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Radiation Protection aspects

Radiation Protection aspects. S. Roesler (DGS-RP) based on discussions with and information from M.Brugger, G.Dumont, D.Forkel-Wirth, L.Gatignon, M.Magistris, D.Perrin, C.Theis, V.Tromel, H.Vincke, M.Widorski. East Area Day 1 February 2012. Outline.

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Radiation Protection aspects

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  1. Radiation Protection aspects S. Roesler (DGS-RP) based on discussions with and information from M.Brugger, G.Dumont, D.Forkel-Wirth, L.Gatignon, M.Magistris, D.Perrin, C.Theis, V.Tromel, H.Vincke, M.Widorski East Area Day 1 February 2012

  2. Outline 1) Present situation and RP justification for consolidation 2) Dismantling and refurbishment 3) Design of new facility 4) Monitoring and operation 5) Summary and conclusions - work planning and ALARA - work on radioactive material - Radioactive waste - shielding - activation of components and optimization - air activation - cooling water activation - RAMSES - buffer zones East Area Day – RP Aspects

  3. Present situation – targetarea • Not optimized according to modern radiation protection practices • ageing components frequent repair, water leaks,... • significant losses, long passages of beam through air, tight space, difficult access • comparably high individual and collective doses • unjustified activation of air • corrosioncontamination risks • no ventilation system risk assessments difficult • faster corrosion • single water cooling circuit for target area and experiments • unjustified exposure of experimenters to activated water • large volume of activated water • A consolidation is urgently required and encouraged by RP East Area Day – RP Aspects

  4. East Area Day

  5. Present situation – mixed field test facilities • no ventilation system • confined target area intensity limitations • high energy muon cone (109 p/pulse at 400 GeV) • space constraints for placing equipment H4IRRAD CNRAD • parasitic operation, access only during stops of CNGS • no fast access • no tests of power converters possible Optimized within the constraints of the respective areas. Nevertheless, a dedicated test facility would be of advantage from an RP point-of-view. East Area Day – RP Aspects

  6. Dismantling and refurbishment – ALARA (presently under revision) Optimization is a legal requirement if accumulated individual dose exceeds 100 μSv/year (ALARA) (Safety Code F) Optimization includes • work coordination • work procedures • handling tools • design • material Level II+III: Detailed work-and-dose-planning (WDP/DIMR) Level III: ALARA committee Many dismanteling activities most likely Level II interventions East Area Day – RP Aspects

  7. Dismantling and refurbishment – ALARA Example of a work-and-dose-planning document East Area Day – RP Aspects

  8. Dismantling and refurbishment – radioactive material Radioactive = specific and total activities exceed LE or dose rate at 10cm distance > 0.1 μSv/h n ai  Mixture of nuclides: > 1 LE values: ingestion of activity LE leads to a dose of 10 μSv LEi i=1 Source: ORaP, Swiss legislation East Area Day – RP Aspects

  9. Dismantling and refurbishment – radioactive material and waste • all material taken out from target or beam-line areas has to be considered as radioactive • and placed in buffer zones • classification of material by RP measurement (dose rate, induced activity, contamination) • if radioactive: - any work must be performed in appropriate workshops • - equipment of workshop depends of type of work and radiological risks • - use of centralized workshops (Bat 867) strongly preferred • shielding to be re-used must be cleaned and painted by specialized company (removal of • rust and corrosion products in order to avoid spread of activated particles) • foresee storage space for radioactive components and shielding • radioactive material that cannot be re-used will have to be disposed of as radioactive waste • estimate of the amount of radioactive waste (volume, activity) prior to dismantling • assess the presence of waste that requires special attention (e.g., radioactive waste with • chemical risks) • in case container are needed they should be provided by the departments (take into • account delay for delivery) East Area Day – RP Aspects

  10. Dismantling and refurbishment – Example: Q74-02 • Q74-02: first quadrupole magnet in T9 line, • replaced in 2007, recently considered for re-installation • Measurements (Jan 2012): • max. residual dose rate (contact) 650 µSv/h • (40cm) 50 µSv/h • surface contamination 24.4 Bq/cm2 East Area Day – RP Aspects

  11. Design – shielding Goal: Supervised Radiation Area in East Hall outside of shielding enclosure Non-designated Area outside of East Hall East Area Day – RP Aspects

  12. Design – shielding Outside East Hall East Area Day – RP Aspects

  13. Design – shielding • shielding must not only satisfy limits but must also be optimized (ALARA) for workplaces • around the facility Safety Code F • consider incidents/accidents (e.g., accidental beam-losses): stay well below legal limits • for such events (6 mSv / 1 mSv inside / outside of hall) • if possible, shielding should be air-tight in order to separate air volumes • preliminary shielding studies have been performed and are integrated into the present • design; more detailed studies are needed, in particular for mazes, accidents and in order • to optimize design East Area Day – RP Aspects

  14. Design – activation of components • calculation of residual dose rates for most critical areas (target area, irradiation areas) • estimation of job doses (e.g., for recurrent or major work) and optimization of design • Design goal: < 2mSv/person/intervention Example: LHC collimators (one week cooling) • design optimizations don’t have to be expensive, e.g., connectors, valves easy to reach, • cables away from loss points (if possible),… • some residual dose rate predictions exist (mixed field facility), needed for other areas • (e.g., target area) East Area Day – RP Aspects

  15. Design – air activation Goal: < 1 µSv per hour stay in Radiation Areas (< 0.1 CA) monitoring of releases into environment Dedicated ventilation systems needed for target area and irradiation facility 2×1010 protons/s, 26GeV (generic study) 100 µSv • Requirements: • (general requirements on ventilation systems being discussed • by Ventilation Working Group) • no air flow between primary beam areas and occupied • areas • closed ventilation during operation (~100% recirculation) • flush with fresh air before access • controlled release point with activity monitoring 10 µSv 1 µSv Detailed study of air activation still has to be performed. East Area Day – RP Aspects

  16. Design – water activation • avoid unjustified contact of experimenters/workers with activated water • avoid dissemination of activated water Goal: • separate cooling water circuits for primary and secondary beam areas • study to estimate water activation to be performed East Area Day – RP Aspects

  17. Operation – radiation monitoring Present situation (Arcon) 10 radiation area monitors 7 induced activity monitors* * One of which used also for the measurement of pulsed radiation East Area Day – RP Aspects

  18. Operation – radiation monitoring * Old system based on VME chassis which cannot be compared to the new modular monitoring stations • additional monitoring budget (150 kCHF) reserved in irradiation facility budget • final monitor numbers and locations to be defined as soon as RP studies for final layout • are completed East Area Day – RP Aspects

  19. Operation – buffer zones • Two buffer zones for material from target area and irradiation facility: • similar to those presently being integrated around PS complex • in proximity to access point • 40cm concrete shielding, controlled access • containing shelves, waste bins, PC with ethernet for traceability system East Area Day – RP Aspects

  20. Summary and conclusions • The present East Area is not optimized according to modern radiation protection practices. • (high losses, tight space, no ventilation, corrosion, single cooling circuit,...) • Thus, a consolidation (especially of the target area) is urgently required and supported by • RP, if possible during LS1. • Preliminary shielding studies have been performed and are integrated into the present design, • further and more detailed studies are needed, in particular for mazes, accidents as well • as for activation of components, liquids and air. • The monitoring (RAMSES) budget requirement of 300+150kCHF seems appropriate. • The manpower needs have to be revised once a draft schedule is available. • A dedicated mixed-field facility for testing electronics equipment (replacing H4IRRAD and • CNRAD) would be of advantage from an RP point-of-view. • All work has to be well planned and optimized (ALARA, DIMR level I or II). RP is available • for advice. East Area Day – RP Aspects

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