2 Deposition Data Analysis
3.3 Effective UNSCEAR Collective Dose Commitments
3.3.2 Effective UNSCEAR Collective Dose Commitments for the VRS
Cs-137, Sr-90, and I-131 in Table 18, Table 22, and Table 26, respectively, were computed for the VRS. For Cs-137, Figure 46 and Figure 47 illustrate the frequency and cumulative percentages for the maximum collective dose commitments for the overall and transboundary region, respectively, assuming no threshold. Table 47 and Table 48 provide the maximum collective dose commitment for the region as well as each country in the region as a function of the assumed threshold level. (The collective dose commitments are also broken down by pathway for information purposes.) Note that the maximum collective VRS dose commitments (for the no threshold hypothesis) are rank-ordered as follows:19
19 In this assessment, the regional value corresponds to the maximum collective dose over the whole region on any given day in CY2000, and thus does not correspond to either the maximum for any country or the sum of the maximum values for the countries.
Frequency, Number of Days Frequency, Number of Days
Frequency, Number of Days Frequency, Number of Days
VRS Cs-137: Regional > Japan > China > N. Korea > S. Korea > Russia > Taiwan > Hong Kong
> Alaska (U.S.) > Mongolia > Aleutians (U.S.) > Vietnam
Therefore, even though the maximum dose commitment was found in Russia (as indicated in Table 36), the maximum collective dose is again found in Japan (which is not surprising based upon its high population density and relative proximity to the VRS). However unlike the PRS results, many countries have collective dose commitments within an order of magnitude of that for Japan.
0
Collective dose commitment (person-Sv)
Frequency
Figure 46. Frequency histogram and cumulative percentages for the VRS Cs-137 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
0
Collective dose commitment (person-Sv)
Frequency
Figure 47. Transboundary frequency histogram and cumulative percentages for the VRS Cs-137 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
The effects of the VRS releases are potentially greater than those from the PRS. For example, the maximum collective dose commitments in Table 41 correspond to up to an additional 411 mortalities [19] over the entire region when a mortality risk factor of 5x10-5 per mSv for all ages [19] is used. The additional mortalities from the maximum collective dose commitments for Japan, China, N. Korea, S.
Korea, Russia, and Taiwan are approximately 399, 360, 104, 102, 68, and 13, respectively. Therefore, even the impact on Taiwan, a country not proximate to the VRS, could be considered significant.
Frequency, Number of Days Frequency, Number of Days
Frequency, Number of Days Frequency, Number of Days
Also unlike the results for the PRS analysis, Table 47 and Table 48 indicate that there is much less of an impact of magnitudes of the dose commitments in concert with large populations on the collective VRS dose estimates. That is, the collective dose commitments for the countries (e.g., Japan, China, N.
Korea, S. Korea, and Russia) in the vicinity of the VRS appear relatively insensitive to the
introduction of thresholds into the collective dose commitment computation. Furthermore, even the results after imposing a threshold of 0.1 mSv (or 0.01 rem) translate into 270 additional mortalities in Japan and significant numbers in other countries of interest. This is a result of much higher dose commitments in these countries resulting from the VRS releases. Only when a relatively large threshold (e.g., 1.0 mSv) is imposed do the releases not significantly impact countries outside of Russia.
For Sr-90, Figure 48 and Figure 49 illustrate the frequency and cumulative percentages for the maximum collective dose commitments for the overall and transboundary region, respectively, assuming no threshold. Table 49 and Table 50 provide the maximum collective dose commitment for the region as well as each country in the region as a function of the assumed threshold level. Note that the maximum collective VRS dose commitments (for the no threshold hypothesis) have the same ordering as those for the Cs-137. Again, even though the maximum dose commitment was found in Russia (as indicated in Table 37), the maximum collective dose is found in Japan. The number of additional mortalities can be as high as 166 for the region and 146 and 164 for China and Japan, respectively, or less than one-half those from the VRS Cs-137 releases. The results in Table 49 and Table 50 confirm the insensitivity of the collective dose estimates to the imposition of thresholds because the relative magnitudes of the dose commitments as indicated above for Cs-137.
0 20 40 60 80 100 120
1.60E+00 3.71E+0
2 7.41E+0
2 1.11E+03
1.48E+0 3 1.85E+0
3 2.22E+03
2.59E+03 2.96E+
03More
Collective dose commitment (person-Sv)
Frequency
0 20 40 60 80 100 120
Cumulative(%)
0 10 20 30 40 50 60 70 80 90
9.29E+06 9.53E+07
1.81E+0 8 2.67E+08
3.53E+0 8 4.39E+08
5.25E+08 6.11E+0
8 6.97E+08
More Total population, persons
Frequency
0 20 40 60 80 100 120
Cumulative(%)
Figure 48. Frequency histogram and cumulative percentages for the VRS Sr-90 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
Frequency, Number of Days Frequency, Number of Days
0 20 40 60 80 100 120 140 160
5.77E -01 3.70E+0
2 7.39E+0
2 1.11E+03
1.48E+0 3 1.85E+03
2.22E+0 3 2.58E+0
3 2.95E+0
3 More Collective dose commitment (person-Sv)
Frequency
0 20 40 60 80 100 120
Cumulative(%)
0 10 20 30 40 50 60 70 80 90
7.58E+06 9.34E+07
1.79E+0 8 2.65E+08
3.51E +08 4.37E+0
8 5.22E+0
8 6.08E+0
8 6.94E+0
8 More Total population, persons
Frequency
0 20 40 60 80 100 120
Cumulative(%)
Figure 49. Transboundary frequency histogram and cumulative percentages for the VRS Sr-90 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
For I-131, Figure 50 and Figure 51 illustrate the frequency and cumulative percentages for the maximum collective dose commitments for the overall and transboundary region, respectively, assuming no threshold. Table 51 and Table 52 provide the maximum collective dose commitment for the region as well as each country in the region as a function of the assumed threshold level. Note that the maximum collective PRS dose commitments (for the no threshold hypothesis) are rank-ordered as follows:
VRS I-131: Regional > Japan > China > S. Korea > N. Korea > Russia > Aleutians (U.S.) > Mongolia
> Alaska (U.S.)
Thus for I-131, the maximum collective VRS dose commitment is found in Japan (which is unlike the results found for the corresponding PRS releases). Unlike the Cs-137 and Sr-90 results, the I-131 releases translate into ten or fewer additional mortalities. Also unlike the VRS results for Cs-137 and Sr-90, the collective doses are relatively sensitive to the imposition of a threshold (because of the much smaller dose commitments for I-131 in countries other than Russia). This is not surprising based upon the higher deposition velocity of I-131. Again, the results in Table 51 and Table 52 indicate that little I-131 from the VRS releases impacts any countries other than Russia. Furthermore, the impact is much smaller than that for either Cs-137 or Sr-90 releases from the PRS. None of the collective dose commitments translate into a single mortality per 1 000 000 persons.
Frequency, Number of Days Frequency, Number of Days
0 Collective dose commitment (person-Sv)
Frequency
Figure 50. Frequency histogram and cumulative percentages for the VRS I-131 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
0 Collective dose commitment (person-Sv)
Frequency
Figure 51. Transboundary frequency histogram and cumulative percentages for the VRS I-131 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
3.3.2.1 Specific Case Examples: Japan and U.S. Collective Dose Commitments from the VRS
Figure 52 illustrates the collective dose results for Japan from the VRS releases for CY2000. Using a mortality risk factor of 5x10-5 per mSv for all ages [19], the maximum collective dose commitment of 7990 person-Sv would translate into almost 400 additional mortalities or 3.2 additional mortalities per 1 000 000 persons. However, the information in Figure 52 indicates that this would be a
low-probability event for CY2000. Over 60% of the maximum collective dose commitments are less than 420 person-Sv, which would translate into 22 additional mortalities.
Frequency, Number of Days Frequency, Number of Days
Frequency, Number of Days Frequency, Number of Days
0 Collective dose commitment (person-Sv)
Frequency
Figure 52. Japan Results: Frequency histogram and cumulative percentages for the VRS Cs-137 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
The results for the collective dose commitments from the VRS for the U.S. territories considered in this report are illustrated in Figure 53 and Figure 54. Note that, when a mortality risk factor of 5x10-5 per mSv for all ages [19] is employed, none of the collective dose commitments shown in these figures translate into a single, additional mortality from the VRS releases for CY2000. Furthermore, none of the collective dose commitments translate into a single additional mortality per 1 000 000 persons.
0 Collective dose commitment (person-Sv)
Frequency
Figure 53. Alaska (U.S.) Results: Frequency histogram and cumulative percentages for the VRS Cs-137 effective collective dose commitments (left) and corresponding populations (right) for CY2000.
No Threshold Basis.
Frequency, Number of Days Frequency, Number of Days
Frequency, Number of Days Frequency, Number of Days
0 Collective dose commitment (person-Sv)
Frequency
Figure 54. Aleutian Islands (U.S.) Results: Frequency histogram and cumulative percentages for the VRS Cs-137 effective collective dose commitments (left) and corresponding populations (right) for CY2000. No Threshold Basis.
3.3.3 Summary of the Effective UNSCEAR Collective Dose Commitments