Radiation conditions on the territory of Russia in 1994–1995

Abstract

The present radiation conditions on the territory of the Russian Federation formed over a period of decades and are a consequence of the development of the nuclear-fuel cycle, the production and testing of nuclear weapons, and accidents at the Industrial Association "Mayak" and Cbernobyl nuclear power plant in 1986. We shall briefly describe the radioactive contamination of the environment in 1994-1995. Radioactive Contamination of the Atmospheric Layer Near the Ground. The radioactive contamination of the atmosphere near the ground is monitored by Rosgidromet by the method of analyzing aerosol samples collected by means of air-filtering units at 53 observation points and with vertical screens at 13 observation points as well as samples of atmospheric precipitation which are collected with the aid of horizontal boards at 445 points and stations, including in the near zones for monitoring different radiation-hazardous objects.On the territory of Russia the concentration of the total fl-activity of nuclides in the atmosphere near the ground in 1995 equaled -2.2.10 -4 Bq/m 3 on the average, which is 10% higher than the average value for 1994. The total fl-activity of atmospheric precipitation on the underlying surface was equal to an average of 1.5 and 1.6 Bq/(m2-day) in 1994 and 1995, respectively. The maximum precipitation and concentration of t3-active radionuclides are observed systematically in regions of uranium deposits and locations where building materials, containing tailings and other wastes from uranium mining, are used --Chitin, Irkutsk, Omsk, and other regions.The largest number of cases of a short-time ten-fold increase above the background level for atmospheric precipitation and a five-fold increase for concentration of radionuclides in air during the last two years was observed in the Nizhegorod region. In all cases a high contamination was noted for not more than 1 day, and only products of decay of radium and thorium were found in the samples.Outside the territories contaminated as a result of the Chernobyl accident, the average 137Cs concentration in air in 1994-1995 fluctuated from (2-4).10 -7 Bq/m 3 in Zapolyar'e and in the northern regions of Eastern Siberia up to 3.6.10 -6 Bq/m 3 in the southern portion of the European part of Russia. The weighted-mean 137Cs concentration in air over the territory of Russia in 1995 was equal to 5.1-10 -7 Bq/m 3, which is somewhat lower than the 1994 level (6-10 -7 Bq/m3). In 1995 the highest monthly average concentration of 137Cs in air was observed in August-September in Ryazan' (3.8.10 -6 and 4.3.10 -6 Bq/m 3, respectively, and in August-October in Obninsk (4.5-10 -6 and 3.5-10 -6 Bq/m 3, respectively). This is ten times higher than the average concentration over the country, but 106 times lower than admissible for category B population (AC B = 18.1 Bq/m3). The 9~ concentration in air in 1994-1995 did not change and was equal to 1.6-10 -7 Bq/m 3. The atmospheric fallout of 137Cs in 1995 constituted an average of 1 Bq/(m2-yr), which is 1.4 times lower than...

Method for Using Measurements of the Contamination of Bottom Deposits to Estimate the Source of Radioactive Substances Flowing into a River

“…Table 1 shows the results of investigations performed by the routine investigation service of the Novovoronezh nuclear power plant at two points on the left-hand bank of the Don River downstream from the aperture of the discharge channel of the first two power-generating units [5][6][7]. It should be noted that the 60 Co content presented is characteristic only for a local spot of the bottom of the Don River, whose total area is less than 6000 m 2 .…”

“…It is well known since 1995 that the radiation incident which occurred in the storage facility for liquid wastes at the Novovoronezh nuclear power plant in 1985 has been affecting the local contamination of bottom deposits with 60 Co in the zone where the contaminated ground waters are dishcarged (aperture of the discharge channel of the first two power-generating units) [5][6][7]. It is difficult to obtain a reliable estimate of the 60 Co concentration in Don River water downstream from the source, since the measurements are discrete and the content of this nuclide in the water during the entire period of time was at trace levels, as a rule, close to the limit of detection.…”

Krypton and Xenon Radionuclides Monitoring in the Northwest Region of Russia

“…Kr mean concentration in the atmosphere of Cherepovets, Novomoskovsk, and Mariupol, Bq/m 3 (MAKHON'KO, 1990;MAKHON'KO, 1992) …”