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Radiation Protection aspects of the Switch-Yard operation

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. RP measurements.

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Radiation Protection aspects of the Switch-Yard operation

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

  2. Outline • RP measurements • Operational aspects • Additional monitoring • Conclusions PS-CSAP 10/10/2013

  3. RP measurements • 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 PS-CSAP 10/10/2013

  4. Measurements • PATP501(RAMSES monitor) installed in the area • Losses created by BE-OP (EN-STI had moved the stopper in the beam path) 2nd losses 2 intensities 1st losses Residual dose rate in the area Monitor out of the PS Scan PS-CSAP 10/10/2013

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

  6. Scanning for worst configuration • 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 mSv per pulse • Pos. 2: 710 mSv/h / 0.23 mSv per pulse • Pos.3 : 4.2 mSv/h / 1.4 mSv per pulse Pos. 2 Pos. 1 (Pos. 3 not accessible with beam) Pos. 3 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) PS-CSAP 10/10/2013

  7. Operational considerations • 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…) Survey (mSv/h @ 40 cm) 26/06/2012 18/09/2012 06/11/2012 PS-CSAP 10/10/2013

  8. Missing RP monitor • 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 mSv/h at the center of the ring • One single monitor would protect both areas (alarm panel at both locations) Monitor PS-CSAP 10/10/2013

  9. Missing RP monitor • 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) ! PS-CSAP 10/10/2013

  10. Conclusions • 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 PS-CSAP 10/10/2013

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