Tritium contaminated soil in sites for Semipalatinsk above-ground nuclear tests

Semipalatinsk above-ground nuclear tests caused atmospheric fallout and radioactive contamination of the environment that resulted in the synthesis of great amount of radioisotopes. Tritium was the basic isotope generated in the soil as a result of above-ground nuclear tests. Previously many researchers believed that tritium contamination of the soil occurred in sites for underground nuclear tests only. The research of tritium content in areas for above-ground nuclear tests was not taken into consideration. However, during the work in the site for above-ground tests “Experimental Field”, we examined the tritium content in soil and numerically estimated the specific activity of 3H. Because the radioisotope may be produced from the following activation reactions while nuclear explosions: 6Li3 + n → 4He2 + 3Н; 10B5 + n → 24He2 + 3Н; 14N + n → 12C + 3Н, as well as 151Eu63 + n → 152Eu63 , we selected soil samples to test for 3H, as well as for 152Eu. Then analysis results were compared for establishing relationship between the isotopes and investigating the mechanism of 3H production. The article presents results of detailed study of soil contaminated with tritium in the “Experimental Field” site. 3H content in soil and the isotope distribution in epicenter zones of technical sites and in sites located in different distance from the epicenter are presented. Correlated dependence of the 3Н content on the 152Eu content that allowed us to discover the basic mechanism of the tritium production, that was a neutron-activation reaction occurred at the time of above-ground nuclear tests.