SPECIAL RESEARCHES OF CLAY SOILS WHICH ARE NOT REGULATED ON NPP SITES

Abstract

Problem statement. The article presents the results of special non-normative research for saline clay soils sampled from excavations during the nuclear power plants’ construction at different times and in different countries. Of the NPP sites located in the arid climate zone, only the Crimean NPP, which is not yet under construction, the planned NPP in Uzbekistan and possibly the NPP in Egypt are close to the engineering and geological conditions relative to the described NPP site to a large extent. The purpose of the article. The researches’ purpose is to estimate the degree of leakages impact from technological pipelines for production water of different composition and temperature, which affect the soil properties of the foundations for responsible buildings and structures of NPPs and other critical energy facilities. The need for such research is obvious to ensure the safe operation of nuclear power plants, especially when NPP are located in difficult seismotectonic and geological conditions. Conclusions. The non-regulated method for investigating the plastic properties of clay soils proposed in this article is a combination of several already tested research methods. The essence and difference of this indirect method is to investigate the soils plastic properties only after their pretreatment at different times with ground water of different temperatures. The test process partially simulates the impact on soil bases of possible short-term (instantaneous) or long-term leakages from technological thermal water supply communications, which would result in significant ground water warming. As a work result, the upper horizons of the soils for some NPP sites were prone to soaking, including at elevated temperatures, but no fundamental differences from these impacts have yet been found. The results of these researches correlate quite well with the previously performed investigations on soils leaching in the upper part of the geological section of the NPP sites. As a result, the upper soil horizons of some NPP sites were prone to soaking, including at elevated temperatures, but no fundamental differences from these effects have yet been identified. The results of the conducted research correlate quite well with the previously performed studies on soil leaching in the upper part of the NPP sites geological section.