ST. PETERSBURG, October 12 (Itar-Tass) —— Now there is no active source of cesium pollution in the Gulf of Finland, so all suspicions about poor performance of the Leningrad nuclear power plant are unfounded, the head of the St. Petersburg Green Cross, Natalia Matveyeva, said on Wednesday. She explained that during a recent joint expedition of environmentalists and nuclear scientists with the participation of activists of the Green Cross and staff of the Leningrad nuclear power plant samples were collected of sand and silt from the bottom of the Ust-Luga harbor of the Vyborg Bay, as well as in the immediate vicinity of the Leningrad nuclear power plant.
"After processing the samples taken we saw that the amount of cesium-137 is greater at the mouth of the rivers flowing from areas affected by the "Chernobyl fallout.” On the average the tests showed the level of cesium-137 was equal to a dose of 600-800 Bq per one cubic meter of mud. But the main thing is the isotope cesium-134, with a half-life of 1.5 years was not found at all," she said.
The monitoring experts at the Khloponin Radium Institute have conducted since 1970 has allowed the scientists to conclude that "the level of contamination in shallow and semi-enclosed Baltic Sea areas with isotopes of cesium and strontium is much higher than in the Atlantic and Pacific oceans." In the mid-80s of last century there were identified and assessed the main sources of radionuclides in the Baltic Sea basin. More than four-fifths of them are from what the scientists say was the global source, in other words, a consequence of atmospheric nuclear tests, most of which were made in the 1960s. Almost one-fifth of the contamination, according estimates, was then brought through the Danish straits by North Sea water, polluted by West European plants processing nuclear fuel. The share of pollution from the NPPs, located in different countries of the Baltic region, did not exceed two percent in these estimates. A significant impact on the contamination of the Baltic Sea was caused by the Chernobyl disaster. One of the hardest-hit areas of Gulf of Finland was the Koporsky Bay. In the year of the Chernobyl accident the level of cesium-137 there was 60 times above the previous readings of 1985.
"The analysis of sediment samples taken annually shows a gradual decrease in the level of contamination," said the head of radio-ecological and analytical studies at the Radium Institute, Andrei Stepanov. In Koporsky Bay the level of cesium-137 currently found in the water has been down to the pre-Chernobyl level, and in the sediment no radionuclides of artificial origin are observed at all. According to scientists, this is the merit of the Leningrad NPP.
"The strong flow of cooling water discharged by the NPP and the complete absence of silt, which is the main medium accumulating radio nuclides the Koporsky Bay is cleaned," said the scientist.