RESULTS OF SPLIT SAMPLES QUALITY CONTROL STUDY (RADIOACTIVITY): 1997

Sample A:
Variable Lab 1 Lab 2a Lab 2b Lab 3
Alpha activity (Bq/l ) - 5,19 5,19 3,70
Beta activity (Bq/l ) - 1,63 1,63 6,30
Uranium-238 3100 mBq/l

(250 ppb*)

 2,49 mBq/l 2490 mBq/l 2000 mBq/l
Uranium-235 96 mBq/l

(1,2 ppb)

 0,113 mBq/l 113 mBq/l 92,8 mBq/l
Thorium-232 <4 mBq/l

(<1ppb)

 <2,58 mBq/l <2,58 mBq/l 1,5 mBq/l
Radium-224 - -0,00354 mBq/l -3,54 mBq/l <1,2 mBq/l
Radium-226 - 0,373 mBq/l 373 mBq/l 156 mBq/l

* 1ppb U-238 = 12,4 mBq/l

1ppb U-235 = 79,7 mBq/l

1ppb Th-232 = 4,0 mBq/l

Sample B:
Variable Lab 1 Lab 2a Lab 2b Lab 3
Alpha activity (Bq/l ) - 4,07 4,07 2,90
Beta activity (Bq/l ) - 0,625 0,625 6,80
Uranium-238 1984 mBq/l

(160 ppb*)

 1,84 mBq/l 1840 mBq/l 1490 mBq/l
Uranium-235 56 mBq/l

(0,7 ppb)

 0,0832 mBq/l 83,2 mBq/l 70,6 mBq/l
Thorium-232 <4 mBq/l

(<1ppb)

 <2,58 mBq/l <2,58 mBq/l 1,5 mBq/l
Radium-224 - 0,0561 mBq/l 56,1 mBq/l <1,4 mBq/l
Radium-226 - 0,156 mBq/l 156 mBq/l 42,7 mBq/l

* 1ppb U-238 = 12,4 mBq/l

Sample C:
Variable Lab 1 Lab 2a Lab 2b Lab 3
Alpha activity (Bq/l ) - 0,0550 Bq/l 0,0550 Bq/l <0,66
Beta activity (Bq/l ) - 0,226 Bq/l 0,226 Bq/l 2,70
Uranium-238 30 mBq/l

(2,4 ppb*)

 0,0571 mBq/l 57,1 mBq/l 31,7 mBq/l
Uranium-235 <8 mBq/l

(<0,1 ppb)

 0,00259 mBq/l 2,59 mBq/l 1,4 mBq/l
Thorium-232 <4 mBq/l

(<1ppb)

 <2,58 mBq/l <2,58 mBq/l 1,5 mBq/l
Radium-224 - 0,648 mBq/l 648 mBq/l <5,3 mBq/l
Radium-226 - 0,227 mBq/l 227 mBq/l <4,2 mBq/l

* 1ppb U-238 = 12,4 mBq/l