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Dosimetry and IMPACT

Dosimetry and IMPACT. with input from A. Dorsival, P. Carbonez, G. Dumont.

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Dosimetry and IMPACT

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  1. Dosimetry and IMPACT with input from A. Dorsival, P. Carbonez, G. Dumont

  2. Applying the ALARA principle at CERN is made easier by the operational dosimeter and by the newly instated IMPACT tool that allows extracting dose histories of interveners.However, a structured preparation process involving all major stake holders, clear documenting of the intervention and of lessons learnt and a culture of maturity remain all-important to keep doses to the personnel as low as reasonably achievable. RSSO networking meeting - IMPACT and Dosimetry

  3. ALARA at CERN since 2006 Applying ALARA principles at CERN has raised awareness and reduced the individual personnel doses. LHC fails RSSO networking meeting - IMPACT and Dosimetry

  4. ALARA at CERN since 2006 Since LS1, new tools allow for a better preparation and a better follow-up of ALARA interventions. The goal is NOT to have no deviations, but to detect, report and understand those that occur as well as learn from them and document the lessons learnt for the future. (See Thijs’s presentation) Example: TCC2/TDC2 cable exchange (S. Evrard) Integrated dose estimate over time (from WDP & work planning) Real integrated dose over time (from IMPACT) Weekly dose (from IMPACT) RSSO networking meeting - IMPACT and Dosimetry

  5. Dosimetry An area’s classification defines which dosimeter is required. Personal dosimeter More on EDMS 810149, page 9 Operational dosimeter RSSO networking meeting - IMPACT and Dosimetry

  6. Dosimetry Different dosimeters serve different purposes. Personal dosimeter Operational dosimeter • Should be read in DBR at least once a month • Always ON Background subtraction 2.3µSv/day for each reading period • Monthly rounding down to 0µSv (from max. 75µSv) or rounding to nearest multiple of 0.1mSv • Current issues with life-time: dosimeter can showhigher dose • Under investigation • Inform Dosimeter Service when noticed • Should be put in LDM before and after every entry to be switched ON and OFF • Maximum 8 hours ON  No background subtraction • No rounding, monthly dose is sum of doses taken • Each dose is sent to “dosiserv” database and is linked to IMPACT / intervention New! LDM DBR Dose follow-up! RSSO networking meeting - IMPACT and Dosimetry

  7. Dosimetry Different dosimeters serve different purposes. Personal dosimeter Operational dosimeter • Give an estimate of integrated work dose taken at CERN • Detect anomalies a posteriori • Inform and reassure workers unfamiliar to radiation areas • [and surely much more] • Measure real doses taken at CERN during specific interventions • Detect surprises in real-time (alarm set per intervention) • Allow analysis of interventions a posteriori, leading to • Feedback • Lessons learnt • Maturity • Lower doses in the future ALARA principle More on EDMS 1378481, P. Carbonez Also, visit the new dosimetry website at:http://dosimetry.web.cern.ch/en RSSO networking meeting - IMPACT and Dosimetry

  8. ALARA Levels ALARA levels define the preparation and approval process. Preparation Level II Detailed Work Dose Planning Optimization with RSSO/RP Approval GL/RP/RSSO Preparation Level III Detailed Work Dose Planning Optimization with RSSO/RP/RSO Approval ALARA committee • Primary criteria • Secondary criteria RSSO networking meeting - IMPACT and Dosimetry

  9. Operational Dosimetry & IMPACT Combining the operational dosimetry with IMPACT makes correct dose information available to all. (*) Now Then • Significant gain of time and quality • Dosimeter’s alarm level can be set per intervention • Information rapidly available at centralized location (*) See a next slide for details on dose visibility RSSO networking meeting - IMPACT and Dosimetry

  10. Operational Dosimetry & IMPACT Correct usage of the LDM & IMPACT is a prerequisite for useful dose follow-up. • There is no link (yet) between the operational dosimeter / LDM system and the access system • The access system checks whether the person-ID presented (personal dosimeter) has the correct access rights and is registered in one of the valid IMPACT interventions starting from that point • The access system does not check • Whether the person has presented an operational dosimeter, entered the correct IMPACT number or entered anything at all in the LDM • Whether a dosimeter is present / switched on RSSO networking meeting - IMPACT and Dosimetry

  11. Operational Dosimetry & IMPACT Future upgrades (2015) of the access system and hardware should reduce the number of possible errors. • Detect active operational dosimeter: A reader checks whether an active operational dosimeter is present. This is one of the pre-requisites for access. • Facilitate IMPACT choice: The access point has an extended display that suggests a list of IMPACTS to the identified user More on EDMS 1378481, G. Dumont RSSO networking meeting - IMPACT and Dosimetry

  12. Dose History & IMPACT IMPACT allows for easy dose history extraction and radiological work follow-up. Access doses in IMPACT via the DIMR, the Activity or via the Radiation Dose Reports RSSO networking meeting - IMPACT and Dosimetry

  13. Dose Visibility in IMPACT Dose visibility is a compromise between privacy and professional performance • RSSOs have same read access as their group leader, i.e. sees dose history of: • All members of the group participating in anyactivity • All participants of any activity created by a member of group”(“responsible” in IMPACT) • RSO sees same as department leader • RP-technicians see the doses for all members participating in the activities attributed to them • PCRs see dose of their personnel only (new next year: project leader role) RSSO networking meeting - IMPACT and Dosimetry

  14. Example of Dose Extraction Regular checking of personnel dose allows detecting anomalies, faulty dosimeters and reassures people. • Check once a month whether any of your group’s members has • > 1 mSv difference between operational and personal dosimeter over the last 12 months (e.g. the personal dosimeter might be badly calibrated, at end-of-life or have been dropped next to a source) • >1.5 mSv (>2 mSv for LS1) operational dose over the last 12 months • Any other unusual behavior • Discuss with the person concerned • If anomy detected or action needed, inform the Dosimeter Service & RSO of your findings RSSO networking meeting - IMPACT and Dosimetry

  15. Example of Dose Extraction Doses for an activity are shown per person and per day, not in function of progress of the work. • Ideal dose-work graph for follow-up of activity is dose vs progress, we only get dose vs time from IMPACT RSSO networking meeting - IMPACT and Dosimetry

  16. Example of Dose Follow-up Daily RP-follow-up takes place in ISOLDE, but is not feasible for long interventions in larger areas. Extract from WDP RSSO networking meeting - IMPACT and Dosimetry

  17. Exercise: Using IMPACT for Dose Follow-up Work Break Down structure, together with General Work Planning & Work Dose Planning link progress to dose. Work Breakdown Structure General Work Planning (activities in radiation areas are in blue) RSSO networking meeting - IMPACT and Dosimetry

  18. 17 27 13 167 35 90 100 33 3. Radiation Work Planning and Work Dose Planning (list) 33 RSSO networking meeting - IMPACT and Dosimetry

  19. 17 27 13 4. Dose estimate vs time 167 35 90 100 33 33 3 Expected dose = 515 2 Estimated dose (µSv) 1 Time (days) RSSO networking meeting - IMPACT and Dosimetry

  20. 17 27 13 5. Estimates dose vs real dose at pre-defined moments 167 35 33 60 90 100 20 33 Dose expected from planned work: 100% of 17 + 50% of 13 = 23 Dose expected from real work: 100% of 17 + 10% of 13 = 18 Real dose: 20 1 Dose expected from planned work = 92 + 67% of 167 = 204 Dose expected from real work: 92 Real dose: 150 !!!  Problem needs to be investigated Results from investigation  modifications are integrated in dose planning 2 Estimated dose (µSv) 3 Dose expected from planned (modified) work and real work = 462 Real dose: 393 RSSO networking meeting - IMPACT and Dosimetry

  21. 17 27 13 167 Conclusion: comparison 35 33 60 90 100 20 33 Estimated dose (µSv) RSSO networking meeting - IMPACT and Dosimetry

  22. Summary IMPACT and the operational dosimeter allow efficient follow-up of on-going interventions as well as a verification of doses from members of the group. In order to retain lessons learnt from LS1 and to prepare the radiological follow-up methodology for LS2, feedback and lessons learnt from the main LS1 interventions will be collected, documented and presented (ALARA or ENTM). All this is part of the overall ALARA approach. Since the RSSOs will be the first users, feedback and comments (as well as volunteers for first testing) are very welcome. RSSO networking meeting - IMPACT and Dosimetry

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