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Radon and variable rock stress

Radon and variable rock stress. Radon variations in an underground gallery Pumping Storage Facility, SEO, L-Vianden. Francis Massen, Physics Lab, Lycée Classique Diekirch Antoine Kies, LPR, Université du Luxembourg. Upper basins 1 & 2. basin 1. basin 2. SEO main figures :.

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Radon and variable rock stress

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  1. Radon and variable rock stress Radon variations in an underground galleryPumping Storage Facility, SEO, L-Vianden Francis Massen, Physics Lab, Lycée Classique DiekirchAntoine Kies, LPR, Université du Luxembourg

  2. Upper basins 1 & 2 basin 1 basin 2

  3. SEO main figures: Construction : 1959 to 1964 Maximum used volume of basins : 6.8 million m3 Maximum water level change : 16 m ~ 1.6 at Flow during power generation : 432.5 m3/s Mean daily power generation time: 4.25hMean daily pumping time: 7.25h www.seo.lu

  4. Water outlets

  5. Location of stations B2_stat1 B2_stat2 B1_stat2 B1_stat1 B1_stat3 B2_stat3( in use since July04) galleries

  6. Geology basin1 basin2

  7. Fractures and fillings (J. Bintz, 1964) Voids were filled with concreteduring construction work!

  8. Interior of gallery

  9. Boreholes ~16cm diameter 1m concrete 40cm rock

  10. Difference in radon signal between basin1 and basin2 21Nov02 – 13Dec02, 4 stations [100uRoe/h ~1uSv/h ~100 Bq/m3 EER]

  11. Basin1, station1: influence of atmospheric pressure variations May02 Possible anticorrelation with atmospheric pressure …. large voids in underground?

  12. Basin2 stat1: radon and water level (station1, 21Nov02-13Dec02)

  13. Basin2 stat2: radon and water level (station2, 02 – 30 Apr.04)

  14. Basin2: stations 1,2,3 : 04Aug-27Sep 2004Vanishing signal…. Autocorrelation of radon 24h stat1 190m stat2 245m stat3 why? approx.direction offissures

  15. Gravitational effects stat1stat2stat3

  16. Water level modulates existing radon background 24 hours Emptying basin 2: radon regains background level in ~24h

  17. Time lag between radon and water level: Basin2, station1 21Nov02 - 13 Dec02

  18. Time lag between radon and water level: Basin2, station2 21Nov02 - 13 Dec02

  19. Is the delay between radon and water level ~ constant?…. YES!

  20. More time lags between radon and water level: from…to days B2stat1 B2stat2 B2stat3 21Nov02-05Feb03 77 93 246 12-18Jun03 7 36 263 02-30Apr04 29 109 278 04Aug-27Sep04 55 205 240 (300)______________________________________________________ ? ?

  21. Relation between radon concentration and water level: B2 stat1

  22. Better fit: parabolic

  23. Relation between radon concentration and water level: B2 stat2

  24. Explication? Basin 1 B1_stat3 Basin 2 stat1 Stations 1 and 2 lie in a fissuresystem with one dominatingorientation  preferentialmigration path for radon  strong water level dependance stat2 Fissure system is random: no dominant migration path  no water level dependance stat3

  25. RM80 Aware counter “Pancake” Geiger tube (,,) Sensor driven by serial or parallelport of (notebook) computerSensor is not waterproof: usually will be sealed in PET bag with calcium chloride CaCl2 as desiccant.Many humidity related problems! Price: ~319 US$www.aw-el.com

  26. Calibration of RM80 Calibration was done in-situ , (in gallery with no ventilation)comparing readings of a RM80 and a Alphaguard: borehole

  27. RM80 and Radim sensor (borehole B2 stat2)

  28. Computer problems 1. Protection against humidity: never shut down! 2. Protection against fine dust: seal floppy drive by tape; install Laplink in case of floppy malfunction 3. Use only notebooks: power outage protection! 4. Save backlight tubes: shut off screen 5. Use surge protectors (many lightning impacts!) 6. Combat computer clock drift: RIGHTIME software 7. Use only old equipment!

  29. Software Very large data files ( > 150000 lines): use DADiSP

  30. DADiSP www.dadisp.com Price: 1995 US$ Same as full version, limited in number of windows and data size

  31. Merci de votre attention… antoine.kies@uni.lu francis.massen@education.lu et claude.boes@bigfoot.com http://meteo.lcd.lu/papers/http://www.speleo.lu

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