1. Air activation inside and around the SPS beam dump M. Baudin H. Vincke DGS-RP-AS

2. Content Irradiation and ventilation parameters Dose given to personnel entering ECX5 due to airborne radioactivity – Air activation with a closed dump – Air activation with a vented dump Conclusions and dose given to the environment

3. Irradiation and ventilation parameters

4. 3 scenarios used for calculations – 10 years of operation, with 2E18 protons.s -1 per year spread equally over 365 days (6.4E10 p.s -1 ) – 1 day with 5E12 p.s -1 (most pessimistic case) – 1 h with 1.5E12 p.s -1 (realistic pessimistic case) Venting rates: – Closed dump: 20000 m 3.h -1 in the hall outside dump shielding; – Vented dump: 0.1 m 3.h -1 in the dump shielding, 20000 m 3.h -1 outside. All results presented in these slides only account for the dose induced by activated air and not by the residual material activation.

5. With a closed dump

6. Air activation with a closed dump

7. Activation is dominated by 14 C  activation triggered dose rate will not decay within thousands of years

8. Air activation with a closed dump

12. With a vented dump

13. Air activation with a vented dump Due to the ventilation of the dump the activation will vanish completely within a few days inhaling

14. Air activation with a vented dump

15. Due to the ventilation of the dump the activation will vanish completely within a week (time can be reduced by increasing ventilation speed)

16. Air activation with a vented dump

18. Conclusions: normal operation over long term Closed core Vented core

19. Considering the normal operations over 10 years, 6.4E10 p.s -1, the vented core appears to be mandatory: – Almost identical dose rates outside of shielding – Dose rates more than 100 times lower inside shielding with 0.1 m 3.h -1 venting. Conclusions: normal operation over long term

20. Conclusions: intense operation over 1 day Closed coreVented core

21. An extreme scenario that shows air activation can be an issue even with ventilation Increased venting rate or longer cooling times might be considered in such a case However, the stress conditions (1.5E12 s -1 over 1 hour) used in the thermal studies of the dump give satisfactory results for air activation General comment: In order to reduce airborne radioactivity production air volume inside dump should be as low as possible. Conclusions: intense operation over 1 day

22. Doses given to the environment

23. 2 air volumes considered between dump and shielding with a factor of ~2.5 Small: 2.71 m 3 inside: – Closed core: 3.98E-2 µSv.year -1 – Vented core: 0.557 µSv.year -1 Large: 7.43 m 3 inside: – Closed core: 4.12E-2 µSv.year -1 – Vented core: 1.20 µSv.year -1 Doses released to the environment are acceptable, but the inside air volume should be kept to a minimum.