1. Simulation of heat load at JHF decay pipe and beam dump KEK Yoshinari Hayato

2. Introduction Thermal expansion rates are different. High intensity beam Secondary particles hit the wall of the decay volume. Non negligible energy deposit filled with He. Pressure will be increased. Wall of the decay volume consists from The decay tunnel will be Rise of the temperature iron and concrete. Temperature control becomes important.

3. Design of the decay tunnel top view side view Decay tunnel Target station Width x Height x Length = 3m x 3~6m x 130m(in total) Wall : Iron (thickness : 16mm)

4. Energy deposit around the tunnel Estimated energy deposit (from 45m to 130m) Deposited energy Thickness of iron : 1.6cm (actual width 3m, height 3~6m) Assume the cylindrical decay volume. radius of the tunnel is constant (r=1.5m). (wall of the decay tunnel)

5. Energy deposit in the tunnel Most inner part (R~1.5m) R<2m Assume the cylindrical decay volume. radius of the tunnel is constant (r=1.5m). Estimated energy deposit (z : from 45m to 130m) In the concrete.

6. Estimation of the temperature Put 3cm x 3cm water pipes Surface of decay tunnel Temperature at the ground surface Condition of the simulation concrete water pipes He wall (iron) 1.5m 3m (Assume the worst case.) 1m Distance between the pipes : 1m

7. Worst case (without cooling) He concrete Surface Maximum temperature (after 6 months) He & iron Pressure ~5atm Melting point of Iron Need to be cooled!

8. Cooled decay volume (example) Maximum temperature (after 6 months) Iron (wall) Concrete water pipes wall (iron) He concrete Surface Around the tunnelEntire volume concrete He Ground

9. Energy deposit at the beam dump Energy deposit in the iron Maximum energy deposit Specific heat of iron Need to use carbon around the central region. (to reduce the energy concentration.) at the end of the decay volume

10. Summary Energy deposit in the iron and concrete concrete iron Water cooling pipe seems to be ok. (every 1m, 3cm x 3cm) maximum temperature iron concrete Without cooling maximum temperature

11. At the beam dump, maximum energy deposit Necessary to remove the heat. Use carbon around the beam center. Necessary to reduce the energy concentration. water circulation?