1. Radiation safety evaluation for “KAMABOKO” Main Linac Tunnel KEK-APL : T.Sanami, S.Ban KEK-ACC : A.Enomoto, M.Miyahara ILC Mechanical & Electrical Review and CFS Baseline Technical Review at CERN (21-23 March 2012)

2. Background Cost optimization for RDR design “KAMABOKO” single tunnel with Separation wall -Two tunnel area with affordable cost Advantage: Service tunnel Higher ceiling Controllable shield thickness

3. Radiation safety design Radiation Safety design for ILC-ML tunnel Direct radiations Thickness of the wall Design for special sections - Personal passage way, Waveguide hole, penetrations, tune-up dumps, collimators, etc Induced activities Activity in air, water Damage for devices Operation and decommissioning

4. Methodology Beam loss : 1 W/m for normal operation (Not authorized yet) 18 MW for system failure Limitation : 20 mSv/event/year (KEK) (How many events ?) 20  Sv/h for normal operation (KEK) Tools : Bulk wall thickness : Jenkins empirical equation Maze and holes : MARS Monte-Carlo code Induced activity : IAEA technical rep. 188 (Swanson)

5. Bulk wall thickness 3.5m = 250mSv/h for 18 MW loss

6. Personal passage way+ Waveguide hole A B A B Heavy concrete Change thickness Plan viewElevation view Every 500m Every 20m

7. Model for Monte-Carlo calculation 90 cm width crank with one 10cm thick iron slide door Uniform line loss along the beam line 1 mrad grazing angle Plan viewElevation view

8. Dose rate for 1 W/m uniform loss 1  Sv/h for 1 W/m < 20  Sv/h Plan viewElevation view

9. Radioactivity in air Beam loss rate Length of ventilation unit Total exhaust time Beam loss power Fraction of energy deposit to air L_pathUnit volume Surface area Thermal neutron production rate Neutron production rate W/mmhkW mm3cm2n/s ILCML air condition unit 15000350.01289000782504.8E+99.5E+12 1 W/m uniform loss 5000 m ventilation unit 1/3 of air is replaced per 1 hour Site boundary at exit of the vertical shaft Fresh air

10. Radioactivity in air Nuclide Saturation activity Saturation activity concentration Limit of activity in air Limit of activity in exhaust Ratio to air limit Ratio to exhaust limit Half life Cooling time Ratio to exhaust limit after cooling Bq/m/kWBq/cm3 hh 3-H50000005.61798E-060.80.0057E-060.0011106872 0.1 7-Be10000001.1236E-060.50.0022E-060.00061286.4 11-C100000001.1236E-050.20.00076E-050.01610.34 13-N5200000000.000584270.20.00070.00290.83470.166 15-O560000006.29213E-050.20.00070.00030.08990.034 38-Cl2200002.47191E-070.30.0038E-078E-050.62 39-Cl15000001.68539E-060.30.0036E-060.00060.9367 41-Ar 6.52484E-050.10.00050.00070.13051.83 Total0.0041.0734 0.5995

11. Radioactivity in water Beam powerBeam loss fractionBeam loss power Amount of cooling water Ratio to deposit power kW cm^3 ILCML tunnel unit 1.80E+040.00027785.000E+002.03E+070.0020 5000 m long 2 “diam. X 2 1 W/m loss for 5000 m Cooling water inside the accelerator tunnel Closed loop water pipes Nuclide Saturation activity factor Saturation activity Limit of radioactivity in wastewater Ratio to limit Half life Cooling time Ratio to limit after cooling time GBq/kWBq/cm^3 hh 3-H7.40E+003.656.00E+010.061106872.00 1 0.06 7-Be1.48E+000.733.00E+010.0241286.400.02 11-C1.48E+017.303.00E+020.0240.340.00 13-N3.70E+001.835.00E+000.3650.170.00 15-O3.30E+02162.835.00E+0032.5660.030.00 total33.040.09

12. Conclusion “KAMABOKO” tunnel design is evaluated from radiation safety view point The basic concept has possibility to meet requirements of radiation safety criteria Beam loss powers and conditions are important for further evaluation The outstanding merits of “KAMABOKO” tunnel, Two tunnel area with affordable cost, Shorter penetrations, Easier installation, Additional space for utilities, can accommodate with radiation safety design

13. Spare slides

14. RDR Tunnel design Geological conditions (7.5 m separation between two tunnels) Penetration for waveguides (48cm diam. with 7.5 m long ) Personal passage way (Every 500 m, 90 cm width Tunnel separation design Dose rate for 18 MW maximum credible beam loss 500 m 7.5 m

15. Personal passageway Ideas: Keep bulk wall thickness as 3.5 m 1.6 m additional thickness with 8 m long available Maze structure Partially use heavy concrete

16. Elevation view Thinner wall above 3 m Shorten a waveguide hole Smaller hole size Easy installation Additional space for utilities

17. Dose rate for 18 MW point loss 250 mSv/h for 18MW

18. Dose rate for 18 MW point loss 250 mSv/h for 18MW

19. Radioactivity in groundwater ～ 1 mSv/h ～ 5 mSv/h (Depend on environment)

20. WAVEGUIDE HOLE 250 mSv/h for 18MW

21. CRANK WITH DOOR 90 cm width crank with one 10cm thick iron slide door Pseudo Target for 18 MW point loss

22. WAVEGUIDE HOLE 30 cm diam., 2m long waveguide hole at 3m above FL Pseudo Target for 18 MW point loss

23. Radioactivity in water Nuclide Saturation activity factor Saturation activity Limit of radioactivity in wastewater Ratio to limit Half life Cooling time Ratio to limit after cooling time GBq/kWBq/cm^3 hh 3-H7.40E+003.656.00E+010.061106872.00 1 0.06 7-Be1.48E+000.733.00E+010.0241286.400.02 11-C1.48E+017.303.00E+020.0240.340.00 13-N3.70E+001.835.00E+000.3650.170.00 15-O3.30E+02162.835.00E+0032.5660.030.00 total33.040.09