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Linac and Booster Radiation Shielding Status, Plans and Constraints

Linac and Booster Radiation Shielding Status, Plans and Constraints. John E. Anderson Jr. Proton Source Meeting December 7, 2010. Outline. Shielding Assessment Beam Intensity Limits MCR Operational Intensity Limits Linac SA Intensity Limits Booster SA Intensity Limits

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Linac and Booster Radiation Shielding Status, Plans and Constraints

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  1. Linac and Booster Radiation Shielding Status, Plans and Constraints John E. Anderson Jr. Proton Source Meeting December 7, 2010

  2. Outline • Shielding Assessment Beam Intensity Limits • MCR Operational Intensity Limits • Linac SA Intensity Limits • Booster SA Intensity Limits • Booster Reassessment Efforts • Booster Operational Issues Proton Source Meeting December 7, 2010

  3. Shielding Assessment Intensity Limits • Operating Intensity Limits • Beam intensity limit based on the FRCM • Accelerator Safety Envelope (ASE) Intensity Limits • DOE approved beam intensity limit • May or may not be equal to the Operating Intensity Limit (Currently is for Linac and Booster) • Based on a 10 mrem accident to a member of the public or an untrained worker • Exceeding limit reported to Head Office of Science Proton Source Meeting December 7, 2010

  4. Shielding Assessment Intensity Limits • Both Operating and ASE Intensity Limits are defined in Appendix A of the laboratory Safety Assessment Document • Limits are approved by • Fermilab Director • DOE Fermi Site Office Manager Proton Source Meeting December 7, 2010

  5. Main Control Room Operational Limits • Beam Permit • Based on ASE • Approved by Division Head • Operational Limit • Some % less than Beam Permit • Generally 5-10% less • Warning Limit • Some % less than Operational Limit • Generally 5-10% less Proton Source Meeting December 7, 2010

  6. 1993 Linac Shielding Assessment • Operating and ASE Intensity Limits • 3.54 E17 protons / hour • MCR Operational Limit • 3.34 E17 protons / hour ~-5% • MCR Warning Limit • 3.185 E17 protons / hour ~-5% • Current limits exceed future programmatic needs • No plans to do anything further • Continue to monitor Linac tech area offices Proton Source Meeting December 7, 2010

  7. 1998 Booster Shielding Assessment • Operating and ASE Intensity Limits • 1.8 E17 protons / hour • MCR Operational Limit • 1.22 E17 protons / hour ~-30% • MCR Warning Limit • 1.09 E17 protons / hour ~-10% • Can raise the MCR warning limit to~1.5 E17 protons / hour Proton Source Meeting December 7, 2010

  8. 1998 Booster Shielding Assessment • “Nowhere around the Booster ring is there sufficient shielding to prevent FRCM limits from being exceeded under DC accident conditions at the intensities required to meet current programmatic goals (1.35E17 protons / hour).” • References 1991 Booster Assessment beam loss measurements at penetrations to determine current Operational Limits of1.8 E17 protons / hour Proton Source Meeting December 7, 2010

  9. 1998 Booster Shielding Assessment • Assessment shows losses limited to long and short strait locations • Assessment based on studies to determine shower max locations • 51 interlocked detectors placed approximately at shower max locations Proton Source Meeting December 7, 2010

  10. 1998 Booster Shielding Assessment • Issues • Machine modifications may change loss locations thus invalidating the assessment • Correction element upgrades • Machine realignment • Collimators at L6 and L7 • Others? • With machine modifications since 1998, is the current assessment still valid? • Limited information available about penetration dose rates and studies. Proton Source Meeting December 7, 2010

  11. Booster Shielding Assessment Efforts • Current reassessment efforts • Assessing for 2.0 E17 protons / hour • Roger Dixon Guidance • Converting Booster to Incremental Shielding Assessment Methodology • Being done to identify all penetrations, problem areas, and allow for intensity scaling • Expect assessment to be complete in January 2011 • Will need to find mitigations for problem areas Proton Source Meeting December 7, 2010

  12. Booster Shielding Assessment Efforts • Labyrinth and penetration spreadsheets created • 7 labyrinths and 190 penetrations • 182 penetrations fail at 2E17 protons / hour • MARS models of penetrations filled with poly also fail • Can a point loss be created under a penetration? • Need technical justification if used • Can ropes and signs be used to barrier front of penetrations? • Limits access to equipment • Can sand be used to fill penetrations vs. poly? • Penetrations pass • Passive control Proton Source Meeting December 7, 2010

  13. Booster Tower West Operational Issues • Booster L6 area collimators • Routinely measure rates in the Booster Tower West Stairwell and upstairs offices BTW-201 & 202 • Need to identify source and better shield the area Proton Source Meeting December 7, 2010

  14. Booster Tower West Operational Issues Proton Source Meeting December 7, 2010

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