Beam Loss and Radiation Working Group: Conclusions G. Arduini, M. Benedikt, M. Giovannozzi, B. Goddard, C. Hill, E. Métral, E. Shaposhnikova – AB D. Forkel-Wirth, T. Otto, H. Vincke – SC/RP 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

BLRWG@LII - G.Arduini - AB/ABP Major issues Analysis of the radiological impact assuming nominal p.o.t. (i.e. requests from expt.) and losses measured during operation, CNGS test in 2004 and LHC MDs. Major Issues ordered as a function of their decreasing impact on the public and the personnel: The PS bridge and the PS North and South Hall TDC2/TCC2 areas in the SPS Air release points in Meyrin (in particular TT10) Straight section 31 in the PS ECA4 area in the SPS 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

BLRWG@LII - G.Arduini - AB/ABP PS bridge Small losses in MMU8 (0.8%) during CT extraction for CNGS and FT beams. Important radiological impact because of the insufficient shielding (1.8 – 2.6 and 3.4 m): 490 mSv/h on top of the PS bridge Stray radiation at CERN fence (~450mSv/y – above legal limit = 300 mSv/y and above “optimization limit” = 10 mSv/y) North Hall South Hall PS M. Poehler – TS/CE 1.8 to 3.4 m 4.8 m  +1.4 m shielding Drawing office: up to 2.5 mSv/y for 2000 h of work. MCR 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

PS bridge (proposed actions) Origin of the losses  We need to address this Top of the PS bridge = controlled area (done) Additional radiation monitors for benchmarking the code (being done) Reinforcement of the shielding to 4.8 m all along the bridge  Dose rate at the fence to ~10mSv/y. FEASIBLE (TS/CE) but detailed study (0.3 FTE – TS/CE) is required + 1-2 MCHF to realize it. Need to study LINAC4 impact in the South Hall 3. Digitalisation by 12 bit ADC and generation of reset signal. Sampling period 100 ms and reset after each PS cycle. (only upper 8 ADC bit are used). 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

TDC2/TCC2 (SPS North Area) Air activation: Normally the air is re-circulated (no fresh air intake) even during access  Additional dose by inhalation Injection/extraction unit exists and can be started any time locally. No radiation monitoring of the air released through TDC2/TCC2 stack No air monitoring in the tunnel. Accidental activation of the extraction system during beam operation  10mSv to the public (critical group) in few days Exemption limit for 3H is 2x10^5 Bq/kg 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

TDC2/TCC2 (proposed actions) Radiation Monitoring of the air released at the TDC2/TCC2 ventilation outlet Ventilation system will be started manually with a key in possession of SC/RP Radiation monitoring of the air in TDC2/TCC2 Mainly for the CV part Ideal solution: zone controlled  ventilation can be switched ON, i.e. electrical power available Zone closed  ventilation no electricity  must be off Last point: FTE required for FLUKA simulations (for calibration) and detector development. 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

Air release points in Meyrin Major contributions to dose to the public: TT10 (4.2 mSv/y) ISOLDE (3.5 mSv/y) PS ring (1.8 mSv/y) Air in the SPS tunnel between LSS6 and LSS2 is extracted through TT10 Radioactive air release mainly due to: high energy dump in the SPS LSS2 extraction Losses TT2-TT10 H. Vincke LHC MD NO BEAM MD CNGS TEST || FT Swiss customs and St. Genis Hostel The sum is already close to 10 muSv/y 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

Air release points in Meyrin (proposed actions) Air radiation monitoring data available in CCC Need to confirm/refine the above correlation and to study the dependence on the mode of operation of the ventilation in TT10 (will be done)  need follow-up on the mode of operation of the ventilation (TT10 ventilation unit ON/OFF?). Minimization of the beam dumped at high energy (during operation and studies) TOF, 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

Straight Section 31 in the PS >100 mSv/y >10 mSv/y Losses (ES septum) during CT extraction for CNGS and FT beams Expect > 100 mSv/y in the office space close to that area (48 offices, 65 people: 5 from AB/BI, 7 from SC/RP, 14 AB Hon. Members, 39 from PH and IT, all full time?) Additional contribution to the dose at the fence Residual radiation in SS31 (~3mSv/h 4 weeks after a machine stop) Working year of 2000 h. 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP T. Otto

Straight Section 31 in the PS (proposed actions) New MTE: real solution to reduce the losses  Need to contribute (money will be made available) Radiation monitoring of the office space to benchmark simulation results in 2006 (will be done) If radiation measurements confirm the simulations: Temporary relocation of the personnel (at least those at full time) Increase the earth shielding by 1.5 m. (TS/CE – 100-200 kCHF) Monitoring of the air activation in the tunnel required to benchmark the estimates for the air activation from the PS ring. Action: AB/ABP, AB/BT, AB/PO, AT/MEL, AT/VAC – 17 FTE + 6.2 MCHF 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

BLRWG@LII - G.Arduini - AB/ABP ECA4 Forbidden area in case of systematic loss – VERY UNLIKELY Particles in the beam gap between the two CNGS batches (0.7% of the beam): <0.1% lost on TPSG protection element in front of extraction septa After shielding upgrade (SD 2004-2006) for nominal CNGS operation  H. Vincke <1.5mSv/h <25mSv/h <7mSv/h 6 mSv/y limit for simple controlled area (3 muSv/h) for a working year with 2000 h Forbidden area (>100 mSv/h) in case of systematic full beam loss 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

ECA4 (proposed actions) Access to the gangways located in ECA4 (2 highest levels) closed with safety keys (being done) Measurements of the dose rates during CNGS commissioning and operation Abort gap measurement and cleaning (will be done)  Need to study phenomena leading to the population of the gap. 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP

Summary and Conclusions In 2006 strongest limitation for high intensity operation losses under the PS bridge  limit to ~2×1019 p.o.t. understanding of the cause of the loss Implications of LINAC4 installation in South Hall Environmental monitoring in TDC2/TCC2 and interlocking of the ventilation system to prevent accidental release of activated air is needed. Release of radioactive air in Meyrin needs to be kept under control and the different contributions fully identified New Multi-Turn Extraction only mean to reduce the losses in SS31. ECA4 access conditions might be reviewed at the end of the run supported by the radiation monitoring data. Here the major issues and upgrades requiring additional resources are listed. 10th April 2006 BLRWG@LII - G.Arduini - AB/ABP