Figure 1
Handheld compass model M.49
Figure 2
Handheld compass model M.53 S1
Figure 3
Handheld compass model M.53 S99
Figure 4
Handheld compass model Bézard (big)
Figure 5
Handheld compass model Bézard (small)
Figure 6
Specific hand positions for holding a compass during its use: a) determination of the main sides of the world; b) determination of the azimuth; c) reading the azimuth in degrees; and d) determination of the local angle below the horizon
Table 1
Measured ambient dose equivalent rates for the three compass models showing radium presence by measurement position and distance (means of 90 ten-second readings per position and distance)
| Measurement position (distance in cm) | H*(10) (nSv/h) | |||||
|---|---|---|---|---|---|---|
| M.49 | M.53 S1 | Bézard (small) | ||||
| Mean | Max | Mean | Max | Mean | Max | |
| H0 (background) | 134 | 166 | 134 | 166 | 134 | 166 |
| H1(0) | 6070 | 7960 | 1260 | 1570 | 622 | 936 |
| H1(100) | 154 | 191 | 137 | 191 | 127 | 154 |
| H2(0) | 4630 | 5120 | 1230 | 1750 | 494 | 631 |
| H2(100) | 162 | 181 | 169 | 204 | 155 | 173 |
| H3(0) | 6620 | 8840 | 1470 | 1900 | 672 | 921 |
| H3(100) | 152 | 176 | 153 | 167 | 129 | 154 |
| H4(0) | 8140 | 9450 | 1830 | 2340 | 554 | 709 |
| H4(100) | 156 | 177 | 147 | 226 | 164 | 220 |
[i] H0 – background dose rate without compass; H1(0 or 100) – dose rate for the compass in position 1 (bottom part of the compass inside the leather case); H2(0 or 100) – dose rate for the compass in position 2 (top part of the compass inside the leather case); H3(0 or 100) – dose rate for the compass in position 3 (bottom part of the compass outside the case); H4(0 or 100) – dose rate for the compass in position 4 (top part of the compass without the cover). Designations in brackets, either 0 or 100, denote measurement distance from the source, namely 0 or 100 cm
Figure 7
Background spectrum
Figure 8
Gamma spectrum of the handheld compass model M.49
Figure 9
Gamma spectrum of the handheld compass model M.53 S1
Figure 10
Gamma spectrum of the handheld compass model Bézard (small)
Figure 11
Gamma spectrum of the handheld compass model M.53 S99
Figure 12
Gamma spectrum of the handheld compass model Bézard (big)
Figure 13
Gamma spectrum of the cotton swab used to wipe the surfaces of the handheld compasses with confirmed presence of radioluminescent paint
Table 2
Calculated annual effective dose while using the compass in the left-hand position for two scenarios: frequent (daily) use and occasional use (in a very conservative estimation)
| Annual effective dose E (mSv) | M.49 | M.53 S1 | Bézard (small model) | |||
|---|---|---|---|---|---|---|
| 2 h/day | 40 h/year | 2 h/day | 40 h/year | 2 h/day | 40 h/year | |
| 2.6* | 0.14 | 0.66 | 0.04 | 0.39 | 0.02 | |
* – exceeding the ICRP limit of 1 mSv/year for the general public (5)