Radiation Protection aspects of the Switch-Yard operation V. Donate, G. Dumont, Joachim Vollaire on behalf of DGS-RP

Outline  RP measurements  Operational aspects  Additional monitoring  Conclusions 2EDMS PS-CSAP 10/10/2013

RP measurements EDMS PS-CSAP 10/10/20133  Objective: Assess the maximum dose rate in the accessible part of the PS in case of beam loss in the BTM line and BHZ10 failure

Measurements 4  PATP501(RAMSES monitor) installed in the area  Losses created by BE-OP (EN-STI had moved the stopper in the beam path) Residual dose rate in the area EDMS PS-CSAP 10/10/ st losses Scan 2 nd losses 2 intensities Monitor out of the PS

First beam loss created 5  3 pulses to the stopper (1.14e13 ppp)  Rescaling: 3.3e13 ppp and 3000 pulses/h  Pos. 1: 340  Sv/h / 0.11  Sv per pulse  Pos. 2: 155  Sv/h / 0.05  Sv per pulse  Pos.3 : 700  Sv/h / 0.23  Sv per pulse Pos. 1 Pos. 3 Pos. 2 (Pos. 3 not accessible with beam) EDMS PS-CSAP 10/10/2013 Stopper

Pos. 1 Pos. 3 Pos. 2 Scanning for worst configuration 6  Selected configuration :  BHZ10 off + BTM.QNO.5 off (BTP in)  Rescaling: 3.3e13 ppp and 3000 pulses/h  Pos. 1: 1.97 mSv/h / 0.7  Sv per pulse  Pos. 2: 710  Sv/h / 0.23  Sv per pulse  Pos.3 : 4.2 mSv/h / 1.4  Sv per pulse (Pos. 3 not accessible with beam) Even for this worst case, for losses limited to a few pulses (interlock) the dose is relatively low (to be put in perspective with residual dose rate levels) EDMS PS-CSAP 10/10/2013

Operational considerations 7  Alarm thresholds to be set according to residual dose rate when access is granted in the PS (RPO / piquet)  Short access, the dose rate decrease quickly  Status of “Porte secteur inter-zone” during technical stops and shutdown (left open ?)  Loss of flexibility in access to different areas (higher exposure…) 18/09/2012 Survey 40 cm) 06/11/201226/06/2012 EDMS PS-CSAP 10/10/2013

Missing RP monitor 8  Risks associated to a loss of the Linac2(4) beam (LTB)  Possible exposure of personnel in the center of the ring or SS12 area  Measurements done with full beam loss in the LTB line leads to 800  Sv/h at the center of the ring  One single monitor would protect both areas (alarm panel at both locations) EDMS PS-CSAP 10/10/2013 Monitor

Missing RP monitor 9  PATP501 paid on R2L budget anticipating the creation of this new operational mode  RP monitoring not ready to allow Switchyard operation with PS access.  Currently missing 45 kCHF to ensure proper monitoring of accessible areas in Switchyard mode (two areas currently uncovered in case of beam losses in the LTB line) ! EDMS PS-CSAP 10/10/2013

Conclusions 10  Beam losses in the BTM line leads to limited exposure of personnel in the PS ring area (interlock SIL2)  Operational procedure to be developed (to define the alarm thresholds for the PATP501 monitor)  Problem of induced radioactivity…. which will decrease with time (need to adapt the alarm threshold)….  Status of doors to be agreed upon (EN / BE / RP….) for different periods (shutdown, TS…)  RP is missing 45 kCHF to install the necessary monitoring for the switchyard operation mode….  As part of the PS ventilation commissioning study air flow between the PSB and PS (smoke test ?) to see if activated air could come from the PSB EDMS PS-CSAP 10/10/2013