum 16) Section supported by tunnel walls and micro-pillars

7. Soil Sampling Soil sampling on top of rte Goward and SMH16 to check eventual contamination -samples taken, intervention without any issue -Analysis progressing, results expected soon Carottage done near the PS walls to validate CE design for SMH16 - evaluation of geotechnical properties of the molasse under PS tunnel - Phase 3 of design work (CE detailed studies) will take into account these results

8. Risk assessment, planning, next steps -EDMS document with description of shielding increase will be circulated for comments/approval as done for R.te Goward -Phase 3 of CE studies will be launched to optimize the current design and prepare the detailed project - First revision of the cost: ~ 1.9 MCHF (only main works, without studies) - Duration: 6 months - We are probably reaching the maximum shielding we can put on top of the machine and still keeping the intervention and the risk associated at a reasonable level. -The shielding has been dimensioned to be compatible with MTE operation and the installation of the dummy septum (loss displacement by 1 straight section) A better shielding should not encourage to have more losses….