Radiation%20Quantities%20and%20Units

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Correlation of Radon Exhalation Rates from
Granites with Radium Contents
M. I. Al-Jarallaha, Fazal-ur-Rehmana,b, M. S.
Musazaya, A. Aksoyb Department of Physics, b
Center for Applied Physical Sciences (CAPS) King
Fahd University of Petroleum and Minerals,
Dhahran 31261, Saudi Arabia  
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ABSTRACT

1. Radon exhalation rates for 152 samples of granite
   tiles used in Saudi Arabia were determined
2. Active and passive measuring techniques were used
   in this study.
3. In the active technique, a PC-based radon gas
   analyzer with emanation container was used.
4. In the passive technique, CR-39 nuclear track
   detectors with the Can technique were applied
   for 30 days.
5. Radium contents of 21 samples of granite tiles
   were measured using HPGe-based gamma spectroscopy
6. The radon exhalation rates measured by the active
   technique showed a good linear correlation with
   radium content (R2 0.9).

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• Fig. 1. Schematic diagram showing the active
  set-up used for the exhalation measurements
  of samples with AlphaGUARD.

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• Fig 2. A PC-based Active Radon Measuring System
  containing radon gas analyzer type AlphaGUARD
  2000 PRQ along with emanation container.

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Activity (Bq m-3)
Time (h)

• Fig. 3 Buildup of radon exhaled from a granite
  sample measured by the active system. The x-axis
  shows the real time of buildup while the y-axis
  shows the radon concentration in the container.
  The bold line shows the log fit.

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• Fig. 4. Frequency distribution of radon
  exhalation rate measurements from the granite
  tiles using the active technique.

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Fig. 5. Schematic diagram showing the passive
setup where an NTD is placed on the
surface of granite tile and surrounded by a
sealed vessel
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• Fig. 6 Photograph showing the can technique
  where two cans, enclosing the NTDs, are placed on
  two locations of the surface of each granite
  tile.

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Fig. 7
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• Fig. 8 Track density in the NTDs is being
  measured using an optical microscope associated
  with Image Analyzing System.

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• Fig. 9 Correlation of track production rate
  (passive technique) and radon exhalation rate
  (active technique) measurements from granite
  tiles.

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Fig. 10 Correlation between activity of radon
emanated per unit mass and the actual radium
content (Ra Rn).
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Table 1 The Increment in the radon
concentration (Bq m-3) due to the presence of
tiles for maximum and average exhalation rates at
ventilation rates of 0 and 0.1 h-1.
f 0 f 0.1 h-1 Ratio (f0/f0.1)
?C for Emax (Bq m-3) 467 35 13
?C for ESH (Bq m-3) 290 22 13
?C for Eave (Bq m-3) 60 4.5 13
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CONCLUSION

• It was found that all building materials exhale
  radon with a very wide range.
• 2. Most of granites showed relatively higher
  radon exhalation rates (lt0.12 to 10.6 Bq m-2
  h-1).
• 3. The reproducibility measurements of the radon
  exhalation rates with both the passive and active
  techniques for granite tiles were found 7 and 5
  respectively.
• 4. A correlation was found between radon
  exhalation rate and the radium content (R2 0.9).
• The contribution of building materials of high
  radon exhalation rates in indoor radon
  concentration can be significant. up to 470 Bq
  m-3, for the
• highest radon exhalation and zero ventilation.
• Regular ventilation is very effective in reducing
  radon concentration ( A ventilation of 0.1 h-1
  reduces radon concentration from 470 to 35 Bq
  m-3).
• Most users of granite are unaware of its Uranium
  content and are unable to measure its radon
  exhalation rates. Therefore, we suggest adding
  extra information to the identification of
  granites, namely its Uranium content and radon
  exhalation rate and this should be accessible to
  the users.

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Thank you