1. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Radiation Protection for Mini-BooNE & NuMI 18 March, 2002 Mini-BooNE inputs from Peter Kasper & Craig Moore NuMI inputs from Nancy Grossman

2. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) ·Primary Beam Momentum- 8.9 GeV/c. beam from FNAL Booster. ·Spill length 1.6 microseconds. ·Intensity - 5x10 12 ppp Rep rate 15 Hz (5 Hz Beam) 2x10 7 seconds/yr. ∫ Protons = 5 x 10 20 p/year. – this annual flux is > than the sum of all previous Booster operation over 30 years. – main obstacles being addressed for achieving proton flux goals are Booster radiation problems both above the machine & in the tunnel. MiniBooNE Primary Beam

3. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Rad Monitor Readings (normalized to trip setting) AFTER Shielding Upgrade

4. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Normalized Rad. Monitor Readings vs. Booster Intensity

5. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Path to Meeting Booster Flux Goals for MiniBooNE Further improvements to external Booster shielding very expensive & not considered worthwhile. Current level of shielding makes component activation in Booster tunnel the ultimate limit. –for current operating conditions (6e15 p/hr at ~ 4.5e12 p/cycle) contact levels of > several Rem exist at hottest locations and > 0.1 Rem on RF cavities. Scaling up by x 20 for BooNE is not viable. Remediation plans include: –new orbit control system. –collimation system to move losses to lower energy and to well shielded areas.

6. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Schematic Layout of MiniBooNE Beamline

7. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Four Main Types of Concerns: ·Ground Water Activation - Not a problem due to clay soil ~ impervious to water flow. ·Air Activation - Hold air to allow short lived isotopes to decay, restrict access. ·Prompt Radiation- Dirt + Radiation Monitors (to begin with). ·Residual Radiation - Loss Monitors at specific potential loss points + 5 Total Loss Monitors. Remediation efforts: ·increase beam transport apertures. ·utilize an Electronic Berm to help remediate all four concerns. (sense 2% loss averaged over several pulses or >6% over 1 pulse.). ·implement an Autotune program for reliable operation of this almost continuous beam. MiniBooNE Beamline & Targeting Radiation Safety

8. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) l Regions l MI/Extraction l Pre-target Region l Target Hall l Decay Tunnel l Hadron Absorber l Mitigation l Passive shielding l Interlocked radiation detectors l Beam permit system l Administrative Controls l Radiological Areas l Prompt radiation l Residual activation of enclosures and components l Airborne activation l Groundwater activation l Designs are reviewed in accordance with Chapter 8 of the Fermilab Radiological Control Manual (FRCM). NuMI Radiation Protection

9. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) NuMI Radiation Protection Overview Schematic

10. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Groundwater protection drives: $$$ –Primary beamline allowable losses –Target Hall shielding (top excluded) –Decay pipe shielding –Bottom & 1 Side of Hadron Absorber shielding Residual Activation drives : $ –Primary beamline allowable losses –Top of Target Hall shielding plus Top & Side of Hadron Absorber shielding Air Activation drives : –Target Hall chase must be “sealed” at some level and radioactive air contained –Ventilation rate through the Target Hall above the shielding and through the Decay Tunnel must be relatively low to allow decay in transit to the vent. Prompt Radiation: –Not much of a concern due to beamline deep underground and access limited to support rooms and MINOS cavern. NuMI Radiation Protection Overview

11. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Prompt Radiation Labyrinth and penetration exit dose rates based on MARS source terms and standard attenuation curves.

12. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL)  Limits for drinking water supplies and for Illinois “Class 1” groundwater resources (water that potentially could be drinking water) are the same.  The “point” of the regulation is to protect the resource from which the drinking water originates.  3 H (12.3 year half-life) and 22 Na (2.67 year half-life).  Note surface water limits are 100 times higher for 3 H and 25 times higher for 22 Na.  For mixtures of radionuclides, a weighted sum is used. The annual average concentrations must be below the limits. Groundwater Protection Regulations

13. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Shielding not a practical choice thru most of primary transport. Require fractional operational losses along NuMI primary beam to be below 10 -4 (10 -6 in the lined carrier tunnel interface region, where geometry provides some shield). –Detailed simulations (MARS14) of the primary beamline and possible accident and DC (continuous) loss conditions have been studied. Solution approach discussed in primary beam presentation. Considerable attention to primary design, installation, commissioning and operation required. –Solutions are founded well by significant prior experience. –Rigorous beam permit system provides groundwater protection. All other measures are to enable smooth high intensity operation. Groundwater Protection: NuMI Primary Beam

14. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Water flows into the tunnel rapidly, thus not highly activated and is released to the surface waters. NuMI, in discussions with FNAL and DOE Fermi, was given the charge to keep the levels of the water flowing into the tunnel (within the aquifer region) to below groundwater limits, including uncertainties and taking credit for water flow. Have monitoring wells. Groundwater Protection: NuMI Secondary Bean (Unlined Tunnels)

15. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Regulations: Annual Dose < 10 mrem (all FNAL) at site boundary. Radionuclides of concern are: – 11 C, 13 N, 41 Ar (although 7 Be, 3 H, 15 O were also calculated). – 11 C, 13 N are produced by spallation reactions. – 41 Ar is produced by thermal neutron capture, thus hard to predict amount, assume 2.5% based on measurements at FNAL. Goal for NuMI is < 45 Ci/year (~2.5 mrem/year, or 1/4 site limit). Majority of the air activation occurs inside the Target Pile. Closed system at negative pressure relative to the air outside the shield. Calculations based on re-circulation and 1000 cfm ventilation, ~20 Ci/year. Can adjust ventilation rate as needed to reach this. Airborne Activation

16. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) MARS14 Residuals: 30 days irradiation, 1 day cool down @2E13protons/sec Residual Activation

17. BooNE / NuMI Rad. Protection NBI 2002 S. Childress (FNAL) Prompt Radiation Levels are only a concern in the Power Supply Area (beam on occupancy) at Target Hall level. Groundwater calculations incorporate water flow, resulting in the main concern being in the lined regions of NuMI where water can not flow rapidly into the tunnel. Considerable shielding. –Primary beam losses must be kept very low. –Open apertures, improved optics, current/voltage limits, beam monitoring and permit system. Air Activation levels result in enclosing the Target Chase and re- circulating the air. Residual Dose rate calculations using MARS14 have been well- benchmarked with good results. –Extensive modeling of the NuMI Target Hall using MARS 14. –Include cracks in the models. Believe have “good” predictions for residual dose rate levels. NuMI Radiation Protection Summary