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TABLE 24-1 Forecast of Expected Changes in Total Land Area in Russia with Varying Levels of Cesium-137 Radioactive Contamination Due to the Chernobyl Accident

Year

Area (in km2) with Varying Levels of Local Cs-137 Contamination

>40 Ci/km2

15-20 Ci/km2

5-15 Ci/km2

1-5 Ci/km2

1986

580

2,070

5,780

56,260

1996

310

1,900

5,330

48,980

2006

40

1,280

3,540

26,260

2016

 

850

2,780

18,920

2026

 

625

2,700

15,040

2036

 

190

2,340

12,500

2046

 

100

1,500

10,930

tions were made to determine how long it would take for each to move to the next lowest contamination category as a result of radioactive decay. The results of these calculations are presented in Table 24-3, which indicates that there will be no population centers with contamination levels greater than 40 Ci/km2 (1,480 kBq/m2) by 2020, greater than 15 Ci/km2 (555 kBq/m2) by 2063, greater than 5 Ci/km2 (185 kBq/m2) by 2110, and greater than 1 Ci/Km2 (37 kBq/m2) by 2180.

Bryansk Oblast suffered the most contamination from the Chernobyl accident of any Russian region. Therefore, information was compiled on the contamination status of the near-earth atmosphere (up to approximately 5 km from the earth’s surface) and bodies of water in this particular oblast. Figure 24-1 provides information on the change in the average annual cesium-137 activity by volume in the near-earth atmosphere over the city of Bryansk. From this figure, it is clear that the activity by volume decreased by an order of magnitude from 1987 to 1995. During the next 10 years, it changed insignificantly, fluctuating within the range of 1-3 × 106 Bq/m3. This amount is seven orders of magnitude lower than the activity by volume allowable for the population, as established by the Radiation Safety Norms (RSN-99).3 Levels of cesium-137 atmospheric fallout are cited for the population center of Krasnaya Gora (Figure 24-2), where the level of cesium-137 contamination is close to 5 Ci/km2 (185 kBq/m2), while near this town there is an area with substantially higher levels of soil contamination. Figure 24-2 shows that the level of atmospheric fallout declined by two orders of magnitude in the 5 years following 1986, changed insignificantly from 1991 through 2001, and subsequently fell to five times less by 2005. Figure 24-3 indicates that cesium-137 concentrations in the soil due to atmospheric fallout over 19 years totaled 11.5 kBq/m2, which is 6.2 percent of initial contamination.

3

Ministry of Health of the Russian Federation. 1999. Radiation security norms (RSN-99).



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